Shameless update from Dale Kramer

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.

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.

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

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

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.

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.

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.

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

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.

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.