Shameless update from Dale Kramer

[DaleKramer]

Some of you know who I am and that I have not had a real sailplane since I sold my Ventus2CX a few years ago. I am still waiting for Flarms to be mandatory in all contests before I try to find a way back into competition.

What I have been doing is flying my electric Lazair and RV8.

A lot of you know I designed the Lazair ultralight aircraft and now I have come up with a new aircraft design that some of you may be interested in (and I have started a Kickstarter campaign to try to fund it).

I hope you'll at least look at my design and who knows, someday I may visit a contest in a vLazair.

Here is a link for more information:
https://www.kickstarter.com/projects/1553012513/vlazair-model-of-230mph-3hr-flight-vertical-takeof

Or just go to Kickstarter and search for vLazair (don't forget the 'v').

[[email protected]]

Mandatory Flarms? Maybe if folks arent so busy playing with all their cockpit electronics they can keep their eyes outside where they belong. Flarms are not the answer, decent airmanship is. And heaven forbid any more dang things become mandatory. We cant legislate away idiocy.

[Craig Funston]

On Wednesday, March 16, 2016 at 7:07:51 AM UTC-7, DaleKramer wrote:
> Some of you know who I am and that I have not had a real sailplane since I sold my Ventus2CX a few years ago. I am still waiting for Flarms to be mandatory in all contests before I try to find a way back into competition.
>
> What I have been doing is flying my electric Lazair and RV8.
>
> A lot of you know I designed the Lazair ultralight aircraft and now I have come up with a new aircraft design that some of you may be interested in (and I have started a Kickstarter campaign to try to fund it).
>
> I hope you'll at least look at my design and who knows, someday I may visit a contest in a vLazair.
>
> Here is a link for more information:
> https://www.kickstarter.com/projects/1553012513/vlazair-model-of-230mph-3hr-flight-vertical-takeof
>
> Or just go to Kickstarter and search for vLazair (don't forget the 'v').

Very cool stuff Dale. Looking forward to seeing your progress. I really enjoyed seeing your build blog on the eLazair several years ago. Will you be be blogging this one as well?

Oh, and thanks for the FLARM plug too :-)

Craig Funston
7Q

[DaleKramer]

Craig,

Thanks, right now I plan to have sort of a log on its Kickstarter page, at least for the 1/4 scale vLazair.

Dale

[Steve Koerner]

On Wednesday, March 16, 2016 at 12:22:12 PM UTC-7, DaleKramer wrote:
> Craig,
>
> Thanks, right now I plan to have sort of a log on its Kickstarter page, at least for the 1/4 scale vLazair.
>
> Dale

Cool concept. There are a couple things I can see to worry about. It would seem like transitioning from horizontal to vertical landing would involve a risk that the pilot not make it all the way down to the parked position before his 3-4 minute battery life expires.

The other thing that looks worrisome is vulnerability to ground wind in the vertical standing position.

Dale will be pleased to know that the upcoming Nephi nationals does require PowerFlarm. Hopefully that trend will continue.

[DaleKramer]

Hi Steve,
The transitions should be very quick. Thrust to weight will be about 1.3/1 so acceleration into cruise should be very quick. Landing transitions will basically be just a normal final approach to a touchdown spot but with the idea of being 50 ft high (or so) when you get there. This transition will be very easy to verify and demonstrate with the 1/4 scale. Can always add a few more pounds of battery if needed.
I am hoping to design the gear such that a single person can tip it from tail to nosegear if it gets windy for a tiedown.
What will be strange is that the 'ideal' landing direction will be a 90 degree crosswind landing wrt wind efects.
Great comments!
I saw that for Nephi, hope it continues for a while. Can't afford a glider yet.
Thanks,
Dale

[Steve Koerner]

On Wednesday, March 16, 2016 at 1:12:18 PM UTC-7, DaleKramer wrote:
> Hi Steve,
> The transitions should be very quick. Thrust to weight will be about 1.3/1 so acceleration into cruise should be very quick. Landing transitions will basically be just a normal final approach to a touchdown spot but with the idea of being 50 ft high (or so) when you get there. This transition will be very easy to verify and demonstrate with the 1/4 scale. Can always add a few more pounds of battery if needed.
> I am hoping to design the gear such that a single person can tip it from tail to nosegear if it gets windy for a tiedown.
> What will be strange is that the 'ideal' landing direction will be a 90 degree crosswind landing wrt wind efects.
> Great comments!
> I saw that for Nephi, hope it continues for a while. Can't afford a glider yet.
> Thanks,
> Dale

It will be interesting to see how that vertical landing works out with the model. I can't visualize how a normal approach speed can get you to a vertical position. Without thrust vector control it seems like it would require a high approach speed in order to then pull up to a vertical position and begin backing.

Have you modeled the vertical landing? How high does the aircraft get if things are done correctly? What speed does it back down at? Will the landing be autonomous or pilot controlled?

I can swallow the idea of vertical take-off much more readily than the landing. Maybe I'm just not visualizing the dynamics of the landing problem correctly.

[Andrzej Kobus]

On Wednesday, March 16, 2016 at 10:07:51 AM UTC-4, DaleKramer wrote:
> Some of you know who I am and that I have not had a real sailplane since I sold my Ventus2CX a few years ago. I am still waiting for Flarms to be mandatory in all contests before I try to find a way back into competition.
>
> What I have been doing is flying my electric Lazair and RV8.
>
> A lot of you know I designed the Lazair ultralight aircraft and now I have come up with a new aircraft design that some of you may be interested in (and I have started a Kickstarter campaign to try to fund it).
>
> I hope you'll at least look at my design and who knows, someday I may visit a contest in a vLazair.
>
> Here is a link for more information:
> https://www.kickstarter.com/projects/1553012513/vlazair-model-of-230mph-3hr-flight-vertical-takeof
>
> Or just go to Kickstarter and search for vLazair (don't forget the 'v').

Dale, good to hear there is still hope we will see you back in contest flying :)

Andrzej

[Steve Koerner]

Thinking about that some more, you don't necessarily have to approach at a higher speed and pull up. With enough thrust you can power your way through deep stall. Yet I still think it questionable that you can have enough battery life to assuredly get landed before it all comes to an end. I hope it works.

[DaleKramer]

Steve,
Sorry, been busy, but yes you got it. With top electrics OFF and bottom electrics ON FULL, and wingtip electrics on 1/2 and Rotax on FULL there is still 1:1 thrust and about 900 ft-lbs of thrust pitch UP moment available (plus aerodynamic pitch up from elevators). It should pitch up to hover relatively easily. There are two throttles for manual flight, one for electric and one for Rotax. Yes there will be a auto transition mode. Electrics don't even come on until slow speed (fixed pitch props). Multirotors come down very quickly and very stable with a good controller, not like the limitations of the 1950's tail sitters (all manual control).
Glad you are thinking about it :)

Dale

[bumper[_4_]]

"Multirotors come down very quickly and very stable with a good controller, not like the limitations of the 1950's tail sitters (all manual control)."

Vortex ring state can occur when settling under power with helicopters as the rotor settles into its own downwash. This has caused a number of crashes including the V-22 Osprey. So there is risk in "coming down very quickly". Once this occurs in helicopters (and I've only personally hovered models and real ones in forward flight :c) adding power simply feeds into the vortex problem. The save is to apply cyclic and move off into clean air. Is that an option with a tail sitter? Is there a "save"?

Another question is that once pitched up to land, would Rotax failure have a recovery mode?

[DaleKramer]

Oops, that is 900 ftlbs in static conditions. It would be much less at any significant transition speed but still, I think the transition can be done without much of a zoom up. There have been all electric and 'similar aerodynamics' transition models built before and the videos I have seen of their transitions did not show much of a pull up but of course each design is different.
Bumper, yes vortex ring state conditions are possible. I believe that that risk can be reduced by adding some forward translation when you let down and by staying away from other vlift vehicles. Once near the ground of course you need to slow all movement down.
These conditions we are talking about the need for testing, just highlight why I am building a 1/4 scale model right now, not the full scale.
Didn't the Osprey put some sort of restriction on landing in close proximity to other Ospreys as an acceptable risk reduction for this issue?
Interesting to note that this condition only became apparent, years into the multi billion (I think billion) dollar program. Glad we all can take advantage of their experience.
Rotax failure results in the need for airbags if you are in transition or hover. Since all these failure we are talking about are for hover or neaar hover conditions, they would all happen close to the ground where the likelihood of a whole vehicle 'parachute' letdown or ejection seat failure would be very high. Having survived a very high rate of descent sailplane accident, where trouble began at a very altitude, I can say that, at least in my case, I believe that cockpit air bags would have greatly reduced my injuries.
For the past few years I have toyed, as many others have, with the idea of manned 'multirotor' designs. The keys to having a design with 'acceptable risk' failure modes is spending most of the flight time in aerodynamic flight, using more than 3 or 4 rotors for hover, redundant motor controllers and hover controllers (yet to be worked out) and airbags :) I also considered just doing transitions over water (it is softer :) with a landing pad of waters edge, which is funny at first but may be a good practice for risk reduction whenever possible.

[DaleKramer]

Edit 'when trouble vegan at a very LOW altitude'

[DaleKramer]

Edit 'when trouble began at a very LOW altitude' and 'landing pad AT waters edge'
and a few other typos, oh well!

[WB]

On Thursday, March 17, 2016 at 6:17:09 AM UTC-5, DaleKramer wrote:
> Oops, that is 900 ftlbs in static conditions. It would be much less at any significant transition speed but still, I think the transition can be done without much of a zoom up. There have been all electric and 'similar aerodynamics' transition models built before and the videos I have seen of their transitions did not show much of a pull up but of course each design is different.
> Bumper, yes vortex ring state conditions are possible. I believe that that risk can be reduced by adding some forward translation when you let down and by staying away from other vlift vehicles. Once near the ground of course you need to slow all movement down.
> These conditions we are talking about the need for testing, just highlight why I am building a 1/4 scale model right now, not the full scale.
> Didn't the Osprey put some sort of restriction on landing in close proximity to other Ospreys as an acceptable risk reduction for this issue?
> Interesting to note that this condition only became apparent, years into the multi billion (I think billion) dollar program. Glad we all can take advantage of their experience.
> Rotax failure results in the need for airbags if you are in transition or hover. Since all these failure we are talking about are for hover or neaar hover conditions, they would all happen close to the ground where the likelihood of a whole vehicle 'parachute' letdown or ejection seat failure would be very high. Having survived a very high rate of descent sailplane accident, where trouble began at a very altitude, I can say that, at least in my case, I believe that cockpit air bags would have greatly reduced my injuries.
> For the past few years I have toyed, as many others have, with the idea of manned 'multirotor' designs. The keys to having a design with 'acceptable risk' failure modes is spending most of the flight time in aerodynamic flight, using more than 3 or 4 rotors for hover, redundant motor controllers and hover controllers (yet to be worked out) and airbags :) I also considered just doing transitions over water (it is softer :) with a landing pad of waters edge, which is funny at first but may be a good practice for risk reduction whenever possible.

Borrow a foam pit from the extreme sports folks.

[Paul Agnew]

Vortex ring state has nothing to do with "staying away from other vlift vehicles." VRS is the interaction with your own vortex that decreases the relative angle of attack on your own airfoils/rotor blades. The recovery is to lower collective (altitude permitting) and use cyclic to pitch forward in order to fly out of the ring state - essentially to leave the vortex behind you. Simple adding power will exacerbate the "settling with power" and accelerate your descent.

I've encountered settling with power a couple of times back when I flew helicopters. The worst was when holding a stationary position at 1000' in a Bell 47 with a skysign (grid of lights). The bottom suddenly dropped out and the entire ship started shuddering as the blades went in an out of a stalled or zero lift state. Recovery was textbook and we lost about 200' feet.

How to recover in something like this proposed VTOL will be a large hurdle to surmount for certification and for overall safety of the design.

Paul A.
(Knocking the dust off my CFI-Rotorcraft...)
Jupiter, FL

[DaleKramer]

Thanks Paul, I added that statement only because I understood that the Osprey had that recommendation added to its operation requirements.

Who knows, having propellers on 3 different horizontal planes during hover and that are so spread out versus their diameter, could reduce the chances of vortex ring state significantly.

In any case, we are talking about a condition that seems common to VTOL and helicopters which tells me that there is no reason to stop the development of my design due to some foreseeable consideration.

The proposed full scale vLazair would be an LSA with minimal certification issues.

Dale

[kirk.stant]

On Wednesday, March 16, 2016 at 2:04:29 PM UTC-5, wrote:
> Mandatory Flarms? Maybe if folks arent so busy playing with all their cockpit electronics they can keep their eyes outside where they belong. Flarms are not the answer, decent airmanship is. And heaven forbid any more dang things become mandatory. We cant legislate away idiocy.

Why not? We mandate parachutes, at about the same cost, and for the same reason: "See and Avoid" is really the "Big Sky Theory" and even the best lookout can't always detect a threat in time to prevent a collision.

Flarm is a valuable tool to help prevent a mid-air. When it fails (perhaps because the other guy doesn't believe in Flarm), your parachute is the next tool to use to save your life.

To me, idiocy is ignoring actual threats and practical solutions.

Kirk
66

[Craig Funston]

On Thursday, March 17, 2016 at 9:02:45 AM UTC-7, kirk.stant wrote:
> On Wednesday, March 16, 2016 at 2:04:29 PM UTC-5, wrote:
> > Mandatory Flarms? Maybe if folks arent so busy playing with all their cockpit electronics they can keep their eyes outside where they belong. Flarms are not the answer, decent airmanship is. And heaven forbid any more dang things become mandatory. We cant legislate away idiocy.
>
> Why not? We mandate parachutes, at about the same cost, and for the same reason: "See and Avoid" is really the "Big Sky Theory" and even the best lookout can't always detect a threat in time to prevent a collision.
>
> Flarm is a valuable tool to help prevent a mid-air. When it fails (perhaps because the other guy doesn't believe in Flarm), your parachute is the next tool to use to save your life.
>
> To me, idiocy is ignoring actual threats and practical solutions.
>
> Kirk
> 66

Hi Kirk,

I'm totally with you on Flarm, but I was marveling this morning about how we were having a great technical discussion about relatively high level stuff with Dale & how brave he was to start it here. I know Dale is the one that threw out the Flarm bait and I bit too, but we've got so many other threads to beat each other up about Flarm that it would be a shame to derail this nice discussion.

Cheers,
Craig

[DaleKramer]

Sounds to me like this 'Radar' feature is what may be promoting more heads down use of Flarm. I don't think I am in favor of 'Radar' use.
Thanks Kirk!

Dale

[DaleKramer]

Craig, if it keeps people reading this thread and sends a few people to Kickstarter to buy a $10 signed vLazair print then I'm OK with it :)

Dale

[JS]

On Thursday, March 17, 2016 at 9:20:36 AM UTC-7, DaleKramer wrote:
> Craig, if it keeps people reading this thread and sends a few people to Kickstarter to buy a $10 signed vLazair print then I'm OK with it :)
>
> Dale

Dale:
A second engine is listed for battery charging. Isn't it possible to charge the batteries from the Rotax?
Jim

[[email protected]]

I sure appreciate all the comments here and definitely dont want hijack this thread, dale your concept is definitly interesting, and at the very least the engineering study regarding the vstol portion of this project is a helpfull excercise and I am sure will be coming our way from other developers in the future.
As to flarm and other anti collision systems, my point has been that these systems create a detrimental false sense of security. I have experience flying gliders in three very conjested airspace areas, las vegas nv, minden/reno and pensacola. The key to each of these areas was EYEBALL awareness. As a commercial pilot, I never fully trust air traffic control or anti collision hardware, i trust situational awareness period.
The second aspect has to do with freedom. If you want a european type air traffic control system, then keep laying down when federal or association dictated mandates are being proposed, always under the unbrella of "safety". Your freedom to fly will dissapear or be economically handicapped. Reality is, the skies are no more crowded today than they were 10 years ago. That is a myth being propogated by the faa. The exact situation was encountered by derick piggot years ago in UK when their fed agency was expanding airspace restrictions and shutting down gliderports. Thank God he and others stood up and didnt take the governmental over reach laying down.

[DaleKramer]

Jim, that is correct, in the full scale vLazair there is an onboard 15kw generator, powered by a separate gas motor, that charges the batteries in flight. Should never need to charge batteries from the power grid and it will only take about 15 minutes in flight to charge the last landing and last takeoff. The generator is just a JM1 motor attached to a gas motor and its 3 phase output rectified. Generator runs at governed rpm which sets charge voltage. Very light setup.

Dale

[DaleKramer]

On Thursday, March 17, 2016 at 12:37:42 PM UTC-4, wrote:
> As to flarm and other anti collision systems, my point has been that these systems create a detrimental false sense of security.

I am a little wary of this point, I don't drive faster because I wear a seatbelt nor do I worry about glancing at my speedometer to make sure that I am driving safely and matching the posted safe speed limit on an on ramp. My speedometer is giving me a real sense of security if someone hasn't modified that safe speed sign.

Dale

[DaleKramer]

Holding a steady voltage with a Rotax installed generator is more complex, besides, I want the generator on board when I remove the wings and Rotax so that I can drive the remaining 'motorcycle' around on the road.

Dale

[[email protected]]

LOL I like that Dale

[Craig Funston]

On Thursday, March 17, 2016 at 9:53:08 AM UTC-7, DaleKramer wrote:
> Holding a steady voltage with a Rotax installed generator is more complex, besides, I want the generator on board when I remove the wings and Rotax so that I can drive the remaining 'motorcycle' around on the road.
>
> Dale

Dale, the JM1 + gas motor and some batteries sounds like a good hybrid option for a FES setup. What's the weight and output on the charging unit?

[DaleKramer]

Is that Flywheel Energy Storage or Flat Earth Society? :)

I haven't found the gas motor I want yet for the 15kw output but I have lots of choices in the 8-10kw. Since this is needed much farther down the road, I have not put much detail design into it. I think I can build this for 25-30lbs. The JM1 only weighs 6 lbs. 10kw may be fine for me since who cares much if it takes 22 minutes to charge up during cruise versus 15 minutes.

[DaleKramer]

Battery weight, you pick.

[DaleKramer]

We have JM1's wound at 115 kv (I think that is RMS) but you can have change that on ordering.

[Paul Agnew]

"Who knows, having propellers on 3 different horizontal planes during hover and that are so spread out versus their diameter, could reduce the chances of vortex ring state significantly."

Take into account the interaction between the upper propellers/rotors and the lower with wind affecting the downwash angle. To my eye, you could easily end up with blanking of the lower rotors or unpredictable changes in angle of attack with any wind.

Good luck. It's fun to solve problems.

[Craig Funston]

On Thursday, March 17, 2016 at 10:38:42 AM UTC-7, DaleKramer wrote:
> Is that Flywheel Energy Storage or Flat Earth Society? :)
>
> I haven't found the gas motor I want yet for the 15kw output but I have lots of choices in the 8-10kw. Since this is needed much farther down the road, I have not put much detail design into it. I think I can build this for 25-30lbs. The JM1 only weighs 6 lbs. 10kw may be fine for me since who cares much if it takes 22 minutes to charge up during cruise versus 15 minutes.

Dale, that would be the electric glider that goes into regeneration mode when you're in thermals. Take that booming 10 knotter and dial in the regen until you can't climb. Hang in there until you've extracted the energy you want so you can skip all those wimpy thermals in between the good ones. We used to call that L/D ;-) Somewhere i came across a very technical paper on this, but haven't checked the numbers. The catch is always in underestimating the losses and overestimating the efficiency.

Hybrid glider might end up working, but what a bummer to have a gasoline motor running constantly at low output to charge batteries.

[DaleKramer]

Regeneration in thermals used to be high on my list of things to try but now I just do not see being able to get much efficiency out of the process. Traction props just aren't very efficient at being a windmill blade.

[DaleKramer]

Paul,

None of the rotors are directly in the propwash cone of the others, so I do not see any direct interaction between them causing a blanketing effect that reduces AOA of other other rotors.

Thanks for the comments, all welcome.

Dale

[Paul Agnew]

You might be assuming zero wind. Stationary hovering with no wind fits what you've said. However, when you add in wind, the downwash from the upper rotors will not be perfectly vertical and will be influenced by the wind direction and speed. It's easy to envision the downwash moving downward at an angle that would cause it to intersect with one of the lower rotors. Adding or subtracting a few knots or a few degrees could correct or exacerbate the effect. Exactly what wind speed would cause a loss of lower rotor effectiveness would be an interesting vector to work out. Perhaps that would be a design limitation that could be demonstrated and placarded.

I envision it like doing a 360 hovering turn with a good wind in a conventional helicopter. As some point, you hit a spot where the tail rotor loses effectiveness as the wind affects its angle of attack. Mentally flip it 90 degrees and imagine the wind being the downwash from an upper rotor and you'll get what I'm thinking about.

Good luck!

Paul A.

[bumper[_4_]]

If you used tilting ducted fans, instead of a tilting seat, it would not be as innovative. The ducts would also add drag in horizontal flight compared to folding props. But, if I understand correctly, ducted fans are much less prone to the vortex ring problem.

[DaleKramer]

I've spent a lot of time today reading up on VRS and AsymVR in the case of the V-22. What I can conclude so far is that my my vLazair design departs radically from any VRS states that have been analyzed for both helicopters and VTOLS.

So that leaves extensive testing of the 1/4 scale model of the vLazair as my best course of action (good thing that is what I had planned :). It looks like dreaming up all these possible conditions where VRS may cause an issue and then testing those conditions with the model. That will be fun to do.

Thanks again, Dale

[DaleKramer]

On Thursday, March 17, 2016 at 6:31:51 PM UTC-4, bumper wrote:
> If you used tilting ducted fans, instead of a tilting seat, it would not be as innovative. The ducts would also add drag in horizontal flight compared to folding props. But, if I understand correctly, ducted fans are much less prone to the vortex ring problem.

For this transitional design I think ducted fans would weigh too much, reduce my top speed too much and cause too many structural problems. Tilting fans is what I am trying to avoid ... synchronization issues, tilt mechanism weights, complexity ... I am trying to have a design that people can relate to as 'somewhat' of a conventional airplane shape during cruise.

[2G]

On Thursday, March 17, 2016 at 4:19:30 PM UTC-7, DaleKramer wrote:
> On Thursday, March 17, 2016 at 6:31:51 PM UTC-4, bumper wrote:
> > If you used tilting ducted fans, instead of a tilting seat, it would not be as innovative. The ducts would also add drag in horizontal flight compared to folding props. But, if I understand correctly, ducted fans are much less prone to the vortex ring problem.
>
> For this transitional design I think ducted fans would weigh too much, reduce my top speed too much and cause too many structural problems. Tilting fans is what I am trying to avoid ... synchronization issues, tilt mechanism weights, complexity ... I am trying to have a design that people can relate to as 'somewhat' of a conventional airplane shape during cruise.

Your "design" looks to have a very high disk loading. What CAD analysis (if any) have you done of this design, and what CAD tools did you use?

Tom

[bumper[_4_]]

On Thursday, March 17, 2016 at 4:19:30 PM UTC-7, DaleKramer wrote:
> On Thursday, March 17, 2016 at 6:31:51 PM UTC-4, bumper wrote:
> > If you used tilting ducted fans, instead of a tilting seat, it would not be as innovative. The ducts would also add drag in horizontal flight compared to folding props. But, if I understand correctly, ducted fans are much less prone to the vortex ring problem.
>
> For this transitional design I think ducted fans would weigh too much, reduce my top speed too much and cause too many structural problems. Tilting fans is what I am trying to avoid ... synchronization issues, tilt mechanism weights, complexity ... I am trying to have a design that people can relate to as 'somewhat' of a conventional airplane shape during cruise.

Dale,

I'm no engineer, but have experienced vortex ring effect caused by too fast a descent into one's own downwash with models, both helicopters and quad-rotors.

I'm guessing vortex ring will be the major design obstacle you'll need to overcome. Consider that in a crosswind, and while maintaining position over the ground descending, the prop wash from the front prop and wing tip props will be moving laterally, so even though they are not positioned in line with, their disturbed air can still conflict with the rear props.

With a limited time envelope to descend and land, there may be considerable pressure on the pilot to descend expeditiously if hand flying. Would this be automated in some manner, or with say a green safe to land "descent profile" indication below a given safe altitude and allowable descent rate, etc.. If, for some reason, the pilot has to abort a landing, say due to wind conditions or surface irregularities, would a vertical take off after a partial descent be possible?

You are on the right track testing with a model, as that should show up any issues.

[DaleKramer]

On Thursday, March 17, 2016 at 10:36:06 PM UTC-4, 2G wrote:
> Your "design" looks to have a very high disk loading. What CAD analysis (if any) have you done of this design, and what CAD tools did you use?
>
> Tom

I assume you are asking about rotor disk loading in hover mode which is about 18 lbs.ft^2

And my hover lift efficiency is about 5 hp/lb

I don't see either of those being 'high' unless you start comparing the design out of category. I believe the nearest category for hovering should be multirotor. In the multirotor category I would expect it to 'above normal' because I use the same props/rotors to achieve static thrust for hover and for traction thrust at high airspeeds during cruise, so compromises are made for both flight conditions.

I am a little confused in that I traditionally think of CAD programs as simply the program used to draw a design on a computer. From the question I think you might mean CAE or CFD or simply analysis tools like XFLR5.

In any case I used XFLR5 for aerodynamics analysis, Javaprop for prop analysis and I have not done any CFD yet.

[DaleKramer]

On Friday, March 18, 2016 at 12:08:46 AM UTC-4, bumper wrote:
> Would this be automated in some manner, or with say a green safe to land "descent profile" indication below a given safe altitude and allowable descent rate, etc. If, for some reason, the pilot has to abort a landing, say due to wind conditions or surface irregularities, would a vertical take off after a partial descent be possible?
>
> You are on the right track testing with a model, as that should show up any issues.

Yes there will be automation of some flight maneuvers, after all this could not even be attempted if I was not relying on the multirotor controller for automation of heading and attitude during hover. Adding automated features beyond that is somewhat trivial, especially since I plan to have all control done with 'fly by wire'.

However, I am a firm believer in having a design that is as close to humanly flyable under as many failure modes as possible so I just don't want to start automating things too quickly.

This is a great thread and has given me much to consider, however I am going to have to start concentrating on getting people to pledge on the Kickstarter campaign. If it that campaign fails, I will have to find another way of building the 1/4 scale. So, I will have to slow down the posting here and get my brain into another gear now :)

[K m]

On Thursday, March 17, 2016 at 10:37:42 AM UTC-6, wrote:
>
> As to flarm and other anti collision systems, my point has been that these systems create a detrimental false sense of security.......

The holes in your logic are big enough to fly an open class glider through. The idea is not to provide "False sense" but another useful tool to avoid mid airs and near mid airs. Transponders, TCAS, and ATC ARE part of your "Situational Awareness" and if you are a commercial pilot I am a world class soaring competitor;).
Further, The Govt isn't Mandating PF (Or expanding restrictions), certain contest directors are. And I would add with good cause. At contests Ive been to where they PF is not required it is nearly universal and almost a de facto requirement. The funniest thing with your post is drawing a parallel between exercising poor judgement and freedom. I can't argue with that logic but at least do us a favor if you fly in the airspace you mention and use your transponder.
Lets enjoy the rest of the thread

[[email protected]]

Kn thanks for the response. It shows the very lack of forsight that my post is trying to draw attention to. I make my living commercial flying and am intimately aware of the usefulness of anti collision devices having to work with them on a daily basis. But as to "sport" flying I am ever conscious of the trickle down that occurs from the commercial side of the industry. If you want more federal or contest mandates you clearly cannot see the end result, which will be restrictions on flying freedom. Half the guys I know who contest fly get so tired of the false alarms with their flarms, they have them turned down to squat. Its used more for tool to find the guy who has located the next thermal or their unspoken competion "team" partner than an anti collision device.
As to "open class holes" your short sightedness is a blaring example. If a guy wants to have a flarm or transponder in his bird, great, but it IS NOT the primary answer to collision avoidance. The sooner you acknowledge that fact, the sooner our soaring skies will be safer.

[DaleKramer]

To me, turning the volume down on a collision warning device is like using your parachute as a cushion and not even putting it on. Personally, I'd rather have a Flarm than a parachute. A few false warnings wouldn't bother me in the least. I am sure they haven't had a friend die in a head on collision that Flarm would likely have prevented. Sorry I just had to comment on that.

[[email protected]]

Dale I do Agree with you and sorry I had to jump into this topic again, i would rather hear more discussion of your project. I did have make that point however beacause there is a prevelent belief that more and more tecnology is the answer to aeronautical problems. My point all along has been proper and diligent airmanship which may include some of these electrical tools IS the answer. I fight against attitudes that look at a new piece of tec as the magic bullet. The dirth that exists is the lack of airmanship. As a cgi-g I see this. stall spin is still the biggest killer after all these years of "advancement" for example. We have guys that can operate innumeral computer systems in flight but still cant recognise an incipent spin or for that matter compute a final glide without 3k worth of electronics. Enough of the soap box, the very best of luck on your project.

[[email protected]]

Those of us who have been saved by a PowerFlarm alert may be more passionate about its usage than others. Last year I was saved from being run over by a twin coming at me from my 4 o'clock. I never would have seen it. I'm sorry, but most people, including myself don't regularly look over our shoulders to scan that part of the sky.

I am proud that Nephi has mandated PowerFlarm at all of our events since the beginning and I think that decision starting 4 events ago, saved my life last event. By the way, I have never had a single false PowerFlarm alert. Must be an installation thing. If you are getting false alerts, something is not right.

Best,
Bruno - B4

[K m]

On Friday, March 18, 2016 at 9:28:22 AM UTC-6, wrote:
AGCA,
Thanks for the response. You keep making straw man arguments to issues that no one is raising. To connect the dots from from advocating safety technology and lapses in airmanship is absurd (As is the false alarm thing). I purchased one of the first PF units sold in the US and while the installation can be a bit arbitrary and frustrating, If your buddies are regularly getting false alarms they are doing something wrong.
My club meets regularly with ACT and they have ability to play scope and audio in real time. I watched a near mid air (Between a glider and a B737) that resulted in a TCAS RA at over 17,000ft. Using your logic, 166 people would have payed the price for this pilots "Freedom". But, To the rest of the soaring community, "Freedom" also means responsibility. Responsibility to others in the sport and innocent bystanders who share the airspace. Do us a favor and start another thread.

[[email protected]]

Kn I make every attempt to end this thread as Dale and others have seen, but you perpetuate the argument. As for creating straw men, you fail to get the basic point. This happens daily here at this site where those with little experience and hardly any dog-in-the-fight speal ad nausium . Hold to your viewpount, I will continue to hold to mine with my eyes outside the cockpit and my poltical foresight attuned to anything which infringes on flight liberty. Move to EU and enjoy their system.

[2G]

On Friday, March 18, 2016 at 5:27:44 AM UTC-7, DaleKramer wrote:
> On Thursday, March 17, 2016 at 10:36:06 PM UTC-4, 2G wrote:
> > Your "design" looks to have a very high disk loading. What CAD analysis (if any) have you done of this design, and what CAD tools did you use?
> >
> > Tom
>
> I assume you are asking about rotor disk loading in hover mode which is about 18 lbs.ft^2
>
> And my hover lift efficiency is about 5 hp/lb
>
> I don't see either of those being 'high' unless you start comparing the design out of category. I believe the nearest category for hovering should be multirotor. In the multirotor category I would expect it to 'above normal' because I use the same props/rotors to achieve static thrust for hover and for traction thrust at high airspeeds during cruise, so compromises are made for both flight conditions.
>
> I am a little confused in that I traditionally think of CAD programs as simply the program used to draw a design on a computer. From the question I think you might mean CAE or CFD or simply analysis tools like XFLR5.
>
> In any case I used XFLR5 for aerodynamics analysis, Javaprop for prop analysis and I have not done any CFD yet.

CAD, or computer-aided design, covers the gamut of software tools, not just basic drafting. I was thinking of aeronautical engineering tools, however. You obviously have available drafting tools.

Your disk loading is quite high, between a Super Stallion and an Osprey. This precludes an autorotate capability. Having 5 motors operating to sustain a hover represents a corresponding high failure probability with no recovery.

How would you land conventionally with propellers on the wing tips? Would they fold back?

I think it is incumbent upon you to disclose to potential investors that you are not an engineer (unless you have an aeronautical engineer on your team, of course).

[DaleKramer]

1. Nowhere have I indicated that there was an auto-rotate capability.
2. I said that I traditionally think of CAD as drawing programs, I believe that is backed up by the current Wikipedia definition of CAD.
3. The answer to your folding props question is clearly stated on the link I provided. I choose let you go read it there.
4. I have also disclosed an extensive biography on the link provided and encouraged people to read it, as should you.
What is your agenda?

[DaleKramer]

5. You choose to define my rotor disk loading as 'high' with examples of air vehicles of two different categories, why?
6. There are 7 motors used during hover on the vLazair and your assumption appears to be that a failure of any single one, would have no recovery. That is incorrect. Multirotors can operate with one or more rotors disabled, depending on design.

[2G]

On Friday, March 18, 2016 at 6:03:54 PM UTC-7, DaleKramer wrote:
> 1. Nowhere have I indicated that there was an auto-rotate capability.
> 2. I said that I traditionally think of CAD as drawing programs, I believe that is backed up by the current Wikipedia definition of CAD.
> 3. The answer to your folding props question is clearly stated on the link I provided. I choose let you go read it there.
> 4. I have also disclosed an extensive biography on the link provided and encouraged people to read it, as should you.
> What is your agenda?

I have no agenda, what is yours?

[2G]

On Friday, March 18, 2016 at 6:24:20 PM UTC-7, DaleKramer wrote:
> 5. You choose to define my rotor disk loading as 'high' with examples of air vehicles of two different categories, why?
> 6. There are 7 motors used during hover on the vLazair and your assumption appears to be that a failure of any single one, would have no recovery. That is incorrect. Multirotors can operate with one or more rotors disabled, depending on design.

It is high because it IS high. It is 5-6 times higher than an R22.

Seven motors is an even higher probability of failure. I have seen no DESIGN data (vs speculation) that indicates your "design" will function with the failure of any motor.

Let me remind you: you presented yourself initially as "shameless" self promotion. If you don't like criticism go someplace else.

[DaleKramer]

On Friday, March 18, 2016 at 11:27:49 PM UTC-4, 2G wrote:
> I have no agenda, what is yours?

My agenda has been clearly stated, yours has not.
Your comments definitely indicate that you did not read the information at the link I provided and if you did, you did not evaluate any of in that manner that I would expect and engineer to evaluate the information.

[DaleKramer]

On Friday, March 18, 2016 at 11:33:01 PM UTC-4, 2G wrote:
> It is high because it IS high. It is 5-6 times higher than an R22.

Ok, so let us concentrate again on the rotor disk loading.
If you had evaluated the design as an engineer, then I would not have to had to assume that you were asking about rotor disk loading versus propeller disk loading. An engineering evaluation would have understood that there are two flight modes that use different disk loading calculations and the question would have been more specific.

Following that, you seem to have categorically determined that it has a very high rotor disk loading without specifying a class. When you start defining the class, you cite vehicles in 2 classes and now finally you are for some reason comparing my design only to a helicopter. It is obviously NOT a helicopter! It is not even in the Osprey tiltrotor class. The closest conventionally categorized class it could be put in is the tiltwing class and in that class it has a low rotor disk loading.

I believe if anyone should be criticized here it is not me.

Somehow we have rubbed each other the wrong way, for that I am sorry.

[DaleKramer]

On Saturday, March 19, 2016 at 12:11:30 AM UTC-4, DaleKramer wrote:
> Your comments definitely indicate that you did not read the information at the link I provided and if you did, you did not evaluate any of in that manner that I would expect and engineer to evaluate the information.

Sorry, sometimes fingers don't type what my brain thinks :)

Should be:
Your comments definitely indicate that you did not read the information at the link I provided and if you did, you did not evaluate any of it in a manner that I would expect an engineer to evaluate the information.

[2G]

On Friday, March 18, 2016 at 10:04:29 PM UTC-7, DaleKramer wrote:
> On Saturday, March 19, 2016 at 12:11:30 AM UTC-4, DaleKramer wrote:
> > Your comments definitely indicate that you did not read the information at the link I provided and if you did, you did not evaluate any of in that manner that I would expect and engineer to evaluate the information.
>
> Sorry, sometimes fingers don't type what my brain thinks :)
>
> Should be:
> Your comments definitely indicate that you did not read the information at the link I provided and if you did, you did not evaluate any of it in a manner that I would expect an engineer to evaluate the information.

You seem awfully defensive at answering questions for someone seeking public investment in your project. You should EXPECT critical questions such as mine. Investors DO NOT like being belittled for asking reasonable questions.. Your disk loading is SEVEN times higher than an R22; that is a HIGH disk loading.

Your material provides nothing about how this aircraft will be controlled during hover flight and transition from hovering to forward flight. I assume this will be done by thrust vectoring, but I do not know. This means that power must be reduced in some of the electric motors, exacerbating the effects of a motor failure.

[DaleKramer]

I believe I have answered every question.

There is NO reason to compare my design to a helicopter in terms of disc loading since it does not operate like one.

I suggest to you that you read up on multirotor design and control.

I believe that this revolution of flight, over the last decade, has resulted in more multirotor controlled air vehicles flying than all other air vehicles combined.

Yes, perhaps I should mention a little more about that in the link.

[2G]

On Saturday, March 19, 2016 at 11:21:45 AM UTC-7, DaleKramer wrote:
> I believe I have answered every question.
>
> There is NO reason to compare my design to a helicopter in terms of disc loading since it does not operate like one.
>
> I suggest to you that you read up on multirotor design and control.
>
> I believe that this revolution of flight, over the last decade, has resulted in more multirotor controlled air vehicles flying than all other air vehicles combined.
>
> Yes, perhaps I should mention a little more about that in the link.

I didn't say that you didn't answer the questions; it was your attitude towards me that I called you on.

Your "design" is not a revolution, just a variation on a concept that has been tried in the past and rejected by every aviation company since.

Further review caused me pause; the pilot, along with all controls and instruments, must rotate in two dimensions AND open the cockpit to the full prop down wash during the most critical phases of flight: takeoff and landing. Is this so?

[DaleKramer]

On Saturday, March 19, 2016 at 6:04:23 PM UTC-4, 2G wrote:
> On Saturday, March 19, 2016 at 11:21:45 AM UTC-7, DaleKramer wrote:
> > I believe I have answered every question.
> >
> > There is NO reason to compare my design to a helicopter in terms of disc loading since it does not operate like one.
> >
> > I suggest to you that you read up on multirotor design and control.
> >
> > I believe that this revolution of flight, over the last decade, has resulted in more multirotor controlled air vehicles flying than all other air vehicles combined.
> >
> > Yes, perhaps I should mention a little more about that in the link.
>
> I didn't say that you didn't answer the questions; it was your attitude towards me that I called you on.
>
> Your "design" is not a revolution, just a variation on a concept that has been tried in the past and rejected by every aviation company since.
>
> Further review caused me pause; the pilot, along with all controls and instruments, must rotate in two dimensions AND open the cockpit to the full prop down wash during the most critical phases of flight: takeoff and landing. Is this so?

Attitude goes both ways.

I has also been said that no designs are revolutions, just variations.

In hover flight the pilots seat only ever opens a maximum of 90 degrees, the final 20 degrees is when engines are shut down. At 90 degrees, the pilots upper torso is still in the fuselage, the pilots legs from the waist down are enclosed in a secondary shell (with airbags). Airflow should be no worse than an open cockpit aircraft or a motorcycle. This is a 'sport' design and I don't expect it to appeal to the non-sporting. The pilots seat could be fully enclosed and still rotate, but I choose not to do that initially.

The controls are fly by wire so there is very little complexity in that 110 degree travel joint.

[DaleKramer]

And for the record, to my knowledge, I did not says that this was a revolutionary design.

[2G]

On Saturday, March 19, 2016 at 5:00:26 PM UTC-7, DaleKramer wrote:
> And for the record, to my knowledge, I did not says that this was a revolutionary design.

Again, your attitude stinks! I can't fix stupid - you shouldn't be attempting a public venture, it just isn't your style.

You wrote "I believe that this revolution of flight". Case closed.

[2G]

On Saturday, March 19, 2016 at 4:50:48 PM UTC-7, DaleKramer wrote:
> On Saturday, March 19, 2016 at 6:04:23 PM UTC-4, 2G wrote:
> > On Saturday, March 19, 2016 at 11:21:45 AM UTC-7, DaleKramer wrote:
> > > I believe I have answered every question.
> > >
> > > There is NO reason to compare my design to a helicopter in terms of disc loading since it does not operate like one.
> > >
> > > I suggest to you that you read up on multirotor design and control.
> > >
> > > I believe that this revolution of flight, over the last decade, has resulted in more multirotor controlled air vehicles flying than all other air vehicles combined.
> > >
> > > Yes, perhaps I should mention a little more about that in the link.
> >
> > I didn't say that you didn't answer the questions; it was your attitude towards me that I called you on.
> >
> > Your "design" is not a revolution, just a variation on a concept that has been tried in the past and rejected by every aviation company since.
> >
> > Further review caused me pause; the pilot, along with all controls and instruments, must rotate in two dimensions AND open the cockpit to the full prop down wash during the most critical phases of flight: takeoff and landing. Is this so?
>
> Attitude goes both ways.
>
> I has also been said that no designs are revolutions, just variations.
>
> In hover flight the pilots seat only ever opens a maximum of 90 degrees, the final 20 degrees is when engines are shut down. At 90 degrees, the pilots upper torso is still in the fuselage, the pilots legs from the waist down are enclosed in a secondary shell (with airbags). Airflow should be no worse than an open cockpit aircraft or a motorcycle. This is a 'sport' design and I don't expect it to appeal to the non-sporting. The pilots seat could be fully enclosed and still rotate, but I choose not to do that initially.
>
> The controls are fly by wire so there is very little complexity in that 110 degree travel joint.

Your images show the legs forward in level flight, and the legs 90 degrees out of the plane in the opposite direction. I fail to see how this can be done with a rotation about just one axis. In any event, this requires a major body motion at a critical moment. Have you ever heard of "vertigo" and what causes it? This can be caused by just tilting the head down. Apparently you are completely unaware of this.

[[email protected]]

2G there is a lot of "stinking attitude" as you say here, but I am afraid its coming from you :) Thats not an unusual thing for this web site lol. I dont know much about mr kramer but I do know that he has not only sucessfully designed aircraft but also sold them to other folks who enjoy them. Will this project work? Who knows, there are definitely huge tecnological challenges here, and this guy is going to need help from other specialized engineers. That being said, your attitude is the type which I am sure the wright bros encountered all day long, namely folks who have'nt done squat themselves but sure can point out all the faults in another persons aspirations. Surely Dale knows this is not the forum to use for gaining serious investment capital, or for that matter "intelligent" aerodynamic advice. He appears to just be getting his ideas out into the public "air" a bit. So dude, lighten up, and at least applaude the guy for thinking outside the box.

[Andy Blackburn[_3_]]

On Friday, March 18, 2016 at 9:36:51 PM UTC-7, DaleKramer wrote:
> On Friday, March 18, 2016 at 11:33:01 PM UTC-4, 2G wrote:
> > It is high because it IS high. It is 5-6 times higher than an R22.
>
> Ok, so let us concentrate again on the rotor disk loading.
> If you had evaluated the design as an engineer, then I would not have to had to assume that you were asking about rotor disk loading versus propeller disk loading. An engineering evaluation would have understood that there are two flight modes that use different disk loading calculations and the question would have been more specific.
>
> Following that, you seem to have categorically determined that it has a very high rotor disk loading without specifying a class. When you start defining the class, you cite vehicles in 2 classes and now finally you are for some reason comparing my design only to a helicopter. It is obviously NOT a helicopter! It is not even in the Osprey tiltrotor class. The closest conventionally categorized class it could be put in is the tiltwing class and in that class it has a low rotor disk loading.
>
> I believe if anyone should be criticized here it is not me.
>
> Somehow we have rubbed each other the wrong way, for that I am sorry.

Dale - It's a pretty clever design. Thanks for sharing - gutsy move.

I expect the main reason to care about disk loading is to work out how many RPM at what propeller lift coefficient you need to produce enough total mass flow to hover. Presumably with the main engine running along with six electric motors you are within the operating parameters of the engines/props you have fitted and the thing can actually hover. It certainly appears to be a more highly loaded hovering design that a traditional single rotor helicopter in the same weight class, but I don't necessarily see that as particularly a big deal for what it's trying to do. I also expect that going to a higher disk loading than a typical conventional single rotor design will have some impact on efficiency and therefore endurance, but since you are not spending much time in vertical mode it's not a big factor for this design.. The bigger considerations here are the overall layout for prop tip clearance and commercially available brushless motor designs and the fact that you need multiple, displaced sources of thrust to control the thing in hover.

I'd have some questions about stability and control in hover mode. First, there is a fair amount of weight above the center of thrust for the electric motors - this includes the pilot and particularly the gas motor which is on a pretty long moment arm. This is a little like balancing a broomstick on the palm of your hand. You will need to counter any static or dynamic pitching moment with differential thrust on the electric motors, which could be problematic particularly in a low-speed transition between hover and forward flight when you have no aerodynamic elevator authority. Presumably the gas motor is pulling pretty hard which is stabilizing as long as you are vertical, but it doesn't provide any restoring pitch moment if you are at some intermediate pitch attitude, but not yet flying like an airplane. You'd need to use differential thrust on the electrics to keep the nose from tipping over, all while providing enough total thrust to hold hover.

A second potential issue is how to counteract the torque of the gas motor and prop, which see to be substantially larger than the electric motors and props. Since hexacopter yaw is controlled by adjusting the speed of the three clockwise turning versus three counter-clockwise turning props you'd have to have enough available angular momentum delta in three electric motors which are not on the centerline to counteract the angular momentum delta of the big gas motor which is on the centerline. I'm not sure how much being off centerline will affect the overall yawing moment.

Ideally, you'd like to be able to handle an electric motor bearing failure at an inopportune time in transition without losing control of the aircraft.. Some model hexacopter controllers deliberately gyrate in yaw to hold attitude with a single engine out. This probably wouldn't be a pleasant experience for a pilot onboard so you might need to consider how (or whether) you want to deal with that scenario.

Glad you're building a model first - lots of interesting challenges to work out.

I wouldn't worry too much about addressing Tom's criticism(s). He is oftentimes challenged understanding or conceding any points not made by him - though it certainly appears in this case that he's mistaken the bottom of the airplane (with the nose wheel stalk) for the top in your drawing of the aircraft with the pilot seat in hover orientation.

Andy

[[email protected]]

And oh by the way 2g, you questioned mr kramers academic credentials, just remember the wrights were'nt college educated, no degrees and they still beat the pants off of Langley, the college golden boy with all the "knowledge" and all the cash. Innovation and smarts are where you find them, sheepskin non mandatory or for that matter even desired. Most of the greatest innovations have come out of garages not universities.

[Andy Blackburn[_3_]]

On Sunday, March 20, 2016 at 4:41:42 AM UTC-7, Andy Blackburn wrote:
>
> A second potential issue is how to counteract the torque of the gas motor and prop, which see to be substantially larger than the electric motors and props.

Re-read the Kickstarter description. Offset angle on the electrics should help. Presumably you'll get additional torque when accelerating to transition. You'll need to handle the variation presumably by accelerating the electric motors spinning the opposite direction from he main gas motor. I'm guessing you might need some limits on how much you can accelerate so you don't run out of countering torque.

[DaleKramer]

On Sunday, March 20, 2016 at 1:39:25 AM UTC-4, 2G wrote:
> On Saturday, March 19, 2016 at 5:00:26 PM UTC-7, DaleKramer wrote:
> > And for the record, to my knowledge, I did not says that this was a revolutionary design.
>
> Again, your attitude stinks! I can't fix stupid - you shouldn't be attempting a public venture, it just isn't your style.
>
> You wrote "I believe that this revolution of flight". Case closed.

Wow, I have heard of out of context before but this is still hard to believe!

When I said that and in the same sentence you can tell that I was referring to multirotors in general. In fact the word vLazair or 'my design' in nowhere to be found in that particular post.

This is what I mean when I speak of agenda.

You are correct about something, case closed, I choose to end further response to your posts.

I will respond to the other intelligent and 'non-attacking' posts when I calm down.

[DaleKramer]

On Sunday, March 20, 2016 at 9:41:56 AM UTC-4, DaleKramer wrote:
> On Sunday, March 20, 2016 at 1:39:25 AM UTC-4, 2G wrote:
> > On Saturday, March 19, 2016 at 5:00:26 PM UTC-7, DaleKramer wrote:
> > > And for the record, to my knowledge, I did not says that this was a revolutionary design.
> >
> > Again, your attitude stinks! I can't fix stupid - you shouldn't be attempting a public venture, it just isn't your style.
> >
> > You wrote "I believe that this revolution of flight". Case closed.
>
> Wow, I have heard of out of context before but this is still hard to believe!
>
> When I said that and in the same sentence you can tell that I was referring to multirotors in general. In fact the word vLazair or 'my design' in nowhere to be found in that particular post.
>
> This is what I mean when I speak of agenda.
>
> You are correct about something, case closed, I choose to end further response to your posts.
>
> I will respond to the other intelligent and 'non-attacking' posts when I calm down.

Sorry, 'my design' is there but not in relation to that statement.

[[email protected]]

Time to calm down dale, before you blow a gasket and we dont see your labors come to fruition. Attitudes like 2g are always around, gotta plug your ears to them and keep them open to supportive advice and supportive criticism which is both warrented and helpfull.

[DaleKramer]

On Sunday, March 20, 2016 at 7:26:55 AM UTC-4, wrote:
> Surely Dale knows this is not the forum to use for gaining serious investment capital, or for that matter "intelligent" aerodynamic advice.

That is for sure! Exactly zero of the backers so far have been from my soaring acquaintances.

So I am still here because it is somewhat enjoyable and stimulating to share these ideas now.

[DaleKramer]

On Sunday, March 20, 2016 at 7:41:42 AM UTC-4, Andy Blackburn wrote:
> Dale - It's a pretty clever design. Thanks for sharing - gutsy move. ......

Thanks!

I am sure that a rotor disk loading of 18 lbs/ft^2 and thrust efficiency of about 5 lbs/hp is well within any theoretically feasible region for rotor design. At least it better be. I am basing my hover ability on motors and propellers that already exist. In fact on our Joby JM1 motors with 36x20 props at 4400 rpm we are getting about 110 lbs of static thrust at about 14 kw input to the motor controllers. That is about 5.9 lbs thrust/input hp (not motor shaft power!). This setup propels the eLazair in level flight at over 60 mph (the eLazair is pretty high drag at these speeds).
So, with about 500 lbs of static thrust from a WOT Rotax and 660 lbs from WOT electrics, the thrust to weight will be about 1.3/1. The electrics should only need about 1/2 power for hover.
The unknown is what amount of a zoom pullup versus a slow pullup and rotation thru a deep stall will be required. Rather than speculate on that I am just going to test it with model and full scale testing.
The transition is a very complex mixing of aerodynamic lift, aerodynamic drag, aerodynamic moments, thrust, thrust moments, mass and moments of inertia (probably other things too :). I am sure I could spend a lot of time trying to model that mathematically but I choose not to at this point.

I think the broomstick analogy is not real good one for visualization because in my case the correction needed to bring the object into balance is not a sideways movement of the hand but simply an application of thrust moment about the center of gravity. During transition, the WOT signal sent to the multirotor controller should automatically result in WOT on the lower tail motors and 0 throttle on the upper tail motors and likely 1/2 power on the wing motors. Also there is still the elevator pitching moment that can be increased by design (at the risk of making high speed horizontal flight twitchy unless I use a separate, thrust vectoring horizontal plane or fly by trim tabs in high speed which I choose not to do right now). 3D RC modeling has shown what large area, high deflection surfaces can do. To start out I use the KISS principle and add from there.

Yes the electric nacelle 'tilt' method of countering the Rotax torque is expected to work for gross torque cancelling and the 'fine' adjustments will still be from the multirotor control of the electric motor counter rotations.

I am hoping to be able to handle at least one electric motor failure and possibly 2, depending on which 2. Model testing will determine this.

[DaleKramer]

I am not saying the mechanical dynamics behind the broomstick analogy is different, just the visualization of it is a little different.

[DaleKramer]

On Sunday, March 20, 2016 at 8:48:34 AM UTC-4, Andy Blackburn wrote:
> I'm guessing you might need some limits on how much you can accelerate so you don't run out of countering torque.

Don't forget full span aileron authority coming on board as you accelerate. I once landed my glider with 150 lbs of water in one wing and zero in the other, did not have wing drop till around running speed, just ended up with worn down urethane tip skid :)

[Steve Koerner]

I don't think the dynamics of the mass moment being above the electric drives is necessarily a problem. The two necessities for electronic stabilization are that the drive moments are sufficient and that the electric drive dynamics are faster than possible plant disturbances. So the rate of spin up of the electric motor / prop system will need to be significantly faster than the rate that the broomstick can tip over or otherwise be perturbed by aero effects. The need for fast dynamics on the electric drives, in fact, argues for high disk loading.

The amazing effectiveness of electronic broomstick stabilization is routinely demonstrated by the various two wheel inventions that people zoom around on these days.

[DaleKramer]

On Sunday, March 20, 2016 at 2:16:28 PM UTC-4, Steve Koerner wrote:
> I don't think the dynamics of the mass moment being above the electric drives is necessarily a problem. The two necessities for electronic stabilization are that the drive moments are sufficient and that the electric drive dynamics are faster than possible plant disturbances. So the rate of spin up of the electric motor / prop system will need to be significantly faster than the rate that the broomstick can tip over or otherwise be perturbed by aero effects. The need for fast dynamics on the electric drives, in fact, argues for high disk loading.
>
> The amazing effectiveness of electronic broomstick stabilization is routinely demonstrated by the various two wheel inventions that people zoom around on these days.

Agreed, but I have my doubts that these were all created by mathematically analyzing all of the Newtonian physics involved before they came into existence.

There is just a lot more involved in the transitions of the vLazair.

Keep thinking of more that I would need to calculate, derivatives of time, as you describe above.

[Andy Blackburn[_3_]]

On Sunday, March 20, 2016 at 9:53:48 AM UTC-7, DaleKramer wrote:
> I am not saying the mechanical dynamics behind the broomstick analogy is different, just the visualization of it is a little different.

You are correct - it was a crude analogy. The main point (which you clearly understand) is that whole thing in vertical flight is quite likely statically unstable and if it tips over beyond a certain angle of vertical it is likely to flop over nose down. Unless you have enough altitude when this happens to get flying speed and pull out...well it could be a problem. Ideally you want to keep it stable so you never get to that angle until you have flying speed, which entails tipping over with differential electric thrust enough to get flying speed through the deep stall where the wing and elevator can operate. Yes indeed adding big controls on the tail and big old Fowler flaps on the wing could help you get stable at a higher angle of attack and lower speed. Lots of the hybrid aircraft-helicopter designs I've seen resort to tilt-wing to facilitate the transition more easily but all of that adds weight and complexity.

A simple calculation would be (without benefit of the dimensions on your plans) 220 lbs of thrust from the bottom tail motors produces a nose-up moment of 880 lb-ft based on a 4-foot offset from the center of mass. If the center of mass is 5 feet in front of the lift of those two motors that are trying to hold the nose up and you have a TOW of say 500 lbs you'd end up with a nose-down moment of 2500 lb-ft which would overwhelm the ability of the lower motors to right the aircraft as you approach horizontal. Now calculating the nose-down moment for totally horizontal is not realistic as you'd be accelerating before you ever got to horizontal but a little trig would tell you roughly what kind of angle off vertical the voters have the juice to recover from. Obviously you also have the other motors pulling as well and the prop wash over the tail adds a bit of moment, but the motors on the vertical centerline mostly just reduce the effective mass feeding the nose-down moment for reasonably vertical orientations. They don't help you at all as you approach horizontal. I expect there is somewhere around 30-40 degrees off of vertical where things get interesting and you better have some forward velocity and altitude before you let the nose get that tipped over. Sounds like you have a computer program to figure it all out but my gut feel of is that the last half of the transition to forward flight could get pretty sporty - wing still stalled but the two bottom motors have run out of ability to add enough nose up moment. The reverse maneuver could be even more exciting - a zoom has been mentioned.

Of course with enough thrust almost anything is possible. :-)

Again, thanks for sharing. Interesting design. All in all I think I'd rather have one of these than those scaled-up quadcopter drones people are promoting for personal transportation. Yikes!

Andy

[Andy Blackburn[_3_]]

On Sunday, March 20, 2016 at 8:33:24 AM UTC-7, DaleKramer wrote:
> On Sunday, March 20, 2016 at 7:26:55 AM UTC-4, wrote:
> > Surely Dale knows this is not the forum to use for gaining serious investment capital, or for that matter "intelligent" aerodynamic advice.
>
> That is for sure! Exactly zero of the backers so far have been from my soaring acquaintances.
>

+1, but I want a delivery position...if it works. Fingers crossed.

Andy

[DaleKramer]

Andy, I see that you have excellent experience and obvious insight as to what hurdles I will have to overcome in order to transition at slow airspeeds..

Before I continue I just want to see if you agree with me that it is less critical to iron out these 'low' speed transitions IF #1 the transition to horizontal flight instructions are simply to accelerate vertically to, say 40 (or whatever testing dictates) knots, then slowly push over AND #2 the transition to hover instructions are, apply WOT electrics, do a zoom pull up to vertical from 100 knots and on the way up, when the airspeed is less than 40 knots apply WOT on the Rotax?

Sorry for run on there, I am just trying to present transitions where there is less need for calculations.

And, if we agree on that, the minutia of how slow of an airspeed before pushover and how little zoom altitude is needed can be determined in testing.

I think your simple calculation does not take into account enough variables, mainly airspeed before pushover.

I am hoping 1.3/1 thrust will be adequate but I have ideas to get more if needed.

[DaleKramer]

On Sunday, March 20, 2016 at 3:08:51 PM UTC-4, Andy Blackburn wrote:
> On Sunday, March 20, 2016 at 8:33:24 AM UTC-7, DaleKramer wrote:
> > On Sunday, March 20, 2016 at 7:26:55 AM UTC-4, wrote:
> > > Surely Dale knows this is not the forum to use for gaining serious investment capital, or for that matter "intelligent" aerodynamic advice.
> >
> > That is for sure! Exactly zero of the backers so far have been from my soaring acquaintances.
> >
>
> +1, but I want a delivery position...if it works. Fingers crossed.
>
> Andy


Wow, thanks!

[Steve Koerner]

On Sunday, March 20, 2016 at 11:52:47 AM UTC-7, Andy Blackburn wrote:
> On Sunday, March 20, 2016 at 9:53:48 AM UTC-7, DaleKramer wrote:
> > I am not saying the mechanical dynamics behind the broomstick analogy is different, just the visualization of it is a little different.
>
> You are correct - it was a crude analogy. The main point (which you clearly understand) is that whole thing in vertical flight is quite likely statically unstable and if it tips over beyond a certain angle of vertical it is likely to flop over nose down. Unless you have enough altitude when this happens to get flying speed and pull out...well it could be a problem. Ideally you want to keep it stable so you never get to that angle until you have flying speed, which entails tipping over with differential electric thrust enough to get flying speed through the deep stall where the wing and elevator can operate. Yes indeed adding big controls on the tail and big old Fowler flaps on the wing could help you get stable at a higher angle of attack and lower speed. Lots of the hybrid aircraft-helicopter designs I've seen resort to tilt-wing to facilitate the transition more easily but all of that adds weight and complexity.
>
> A simple calculation would be (without benefit of the dimensions on your plans) 220 lbs of thrust from the bottom tail motors produces a nose-up moment of 880 lb-ft based on a 4-foot offset from the center of mass. If the center of mass is 5 feet in front of the lift of those two motors that are trying to hold the nose up and you have a TOW of say 500 lbs you'd end up with a nose-down moment of 2500 lb-ft which would overwhelm the ability of the lower motors to right the aircraft as you approach horizontal. Now calculating the nose-down moment for totally horizontal is not realistic as you'd be accelerating before you ever got to horizontal but a little trig would tell you roughly what kind of angle off vertical the voters have the juice to recover from. Obviously you also have the other motors pulling as well and the prop wash over the tail adds a bit of moment, but the motors on the vertical centerline mostly just reduce the effective mass feeding the nose-down moment for reasonably vertical orientations. They don't help you at all as you approach horizontal. I expect there is somewhere around 30-40 degrees off of vertical where things get interesting and you better have some forward velocity and altitude before you let the nose get that tipped over. Sounds like you have a computer program to figure it all out but my gut feel of is that the last half of the transition to forward flight could get pretty sporty - wing still stalled but the two bottom motors have run out of ability to add enough nose up moment. The reverse maneuver could be even more exciting - a zoom has been mentioned.
>
> Of course with enough thrust almost anything is possible. :-)
>
> Again, thanks for sharing. Interesting design. All in all I think I'd rather have one of these than those scaled-up quadcopter drones people are promoting for personal transportation. Yikes!
>
> Andy

People have been known to climb aboard rockets. Rockets have the exact same requirement: you have to keep them pointed upward -- at least until you get airspeed for meaningful wing lift.

One could argue that relying upon motors to keep working is pretty routine for flying machines. A helicopter needs to have it's one motor keep working when it's taking off vertically to avoid a dire consequence.

Back to battery life... there must be enough for an aborted landing scenario. That means electrics on as you're screeching to a stop through deep stall deceleration, then maneuvering to the desired landing spot in vertical and letting down sufficiently gradually. If there is too much wind or if the landing site didn't end up in the right place or something is wrong at the site, there must be enough power reserve to blast back up vertically to flying speed and perhaps a horizontal landing elsewhere.

[DaleKramer]

Agreed, right now I am sort of allocating 1 minute WOT electric time with about 3 minutes of reserve (even though hovering should require about 1/2 power in electrics). This is another fine tunable value when the full size vLazair is detail designed. I am hoping that I can make vertical landings that use around 30 seconds of electric time.

[DaleKramer]

On Sunday, March 20, 2016 at 3:08:51 PM UTC-4, Andy Blackburn wrote:
> +1, but I want a delivery position...if it works. Fingers crossed.
>
> Andy

I will consider that a deposit on delivery position #1 :)

[Andy Blackburn[_3_]]

On Sunday, March 20, 2016 at 2:22:53 PM UTC-7, DaleKramer wrote:
> On Sunday, March 20, 2016 at 3:08:51 PM UTC-4, Andy Blackburn wrote:
> > +1, but I want a delivery position...if it works. Fingers crossed.
> >
> > Andy
>
> I will consider that a deposit on delivery position #1 :)

#1? maybe I need a few brave should in front of me.

Yes - way back when I worked at NASA Ames on variable stability helicopters as part of grad school. They had the XV-15 tilt rotor there and well as the RSRA - talk about bad transitions to forward flight. It has a rotor that was an oval cross section with blowing slots on both leading and trailing edges. The idea was to stop the rotor in flight and swap the slots you were blowing out of on the blades that were facing aft (they were symmetric airfoils (fore and aft AND top/bottom) - so "aft" was more of a term of art as it depended entirely on the blowing setup. In forward flight it was an X-wing planform. I understand the transitions were "exciting".

You have an easy problem in comparison.

I agree with enough power and pitch authority you ought to be able to make the transition to forward flight (and back) without to much drama. The question I can't answer with simple math is exactly how much power you need. You've got a swept wing so it ought to be able to produce lift at pretty high AOA which is good. At some point the vertical component of the thrust vector will be insufficient to hold the aircraft in hover and as you continue to pitch over the wing better take up the slack or you will be in ballistic territory. If your total thrust to weight is 1.3:1 you will run out of thrust to hold hover at T*sin(Theta) = W, or Theta = arcsin(1/1.3) = arcsin(0.77) = 50.3 degrees nose up pitch. That might be a bit high, even for a highly swept wing. You'll need to get the elevator unstalled as well if you want to actually fly the thing through the transition with the stick. The hope is that the nose will want to pitch over anyway once you get started so you'd think you could sort of mush your way through the transition until the boundariy layer on the wing gets attached and the wing gets lifting - and hope that it doesn't get so draggy that it wants to mush and settle for very long.

My Dad was the project test pilot for a variation on this theme back in 1958:

https://www.youtube.com/watch?v=wDstVGAmI74

Like I said, with enough thrust you can do pretty much anything you want.

Andy

[Darryl Ramm]

Andy, give up now on the hovercraft and RC drones, just launch one of those F-100D ZEL from you back yard.

On Sunday, March 20, 2016 at 4:30:23 PM UTC-7, Andy Blackburn wrote:
> On Sunday, March 20, 2016 at 2:22:53 PM UTC-7, DaleKramer wrote:
> > On Sunday, March 20, 2016 at 3:08:51 PM UTC-4, Andy Blackburn wrote:
> > > +1, but I want a delivery position...if it works. Fingers crossed.
> > >
> > > Andy
> >
> > I will consider that a deposit on delivery position #1 :)
>
> #1? maybe I need a few brave should in front of me.
>
> Yes - way back when I worked at NASA Ames on variable stability helicopters as part of grad school. They had the XV-15 tilt rotor there and well as the RSRA - talk about bad transitions to forward flight. It has a rotor that was an oval cross section with blowing slots on both leading and trailing edges. The idea was to stop the rotor in flight and swap the slots you were blowing out of on the blades that were facing aft (they were symmetric airfoils (fore and aft AND top/bottom) - so "aft" was more of a term of art as it depended entirely on the blowing setup. In forward flight it was an X-wing planform. I understand the transitions were "exciting".
>
> You have an easy problem in comparison.
>
> I agree with enough power and pitch authority you ought to be able to make the transition to forward flight (and back) without to much drama. The question I can't answer with simple math is exactly how much power you need. You've got a swept wing so it ought to be able to produce lift at pretty high AOA which is good. At some point the vertical component of the thrust vector will be insufficient to hold the aircraft in hover and as you continue to pitch over the wing better take up the slack or you will be in ballistic territory. If your total thrust to weight is 1.3:1 you will run out of thrust to hold hover at T*sin(Theta) = W, or Theta = arcsin(1/1.3) = arcsin(0.77) = 50.3 degrees nose up pitch. That might be a bit high, even for a highly swept wing. You'll need to get the elevator unstalled as well if you want to actually fly the thing through the transition with the stick. The hope is that the nose will want to pitch over anyway once you get started so you'd think you could sort of mush your way through the transition until the boundariy layer on the wing gets attached and the wing gets lifting - and hope that it doesn't get so draggy that it wants to mush and settle for very long.
>
> My Dad was the project test pilot for a variation on this theme back in 1958:
>
> https://www.youtube.com/watch?v=wDstVGAmI74
>
> Like I said, with enough thrust you can do pretty much anything you want.
>
> Andy

[DaleKramer]

Andy,

Sounds like the RSRA had a reaction rotor powered by air, but I don't see that in the specs I found? And are you saying that after the RSRA rotor was stopped, they continued to blow out the 'horizontal flight' trailing edges for some reason?

I was assuming that there may be some loss of altitude during the vLazair 'push' to forward flight. Part of the 'push' transition procedure could not only be 'only push when you get to a certain vertical speed' but also a minimum height above ground to make allowance for a slight height loss. Or worst case it might be 'climb straight to X altitude and then push over, it will dive some but you'll pull out of it :) In the early 3D flight RC model days I had a model with not much over 1/1 thrust. I have never been able to hover very long but I don't remember ever having much altitude loss or control problems coming out of a hover attempt. I know Mr Reynolds and a lot of other things likely skew that example but I can't wait to see what my 1/4 scale will do on these transitions (btw I am planning a tether system for 1/4 scale testing).

Fortunately I believe the stability through transitions will be augmented by the multirotor controller which is closed loop on heading and pitch until the throttle command is shut down to it when horizontal flight is achieved..

I also think it is possible that the aerodynamic controls are not needed at all below their un-stalled AOAs.

Wow, that video clip is awesome! I think of my electrics on the vLazair as a sort of re-chargable JATO system :)

[DaleKramer]

Ah, maybe the blown rotors was just for changing rotor speed during transitions?

[DaleKramer]

Andy,

Since we are doing napkin calcs (I have this on a spreadsheet somewhere): Mass (M) = 850 lbs, Average Unbalanced upward force for 0 to 40 knts (electric props still gives about 80% of static thrust at 40 knts and assume linear decay)(F) = (250 lbs * 0.9 * 32 ft/sec^2) = 7200 lbf, Acceleration upwards = F/M = 8.5 ft/sec^2, Distance to go from 0 to 40 knts (67.5 ft/sec) using v^2=u^2+2as is 270 ft and the time to get there from s=ut+.5at^2 is about 8 seconds.

I hope I did that right, I even have those equations in memory after nearly 40 years :)

So, at 1.3 thrust to weight and a vertical acceleration to 40 knts, this puts us 270 feet high in 8 seconds after liftoff (accounting for some thrust loss at 40 knts on electrics, Rotax variable pitch should pretty well hold its static thrust at 40 knts, aircraft drag at 0 AOA and 40 knts not considered). Wow, rocket calcs :)

Knowing this, my gut felt good about being able to go straight up and pushover fairly easily and quickly so I went on to other things. Should I reconsider, I think 50 or 60 knts may work as well at which point I will add some airframe drag estimates.

[Andy Blackburn[_3_]]

The blowing was to use the blown air to create the trailing edge if the airfoil so you could have a rotor where the clockwise edge was trailing when the rotor was spinning and then when you stop the rotor to fly the blades as wings half the blades blow out if the counter-clockwise newly trailing edge. Without this, you'd have half the rotor ballades trying to fly backwards when you convert them to fixed wings. It's a crazy idea that blowing through a slot on the lower aft edge of a blunt shape creates a trailing edge streamlined effective shape.

[DaleKramer]

Interesting, could they make it like a down flap shape if they blew harder?

[Andy Blackburn[_3_]]

On Sunday, March 20, 2016 at 8:24:39 PM UTC-7, DaleKramer wrote:
> Interesting, could they make it like a down flap shape if they blew harder?

There's a joke in there somewhere...

[DaleKramer]

On Monday, March 21, 2016 at 12:27:00 AM UTC-4, Andy Blackburn wrote:
> On Sunday, March 20, 2016 at 8:24:39 PM UTC-7, DaleKramer wrote:
> > Interesting, could they make it like a down flap shape if they blew harder?
>
> There's a joke in there somewhere...

Actually I am just speculating that, depending on the blowhole angle on the lower 'TE', they might be able to affect the camber of the airfoil if the blew harder, or would that just mess up the 'phantom' airfoil profile.

[Andy Blackburn[_3_]]

I would guess that you could get some tailoring by changing pressure, but the Coanda effect really counts on boundary layer attachment and then separation to do its thing, so there are almost certainly limits. Turns out the RSRA never flew through a transition so the excitement around the hangar was speculative. Some helpful reference material on the technology.

http://www.sikorskyarchives.com/X-WING.php

https://en.m.wikipedia.org/wiki/Blown_flap

Also, some NASA concepts for personal electric VTOL:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110011311.pdf

https://m.youtube.com/watch?v=I_KloqLa2Og

[Jonathan St. Cloud]

And of course even further off subject, the MD NOTAR helicopters use the Coanda effect for the anti-torque. Works beautifully in over 2,000 holding the tick of an MD520.

On Monday, March 21, 2016 at 8:07:17 AM UTC-7, Andy Blackburn wrote:
> I would guess that you could get some tailoring by changing pressure, but the Coanda effect really counts on boundary layer attachment and then separation to do its thing, so there are almost certainly limits. Turns out the RSRA never flew through a transition so the excitement around the hangar was speculative. Some helpful reference material on the technology.
>
> http://www.sikorskyarchives.com/X-WING.php
>
> https://en.m.wikipedia.org/wiki/Blown_flap
>
> Also, some NASA concepts for personal electric VTOL:
>
> http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110011311.pdf
>
> https://m.youtube.com/watch?v=I_KloqLa2Og

[DaleKramer]

Great links, hadn't seen that good of a Puffin desription before or the X wing archive.

[Steve Koerner]

On Sunday, March 20, 2016 at 1:05:18 PM UTC-7, DaleKramer wrote:
> Agreed, right now I am sort of allocating 1 minute WOT electric time with about 3 minutes of reserve (even though hovering should require about 1/2 power in electrics). This is another fine tunable value when the full size vLazair is detail designed. I am hoping that I can make vertical landings that use around 30 seconds of electric time.

I suppose if you can incorporate a very accurate indicator of remaining battery life with an alarm feature, or a separate reserve battery that is switched in when the main gets low, then that might work. I can't help but visualize myself spending several minutes trying to get her lined up to the helicopter pad on my future yacht. The seas are bumpy and the breeze variable -- I think the process might take a few minutes to get landed.

If Andy flies production unit number 1 and lives, and if there are positive reviews on Amazon, I will order unit number 7.

[DaleKramer]

On Monday, March 21, 2016 at 5:41:25 PM UTC-4, Steve Koerner wrote:
> On Sunday, March 20, 2016 at 1:05:18 PM UTC-7, DaleKramer wrote:
> > Agreed, right now I am sort of allocating 1 minute WOT electric time with about 3 minutes of reserve (even though hovering should require about 1/2 power in electrics). This is another fine tunable value when the full size vLazair is detail designed. I am hoping that I can make vertical landings that use around 30 seconds of electric time.
>
> I suppose if you can incorporate a very accurate indicator of remaining battery life with an alarm feature, or a separate reserve battery that is switched in when the main gets low, then that might work. I can't help but visualize myself spending several minutes trying to get her lined up to the helicopter pad on my future yacht. The seas are bumpy and the breeze variable -- I think the process might take a few minutes to get landed.
>
> If Andy flies production unit number 1 and lives, and if there are positive reviews on Amazon, I will order unit number 7.

:) I am with you but at this point I am trying to be realistic in my empty weight predictions. I will increase battery capacity, down the road, if I can. I am really trying to build with existing technology that is available. At this stage I have a perfect 25 lbish pack in mind, by the time I build the full scale we will likely have 300+ whr/kg packs available.

Lucky #7, but Amazon reviews, I really question :)

[DaleKramer]

Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)

https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery

[2G]

On Tuesday, March 22, 2016 at 4:02:40 AM UTC-7, DaleKramer wrote:
> Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)
>
> https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery

I will apologize for using the word "stinking" - I will let your attitude speak for itself.

That said, this design is problematic. For example, you list the battery weight at 25 lb. I calculate that you will need about 100 lbs of battery (batteries cannot be discharged 100% and expect any decent lifetime). And that ONLY allows by your statement, 3-4 min of hovering. This is totally inadequate for any landing I would dare attempt. This means you will need MUCH more battery capacity than you allowed for, but I will stick to this time for the rest of the analysis.

Using freely available references, I calculated the ideal power to hover at sea level (not climb, mind you) at 131 hp with a MTOW of 1175 lb. Using a 0.75 FOM this increases to 175 hp. At a 10,000 ft density altitude this becomes 158 and 211 hp, respectively. Clearly your design is severely under powered. It gets worse when you want to climb and be able to transition from hovering to forward flight, when some of the electric motors will have to be shut down. These same references state that VTOL aircraft have a horsepower loading of less than 2: you are more than double this.

I am not confused about fore and aft. The pilot is faced forward in forward flight; his position must change to an aft facing position AND rotate 90 degrees. That amounts to 2 rotations on 2 axes of 90 and 180 degrees. When, exactly does this occur, while travelling forward in level flight or while hovering? I would assume hovering because of the extreme air blast and speed brake effect. While hovering the pilot WILL be exposed to the full thrust of the main motor. The thought of attempting such a maneuver scares the hell out of me! The potential of vertigo is not just huge - it is virtually certain. Another point that went unanswered.

Andy makes excellent points about the counter-rotation and stability issues.. As currently envisioned, the main motor cannot be operated at full power because the electric motors would not stabilize its torque. This problem is exacerbated when the aircraft tries to transition to horizontal flight when half the electric motors would have to be shut down. Combine an electric motor failure and you have a real problem. Notice that Dale never answered my question about thrust vectoring.

Fly by wire? You have just become a million dollar aircraft! This is completely unrealistic. You REALLY need to consult with engineers who have ACTUALLY designed fly by wire aircraft.

Qualifications are not important? Since the hell when? Building conventional aircraft from who knows what designs is NOT a representation of qualifications. I am approaching this whole project from the viewpoint of an unsophisticated investor; I don't particularly care what Dale does with his own money. BTW, there WERE NO aeronautical engineering schools at the time of the Wright Brothers; they invented it (they also used their OWN money!)

[Steve Koerner]

So 2G,

Does this mean that if Dale builds a model and successfully flies off vertically, transitions to horizontal and lands it vertical, then you will eat the molds that the plane was made from?

Or are you saying that you will only eat the molds if he changes nothing from concept to completion?

[2G]

On Tuesday, March 22, 2016 at 11:07:23 PM UTC-7, Steve Koerner wrote:
> So 2G,
>
> Does this mean that if Dale builds a model and successfully flies off vertically, transitions to horizontal and lands it vertical, then you will eat the molds that the plane was made from?
>
> Or are you saying that you will only eat the molds if he changes nothing from concept to completion?

Are you saying that the experts in the industry like J. Gordon Leishman don't know what they are talking about?

I would be more concerned that Dale builds a full-scale plane and attempts to fly it. All model planes I have seen have grossly higher power-weight ratios than their full-size counterparts.

[Eric Greenwell[_4_]]

DaleKramer wrote on 3/18/2016 5:38 AM:
> This is a great thread and has given me much to consider, however I
> am going to have to start concentrating on getting people to pledge
> on the Kickstarter campaign.

The thread got me to pledge $100. I'm looking forward to seeing the
charge on my credit card next month, which will signal you got the
funding you seek.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[DaleKramer]

Eric,

Thanks for the support!

Dale

[2G]

On Thursday, March 24, 2016 at 7:07:15 AM UTC-7, DaleKramer wrote:
> Eric,
>
> Thanks for the support!
>
> Dale

Has NO ONE come forward to challenge my calculations? It has been 3 days and the only rebuttal had something weird to do about having dinner of molds.

Okay, I DID leave something out, and I admit it. I forgot to mention that horsepower from carbureted engines falls off with altitude, so that 100 hp engine will only produce 70 hp at a 10,000 ft DENSITY altitude.

Here is another factoid that you will find if you bother to check my calculations: power required is INVERSELY proportional to the square root of disk area. This is simple physics, so there is NO avoiding it! Consequently, tail squatters require A LOT more horsepower. Dale's design will require nearly THREE TIMES more horsepower than an R22 simply because of the MUCH higher disk loading - that is WHY I made such a point of the HIGH disk loading. I don't have ANY idea where Dale came up with the number of 1.3X thrust to weight, maybe it was in a dream. It seems like engineering analysis is, at best, an after thought. During my career as a design engineer I can assure you we thought of it otherwise.

Here is an interesting quote I dug up from the book by Ray Prouty (Dale, I assume that you ARE reading the reference books):

"Despite the trend for higher and higher disc loadings in the past 20 years, there does seem to be a practical upper limit. Values of more than about 10 pounds per square foot generate such high induced velocities under the rotor that it is difficult to operate from unprepared sites without filling the air full of flying sticks and stones to break one's bones. It also becomes increasingly difficult to obtain safe autorotational characteristics as disc loadings go up. These are two reasons why VTOL aircraft that depend on heavily loaded propellers for hovering have not yet become operational."

And Dale wants the pilot sitting out in the open to be pelted by those sticks and stones. Whatever...

[Andy Blackburn[_3_]]

On Thursday, March 24, 2016 at 7:07:15 AM UTC-7, DaleKramer wrote:
> Eric,
>
> Thanks for the support!
>
> Dale

This thing crashed this week - pilot walked away, but it was a total writeoff.

http://elytron.aero/#page-home

9B

[Craig Funston]

On Wednesday, March 30, 2016 at 11:26:24 AM UTC-7, Andy Blackburn wrote:
> On Thursday, March 24, 2016 at 7:07:15 AM UTC-7, DaleKramer wrote:
> > Eric,
> >
> > Thanks for the support!
> >
> > Dale
>
> This thing crashed this week - pilot walked away, but it was a total writeoff.
>
> http://elytron.aero/#page-home
>
> 9B

Glad no one was hurt. Their odds for success don't look good.

[Andy Blackburn[_3_]]

I am hesitant to reply, because you make it so not fun, but here goes. I combined your last two posts to make it easier.

I don't think you are an aeronautical engineer either by education (I am times 2 and Dale is by 3/4 of a degree) or by practice (Dale certainly is - he sold a bunch of the LSA he designed). We can quibble about what is or isn't adequate qualification for this sort of contraption. You have a science/engineering background so that will get you some ways, but aircraft design has a bit of art in it - especially for something like what Dale is trying. No one can say for sure how well it will work - which is why a scale model seems prudent. The design is unusual, based on some of the new, large brushless electric motors that are available now so it's an interesting use of evolving technologies.

On Tuesday, March 22, 2016 at 8:20:12 PM UTC-7, 2G wrote:
> On Tuesday, March 22, 2016 at 4:02:40 AM UTC-7, DaleKramer wrote:
> > Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)
> >
> > https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery
>
> I will apologize for using the word "stinking" - I will let your attitude speak for itself.
>
> That said, this design is problematic. For example, you list the battery weight at 25 lb. I calculate that you will need about 100 lbs of battery (batteries cannot be discharged 100% and expect any decent lifetime). And that ONLY allows by your statement, 3-4 min of hovering. This is totally inadequate for any landing I would dare attempt. This means you will need MUCH more battery capacity than you allowed for, but I will stick to this time for the rest of the analysis.

Fine -
>
> Using freely available references, I calculated the ideal power to hover at sea level (not climb, mind you) at 131 hp with a MTOW of 1175 lb. Using a 0.75 FOM this increases to 175 hp. At a 10,000 ft density altitude this becomes 158 and 211 hp, respectively. Clearly your design is severely under powered. It gets worse when you want to climb and be able to transition from hovering to forward flight, when some of the electric motors will have to be shut down. These same references state that VTOL aircraft have a horsepower loading of less than 2: you are more than double this.

Be careful about translating between thrust and horsepower for a mix of gas-piston and brushless DC motors. They have very different characteristics and I don't believe Dale quoted HP on the electrics. Their output doesn't vary with altitude since the aren't aspirated.

>
> I am not confused about fore and aft. The pilot is faced forward in forward flight; his position must change to an aft facing position AND rotate 90 degrees. That amounts to 2 rotations on 2 axes of 90 and 180 degrees. When, exactly does this occur, while travelling forward in level flight or while hovering? I would assume hovering because of the extreme air blast and speed brake effect. While hovering the pilot WILL be exposed to the full thrust of the main motor. The thought of attempting such a maneuver scares the hell out of me! The potential of vertigo is not just huge - it is virtually certain. Another point that went unanswered.

Look at the picture again - as the airplane pitches up 90 degrees to go into hover the pilot's seated position rotates the opposite direction, pitching his legs down 90 degrees through the bottom of the fuselage. In essence the pilot's pitch attitude remains unchanged relative to Earth frame of reference as the aircraft pitches up around him.

>
> Andy makes excellent points about the counter-rotation and stability issues. As currently envisioned, the main motor cannot be operated at full power because the electric motors would not stabilize its torque. This problem is exacerbated when the aircraft tries to transition to horizontal flight when half the electric motors would have to be shut down. Combine an electric motor failure and you have a real problem. Notice that Dale never answered my question about thrust vectoring.

Static versus dynamic tourque. You'll get some from the friction in the propulsion system and more from dynamic application of power. Dale mentioned that canting the electric motors counteracts static torque and if they are canted properly you will get some counter-torque as you apply thrust to the all engines in unison. I can't tell you how much canting of the thrust vector is enough. Presumably there is an optimum angle and it will affect how you apply power across all propulsion systems. It's impossible for me to say whether this will represent a serious control or performance restriction.

Electric motor failure is a concern, but with 4-6 operating at least you have some redundancy since you can't autorotate.
>
> Fly by wire? You have just become a million dollar aircraft! This is completely unrealistic. You REALLY need to consult with engineers who have ACTUALLY designed fly by wire aircraft.

My helicopter drone is fly by wire - it really depends on what you mean by fly by wire. I doubt Dale meant electronically controlled hydraulic actuators on the aerodynamic control surfaces, which would add to cost and weight. I suspect he meant engine controls, which is not a big deal since electric motors are by definition electronically controlled.
>
> Qualifications are not important? Since the hell when? Building conventional aircraft from who knows what designs is NOT a representation of qualifications. I am approaching this whole project from the viewpoint of an unsophisticated investor; I don't particularly care what Dale does with his own money. BTW, there WERE NO aeronautical engineering schools at the time of the Wright Brothers; they invented it (they also used their OWN money!)
>
Dale is plenty experienced - asking for his sheepskin is a bit much. It's not like he's hiding anything. He's been transparent about his background and experience. People need not invest if senior year in college is more important to them than having designed and flown hundreds of examples of an aircraft.

> Has NO ONE come forward to challenge my calculations? It has been 3 days and the only rebuttal had something weird to do about having dinner of molds.
>
> Okay, I DID leave something out, and I admit it. I forgot to mention that horsepower from carbureted engines falls off with altitude, so that 100 hp engine will only produce 70 hp at a 10,000 ft DENSITY altitude.
>
Okay. Maybe get it working at sea level first. Guys in Telluride may have to wait.

> Here is another factoid that you will find if you bother to check my calculations: power required is INVERSELY proportional to the square root of disk area. This is simple physics, so there is NO avoiding it! Consequently, tail squatters require A LOT more horsepower. Dale's design will require nearly THREE TIMES more horsepower than an R22 simply because of the MUCH higher disk loading - that is WHY I made such a point of the HIGH disk loading.. I don't have ANY idea where Dale came up with the number of 1.3X thrust to weight, maybe it was in a dream. It seems like engineering analysis is, at best, an after thought. During my career as a design engineer I can assure you we thought of it otherwise.

I think you are confusing thrust and horsepower. 1.3 thrust to weight isn't a hot rod, but it ought to get off the ground and accelerate reasonably (about 0.3 G), or 10 ft/s/s.

>
> Here is an interesting quote I dug up from the book by Ray Prouty (Dale, I assume that you ARE reading the reference books):
>
> "Despite the trend for higher and higher disc loadings in the past 20 years, there does seem to be a practical upper limit. Values of more than about 10 pounds per square foot generate such high induced velocities under the rotor that it is difficult to operate from unprepared sites without filling the air full of flying sticks and stones to break one's bones. It also becomes increasingly difficult to obtain safe autorotational characteristics as disc loadings go up. These are two reasons why VTOL aircraft that depend on heavily loaded propellers for hovering have not yet become operational."
>
> And Dale wants the pilot sitting out in the open to be pelted by those sticks and stones. Whatever...

It's already been conceded that higher disk loading is less efficient, but for a few minutes of flight, efficiency is not the main concern. As long as the electric motors and props, plus gas engine/prop can deliver enough thrust, the thing should fly. The main purpose of all these designs is to produce a VTOL aircraft that isn't limited the way conventional helicopters are with regard to cruise speed (due to retreating blade stall). That generally means compromising on the efficiency of the vertical lift parts to optimize the whole contraption for cruise speed and efficiency. Dale's design seems like a decent effort at that.

Fire away.

9B

[2G]

On Wednesday, March 30, 2016 at 4:34:36 PM UTC-7, Andy Blackburn wrote:
> I am hesitant to reply, because you make it so not fun, but here goes. I combined your last two posts to make it easier.
>
> I don't think you are an aeronautical engineer either by education (I am times 2 and Dale is by 3/4 of a degree) or by practice (Dale certainly is - he sold a bunch of the LSA he designed). We can quibble about what is or isn't adequate qualification for this sort of contraption. You have a science/engineering background so that will get you some ways, but aircraft design has a bit of art in it - especially for something like what Dale is trying. No one can say for sure how well it will work - which is why a scale model seems prudent. The design is unusual, based on some of the new, large brushless electric motors that are available now so it's an interesting use of evolving technologies.
>
> On Tuesday, March 22, 2016 at 8:20:12 PM UTC-7, 2G wrote:
> > On Tuesday, March 22, 2016 at 4:02:40 AM UTC-7, DaleKramer wrote:
> > > Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)
> > >
> > > https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery
> >
> > I will apologize for using the word "stinking" - I will let your attitude speak for itself.
> >
> > That said, this design is problematic. For example, you list the battery weight at 25 lb. I calculate that you will need about 100 lbs of battery (batteries cannot be discharged 100% and expect any decent lifetime). And that ONLY allows by your statement, 3-4 min of hovering. This is totally inadequate for any landing I would dare attempt. This means you will need MUCH more battery capacity than you allowed for, but I will stick to this time for the rest of the analysis.
>
> Fine -
> >
> > Using freely available references, I calculated the ideal power to hover at sea level (not climb, mind you) at 131 hp with a MTOW of 1175 lb. Using a 0.75 FOM this increases to 175 hp. At a 10,000 ft density altitude this becomes 158 and 211 hp, respectively. Clearly your design is severely under powered. It gets worse when you want to climb and be able to transition from hovering to forward flight, when some of the electric motors will have to be shut down. These same references state that VTOL aircraft have a horsepower loading of less than 2: you are more than double this.
>
> Be careful about translating between thrust and horsepower for a mix of gas-piston and brushless DC motors. They have very different characteristics and I don't believe Dale quoted HP on the electrics. Their output doesn't vary with altitude since the aren't aspirated.
>
> >
> > I am not confused about fore and aft. The pilot is faced forward in forward flight; his position must change to an aft facing position AND rotate 90 degrees. That amounts to 2 rotations on 2 axes of 90 and 180 degrees. When, exactly does this occur, while travelling forward in level flight or while hovering? I would assume hovering because of the extreme air blast and speed brake effect. While hovering the pilot WILL be exposed to the full thrust of the main motor. The thought of attempting such a maneuver scares the hell out of me! The potential of vertigo is not just huge - it is virtually certain. Another point that went unanswered.
>
> Look at the picture again - as the airplane pitches up 90 degrees to go into hover the pilot's seated position rotates the opposite direction, pitching his legs down 90 degrees through the bottom of the fuselage. In essence the pilot's pitch attitude remains unchanged relative to Earth frame of reference as the aircraft pitches up around him.
>
> >
> > Andy makes excellent points about the counter-rotation and stability issues. As currently envisioned, the main motor cannot be operated at full power because the electric motors would not stabilize its torque. This problem is exacerbated when the aircraft tries to transition to horizontal flight when half the electric motors would have to be shut down. Combine an electric motor failure and you have a real problem. Notice that Dale never answered my question about thrust vectoring.
>
> Static versus dynamic tourque. You'll get some from the friction in the propulsion system and more from dynamic application of power. Dale mentioned that canting the electric motors counteracts static torque and if they are canted properly you will get some counter-torque as you apply thrust to the all engines in unison. I can't tell you how much canting of the thrust vector is enough. Presumably there is an optimum angle and it will affect how you apply power across all propulsion systems. It's impossible for me to say whether this will represent a serious control or performance restriction..
>
> Electric motor failure is a concern, but with 4-6 operating at least you have some redundancy since you can't autorotate.
> >
> > Fly by wire? You have just become a million dollar aircraft! This is completely unrealistic. You REALLY need to consult with engineers who have ACTUALLY designed fly by wire aircraft.
>
> My helicopter drone is fly by wire - it really depends on what you mean by fly by wire. I doubt Dale meant electronically controlled hydraulic actuators on the aerodynamic control surfaces, which would add to cost and weight. I suspect he meant engine controls, which is not a big deal since electric motors are by definition electronically controlled.
> >
> > Qualifications are not important? Since the hell when? Building conventional aircraft from who knows what designs is NOT a representation of qualifications. I am approaching this whole project from the viewpoint of an unsophisticated investor; I don't particularly care what Dale does with his own money. BTW, there WERE NO aeronautical engineering schools at the time of the Wright Brothers; they invented it (they also used their OWN money!)
> >
> Dale is plenty experienced - asking for his sheepskin is a bit much. It's not like he's hiding anything. He's been transparent about his background and experience. People need not invest if senior year in college is more important to them than having designed and flown hundreds of examples of an aircraft.
>
> > Has NO ONE come forward to challenge my calculations? It has been 3 days and the only rebuttal had something weird to do about having dinner of molds.
> >
> > Okay, I DID leave something out, and I admit it. I forgot to mention that horsepower from carbureted engines falls off with altitude, so that 100 hp engine will only produce 70 hp at a 10,000 ft DENSITY altitude.
> >
> Okay. Maybe get it working at sea level first. Guys in Telluride may have to wait.
>
> > Here is another factoid that you will find if you bother to check my calculations: power required is INVERSELY proportional to the square root of disk area. This is simple physics, so there is NO avoiding it! Consequently, tail squatters require A LOT more horsepower. Dale's design will require nearly THREE TIMES more horsepower than an R22 simply because of the MUCH higher disk loading - that is WHY I made such a point of the HIGH disk loading. I don't have ANY idea where Dale came up with the number of 1.3X thrust to weight, maybe it was in a dream. It seems like engineering analysis is, at best, an after thought. During my career as a design engineer I can assure you we thought of it otherwise.
>
> I think you are confusing thrust and horsepower. 1.3 thrust to weight isn't a hot rod, but it ought to get off the ground and accelerate reasonably (about 0.3 G), or 10 ft/s/s.
>
>
>
> > Here is an interesting quote I dug up from the book by Ray Prouty (Dale, I assume that you ARE reading the reference books):
> >
> > "Despite the trend for higher and higher disc loadings in the past 20 years, there does seem to be a practical upper limit. Values of more than about 10 pounds per square foot generate such high induced velocities under the rotor that it is difficult to operate from unprepared sites without filling the air full of flying sticks and stones to break one's bones. It also becomes increasingly difficult to obtain safe autorotational characteristics as disc loadings go up. These are two reasons why VTOL aircraft that depend on heavily loaded propellers for hovering have not yet become operational."
> >
> > And Dale wants the pilot sitting out in the open to be pelted by those sticks and stones. Whatever...
>
> It's already been conceded that higher disk loading is less efficient, but for a few minutes of flight, efficiency is not the main concern. As long as the electric motors and props, plus gas engine/prop can deliver enough thrust, the thing should fly. The main purpose of all these designs is to produce a VTOL aircraft that isn't limited the way conventional helicopters are with regard to cruise speed (due to retreating blade stall). That generally means compromising on the efficiency of the vertical lift parts to optimize the whole contraption for cruise speed and efficiency. Dale's design seems like a decent effort at that.
>
> Fire away.
>
> 9B

First, you either have a degree or you don't. You say you do, I respect that. This was brought up totally out of concern for potential investors who deserve to know the qualifications of the team involved. Dale has said he is not a degreed engineer, enough said. I am not an aeronautical engineer, either (but I am not requesting public funding for anything).

HP was calculated because that is how aeronautical engineers approach the problem (I can provide references on request). I simply followed what was clearly explained in these references. HP is required to move an air mass necessary to support the helicopter in hover. Thrust would be more appropriate when dealing with engines rated for thrust (which reciprocating engines are not). I calculated HP based on readily available references by aeronautical engineers. I did make one mistake, however. I used a FOM (figure of merit) of 0.75; this is WAY TOO HIGH for a VTOL (I am surprised you didn't catch it). A realistic FOM will be no higher than 0.5, probably less. This will increase the HP required proportionally. At sea level 190 hp is required just to hover; 247 hp to achieve the 1.3x figure mentioned by Dale.

You didn't challenge any of these HP calculations, just said that thrust is different from HP. Do you agree with my calculations or not? If not, post the correct calculations. I have a spreadsheet I can send you offline.

The electric motors are countering the torque of the gas engine; if the gas engine HP drops so must the electric motors or the aircraft will begin spinning.

HP (for gas engines) decreases with density altitude. If an aircraft can ONLY be flown at sea level it is not much of an aircraft!

Failure of one electric motor means a 2nd motor must be shut down for thrust balancing (as I see it).

No mention has been made of how this thing will control lateral movement while hovering (as is necessary to land on a specific spot). The only way I see this can be done is thru thrust vectoring, which will interact with vertical balancing. To rotate the aircraft while hovering (easy to do with a helicopter) will require decreasing RPMs on either the electric motors or the gas engine, either of which will interact with hovering. This will require a computer to mix these controls and the gas engine will have to be FADEC, not something you see on 912s.

The design is very top-heavy with the gas engine at the highest point. This makes the design very sensitive to wind gusts and the potential to topple over.

I had to look at the drawings several times to figure out what was happening. Not because it wasn't there, but because 1) there were differences between several drawings and 2) the whole concept of the pilot pivoting out of the bottom of the aircraft is so foreign. I will repeat: the pilot will be exposed to high velocity prop wash during takeoff and landing. This will be VERY disorientating (I wouldn't want to fly it!). The fuselage will have 2 very large openings directly opposite of each other; making it strong enough and stiff enough to support flight loads will be extremely challenging. Getting the bottom pan to seal will also be challenging.

Dale said moving the controls was not a problem because it was fly by wire. He is an experienced aircraft builder and I assume he knows what fly by wire means.

I am not interested in skewering anybody; I just want to get to the truth of the matter. It is far better to find the faults with an idea up front and either fix them or trash can it before a lot of time and money are invested in it.

Tom

[[email protected]]

Mercy sakes Tom give it a rest. Nobody is really interested in your analysis least of all anyone who is interested in donating to this project. They will get their info direct from the designer (dale) and will perform their due diligence with folks who specialize in these matters, certainly not from the many times dingleberry comments found in a site like this one. Your really not doing anyone a service debating this topic, its just more stiring of the crap pot.

[Andy Blackburn[_3_]]

On Wednesday, March 30, 2016 at 8:54:53 PM UTC-7, 2G wrote:
> On Wednesday, March 30, 2016 at 4:34:36 PM UTC-7, Andy Blackburn wrote:
> > I am hesitant to reply, because you make it so not fun, but here goes. I combined your last two posts to make it easier.
> >
> > I don't think you are an aeronautical engineer either by education (I am times 2 and Dale is by 3/4 of a degree) or by practice (Dale certainly is - he sold a bunch of the LSA he designed). We can quibble about what is or isn't adequate qualification for this sort of contraption. You have a science/engineering background so that will get you some ways, but aircraft design has a bit of art in it - especially for something like what Dale is trying. No one can say for sure how well it will work - which is why a scale model seems prudent. The design is unusual, based on some of the new, large brushless electric motors that are available now so it's an interesting use of evolving technologies.
> >
> > On Tuesday, March 22, 2016 at 8:20:12 PM UTC-7, 2G wrote:
> > > On Tuesday, March 22, 2016 at 4:02:40 AM UTC-7, DaleKramer wrote:
> > > > Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)
> > > >
> > > > https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery
> > >
> > > I will apologize for using the word "stinking" - I will let your attitude speak for itself.
> > >
> > > That said, this design is problematic. For example, you list the battery weight at 25 lb. I calculate that you will need about 100 lbs of battery (batteries cannot be discharged 100% and expect any decent lifetime). And that ONLY allows by your statement, 3-4 min of hovering. This is totally inadequate for any landing I would dare attempt. This means you will need MUCH more battery capacity than you allowed for, but I will stick to this time for the rest of the analysis.
> >
> > Fine -
> > >
> > > Using freely available references, I calculated the ideal power to hover at sea level (not climb, mind you) at 131 hp with a MTOW of 1175 lb. Using a 0.75 FOM this increases to 175 hp. At a 10,000 ft density altitude this becomes 158 and 211 hp, respectively. Clearly your design is severely under powered. It gets worse when you want to climb and be able to transition from hovering to forward flight, when some of the electric motors will have to be shut down. These same references state that VTOL aircraft have a horsepower loading of less than 2: you are more than double this.
> >
> > Be careful about translating between thrust and horsepower for a mix of gas-piston and brushless DC motors. They have very different characteristics and I don't believe Dale quoted HP on the electrics. Their output doesn't vary with altitude since the aren't aspirated.
> >
> > >
> > > I am not confused about fore and aft. The pilot is faced forward in forward flight; his position must change to an aft facing position AND rotate 90 degrees. That amounts to 2 rotations on 2 axes of 90 and 180 degrees. When, exactly does this occur, while travelling forward in level flight or while hovering? I would assume hovering because of the extreme air blast and speed brake effect. While hovering the pilot WILL be exposed to the full thrust of the main motor. The thought of attempting such a maneuver scares the hell out of me! The potential of vertigo is not just huge - it is virtually certain. Another point that went unanswered.
> >
> > Look at the picture again - as the airplane pitches up 90 degrees to go into hover the pilot's seated position rotates the opposite direction, pitching his legs down 90 degrees through the bottom of the fuselage. In essence the pilot's pitch attitude remains unchanged relative to Earth frame of reference as the aircraft pitches up around him.
> >
> > >
> > > Andy makes excellent points about the counter-rotation and stability issues. As currently envisioned, the main motor cannot be operated at full power because the electric motors would not stabilize its torque. This problem is exacerbated when the aircraft tries to transition to horizontal flight when half the electric motors would have to be shut down. Combine an electric motor failure and you have a real problem. Notice that Dale never answered my question about thrust vectoring.
> >
> > Static versus dynamic tourque. You'll get some from the friction in the propulsion system and more from dynamic application of power. Dale mentioned that canting the electric motors counteracts static torque and if they are canted properly you will get some counter-torque as you apply thrust to the all engines in unison. I can't tell you how much canting of the thrust vector is enough. Presumably there is an optimum angle and it will affect how you apply power across all propulsion systems. It's impossible for me to say whether this will represent a serious control or performance restriction.
> >
> > Electric motor failure is a concern, but with 4-6 operating at least you have some redundancy since you can't autorotate.
> > >
> > > Fly by wire? You have just become a million dollar aircraft! This is completely unrealistic. You REALLY need to consult with engineers who have ACTUALLY designed fly by wire aircraft.
> >
> > My helicopter drone is fly by wire - it really depends on what you mean by fly by wire. I doubt Dale meant electronically controlled hydraulic actuators on the aerodynamic control surfaces, which would add to cost and weight. I suspect he meant engine controls, which is not a big deal since electric motors are by definition electronically controlled.
> > >
> > > Qualifications are not important? Since the hell when? Building conventional aircraft from who knows what designs is NOT a representation of qualifications. I am approaching this whole project from the viewpoint of an unsophisticated investor; I don't particularly care what Dale does with his own money. BTW, there WERE NO aeronautical engineering schools at the time of the Wright Brothers; they invented it (they also used their OWN money!)
> > >
> > Dale is plenty experienced - asking for his sheepskin is a bit much. It's not like he's hiding anything. He's been transparent about his background and experience. People need not invest if senior year in college is more important to them than having designed and flown hundreds of examples of an aircraft.
> >
> > > Has NO ONE come forward to challenge my calculations? It has been 3 days and the only rebuttal had something weird to do about having dinner of molds.
> > >
> > > Okay, I DID leave something out, and I admit it. I forgot to mention that horsepower from carbureted engines falls off with altitude, so that 100 hp engine will only produce 70 hp at a 10,000 ft DENSITY altitude.
> > >
> > Okay. Maybe get it working at sea level first. Guys in Telluride may have to wait.
> >
> > > Here is another factoid that you will find if you bother to check my calculations: power required is INVERSELY proportional to the square root of disk area. This is simple physics, so there is NO avoiding it! Consequently, tail squatters require A LOT more horsepower. Dale's design will require nearly THREE TIMES more horsepower than an R22 simply because of the MUCH higher disk loading - that is WHY I made such a point of the HIGH disk loading. I don't have ANY idea where Dale came up with the number of 1.3X thrust to weight, maybe it was in a dream. It seems like engineering analysis is, at best, an after thought. During my career as a design engineer I can assure you we thought of it otherwise.
> >
> > I think you are confusing thrust and horsepower. 1.3 thrust to weight isn't a hot rod, but it ought to get off the ground and accelerate reasonably (about 0.3 G), or 10 ft/s/s.
> >
> >
> >
> > > Here is an interesting quote I dug up from the book by Ray Prouty (Dale, I assume that you ARE reading the reference books):
> > >
> > > "Despite the trend for higher and higher disc loadings in the past 20 years, there does seem to be a practical upper limit. Values of more than about 10 pounds per square foot generate such high induced velocities under the rotor that it is difficult to operate from unprepared sites without filling the air full of flying sticks and stones to break one's bones. It also becomes increasingly difficult to obtain safe autorotational characteristics as disc loadings go up. These are two reasons why VTOL aircraft that depend on heavily loaded propellers for hovering have not yet become operational."
> > >
> > > And Dale wants the pilot sitting out in the open to be pelted by those sticks and stones. Whatever...
> >
> > It's already been conceded that higher disk loading is less efficient, but for a few minutes of flight, efficiency is not the main concern. As long as the electric motors and props, plus gas engine/prop can deliver enough thrust, the thing should fly. The main purpose of all these designs is to produce a VTOL aircraft that isn't limited the way conventional helicopters are with regard to cruise speed (due to retreating blade stall). That generally means compromising on the efficiency of the vertical lift parts to optimize the whole contraption for cruise speed and efficiency. Dale's design seems like a decent effort at that.
> >
> > Fire away.
> >
> > 9B
>
> First, you either have a degree or you don't. You say you do, I respect that. This was brought up totally out of concern for potential investors who deserve to know the qualifications of the team involved. Dale has said he is not a degreed engineer, enough said. I am not an aeronautical engineer, either (but I am not requesting public funding for anything).
>
> HP was calculated because that is how aeronautical engineers approach the problem (I can provide references on request). I simply followed what was clearly explained in these references. HP is required to move an air mass necessary to support the helicopter in hover. Thrust would be more appropriate when dealing with engines rated for thrust (which reciprocating engines are not). I calculated HP based on readily available references by aeronautical engineers. I did make one mistake, however. I used a FOM (figure of merit) of 0.75; this is WAY TOO HIGH for a VTOL (I am surprised you didn't catch it). A realistic FOM will be no higher than 0.5, probably less. This will increase the HP required proportionally. At sea level 190 hp is required just to hover; 247 hp to achieve the 1.3x figure mentioned by Dale.
>
> You didn't challenge any of these HP calculations, just said that thrust is different from HP. Do you agree with my calculations or not? If not, post the correct calculations. I have a spreadsheet I can send you offline.
>
> The electric motors are countering the torque of the gas engine; if the gas engine HP drops so must the electric motors or the aircraft will begin spinning.
>
> HP (for gas engines) decreases with density altitude. If an aircraft can ONLY be flown at sea level it is not much of an aircraft!
>
> Failure of one electric motor means a 2nd motor must be shut down for thrust balancing (as I see it).
>
> No mention has been made of how this thing will control lateral movement while hovering (as is necessary to land on a specific spot). The only way I see this can be done is thru thrust vectoring, which will interact with vertical balancing. To rotate the aircraft while hovering (easy to do with a helicopter) will require decreasing RPMs on either the electric motors or the gas engine, either of which will interact with hovering. This will require a computer to mix these controls and the gas engine will have to be FADEC, not something you see on 912s.
>
> The design is very top-heavy with the gas engine at the highest point. This makes the design very sensitive to wind gusts and the potential to topple over.
>
> I had to look at the drawings several times to figure out what was happening. Not because it wasn't there, but because 1) there were differences between several drawings and 2) the whole concept of the pilot pivoting out of the bottom of the aircraft is so foreign. I will repeat: the pilot will be exposed to high velocity prop wash during takeoff and landing. This will be VERY disorientating (I wouldn't want to fly it!). The fuselage will have 2 very large openings directly opposite of each other; making it strong enough and stiff enough to support flight loads will be extremely challenging. Getting the bottom pan to seal will also be challenging.
>
> Dale said moving the controls was not a problem because it was fly by wire. He is an experienced aircraft builder and I assume he knows what fly by wire means.
>
> I am not interested in skewering anybody; I just want to get to the truth of the matter. It is far better to find the faults with an idea up front and either fix them or trash can it before a lot of time and money are invested in it.
>
> Tom


My prior reservations about engaging on this have been confirmed.

I welcome a good rational debate in the spirit of learning something new - and I am sure you think you are making salient points Tom, but what people not inside your head are seeing is this:

https://www.youtube.com/watch?v=hnTmBjk-M0c

I wish I could be more helpful, but I can see where this is going. It's a familiar road. At least I was able to clear up the nutating pilot matter. ;-)

Hope you get to build the model Dale. It's an interesting experiment worth my $100.

9B

[Jonathan St. Cloud]

Golly a guy named Will Schumann, was not a degreed aeronautical engineer either. Wonder why in the 80's all the wing platforms went from a straight leading edge and a tapered trailing edge to a tapered leading edge and a straight trailing edge. It was not the design work of famous engineers with university wind tunnels. Just a really smart guy who watched some soaring birds fly and realized the taper of their leading edge looked like a good design (God designed). Just saying. While I certainly am an advocate for higher education, nothing beats being sharp.


On Wednesday, March 30, 2016 at 10:36:34 PM UTC-7, Andy Blackburn wrote:
> On Wednesday, March 30, 2016 at 8:54:53 PM UTC-7, 2G wrote:
> > On Wednesday, March 30, 2016 at 4:34:36 PM UTC-7, Andy Blackburn wrote:
> > > I am hesitant to reply, because you make it so not fun, but here goes.. I combined your last two posts to make it easier.
> > >
> > > I don't think you are an aeronautical engineer either by education (I am times 2 and Dale is by 3/4 of a degree) or by practice (Dale certainly is - he sold a bunch of the LSA he designed). We can quibble about what is or isn't adequate qualification for this sort of contraption. You have a science/engineering background so that will get you some ways, but aircraft design has a bit of art in it - especially for something like what Dale is trying. No one can say for sure how well it will work - which is why a scale model seems prudent. The design is unusual, based on some of the new, large brushless electric motors that are available now so it's an interesting use of evolving technologies.
> > >
> > > On Tuesday, March 22, 2016 at 8:20:12 PM UTC-7, 2G wrote:
> > > > On Tuesday, March 22, 2016 at 4:02:40 AM UTC-7, DaleKramer wrote:
> > > > > Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)
> > > > >
> > > > > https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery
> > > >
> > > > I will apologize for using the word "stinking" - I will let your attitude speak for itself.
> > > >
> > > > That said, this design is problematic. For example, you list the battery weight at 25 lb. I calculate that you will need about 100 lbs of battery (batteries cannot be discharged 100% and expect any decent lifetime). And that ONLY allows by your statement, 3-4 min of hovering. This is totally inadequate for any landing I would dare attempt. This means you will need MUCH more battery capacity than you allowed for, but I will stick to this time for the rest of the analysis.
> > >
> > > Fine -
> > > >
> > > > Using freely available references, I calculated the ideal power to hover at sea level (not climb, mind you) at 131 hp with a MTOW of 1175 lb. Using a 0.75 FOM this increases to 175 hp. At a 10,000 ft density altitude this becomes 158 and 211 hp, respectively. Clearly your design is severely under powered. It gets worse when you want to climb and be able to transition from hovering to forward flight, when some of the electric motors will have to be shut down. These same references state that VTOL aircraft have a horsepower loading of less than 2: you are more than double this.
> > >
> > > Be careful about translating between thrust and horsepower for a mix of gas-piston and brushless DC motors. They have very different characteristics and I don't believe Dale quoted HP on the electrics. Their output doesn't vary with altitude since the aren't aspirated.
> > >
> > > >
> > > > I am not confused about fore and aft. The pilot is faced forward in forward flight; his position must change to an aft facing position AND rotate 90 degrees. That amounts to 2 rotations on 2 axes of 90 and 180 degrees.. When, exactly does this occur, while travelling forward in level flight or while hovering? I would assume hovering because of the extreme air blast and speed brake effect. While hovering the pilot WILL be exposed to the full thrust of the main motor. The thought of attempting such a maneuver scares the hell out of me! The potential of vertigo is not just huge - it is virtually certain. Another point that went unanswered.
> > >
> > > Look at the picture again - as the airplane pitches up 90 degrees to go into hover the pilot's seated position rotates the opposite direction, pitching his legs down 90 degrees through the bottom of the fuselage. In essence the pilot's pitch attitude remains unchanged relative to Earth frame of reference as the aircraft pitches up around him.
> > >
> > > >
> > > > Andy makes excellent points about the counter-rotation and stability issues. As currently envisioned, the main motor cannot be operated at full power because the electric motors would not stabilize its torque. This problem is exacerbated when the aircraft tries to transition to horizontal flight when half the electric motors would have to be shut down. Combine an electric motor failure and you have a real problem. Notice that Dale never answered my question about thrust vectoring.
> > >
> > > Static versus dynamic tourque. You'll get some from the friction in the propulsion system and more from dynamic application of power. Dale mentioned that canting the electric motors counteracts static torque and if they are canted properly you will get some counter-torque as you apply thrust to the all engines in unison. I can't tell you how much canting of the thrust vector is enough. Presumably there is an optimum angle and it will affect how you apply power across all propulsion systems. It's impossible for me to say whether this will represent a serious control or performance restriction.
> > >
> > > Electric motor failure is a concern, but with 4-6 operating at least you have some redundancy since you can't autorotate.
> > > >
> > > > Fly by wire? You have just become a million dollar aircraft! This is completely unrealistic. You REALLY need to consult with engineers who have ACTUALLY designed fly by wire aircraft.
> > >
> > > My helicopter drone is fly by wire - it really depends on what you mean by fly by wire. I doubt Dale meant electronically controlled hydraulic actuators on the aerodynamic control surfaces, which would add to cost and weight. I suspect he meant engine controls, which is not a big deal since electric motors are by definition electronically controlled.
> > > >
> > > > Qualifications are not important? Since the hell when? Building conventional aircraft from who knows what designs is NOT a representation of qualifications. I am approaching this whole project from the viewpoint of an unsophisticated investor; I don't particularly care what Dale does with his own money. BTW, there WERE NO aeronautical engineering schools at the time of the Wright Brothers; they invented it (they also used their OWN money!)
> > > >
> > > Dale is plenty experienced - asking for his sheepskin is a bit much. It's not like he's hiding anything. He's been transparent about his background and experience. People need not invest if senior year in college is more important to them than having designed and flown hundreds of examples of an aircraft.
> > >
> > > > Has NO ONE come forward to challenge my calculations? It has been 3 days and the only rebuttal had something weird to do about having dinner of molds.
> > > >
> > > > Okay, I DID leave something out, and I admit it. I forgot to mention that horsepower from carbureted engines falls off with altitude, so that 100 hp engine will only produce 70 hp at a 10,000 ft DENSITY altitude.
> > > >
> > > Okay. Maybe get it working at sea level first. Guys in Telluride may have to wait.
> > >
> > > > Here is another factoid that you will find if you bother to check my calculations: power required is INVERSELY proportional to the square root of disk area. This is simple physics, so there is NO avoiding it! Consequently, tail squatters require A LOT more horsepower. Dale's design will require nearly THREE TIMES more horsepower than an R22 simply because of the MUCH higher disk loading - that is WHY I made such a point of the HIGH disk loading. I don't have ANY idea where Dale came up with the number of 1.3X thrust to weight, maybe it was in a dream. It seems like engineering analysis is, at best, an after thought. During my career as a design engineer I can assure you we thought of it otherwise.
> > >
> > > I think you are confusing thrust and horsepower. 1.3 thrust to weight isn't a hot rod, but it ought to get off the ground and accelerate reasonably (about 0.3 G), or 10 ft/s/s.
> > >
> > >
> > >
> > > > Here is an interesting quote I dug up from the book by Ray Prouty (Dale, I assume that you ARE reading the reference books):
> > > >
> > > > "Despite the trend for higher and higher disc loadings in the past 20 years, there does seem to be a practical upper limit. Values of more than about 10 pounds per square foot generate such high induced velocities under the rotor that it is difficult to operate from unprepared sites without filling the air full of flying sticks and stones to break one's bones. It also becomes increasingly difficult to obtain safe autorotational characteristics as disc loadings go up. These are two reasons why VTOL aircraft that depend on heavily loaded propellers for hovering have not yet become operational."
> > > >
> > > > And Dale wants the pilot sitting out in the open to be pelted by those sticks and stones. Whatever...
> > >
> > > It's already been conceded that higher disk loading is less efficient, but for a few minutes of flight, efficiency is not the main concern. As long as the electric motors and props, plus gas engine/prop can deliver enough thrust, the thing should fly. The main purpose of all these designs is to produce a VTOL aircraft that isn't limited the way conventional helicopters are with regard to cruise speed (due to retreating blade stall). That generally means compromising on the efficiency of the vertical lift parts to optimize the whole contraption for cruise speed and efficiency. Dale's design seems like a decent effort at that.
> > >
> > > Fire away.
> > >
> > > 9B
> >
> > First, you either have a degree or you don't. You say you do, I respect that. This was brought up totally out of concern for potential investors who deserve to know the qualifications of the team involved. Dale has said he is not a degreed engineer, enough said. I am not an aeronautical engineer, either (but I am not requesting public funding for anything).
> >
> > HP was calculated because that is how aeronautical engineers approach the problem (I can provide references on request). I simply followed what was clearly explained in these references. HP is required to move an air mass necessary to support the helicopter in hover. Thrust would be more appropriate when dealing with engines rated for thrust (which reciprocating engines are not). I calculated HP based on readily available references by aeronautical engineers. I did make one mistake, however. I used a FOM (figure of merit) of 0.75; this is WAY TOO HIGH for a VTOL (I am surprised you didn't catch it). A realistic FOM will be no higher than 0.5, probably less. This will increase the HP required proportionally. At sea level 190 hp is required just to hover; 247 hp to achieve the 1.3x figure mentioned by Dale.
> >
> > You didn't challenge any of these HP calculations, just said that thrust is different from HP. Do you agree with my calculations or not? If not, post the correct calculations. I have a spreadsheet I can send you offline.
> >
> > The electric motors are countering the torque of the gas engine; if the gas engine HP drops so must the electric motors or the aircraft will begin spinning.
> >
> > HP (for gas engines) decreases with density altitude. If an aircraft can ONLY be flown at sea level it is not much of an aircraft!
> >
> > Failure of one electric motor means a 2nd motor must be shut down for thrust balancing (as I see it).
> >
> > No mention has been made of how this thing will control lateral movement while hovering (as is necessary to land on a specific spot). The only way I see this can be done is thru thrust vectoring, which will interact with vertical balancing. To rotate the aircraft while hovering (easy to do with a helicopter) will require decreasing RPMs on either the electric motors or the gas engine, either of which will interact with hovering. This will require a computer to mix these controls and the gas engine will have to be FADEC, not something you see on 912s.
> >
> > The design is very top-heavy with the gas engine at the highest point. This makes the design very sensitive to wind gusts and the potential to topple over.
> >
> > I had to look at the drawings several times to figure out what was happening. Not because it wasn't there, but because 1) there were differences between several drawings and 2) the whole concept of the pilot pivoting out of the bottom of the aircraft is so foreign. I will repeat: the pilot will be exposed to high velocity prop wash during takeoff and landing. This will be VERY disorientating (I wouldn't want to fly it!). The fuselage will have 2 very large openings directly opposite of each other; making it strong enough and stiff enough to support flight loads will be extremely challenging. Getting the bottom pan to seal will also be challenging.
> >
> > Dale said moving the controls was not a problem because it was fly by wire. He is an experienced aircraft builder and I assume he knows what fly by wire means.
> >
> > I am not interested in skewering anybody; I just want to get to the truth of the matter. It is far better to find the faults with an idea up front and either fix them or trash can it before a lot of time and money are invested in it.
> >
> > Tom
>
>
> My prior reservations about engaging on this have been confirmed.
>
> I welcome a good rational debate in the spirit of learning something new - and I am sure you think you are making salient points Tom, but what people not inside your head are seeing is this:
>
> https://www.youtube.com/watch?v=hnTmBjk-M0c
>
> I wish I could be more helpful, but I can see where this is going. It's a familiar road. At least I was able to clear up the nutating pilot matter. ;-)
>
> Hope you get to build the model Dale. It's an interesting experiment worth my $100.
>
> 9B

[2G]

On Wednesday, March 30, 2016 at 10:36:34 PM UTC-7, Andy Blackburn wrote:
> On Wednesday, March 30, 2016 at 8:54:53 PM UTC-7, 2G wrote:
> > On Wednesday, March 30, 2016 at 4:34:36 PM UTC-7, Andy Blackburn wrote:
> > > I am hesitant to reply, because you make it so not fun, but here goes.. I combined your last two posts to make it easier.
> > >
> > > I don't think you are an aeronautical engineer either by education (I am times 2 and Dale is by 3/4 of a degree) or by practice (Dale certainly is - he sold a bunch of the LSA he designed). We can quibble about what is or isn't adequate qualification for this sort of contraption. You have a science/engineering background so that will get you some ways, but aircraft design has a bit of art in it - especially for something like what Dale is trying. No one can say for sure how well it will work - which is why a scale model seems prudent. The design is unusual, based on some of the new, large brushless electric motors that are available now so it's an interesting use of evolving technologies.
> > >
> > > On Tuesday, March 22, 2016 at 8:20:12 PM UTC-7, 2G wrote:
> > > > On Tuesday, March 22, 2016 at 4:02:40 AM UTC-7, DaleKramer wrote:
> > > > > Looks like this is the kind of project that gets funded nowadays on Kickstarter, the world will be such a better place :)
> > > > >
> > > > > https://www.kickstarter.com/projects/darkcultgames/engineers-excuse-dice?ref=discovery
> > > >
> > > > I will apologize for using the word "stinking" - I will let your attitude speak for itself.
> > > >
> > > > That said, this design is problematic. For example, you list the battery weight at 25 lb. I calculate that you will need about 100 lbs of battery (batteries cannot be discharged 100% and expect any decent lifetime). And that ONLY allows by your statement, 3-4 min of hovering. This is totally inadequate for any landing I would dare attempt. This means you will need MUCH more battery capacity than you allowed for, but I will stick to this time for the rest of the analysis.
> > >
> > > Fine -
> > > >
> > > > Using freely available references, I calculated the ideal power to hover at sea level (not climb, mind you) at 131 hp with a MTOW of 1175 lb. Using a 0.75 FOM this increases to 175 hp. At a 10,000 ft density altitude this becomes 158 and 211 hp, respectively. Clearly your design is severely under powered. It gets worse when you want to climb and be able to transition from hovering to forward flight, when some of the electric motors will have to be shut down. These same references state that VTOL aircraft have a horsepower loading of less than 2: you are more than double this.
> > >
> > > Be careful about translating between thrust and horsepower for a mix of gas-piston and brushless DC motors. They have very different characteristics and I don't believe Dale quoted HP on the electrics. Their output doesn't vary with altitude since the aren't aspirated.
> > >
> > > >
> > > > I am not confused about fore and aft. The pilot is faced forward in forward flight; his position must change to an aft facing position AND rotate 90 degrees. That amounts to 2 rotations on 2 axes of 90 and 180 degrees.. When, exactly does this occur, while travelling forward in level flight or while hovering? I would assume hovering because of the extreme air blast and speed brake effect. While hovering the pilot WILL be exposed to the full thrust of the main motor. The thought of attempting such a maneuver scares the hell out of me! The potential of vertigo is not just huge - it is virtually certain. Another point that went unanswered.
> > >
> > > Look at the picture again - as the airplane pitches up 90 degrees to go into hover the pilot's seated position rotates the opposite direction, pitching his legs down 90 degrees through the bottom of the fuselage. In essence the pilot's pitch attitude remains unchanged relative to Earth frame of reference as the aircraft pitches up around him.
> > >
> > > >
> > > > Andy makes excellent points about the counter-rotation and stability issues. As currently envisioned, the main motor cannot be operated at full power because the electric motors would not stabilize its torque. This problem is exacerbated when the aircraft tries to transition to horizontal flight when half the electric motors would have to be shut down. Combine an electric motor failure and you have a real problem. Notice that Dale never answered my question about thrust vectoring.
> > >
> > > Static versus dynamic tourque. You'll get some from the friction in the propulsion system and more from dynamic application of power. Dale mentioned that canting the electric motors counteracts static torque and if they are canted properly you will get some counter-torque as you apply thrust to the all engines in unison. I can't tell you how much canting of the thrust vector is enough. Presumably there is an optimum angle and it will affect how you apply power across all propulsion systems. It's impossible for me to say whether this will represent a serious control or performance restriction.
> > >
> > > Electric motor failure is a concern, but with 4-6 operating at least you have some redundancy since you can't autorotate.
> > > >
> > > > Fly by wire? You have just become a million dollar aircraft! This is completely unrealistic. You REALLY need to consult with engineers who have ACTUALLY designed fly by wire aircraft.
> > >
> > > My helicopter drone is fly by wire - it really depends on what you mean by fly by wire. I doubt Dale meant electronically controlled hydraulic actuators on the aerodynamic control surfaces, which would add to cost and weight. I suspect he meant engine controls, which is not a big deal since electric motors are by definition electronically controlled.
> > > >
> > > > Qualifications are not important? Since the hell when? Building conventional aircraft from who knows what designs is NOT a representation of qualifications. I am approaching this whole project from the viewpoint of an unsophisticated investor; I don't particularly care what Dale does with his own money. BTW, there WERE NO aeronautical engineering schools at the time of the Wright Brothers; they invented it (they also used their OWN money!)
> > > >
> > > Dale is plenty experienced - asking for his sheepskin is a bit much. It's not like he's hiding anything. He's been transparent about his background and experience. People need not invest if senior year in college is more important to them than having designed and flown hundreds of examples of an aircraft.
> > >
> > > > Has NO ONE come forward to challenge my calculations? It has been 3 days and the only rebuttal had something weird to do about having dinner of molds.
> > > >
> > > > Okay, I DID leave something out, and I admit it. I forgot to mention that horsepower from carbureted engines falls off with altitude, so that 100 hp engine will only produce 70 hp at a 10,000 ft DENSITY altitude.
> > > >
> > > Okay. Maybe get it working at sea level first. Guys in Telluride may have to wait.
> > >
> > > > Here is another factoid that you will find if you bother to check my calculations: power required is INVERSELY proportional to the square root of disk area. This is simple physics, so there is NO avoiding it! Consequently, tail squatters require A LOT more horsepower. Dale's design will require nearly THREE TIMES more horsepower than an R22 simply because of the MUCH higher disk loading - that is WHY I made such a point of the HIGH disk loading. I don't have ANY idea where Dale came up with the number of 1.3X thrust to weight, maybe it was in a dream. It seems like engineering analysis is, at best, an after thought. During my career as a design engineer I can assure you we thought of it otherwise.
> > >
> > > I think you are confusing thrust and horsepower. 1.3 thrust to weight isn't a hot rod, but it ought to get off the ground and accelerate reasonably (about 0.3 G), or 10 ft/s/s.
> > >
> > >
> > >
> > > > Here is an interesting quote I dug up from the book by Ray Prouty (Dale, I assume that you ARE reading the reference books):
> > > >
> > > > "Despite the trend for higher and higher disc loadings in the past 20 years, there does seem to be a practical upper limit. Values of more than about 10 pounds per square foot generate such high induced velocities under the rotor that it is difficult to operate from unprepared sites without filling the air full of flying sticks and stones to break one's bones. It also becomes increasingly difficult to obtain safe autorotational characteristics as disc loadings go up. These are two reasons why VTOL aircraft that depend on heavily loaded propellers for hovering have not yet become operational."
> > > >
> > > > And Dale wants the pilot sitting out in the open to be pelted by those sticks and stones. Whatever...
> > >
> > > It's already been conceded that higher disk loading is less efficient, but for a few minutes of flight, efficiency is not the main concern. As long as the electric motors and props, plus gas engine/prop can deliver enough thrust, the thing should fly. The main purpose of all these designs is to produce a VTOL aircraft that isn't limited the way conventional helicopters are with regard to cruise speed (due to retreating blade stall). That generally means compromising on the efficiency of the vertical lift parts to optimize the whole contraption for cruise speed and efficiency. Dale's design seems like a decent effort at that.
> > >
> > > Fire away.
> > >
> > > 9B
> >
> > First, you either have a degree or you don't. You say you do, I respect that. This was brought up totally out of concern for potential investors who deserve to know the qualifications of the team involved. Dale has said he is not a degreed engineer, enough said. I am not an aeronautical engineer, either (but I am not requesting public funding for anything).
> >
> > HP was calculated because that is how aeronautical engineers approach the problem (I can provide references on request). I simply followed what was clearly explained in these references. HP is required to move an air mass necessary to support the helicopter in hover. Thrust would be more appropriate when dealing with engines rated for thrust (which reciprocating engines are not). I calculated HP based on readily available references by aeronautical engineers. I did make one mistake, however. I used a FOM (figure of merit) of 0.75; this is WAY TOO HIGH for a VTOL (I am surprised you didn't catch it). A realistic FOM will be no higher than 0.5, probably less. This will increase the HP required proportionally. At sea level 190 hp is required just to hover; 247 hp to achieve the 1.3x figure mentioned by Dale.
> >
> > You didn't challenge any of these HP calculations, just said that thrust is different from HP. Do you agree with my calculations or not? If not, post the correct calculations. I have a spreadsheet I can send you offline.
> >
> > The electric motors are countering the torque of the gas engine; if the gas engine HP drops so must the electric motors or the aircraft will begin spinning.
> >
> > HP (for gas engines) decreases with density altitude. If an aircraft can ONLY be flown at sea level it is not much of an aircraft!
> >
> > Failure of one electric motor means a 2nd motor must be shut down for thrust balancing (as I see it).
> >
> > No mention has been made of how this thing will control lateral movement while hovering (as is necessary to land on a specific spot). The only way I see this can be done is thru thrust vectoring, which will interact with vertical balancing. To rotate the aircraft while hovering (easy to do with a helicopter) will require decreasing RPMs on either the electric motors or the gas engine, either of which will interact with hovering. This will require a computer to mix these controls and the gas engine will have to be FADEC, not something you see on 912s.
> >
> > The design is very top-heavy with the gas engine at the highest point. This makes the design very sensitive to wind gusts and the potential to topple over.
> >
> > I had to look at the drawings several times to figure out what was happening. Not because it wasn't there, but because 1) there were differences between several drawings and 2) the whole concept of the pilot pivoting out of the bottom of the aircraft is so foreign. I will repeat: the pilot will be exposed to high velocity prop wash during takeoff and landing. This will be VERY disorientating (I wouldn't want to fly it!). The fuselage will have 2 very large openings directly opposite of each other; making it strong enough and stiff enough to support flight loads will be extremely challenging. Getting the bottom pan to seal will also be challenging.
> >
> > Dale said moving the controls was not a problem because it was fly by wire. He is an experienced aircraft builder and I assume he knows what fly by wire means.
> >
> > I am not interested in skewering anybody; I just want to get to the truth of the matter. It is far better to find the faults with an idea up front and either fix them or trash can it before a lot of time and money are invested in it.
> >
> > Tom
>
>
> My prior reservations about engaging on this have been confirmed.
>
> I welcome a good rational debate in the spirit of learning something new - and I am sure you think you are making salient points Tom, but what people not inside your head are seeing is this:
>
> https://www.youtube.com/watch?v=hnTmBjk-M0c
>
> I wish I could be more helpful, but I can see where this is going. It's a familiar road. At least I was able to clear up the nutating pilot matter. ;-)
>
> Hope you get to build the model Dale. It's an interesting experiment worth my $100.
>
> 9B

My apologies: I thought you were actually interested in discussion the technical details of the design. I guess by your non-response my calculations are correct...

[2G]

On Wednesday, March 30, 2016 at 10:02:46 PM UTC-7, wrote:
> Mercy sakes Tom give it a rest. Nobody is really interested in your analysis least of all anyone who is interested in donating to this project. They will get their info direct from the designer (dale) and will perform their due diligence with folks who specialize in these matters, certainly not from the many times dingleberry comments found in a site like this one. Your really not doing anyone a service debating this topic, its just more stiring of the crap pot.

I am SO GLAD that you know what EVERYBODY else is thinking! Now we can just go to you to settle all controversies. BTW I HAD given it a rest until I thought that Andy was actually interested in the technical aspects. Maybe you should tell Andy to give it a rest also. Oh, I guess you just want critical commenters to take a rest. Maybe you can follow this up with a lecture on the First Amendment...

[Andy Blackburn[_3_]]

Sorry Tom - it was devolving into points that were narrower and narrower and mostly not relevant to the fundamental issues, seemingly so you can avoid conceding any points made by others.

There are some legitimate technical issues to figure out. I just don't see anything inherent in this that says the thing can't fly, and believe me helicopters of any type are full of issues. Might the thing benefit from more horsepower? Maybe. Might it kick up dust if you fly it off dry dirt and a bed of twigs? Probably. Will it hover at 10,000 MSL on a hot day? I'd bet a number of helicopters have trouble with that. Will it autorotate? Nope, but it has extra motors. Enough? Maybe, maybe not. Might it be a bit tippy with the motor up front? I think it might, but thinking that doesn't make it an insurmountable problem or Dale a charlatan.

When I worked on helicopters as an engineer at NASA Ames I saw all kinds of crazy crap that clever people made work, some with PhDs in Aero, some who were mechanics. It is the trying that drives progress. I give Dale credit for trying.

[BobW]

<Major snip...>
>
> My apologies: I thought you were actually interested in discussion the
> technical details of the design. I guess by your non-response my
> calculations are correct...
>

They may be or they may not be, and if you're designing such a craft as Dale
Kramer is attempting, I've no doubt you can find qualified people to look over
your shoulder. This is America, have at it!

Given the original topic of this thread (which I took as a "Hey guys! Lookit
this...and oh by the way, here's how you can kick in some money if you're
sufficiently interested in funding further experimentation." sort of post),
"your calculations" seem to have become something of a
terribly-important-to-you sub-focus...probably more important to you than to
many/most of the original intended audience.

I offer this opinion as a degreed aerospace engineer having little
personal/user interest in hybrid VTOL flight, "hybrid" in this context meaning
capable of (some) verticality but of primarily "fixed-wings-based" horizontal
capability. Given today's materials, I simply don't see "serious practicality"
on any near horizon for it...similar in that sense to (say) man-powered
flight. Nevertheless, both are technically interesting (to many, including
me); both have been successfully performed; both will (probably) continue to
be investigated and perhaps even advanced (maybe even in my lifetime). And if
you somehow or other engage my interest sufficiently, I might even be
motivated into "calculation checking" beyond merely noting something I've
missed seeing anyone else note, i.e. that the "main prop atop" configuration
is arguably inherently stable in descending, vertically-oriented, flight
simply by the expedient of momentarily lessening "lower down" thrust. That's
not to suggest the physics of such flight are simple, but to rather suggest
the "balancing a pencil upon one's fingertip" analogy previously noted herein
is more appropriate for a rear-exhaust rocket than a "top-biased descender."

Respectfully,
Bob W.

[Andy Blackburn[_3_]]

On Thursday, March 31, 2016 at 10:20:59 AM UTC-7, BobW wrote:
> <Major snip...>
> >
> > My apologies: I thought you were actually interested in discussion the
> > technical details of the design. I guess by your non-response my
> > calculations are correct...
> >
>
> They may be or they may not be, and if you're designing such a craft as Dale
> Kramer is attempting, I've no doubt you can find qualified people to look over
> your shoulder. This is America, have at it!
>
> Given the original topic of this thread (which I took as a "Hey guys! Lookit
> this...and oh by the way, here's how you can kick in some money if you're
> sufficiently interested in funding further experimentation." sort of post),
> "your calculations" seem to have become something of a
> terribly-important-to-you sub-focus...probably more important to you than to
> many/most of the original intended audience.
>
> I offer this opinion as a degreed aerospace engineer having little
> personal/user interest in hybrid VTOL flight, "hybrid" in this context meaning
> capable of (some) verticality but of primarily "fixed-wings-based" horizontal
> capability. Given today's materials, I simply don't see "serious practicality"
> on any near horizon for it...similar in that sense to (say) man-powered
> flight. Nevertheless, both are technically interesting (to many, including
> me); both have been successfully performed; both will (probably) continue to
> be investigated and perhaps even advanced (maybe even in my lifetime). And if
> you somehow or other engage my interest sufficiently, I might even be
> motivated into "calculation checking" beyond merely noting something I've
> missed seeing anyone else note, i.e. that the "main prop atop" configuration
> is arguably inherently stable in descending, vertically-oriented, flight
> simply by the expedient of momentarily lessening "lower down" thrust. That's
> not to suggest the physics of such flight are simple, but to rather suggest
> the "balancing a pencil upon one's fingertip" analogy previously noted herein
> is more appropriate for a rear-exhaust rocket than a "top-biased descender."
>
> Respectfully,
> Bob W.


Excellent points Bob.

I was thinking more that half the thrust was via electric motors down low and half was from the main reciprocating motor that put a lot of weight up high, but only half the thrust at the stable "on top" location, so it's a bit of a mix that could influence the dynamics of the transition from vertical to horizontal flight. I agree the balancing a pencil analogy really isn't proper for a number of reasons.

VTOL is an heroic act, pretty much no matter how you go about it.

Andy

[[email protected]]

On Thursday, March 31, 2016 at 3:14:00 PM UTC-5, Andy Blackburn wrote:
> On Thursday, March 31, 2016 at 10:20:59 AM UTC-7, BobW wrote:
> > <Major snip...>
> > >
> > > My apologies: I thought you were actually interested in discussion the
> > > technical details of the design. I guess by your non-response my
> > > calculations are correct...
> > >
> >
> > They may be or they may not be, and if you're designing such a craft as Dale
> > Kramer is attempting, I've no doubt you can find qualified people to look over
> > your shoulder. This is America, have at it!
> >
> > Given the original topic of this thread (which I took as a "Hey guys! Lookit
> > this...and oh by the way, here's how you can kick in some money if you're
> > sufficiently interested in funding further experimentation." sort of post),
> > "your calculations" seem to have become something of a
> > terribly-important-to-you sub-focus...probably more important to you than to
> > many/most of the original intended audience.
> >
> > I offer this opinion as a degreed aerospace engineer having little
> > personal/user interest in hybrid VTOL flight, "hybrid" in this context meaning
> > capable of (some) verticality but of primarily "fixed-wings-based" horizontal
> > capability. Given today's materials, I simply don't see "serious practicality"
> > on any near horizon for it...similar in that sense to (say) man-powered
> > flight. Nevertheless, both are technically interesting (to many, including
> > me); both have been successfully performed; both will (probably) continue to
> > be investigated and perhaps even advanced (maybe even in my lifetime). And if
> > you somehow or other engage my interest sufficiently, I might even be
> > motivated into "calculation checking" beyond merely noting something I've
> > missed seeing anyone else note, i.e. that the "main prop atop" configuration
> > is arguably inherently stable in descending, vertically-oriented, flight
> > simply by the expedient of momentarily lessening "lower down" thrust. That's
> > not to suggest the physics of such flight are simple, but to rather suggest
> > the "balancing a pencil upon one's fingertip" analogy previously noted herein
> > is more appropriate for a rear-exhaust rocket than a "top-biased descender."
> >
> > Respectfully,
> > Bob W.
>
>
> Excellent points Bob.
>
> I was thinking more that half the thrust was via electric motors down low and half was from the main reciprocating motor that put a lot of weight up high, but only half the thrust at the stable "on top" location, so it's a bit of a mix that could influence the dynamics of the transition from vertical to horizontal flight. I agree the balancing a pencil analogy really isn't proper for a number of reasons.
>
>
>
> Andy

"VTOL is an heroic act, pretty much no matter how you go about it."
12-year olds with drones do it every day, thanks to cheap flight controllers containing super-cheap gyros and accelerometers. I can teach a caveman to fly one of those in 10 min.
Herb

[Andy Blackburn[_3_]]

Ture - I have a closet full of FAA-licensed drones - and others. All the modern cheap GPS, accelerometers and brushless motors have been a revolution. Making it all human scale and reliable and safe under all the possible failure modes (especially loss of a motor when you can't auto-rotate) and hanging the aircraft off of whirling machinery is where the heroism comes in. The V-22 had lots of problems and is still a bit of a nightmare. That Moeller flying car with ducted fans everywhere was a mess. There were many others in all shapes and forms. Each had its own unique way to kill you. Dale's approach simplifies many things but also has its own unique new challenges.

Andy

[2G]

On Thursday, March 31, 2016 at 9:29:07 AM UTC-7, Andy Blackburn wrote:
> Sorry Tom - it was devolving into points that were narrower and narrower and mostly not relevant to the fundamental issues, seemingly so you can avoid conceding any points made by others.
>
> There are some legitimate technical issues to figure out. I just don't see anything inherent in this that says the thing can't fly, and believe me helicopters of any type are full of issues. Might the thing benefit from more horsepower? Maybe. Might it kick up dust if you fly it off dry dirt and a bed of twigs? Probably. Will it hover at 10,000 MSL on a hot day? I'd bet a number of helicopters have trouble with that. Will it autorotate? Nope, but it has extra motors. Enough? Maybe, maybe not. Might it be a bit tippy with the motor up front? I think it might, but thinking that doesn't make it an insurmountable problem or Dale a charlatan.
>
> When I worked on helicopters as an engineer at NASA Ames I saw all kinds of crazy crap that clever people made work, some with PhDs in Aero, some who were mechanics. It is the trying that drives progress. I give Dale credit for trying.

I give Dale credit for trying too. But trying isn't enough; you also want to have a good chance at succeeding. Design reviews, by there very nature, can be brutal - but they are essential. I am sure you encountered that at Ames.

BTW, the 10k density altitude issue is encountered at airports at 6,000 MSL in the summertime.

[Eric Greenwell[_4_]]

wrote on 3/30/2016 10:02 PM:
> anyone who is interested in donating to this project.

"Donating" is an important distinction in this situation: "donators" -
that's people like me, who send Dale money - are not investing in his
project, and all he guarantees us is reports on his effort, and a poster
or small-medium-large model of the design. "Investors" hope to make
money by owning part of the company, or an entitlement to a portion of
the profit; Dale promises none of that.

If Dale builds that scale model and flies it, successfully or not, I
will think my donation was well-used.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[BobW]

> "VTOL is an heroic act, pretty much no matter how you go about it." 12-year
> olds with drones do it every day, thanks to cheap flight controllers
> containing super-cheap gyros and accelerometers. I can teach a caveman to
> fly one of those in 10 min. Herb
>

Perhaps at the risk of offending troglodytes, maybe I need to spend more time
in caves? Or maybe especially so with VTOL craft, the devil really *is* in the
details.

The quad-copter drone In-law Santa gifted this past Christmas has escaped four
or five times, enjoyed several nights out following two of the escapes, and -
despite having only a five-minute-to-props-stopped "fuel load" - has so far
been successfully piloted-by-me to a single-flight-to-fuel-exhaustion
touchdown exactly once. Every other flight has been terminated because escape
or disaster was imminent, or, (following escapes) desperation-inspired
throttle chopping. By comparison, controlling RC sailplanes is considerably
easier to both predict and accomplish, in my experience.

Bob - VTOL-challenged? - W.

[2G]

On Thursday, March 31, 2016 at 10:20:59 AM UTC-7, BobW wrote:
> <Major snip...>
> >
> > My apologies: I thought you were actually interested in discussion the
> > technical details of the design. I guess by your non-response my
> > calculations are correct...
> >
>
> They may be or they may not be, and if you're designing such a craft as Dale
> Kramer is attempting, I've no doubt you can find qualified people to look over
> your shoulder. This is America, have at it!
>
> Given the original topic of this thread (which I took as a "Hey guys! Lookit
> this...and oh by the way, here's how you can kick in some money if you're
> sufficiently interested in funding further experimentation." sort of post),
> "your calculations" seem to have become something of a
> terribly-important-to-you sub-focus...probably more important to you than to
> many/most of the original intended audience.
>
> I offer this opinion as a degreed aerospace engineer having little
> personal/user interest in hybrid VTOL flight, "hybrid" in this context meaning
> capable of (some) verticality but of primarily "fixed-wings-based" horizontal
> capability. Given today's materials, I simply don't see "serious practicality"
> on any near horizon for it...similar in that sense to (say) man-powered
> flight. Nevertheless, both are technically interesting (to many, including
> me); both have been successfully performed; both will (probably) continue to
> be investigated and perhaps even advanced (maybe even in my lifetime). And if
> you somehow or other engage my interest sufficiently, I might even be
> motivated into "calculation checking" beyond merely noting something I've
> missed seeing anyone else note, i.e. that the "main prop atop" configuration
> is arguably inherently stable in descending, vertically-oriented, flight
> simply by the expedient of momentarily lessening "lower down" thrust. That's
> not to suggest the physics of such flight are simple, but to rather suggest
> the "balancing a pencil upon one's fingertip" analogy previously noted herein
> is more appropriate for a rear-exhaust rocket than a "top-biased descender."
>
> Respectfully,
> Bob W.

I never viewed stability in hover as an issue. After all, there are 6 thrusters at a decent distance from the CG that can be used to balance the a/c (quad copters do it routinely). The susceptibility of the a/c to toppling in ground winds is a different issue (imagine a 30 kt gust just as the a/c was touching down). Another issue is the pilot/seat pan will become a huge airbrake as the a/c is transitioning from horizontal to vertical flight. This will produce a pitching down moment while the a/c is trying to pitch up. The seat pan, be automatically driven, could be part of an unintentional positive feedback loop (the a/c pitches down due to drag, followed by pitch up when the seat pan retracts, then repeat the last two actions).

The power calculation is very simple and can be found in numerous references. Here is one very good one (pg. 9-5):
http://web.aeromech.usyd.edu.au/AERO4206/Documents/p-401.pdf

I have already explained my motivation: providing a fact-based critic for potential investors. I have had CEOs flat-out lie to me about their company's situation (Country Wide Financial, Massey Energy); if someone had exposed those lies to me it could have saved me thousands of dollars (this is not to say Dale is lying about anything!).

Thanks for the thoughtful response!

Tom