Volocopter - safest aircraft in the world

[Kilo-Bravo]

Just an amazing development and a futuristic kind of Ultralight-Helicopter.
Speeking about a new German development, an electrically powered multicopter with 18-electric motors. The craft is steered with a single joystick only.. Taking "hands off the joystick" during flight, the Volocopter VC200 remaines "just as nailed down to the sky", holding its position and height automatically.
In addition, the VC200 will be the first and only aircraft in the world, which could easily be flown and handled by disabled pilots too, without prior extensive and costly modifications of the craft.
Compared to any other type of aircraft, handling the 18-engine Volocopter is extremely simple.
Read the complete story:
http://ul-segelflug.de/f-a-e/519-volocopter-safest-airvehicle-in-the-world.html

Best regards from Germany

Klaus

[Charlie M. (UH & 002 owner/pilot)]

Dude...... sorta sounds like a sale pitch.

If I was a mod here, I would put you in lock-down and give an infraction.

But..... you have some past history, thus I would think a bit.....

[Kilo-Bravo]

Hi Charlie M.

would you mind telling me, why you would like to lock me down or why you do´nt like my threads or informations?
I run a non-profit website, informing others about developments in ultralight-aviations. I do not get paid from anyone for my writing, so whats wrong about that?

Best regards from Germany

Klaus

[Jonathan St. Cloud]

Actually I thought it was kind of cool. This is an aviation related newsgroup. I am a helicopter pilot so it was interesting to me.


On Monday, December 7, 2015 at 3:06:52 AM UTC-8, Kilo-Bravo wrote:
> Hi Charlie M.
>
> would you mind telling me, why you would like to lock me down or why you do´nt like my threads or informations?
> I run a non-profit website, informing others about developments in ultralight-aviations. I do not get paid from anyone for my writing, so whats wrong about that?
>
> Best regards from Germany
>
> Klaus

[Kilo-Bravo]

Thanks Jonathan, I appreciate your comment.

Best regards from Germany
Klaus

[Charlie M. (UH & 002 owner/pilot)]

On Monday, December 7, 2015 at 6:06:52 AM UTC-5, Kilo-Bravo wrote:
> Hi Charlie M.
>
> would you mind telling me, why you would like to lock me down or why you do´nt like my threads or informations?
> I run a non-profit website, informing others about developments in ultralight-aviations. I do not get paid from anyone for my writing, so whats wrong about that?
>
> Best regards from Germany
>
> Klaus

Hello Klaus,

Guess you missed some of the rest of my post.

First impression was this was a "spam post".
I followed the link provided and was blocked by software on my PC
Since I'm an "admin" or a "moderator" on a number of sites, my first impression was this was a spam post.

But, as I mentioned, I see you have done other good posts here so you have some history (a good thing).
Thus I also posted I would have a done a "wait & see" for your post.

Additionally, I can now see your posted link (I also looked at other items on your site) so I can tell a bit more.

I have no way to edit my previous post, I can only delete it.

I am also only another poster here, not any sort of "staff" for this site.

I agree with Jonathan, now that I can see your link it is an interesting idea you presented. It would be good to see if they can extend the flight time a bit more but it's an interesting start.

Charlie.

PS, I apologize if I came off harsh earlier, not really my intention, I was just commenting.

[Dan Marotta]

I agree that it's a very interesting project! I also read Charlie's
post and am glad that he got a look at the site and was able to comment
on the project.

I also agree that newer battery technology is needed to make this
anything more than a high-priced toy, but then that's what our gliders
are, aren't they?

On 12/7/2015 8:44 AM, Kilo-Bravo wrote:
> Thanks Jonathan, I appreciate your comment.
>
> Best regards from Germany
> Klaus

--
Dan, 5J

[Dan Marotta]

I just took another look at a full size picture of the Volocopter and a
thought occurs to me: Imagine all control being accomplished by varying
the speed of those motors. Now imagine the beat frequencies generated
by the rotors. You would go quickly insane without a terrific
noise-cancelling headset! What sort of vibrations would that cause in
the airframe? I guess they've addressed that issue...

On 12/7/2015 10:04 AM, Dan Marotta wrote:
> I agree that it's a very interesting project! I also read Charlie's
> post and am glad that he got a look at the site and was able to
> comment on the project.
>
> I also agree that newer battery technology is needed to make this
> anything more than a high-priced toy, but then that's what our gliders
> are, aren't they?
>
> On 12/7/2015 8:44 AM, Kilo-Bravo wrote:
>> Thanks Jonathan, I appreciate your comment.
>>
>> Best regards from Germany
>> Klaus
>
> --
> Dan, 5J

--
Dan, 5J

[[email protected]]

On Monday, December 7, 2015 at 9:04:51 AM UTC-8, Dan Marotta wrote:
> I also agree that newer battery technology is needed to make this
> anything more than a high-priced toy, but then that's what our
> gliders are, aren't they?
> Dan, 5J

I suppose one could have also criticized the Wright Flyer for having an impractical powerplant, but that would be missing the point :). It is inevitable that battery technology will improve, and when it does, the Volocopter will be ready for it.

[Kilo-Bravo]

Hello Charlie,

thanks for your reply. Even that your excuses sound little bit "strange", I´ll accept your appologies - no hard feeling. I know how I get bored, when idiots try to post spam mails at my website, consuming unnecessary time every day to sort them out.

As you might have reakized by scolling throught UL-Segelflug.de, the majority of my articles are written in German language and only few are translated into english.

I only post an information in rec.aviation.soaring, when I beliefe that a story could be of interest also for pilots and aviation enthusiasts who speek English, not German. Knowing, that my personal translations are far away from being perfect, I still hope they are little better to understand that a quick google-translation.

Hope, you`ll continue to visit my website from time to time, even so I´ll have not many subjects to offer for "chopper-pilots".
Great thing, my sun also is a chopper-pilot, has flown 12 year SAR in UH 1D in German Airforce.

Best regards from Germany

Klaus

[Kilo-Bravo]

Hello Dan,

I fully agree, it all depends on better batteries with more power-density.
After this first success of "bevor unknown people", I would not bee supprised, if Airbus-Helicopters would´nt be interested in this little company and buy up the wrights. Time will show.

Rgds Klaus

[Charlie M. (UH & 002 owner/pilot)]

On Monday, December 7, 2015 at 12:04:51 PM UTC-5, Dan Marotta wrote:

> I also agree that newer battery technology is needed to make this
> anything more than a high-priced toy, but then that's what our
> gliders are, aren't they?

> --
>
> Dan, 5J

Did you see where the site mentioned they were looking at/working on a "hybrid"? Until battery energy density improves (a lot) they will add in a small generator to extend flight time.

[Tango Eight]

On Sunday, December 6, 2015 at 11:35:08 AM UTC-5, Kilo-Bravo wrote:
> Just an amazing development and a futuristic kind of Ultralight-Helicopter.

[[email protected]]

On Tuesday, December 8, 2015 at 8:26:48 AM UTC-6, Charlie M. (UH & 002 owner/pilot) wrote:
> On Monday, December 7, 2015 at 12:04:51 PM UTC-5, Dan Marotta wrote:
>
> > I also agree that newer battery technology is needed to make this
> > anything more than a high-priced toy, but then that's what our
> > gliders are, aren't they?
>
> > --
> >
> > Dan, 5J
>
> Did you see where the site mentioned they were looking at/working on a "hybrid"? Until battery energy density improves (a lot) they will add in a small generator to extend flight time.

I hate to break it to you all but the time when battery capacity will approach the density of carbon fuels will come - never. I read up on that subject and there are limits in the direct conversion of chemical energy into electricity (which is what batteries do) that indicate we are not so far away from those now. We may improve by a factor of 2 but that is not what is needed to make electric flight a x-country activity. It boils down to the physics that chemistry is based on - and we understand those laws very well.
Herb

[Dan Marotta]

I saw that and think it's a good compromise - just like a
diesel-electric locomotive. I don't think batteries will achieve the
power density needed for practical cross country flight in my lifetime,
but that's no reason not to push the boundaries.

On 12/8/2015 7:26 AM, Charlie M. (UH & 002 owner/pilot) wrote:
> On Monday, December 7, 2015 at 12:04:51 PM UTC-5, Dan Marotta wrote:
>
>> I also agree that newer battery technology is needed to make this
>> anything more than a high-priced toy, but then that's what our
>> gliders are, aren't they?
>> --
>>
>> Dan, 5J
> Did you see where the site mentioned they were looking at/working on a "hybrid"? Until battery energy density improves (a lot) they will add in a small generator to extend flight time.

--
Dan, 5J

[Kilo-Bravo]

Dear pilot-friends,

mainly interesting discussion, despite using it as hey-mower, which is not worth to be discussed.

Beginning with Lilienthal, Wright brothers, Charles Lindbergh, Students of Darmstadt, Horten brothers, Wernher von Braun, Bertrand Piccard, just to name a few of earlier "fools", the time they presented their ideas, the overall laughter was assured "it never works!!!"
Most of those visionary aviators succeeded, some of them sure payed with their life for the idea.
Just because time was not ready for the idea at that time, material or production knowledge not yet available.
Would anybody had believed 80 years ago, man ever could fly to the moon and take a walk at its surface? To build a huge and heavy craft like a B747 or an A380?
Or 10 years ago, to build an electric powered twin-trainer like the Pipistrel, operated by quick-change battery-units small enough to fit in an ultralight trainer carrying two people and enabling flight training lasting 45 minutes?

Or the Airbus E-Van, a twin-trainer 550 kg empty-weight, max-speed 220km/h, battery-power at the moment just 40 minutes, but they are convinced of longer lasting batteries for the near future.

Sure nobody would have believed in all those "foolish ideas" 10, 20 or even 50 years ago. All of those foolish ideas came true. They are reality these days.

@ Even
Not being able to glide or autorotate is the worst case for any aircraft of course. Could be loosing an elevator or part of a wing, destruction of the free-wheeling clutch of a chopper or loosing a blade. All of this sure happened in the past - death trap as someone called it. The pilot of the Volocopter still has a last chance by activating its BRS and touch the ground safely, while a common chopper just falls out of the sky like a stone.

@ Herb and Dan
I´m fully convinced, we will have those battery density >2, maybe not in yours or my lifetime, but sometime later. Who cares about that? We already have fully electric-driven airplanes like the Sunseaker with battery and additional solar-cells at top of the wings, so they easily do cross-country flights.
Or the Solar Impulse of Bertrand Piccard, who does a flight around the world without a single drop of fuel, just by solar-power. Not yet compleated, but non-stop five days and 5 nights in the air, thats grate, thats future and thats not a simple ultralight by weight and wingspan!

Take a look at Dean Sigler´s fantastic website "http://blog.cafefoundation.org/". A scientist-based highly qualified website, where you can see what´s possibly already and what scientists all over the world are working at and what they think about future possibilities in battery-density - thinks like that.

Or check the websites of NASA, what scientists and students develop at research-places like the Armstrong Research Center: http://www.nasa.gov/aero/students-electrify-nasa-with-future-airplane-designs
High Voltage Hybrid ElectricPropulsion: http://www.nasa.gov/centers/armstrong/features/CAS_showcase.html

Great scientific visions I believe in to become true and sincerely hope to see one or the other getting true in my time of life.

Best regards from Germany

Klaus

[Dan Marotta]

Klaus,

I like your fire. Keep it up!

Regards and best of luck,
Dan

On 12/9/2015 3:28 AM, Kilo-Bravo wrote:
> Dear pilot-friends,
>
> mainly interesting discussion, despite using it as hey-mower, which is not worth to be discussed.
>
> Beginning with Lilienthal, Wright brothers, Charles Lindbergh, Students of Darmstadt, Horten brothers, Wernher von Braun, Bertrand Piccard, just to name a few of earlier "fools", the time they presented their ideas, the overall laughter was assured "it never works!!!"
> Most of those visionary aviators succeeded, some of them sure payed with their life for the idea.
> Just because time was not ready for the idea at that time, material or production knowledge not yet available.
> Would anybody had believed 80 years ago, man ever could fly to the moon and take a walk at its surface? To build a huge and heavy craft like a B747 or an A380?
> Or 10 years ago, to build an electric powered twin-trainer like the Pipistrel, operated by quick-change battery-units small enough to fit in an ultralight trainer carrying two people and enabling flight training lasting 45 minutes?
>
> Or the Airbus E-Van, a twin-trainer 550 kg empty-weight, max-speed 220km/h, battery-power at the moment just 40 minutes, but they are convinced of longer lasting batteries for the near future.
>
> Sure nobody would have believed in all those "foolish ideas" 10, 20 or even 50 years ago. All of those foolish ideas came true. They are reality these days.
>
> @ Even
> Not being able to glide or autorotate is the worst case for any aircraft of course. Could be loosing an elevator or part of a wing, destruction of the free-wheeling clutch of a chopper or loosing a blade. All of this sure happened in the past - death trap as someone called it. The pilot of the Volocopter still has a last chance by activating its BRS and touch the ground safely, while a common chopper just falls out of the sky like a stone.
>
> @ Herb and Dan
> I´m fully convinced, we will have those battery density >2, maybe not in yours or my lifetime, but sometime later. Who cares about that? We already have fully electric-driven airplanes like the Sunseaker with battery and additional solar-cells at top of the wings, so they easily do cross-country flights.
> Or the Solar Impulse of Bertrand Piccard, who does a flight around the world without a single drop of fuel, just by solar-power. Not yet compleated, but non-stop five days and 5 nights in the air, thats grate, thats future and thats not a simple ultralight by weight and wingspan!
>
> Take a look at Dean Sigler´s fantastic website "http://blog.cafefoundation.org/". A scientist-based highly qualified website, where you can see what´s possibly already and what scientists all over the world are working at and what they think about future possibilities in battery-density - thinks like that.
>
> Or check the websites of NASA, what scientists and students develop at research-places like the Armstrong Research Center: http://www.nasa.gov/aero/students-electrify-nasa-with-future-airplane-designs
> High Voltage Hybrid ElectricPropulsion: http://www.nasa.gov/centers/armstrong/features/CAS_showcase.html
>
> Great scientific visions I believe in to become true and sincerely hope to see one or the other getting true in my time of life.
>
> Best regards from Germany
>
> Klaus

--
Dan, 5J

[J. Nieuwenhuize]

Interesting tidbit of information that I haven't seen in the discussion so far, all hardware is built by DG.

[[email protected]]

Let's start with the safest aircraft in the world statement. I'm sorry but that's quite a claim without data or previous history. All aircraft these days are the safest in the world until a person gets behind the controls. What exactly makes this the safest? I operate some aircraft with up to 8 layers of system redundancy and millions of uneventful hours on the airframe - way more than any ga - but somehow this one is the safest? I'm waiting for the late night infomercial. Claims like this are simply ridiculous.

With that said, I love following developments in aviation and can appreciate qualities in everything out there.

[Martin Gregorie[_5_]]

On Sun, 06 Dec 2015 08:35:05 -0800, Kilo-Bravo wrote:

> Read the complete story:
> http://ul-segelflug.de/f-a-e/519-volocopter-safest-airvehicle-in-the-
world.html
>
>
I did and am unimpressed. I see three major flaws:

1) As others have pointed out, it can't autorotate. Unless it has a lot
of excess power, almost any failure means you'll be on the way down
fairly fast regardless of what is under you. Why? If any one motor fails,
the corresponding opposite motor also has to be turned off (or at least a
number of opposite motors need to throttled) to maintain control, because
if the thing can't be kept absolutely level it will accelerate sideways
toward the dead motor and there's no way this can be prevented without
levelling the support disk because there's no way to generate any side
thrust. So, its a death trap unless it has at least 12% excess thrust
over and above MTOW and, to protect against a double motor failure, that
should be doubled.

2) The more I think about the 'single control column' control system the
less I like it. If pushing the stick forward means 'go forward', how do
you tell it to climb or descend? Control the vertical rate? I see push
buttons and one rotary knob with no markings of calibration. Same
laterally. If pushing the stick left means 'turn left', how do you tell
it to counter a side wind? Are you meant to crab, in which case surely
changing the yaw angle is a bit slow to counter side gusts?

3) I see no mention of control system failures. If all fly-by-wire fixed
wing aircraft have at least doubly redundant systems, surely this needs
them too, so why aren't they mentioned?

This doesn't seem much like 'the world's safest aircraft'. Maybe its the
worlds easiest aircraft for a neophyte to fly, but 'easy to fly' doesn't
mean the same as 'safe'.

Besides, its inefficient. 20 minutes on a charge when the Airbus Industry
E-fan can fly for a hour and both it and an electric Cri-Cri have crossed
the English Channel?


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Kilo-Bravo]

O.K., few of my counterargumenters continue to ignore a safety-device called "Ballistic Rescue System". Why? Just because "What I do not know - I do not like?
You insist at the ability of autorotation as best safety device? Sure it´s one thing, but have a look at the list of the National Transportation & Safety Board at the following link:
http://www.ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=fc06add6-ba7a-491c-b3a0-abf8bd4e5421
In this list, you find 1.929 reports starting 1964 until today, only Helicopters and only categorized "FATAL". I have not read all of them, but sure all mentioned Helicopters had the ability of autorotation by design and build. The theoretical ability of autorotation did not safe a single soul in those fatal accidents.
I´m convinced, that many of those victims could have been saved with a build-in BRS, knowing of course, that during a long earlier period of time, BRS did not exist and even this days, there is no adequate BRS on the market for most of those (heavy) choppers.

Or look through that other list, showing the number of fatal accidents with Ultralights, starting in 1982.
http://www.ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=39fd7e91-f76d-4686-a443-098dbdc6c804

Sure most of them would have the designed ability to glide to the ground, in case of an engine-failure. But this ability did not prevent any of those fatal crashes.

According to German Regulations, all Ultralights must have a build-in BRS. This device has already saved many lives during the last years. Sure not 100%, but a big number.


Just two examples out of many:
When a Czech made DUO-Banjo came to land at a small German airfield in 2013, the pilot tried to keep hight because he was coming short and was flying over a big forest area. About 500 m before the runway, 100 m above the field, he was to slow and the motorglider with retracted engine went into a sudden spin. He pulled the handle and activated the BRS, crashing into the forest but survived the crash "unharmed". With a common motorglider or glider, he sure would have been killed. Some nice pictures you`ll find at this link:
http://www.frankenpost.de/fotos/nachrichten/Flugzeugabsturz-bei-Kulmbach-IMG_0386-JPG;cme467709,2624008

An Ultralight with two occupants crashed into a Ka8-Glider in 200 m hight just about 800 m outside a small airfield in Germany. While at short final, the Ka8 with a student on board turned in to its short final, flying into the Ultralight from the right. The Ultralight was stuck in the fuselage of the glider. As the pilot activated his BRS, both aircraft came down outside the airfield, both aircraft heavily damaged, but all three survived with minor injuries.
http://www.rhein-zeitung.de/region/lokales/koblenz_artikel,-Flugzeugabsturz-in-Winningen-Anlieger-sorgen-sich-um-Sicherheit-_arid,1204088.html#.Vm0z3Xv8Mu2

As I look at those pictures, I´m happy about the fact, that I carry a BRS in my glider, which is fitted to the airframe getting me safely to the ground, instead of carrying a parachute tight to my back, not knowing if I get out in time and in adequate hight in order to get the chute inflated befor I hit the ground and wake-up to see I´m dead.

Best regards from Germany

Klaus

[Martin Gregorie[_5_]]

On Sun, 13 Dec 2015 01:24:19 -0800, Kilo-Bravo wrote:

> O.K., few of my counterargumenters continue to ignore a safety-device
> called "Ballistic Rescue System". Why? Just because "What I do not know
> - I do not like?
>
I've looked through the Volocopter website twice now and have not seen
any mention of BRS or performance details among all the salesy balderdash.
The similarities remind me somewhat of the Moller M400 Skycar.

To my mind BRS is strictly for last ditch use because it seems to be a
destructive device. The crash reports I've read where a BRS was used show
that its use always seems to cause at least major damage to the aircraft.
Take my example of a Volocopter motor failing: if you need to use the BRS
to recover then it also means you get to pay for major repairs or a new
Volocopter. Kerching!! More money for Volocopter. OTOH if it would
autorotate or can balance thrust across the support disk the cost could
be as little as resetting a circuit breaker to up to replacing part of
the control electronics or one motor.

> You insist at the ability of autorotation as best safety device?
>
Not at all. I accept that its useful where there's no other way out, e.g.
to Cirrus 22 that suffered total electric failure after entering cloud
(IFR rated pilot, but entirely electronic panel), should you have to use
it when the problem is engine failure? Thats something all power pilots
are trained for.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Charlie M. (UH & 002 owner/pilot)]

On Sunday, December 13, 2015 at 7:03:36 AM UTC-5, Martin Gregorie wrote:
>
> I've looked through the Volocopter website twice now and have not seen
> any mention of BRS or performance details among all the salesy balderdash..
> The similarities remind me somewhat of the Moller M400 Skycar.
>
> To my mind BRS is strictly for last ditch use because it seems to be a
> destructive device. The crash reports I've read where a BRS was used show
> that its use always seems to cause at least major damage to the aircraft.
> Take my example of a Volocopter motor failing: if you need to use the BRS
> to recover then it also means you get to pay for major repairs or a new
> Volocopter. Kerching!! More money for Volocopter. OTOH if it would
> autorotate or can balance thrust across the support disk the cost could
> be as little as resetting a circuit breaker to up to replacing part of
> the control electronics or one motor.
>
> > You insist at the ability of autorotation as best safety device?
> >
> Not at all. I accept that its useful where there's no other way out, e.g.
> to Cirrus 22 that suffered total electric failure after entering cloud
> (IFR rated pilot, but entirely electronic panel), should you have to use
> it when the problem is engine failure? Thats something all power pilots
> are trained for.
>
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

Read again about 1/2 way down the page.....

"In the unlikely event of a total loss of electricity or total failure of the onboard electronics, causing to stop all motors at the same time, the Volocopter of course can not autorotate to the ground like conventional helicopters. In such an inconvenient situation, the pilot can activate the Ballistic-Rescue-System, which brings him gently to the ground by parachute, together with the Volocopter."

Yes, it seems most BRS "saves" destroy the craft, but you're likely to be alive to argue with the insurance company about getting a new craft. ;-)

As to "Auto rotate" in "conventional choppers, you need height and/or forward speed for it to work (as far as I know), if your're hovering low, you're sorta "along for the ride" straight down. :-0

[Martin Gregorie[_5_]]

On Sun, 13 Dec 2015 06:37:37 -0800, Charlie M. (UH & 002 owner/pilot)
wrote:

> "In the unlikely event of a total loss of electricity or total failure
> of the onboard electronics, causing to stop all motors at the same time,
> the Volocopter of course can not autorotate to the ground like
> conventional helicopters. In such an inconvenient situation, the pilot
> can activate the Ballistic-Rescue-System, which brings him gently to the
> ground by parachute, together with the Volocopter."
>
Yes, I missed that. Fair enough.

> As to "Auto rotate" in "conventional choppers, you need height and/or
> forward speed for it to work (as far as I know), if your're hovering
> low, you're sorta "along for the ride" straight down. :-0
>
I don't know enough about choppers to comment. I'd be interested to see
what anybody who flies them has to say about this: there must be some
inertia in those blades.

BTW, it looks as if the BRS system has a dead zone if deployed from a
slow or stationary vehicle. The rocket extracts the canopy and shrouds,
leaving them fully extended but the canopy still has to inflate. If you
look at videos & photos of BRS deployment, you can see that prompt
canopy opening depends on the airspeed of the aircraft being rescued. In
the material I've seen, the aircraft still had a fair amount of airspeed
when the BRS was fired so the canopy was filled while still being trailed
by the aircraft. As a result height loss during inflation was minimal.
However, if its deployed from a hovering Volocopter, the whole rig would
fall until the canopy had inflated.

Personal view: given than BRS landings seem to be quite hard, the thought
of flying something to which the only way out of any type of emergency is
"fire the BRS" is not reassuring.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Bruce Hoult]

On Sunday, December 13, 2015 at 6:29:14 PM UTC+3, Martin Gregorie wrote:
> > As to "Auto rotate" in "conventional choppers, you need height and/or
> > forward speed for it to work (as far as I know), if your're hovering
> > low, you're sorta "along for the ride" straight down. :-0
> >
> I don't know enough about choppers to comment. I'd be interested to see
> what anybody who flies them has to say about this: there must be some
> inertia in those blades.

They vary.

The common and cheap R22 has very little rotor inertia. If you're hovering higher than maybe five feet then you're going to have a hard landing if the engine stops. Unless you're above 400 ft, in which case you can dive to 55-ish knots, level off, and do a nice flare. If you're doing at least 55 knots then you're ok from any height. It only takes maybe 30 knots to make 200 ft safe.

Other choppers with heavier rotor systems can be ok from below 20 or 30 ft zero speed, or above 300 ft, or maybe even less.

Things such as the Huey or Enstrom can be cut to zero throttle on the ground, picked up and hover-taxi'd a few meters (or turned around 180º) and set back down softly, all on rotor inertia.

I even once saw John "Prickles" de Ridder lift off a Hughes 300 and move it from one side of a fence to the other (turning 180º at the same time) after he'd chopped the throttle.

[Charlie M. (UH & 002 owner/pilot)]

On Sunday, December 13, 2015 at 11:53:58 AM UTC-5, Bruce Hoult wrote:
> On Sunday, December 13, 2015 at 6:29:14 PM UTC+3, Martin Gregorie wrote:
> > > As to "Auto rotate" in "conventional choppers, you need height and/or
> > > forward speed for it to work (as far as I know), if your're hovering
> > > low, you're sorta "along for the ride" straight down. :-0
> > >
> > I don't know enough about choppers to comment. I'd be interested to see
> > what anybody who flies them has to say about this: there must be some
> > inertia in those blades.
>
> They vary.
>
> The common and cheap R22 has very little rotor inertia. If you're hovering higher than maybe five feet then you're going to have a hard landing if the engine stops. Unless you're above 400 ft, in which case you can dive to 55-ish knots, level off, and do a nice flare. If you're doing at least 55 knots then you're ok from any height. It only takes maybe 30 knots to make 200 ft safe.
>
> Other choppers with heavier rotor systems can be ok from below 20 or 30 ft zero speed, or above 300 ft, or maybe even less.
>
> Things such as the Huey or Enstrom can be cut to zero throttle on the ground, picked up and hover-taxi'd a few meters (or turned around 180º) and set back down softly, all on rotor inertia.
>
> I even once saw John "Prickles" de Ridder lift off a Hughes 300 and move it from one side of a fence to the other (turning 180º at the same time) after he'd chopped the throttle.

Great info.

I also found this (since I was curious)...
https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf

I have heard of a "coffin corner" in helicopters that is similar to power planes, that was what I was referring to. The FAA link I provided explains some of this.

[Dan Marotta]

If the Volocopter is capable of steering itself it must be able to vary
the thrust (RPM for fixed rotors) of each motor so, with a single motor
or rotor failure, the system should be able to maintain controlled
flight by varying the other motors.

Having said the above, stating that all of the referenced helicopter
crashes (with autorotation capability) resulted in fatalities is a bit
disingenuous since you also stated up front that they were fatal
accidents. Not all of the helicopter crashes resulted in fatalities.

And the BRS system is not the cure all. I have one in my Pipistrel
Sinus but it scares the hell out of me. If deployed at too low an
altitude, the result is to be on the end of a pendulum swinging into the
ground. If there are high winds, you'd better be able to get out of the
aircraft lest you be killed in the wreck dragging across the ground.
And then there's the unforgettable image of the flaming Cirrus gently
descending to the ground while the occupants burned to death.

I'm reminded of the Piper Cub - an aircraft so safe that it can only
barely kill you.

On 12/13/2015 2:24 AM, Kilo-Bravo wrote:
> O.K., few of my counterargumenters continue to ignore a safety-device called "Ballistic Rescue System". Why? Just because "What I do not know - I do not like?
> You insist at the ability of autorotation as best safety device? Sure it´s one thing, but have a look at the list of the National Transportation & Safety Board at the following link:
> http://www.ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=fc06add6-ba7a-491c-b3a0-abf8bd4e5421
> In this list, you find 1.929 reports starting 1964 until today, only Helicopters and only categorized "FATAL". I have not read all of them, but sure all mentioned Helicopters had the ability of autorotation by design and build. The theoretical ability of autorotation did not safe a single soul in those fatal accidents.
> I´m convinced, that many of those victims could have been saved with a build-in BRS, knowing of course, that during a long earlier period of time, BRS did not exist and even this days, there is no adequate BRS on the market for most of those (heavy) choppers.
>
> Or look through that other list, showing the number of fatal accidents with Ultralights, starting in 1982.
> http://www.ntsb.gov/_layouts/ntsb.aviation/Results.aspx?queryId=39fd7e91-f76d-4686-a443-098dbdc6c804
>
> Sure most of them would have the designed ability to glide to the ground, in case of an engine-failure. But this ability did not prevent any of those fatal crashes.
>
> According to German Regulations, all Ultralights must have a build-in BRS. This device has already saved many lives during the last years. Sure not 100%, but a big number.
>
>
> Just two examples out of many:
> When a Czech made DUO-Banjo came to land at a small German airfield in 2013, the pilot tried to keep hight because he was coming short and was flying over a big forest area. About 500 m before the runway, 100 m above the field, he was to slow and the motorglider with retracted engine went into a sudden spin. He pulled the handle and activated the BRS, crashing into the forest but survived the crash "unharmed". With a common motorglider or glider, he sure would have been killed. Some nice pictures you`ll find at this link:
> http://www.frankenpost.de/fotos/nachrichten/Flugzeugabsturz-bei-Kulmbach-IMG_0386-JPG;cme467709,2624008
>
> An Ultralight with two occupants crashed into a Ka8-Glider in 200 m hight just about 800 m outside a small airfield in Germany. While at short final, the Ka8 with a student on board turned in to its short final, flying into the Ultralight from the right. The Ultralight was stuck in the fuselage of the glider. As the pilot activated his BRS, both aircraft came down outside the airfield, both aircraft heavily damaged, but all three survived with minor injuries.
> http://www.rhein-zeitung.de/region/lokales/koblenz_artikel,-Flugzeugabsturz-in-Winningen-Anlieger-sorgen-sich-um-Sicherheit-_arid,1204088.html#.Vm0z3Xv8Mu2
>
> As I look at those pictures, I´m happy about the fact, that I carry a BRS in my glider, which is fitted to the airframe getting me safely to the ground, instead of carrying a parachute tight to my back, not knowing if I get out in time and in adequate hight in order to get the chute inflated befor I hit the ground and wake-up to see I´m dead.
>
> Best regards from Germany
>
> Klaus

--
Dan, 5J

[Martin Gregorie[_5_]]

On Sun, 13 Dec 2015 08:59:38 -0800, Charlie M. (UH & 002 owner/pilot)
wrote:

> On Sunday, December 13, 2015 at 11:53:58 AM UTC-5, Bruce Hoult wrote:
>> On Sunday, December 13, 2015 at 6:29:14 PM UTC+3, Martin Gregorie
>> wrote:
>> > > As to "Auto rotate" in "conventional choppers, you need height
>> > > and/or forward speed for it to work (as far as I know), if your're
>> > > hovering low, you're sorta "along for the ride" straight down. :-0
>> > >
>> > I don't know enough about choppers to comment. I'd be interested to
>> > see what anybody who flies them has to say about this: there must be
>> > some inertia in those blades.
>>
>> They vary.
>>
>> The common and cheap R22 has very little rotor inertia. If you're
>> hovering higher than maybe five feet then you're going to have a hard
>> landing if the engine stops. Unless you're above 400 ft, in which case
>> you can dive to 55-ish knots, level off, and do a nice flare. If you're
>> doing at least 55 knots then you're ok from any height. It only takes
>> maybe 30 knots to make 200 ft safe.
>>
>> Other choppers with heavier rotor systems can be ok from below 20 or 30
>> ft zero speed, or above 300 ft, or maybe even less.
>>
>> Things such as the Huey or Enstrom can be cut to zero throttle on the
>> ground, picked up and hover-taxi'd a few meters (or turned around 180º)
>> and set back down softly, all on rotor inertia.
>>
>> I even once saw John "Prickles" de Ridder lift off a Hughes 300 and
>> move it from one side of a fence to the other (turning 180º at the same
>> time) after he'd chopped the throttle.
>
> Great info.
>
> I also found this (since I was curious)...
> https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/
helicopter_flying_handbook/media/hfh_ch11.pdf
>
> I have heard of a "coffin corner" in helicopters that is similar to
> power planes, that was what I was referring to. The FAA link I provided
> explains some of this.

Good info from both of you. Thanks for posting.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Charlie M. (UH & 002 owner/pilot)]

On Sunday, December 13, 2015 at 1:56:30 PM UTC-5, Martin Gregorie wrote:
> On Sun, 13 Dec 2015 08:59:38 -0800, Charlie M. (UH & 002 owner/pilot)
> wrote:
>
> > On Sunday, December 13, 2015 at 11:53:58 AM UTC-5, Bruce Hoult wrote:
> >> On Sunday, December 13, 2015 at 6:29:14 PM UTC+3, Martin Gregorie
> >> wrote:
> >> > > As to "Auto rotate" in "conventional choppers, you need height
> >> > > and/or forward speed for it to work (as far as I know), if your're
> >> > > hovering low, you're sorta "along for the ride" straight down. :-0
> >> > >
> >> > I don't know enough about choppers to comment. I'd be interested to
> >> > see what anybody who flies them has to say about this: there must be
> >> > some inertia in those blades.
> >>
> >> They vary.
> >>
> >> The common and cheap R22 has very little rotor inertia. If you're
> >> hovering higher than maybe five feet then you're going to have a hard
> >> landing if the engine stops. Unless you're above 400 ft, in which case
> >> you can dive to 55-ish knots, level off, and do a nice flare. If you're
> >> doing at least 55 knots then you're ok from any height. It only takes
> >> maybe 30 knots to make 200 ft safe.
> >>
> >> Other choppers with heavier rotor systems can be ok from below 20 or 30
> >> ft zero speed, or above 300 ft, or maybe even less.
> >>
> >> Things such as the Huey or Enstrom can be cut to zero throttle on the
> >> ground, picked up and hover-taxi'd a few meters (or turned around 180º)
> >> and set back down softly, all on rotor inertia.
> >>
> >> I even once saw John "Prickles" de Ridder lift off a Hughes 300 and
> >> move it from one side of a fence to the other (turning 180º at the same
> >> time) after he'd chopped the throttle.
> >
> > Great info.
> >
> > I also found this (since I was curious)...
> > https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/
> helicopter_flying_handbook/media/hfh_ch11.pdf
> >
> > I have heard of a "coffin corner" in helicopters that is similar to
> > power planes, that was what I was referring to. The FAA link I provided
> > explains some of this.
>
> Good info from both of you. Thanks for posting.
>
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |

No problem,the discussion piqued my interest, thus (as a ex-CFIG) I wanted to know more.
I knew there were several issues (regardless of aircraft type) that could get you into trouble, but this thread made me look some more.

Thanks to all to help me expand my horizons.

;-)

PS, any day I learn something new is a good day, thanks.

[Eric Greenwell[_4_]]

Martin Gregorie wrote on 12/13/2015 4:01 AM:
> To my mind BRS is strictly for last ditch use because it seems to be a
> destructive device. The crash reports I've read where a BRS was used show
> that its use always seems to cause at least major damage to the aircraft.

My Phoenix touring motorglider has a BRS. My flight manual makes clear
that if the landing is in doubt, it's best to deploy the BRS. Some
situations are:

- Water landing (the aircraft will likely flip over if a landing is
attempted)

- collision with another aircraft that renders it uncontrollable

- loss of power at night out gliding range of an airport

- loss of power over unlandable terrain

- Pilot incapacitation with a parachute deployment by the passenger

The BRS is not considered a "destructive device" in my Phoenix, but a
"life-saving" device.

There are a number of articles and reports on Cirrus' experience with
their BRS. The biggest problem took a while to be realized: pilots were
reluctant to use the BRS if they thought they could manage an emergency
landing - after all, that's been the training for many, many years.

After several fatalities that BRS use would have easily avoided, Cirrus
changed it's training and it's manuals to emphasize using the BRS as the
first choice, and an emergency landing only if can clearly be conducted
with very little risk (eg, engine failure while in the pattern at an
airport might be an example).

This change in emphasis has resulted in fewer fatalities than would have
otherwise occurred, by their reckoning. The remark I remember is "You
will survive with few (or no) injuries, and the aircraft will be
repairable".

--
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

[Eric Greenwell[_4_]]

Martin Gregorie wrote on 12/13/2015 7:26 AM:
> Personal view: given than BRS landings seem to be quite hard, the thought
> of flying something to which the only way out of any type of emergency is
> "fire the BRS" is not reassuring.

I think you do not have a good idea of "quite hard" - BRS systems in
certified aircraft like the Cirrus and Phoenix are sized to land the
aircraft slowly enough to avoid injury most of the time.

I think with the Volocopter - we'll have to wait to see if their testing
backs up their claim of "gently", but it certainly seems achievable,
given the lower max speeds. I'm sure they have a number of ways to deal
with the "dead zone" as you obviously need the aircraft to be moving
through the air for a parachute to work. I'm guessing it would not be
allowed to deploy when hovering (and you don't need it then, either),
perhaps by automatic means.

--
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

[Kilo-Bravo]

Thanks to all of you, supporting what I wrote before and clarified some of the special "chopper-questions". Looks like my english actually is worse than I thought it would be, so not everybody seem to understand what I try to say.

Anyway, who ever has visited the website of e-volo, he should have found at first page the title "Safety first". Clicking at that link, you get a nice picture of the activation-handle for the BRS, as well as a brief description when to use it.
http://www.volocopter.com/index.php/en/safe-en

At this link on YouTube, you get a video showing the first test-shootout of the system.
https://www.youtube.com/watch?v=lffpmcuuOPE

And yes, the chute did NOT deploy at this situation, as the craft is static at the ground, no horizontal nor vertical speed, so no air to do the job inflating the chute of course.
In reality, I could only think about two situations, when a helicopter has no vertical or horizontal speed:

1.) the pilot hovers the craft safely somewhere above the ground in any hight,
sure no vertical and no horizontal speed and of course no need to activate thes BRS.

2.) pilot is not hovering safely in the air and again no horizontal nor any
vertical speed - pilot missed the right moment to activate the BRS ......

After all, the VC200 you see at the e-volo website is just the prototype as stated in my article. It has not been operated with occupants in the cockpit but with adequate ballast. As its preliminary permission by Federal Administration (LBA) allows remote controlled and unmanned test-flights only, until its safe operation is finally proofed and the test-program is completed. After that, they sure get full test-permission by the Authority to be operated with occupants on board the craft.

I´ll follow up the further progress of development and report any news at my website (http://ul-segelflug.de/blog.html), so please feel free to visit my site at any time.

Best regards from Germany,
wishing you all and your family-members a nice Christmas-time and a happy, safe and healthy 2016.

Klaus

[Martin Gregorie[_5_]]

On Sun, 13 Dec 2015 17:36:50 -0800, Eric Greenwell wrote:

> Martin Gregorie wrote on 12/13/2015 7:26 AM:
>> Personal view: given than BRS landings seem to be quite hard, the
>> thought of flying something to which the only way out of any type of
>> emergency is "fire the BRS" is not reassuring.
>
> I think you do not have a good idea of "quite hard" - BRS systems in
> certified aircraft like the Cirrus and Phoenix are sized to land the
> aircraft slowly enough to avoid injury most of the time.
>
IIRC the reports of the first few SR22 BRS recoveries talked about broken
undercarriages and I'm certain I've seen a photo of a BRS-recovered
glider with a smashed nose. Both fit my definition of 'quite hard'.


> I think with the Volocopter - we'll have to wait to see if their testing
> backs up their claim of "gently", but it certainly seems achievable,
> given the lower max speeds. I'm sure they have a number of ways to deal
> with the "dead zone" as you obviously need the aircraft to be moving
> through the air for a parachute to work. I'm guessing it would not be
> allowed to deploy when hovering (and you don't need it then, either),
> perhaps by automatic means.

A situation that would leave it in the dead zone would be if the pilot is
pushing it on battery capacity because he is determined to make his
declared airfield despite a stronger than predicted head wind, the
battery hits zero at less than safe BRS deployment height on approach.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Martin Gregorie[_5_]]

On Mon, 14 Dec 2015 00:43:19 -0800, Kilo-Bravo wrote:

> At this link on YouTube, you get a video showing the first test-shootout
> of the system.
> https://www.youtube.com/watch?v=lffpmcuuOPE
>
> And yes, the chute did NOT deploy at this situation, as the craft is
> static at the ground, no horizontal nor vertical speed, so no air to do
> the job inflating the chute of course.
> In reality, I could only think about two situations, when a helicopter
> has no vertical or horizontal speed:
>
Interesting video. Thanks for posting it.

BTW, from the BRS website "The altitude required is a function of speed
more than height. FAA certified tests have shown that full parachute
inflation could occur as low as 260-290 feet above the ground."

That's 80-90m, but implies that you'd need to be rather higher if flying
slowly or hovering. Bruce's figures for the R22 autorotation recovery
(400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system
would need 150% more height than an R22 for a safe BRS recovery.

> 1.) the pilot hovers the craft safely somewhere above the ground in any
> hight,
> sure no vertical and no horizontal speed and of course no need to
> activate thes BRS.
>
> 2.) pilot is not hovering safely in the air and again no horizontal nor
> any
> vertical speed - pilot missed the right moment to activate the BRS
> .....
>
Murphy says that something will go wrong at some time & place in both
these situations.


> After all, the VC200 you see at the e-volo website is just the prototype
> as stated in my article. It has not been operated with occupants in the
> cockpit but with adequate ballast. As its preliminary permission by
> Federal Administration (LBA) allows remote controlled and unmanned
> test-flights only, until its safe operation is finally proofed and the
> test-program is completed. After that, they sure get full
> test-permission by the Authority to be operated with occupants on board
> the craft.
>
Understood. It will be interesting to see what pilot certification the LBA
decide is needed to fly one.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Bruce Hoult]

On Monday, December 14, 2015 at 4:18:52 PM UTC+3, Martin Gregorie wrote:
> That's 80-90m, but implies that you'd need to be rather higher if flying
> slowly or hovering. Bruce's figures for the R22 autorotation recovery
> (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system
> would need 150% more height than an R22 for a safe BRS recovery.

Just to amplify: 200 ft is always the corner for the R22. 55 knots is the critical speed at max AUW, worst CG and about 3000 ft density altitude. At sea level 53 knots is ok at any altitude, and at 7000 ft you need about 58 knots.

[Martin Gregorie[_5_]]

On Mon, 14 Dec 2015 06:05:33 -0800, Bruce Hoult wrote:

> On Monday, December 14, 2015 at 4:18:52 PM UTC+3, Martin Gregorie wrote:
>> That's 80-90m, but implies that you'd need to be rather higher if
>> flying slowly or hovering. Bruce's figures for the R22 autorotation
>> recovery (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS
>> system would need 150% more height than an R22 for a safe BRS recovery.
>
> Just to amplify: 200 ft is always the corner for the R22. 55 knots is
> the critical speed at max AUW, worst CG and about 3000 ft density
> altitude. At sea level 53 knots is ok at any altitude, and at 7000 ft
> you need about 58 knots.

Understood. I was comparing that 200 ft with the BRS site's quoted 'might
get away with popping it at 260-280ft', this presumably including both
height for the chute to inflate (minimal at speed since the aircraft
pitches up on deployment) followed by the height used up waiting for the
plane to be swinging gently enough for the crew to survive meeting the
ground.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Eric Greenwell[_4_]]

Martin Gregorie wrote on 12/14/2015 5:16 AM:
> That's 80-90m, but implies that you'd need to be rather higher if flying
> slowly or hovering. Bruce's figures for the R22 autorotation recovery
> (400ft/125m hovering, 200ft/62m at 55 kts) indicate that a BRS system
> would need 150% more height than an R22 for a safe BRS recovery.

You are assuming the R22 rotor system is intact and functioning
correctly. If the R22 has a failure in the rotor system, I think it's
"gave over", while the Volocopter could deploy it's BRS even with
multiple rotor or motor failures as long as it's high enough. Sure,
there would be a dead zone of a few hundred feet, but the BRS would work
from there up to it's ceiling.

--
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

[Eric Greenwell[_4_]]

Martin Gregorie wrote on 12/14/2015 4:49 AM:
> A situation that would leave it in the dead zone would be if the pilot is
> pushing it on battery capacity because he is determined to make his
> declared airfield despite a stronger than predicted head wind, the
> battery hits zero at less than safe BRS deployment height on approach.

We are in agreement that you are in trouble if your thrust stops below a
certain altitude; it doesn't matter how you get there - running your
battery or fuel tank to empty is going to ruin your day.

--
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

[Eric Greenwell[_4_]]

Eric Greenwell wrote on 12/14/2015 7:16 PM:
> I think it's "gave over",

That should be "game over"!

--
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

[Martin Gregorie[_5_]]

On Mon, 14 Dec 2015 19:35:53 -0800, Eric Greenwell wrote:

> Eric Greenwell wrote on 12/14/2015 7:16 PM:
>> I think it's "gave over",
>
> That should be "game over"!

Correct!

As for the rest, please bear in mind that is wasn't looking at
catastrophic structural failure where, of course, you're correct. OTOH I
was on about the situation where the only way out from *any* failure in a
Volocopter is to pop the BRS and pointing out that this is fatal if it
happens down in the death zone at a height from where a conventional
aircraft could usually glide or autorotate to a landing.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Eric Greenwell[_4_]]

Martin Gregorie wrote on 12/15/2015 5:58 AM:
> On Mon, 14 Dec 2015 19:35:53 -0800, Eric Greenwell wrote:
>
>> Eric Greenwell wrote on 12/14/2015 7:16 PM:
>>> I think it's "gave over",
>>
>> That should be "game over"!
>
> Correct!
>
> As for the rest, please bear in mind that is wasn't looking at
> catastrophic structural failure where, of course, you're correct. OTOH I
> was on about the situation where the only way out from *any* failure in a
> Volocopter is to pop the BRS and pointing out that this is fatal if it
> happens down in the death zone at a height from where a conventional
> aircraft could usually glide or autorotate to a landing.

Maybe a I misunderstand what "any" failure is. It's obvious losing one
of the thrusters is not a serious problem, as the other seventeen can
handle the load; and actually it could lose several and still land safely.


--
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

[Martin Gregorie[_5_]]

On Wed, 16 Dec 2015 19:10:42 -0800, Eric Greenwell wrote:

> It's obvious losing one
> of the thrusters is not a serious problem, as the other seventeen can
> handle the load; and actually it could lose several and still land
> safely.
>
Don't forget that loosing any one thruster requires a thrust reduction
from the rest that's exactly equivalent to stopping the corresponding
diametrically opposite thruster. It is doesn't do this it will go skating
off sideways in the direction of the failed thruster. This reduces the
max available thrust by 11% which could easily make staying in the air
impossible if the Volocopter is within 11-12% of MTOW or on a hot day. It
may also have implications for a soft landing. AFAIK there is no
available info on the relationship between max available thrust and MTOW.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[[email protected]]

This isn't necessarily true in this case. Yes, if the aircraft had only one engine on each side of the roll axis then a corresponding reduction in the opposing engine would be required. However, with 18 engines and either 8 or 9 engines on each side of the axis (depending on orientation of travel), there are multiple opportunities to increase thrust from other engines on the same side to offset the failed one. Of course, this assumes we're not already at max thrust of the system. In an active system such as this it is unlikely that the pilot would be able to command "true" max thrust of the system as there would be some percentage held in reserve for just this sort of attitude control scenario.

On Thursday, December 17, 2015 at 4:03:19 AM UTC-6, Martin Gregorie wrote:

> >
> Don't forget that loosing any one thruster requires a thrust reduction
> from the rest that's exactly equivalent to stopping the corresponding
> diametrically opposite thruster. It is doesn't do this it will go skating
> off sideways in the direction of the failed thruster. >
>
> --
> martin@ | Martin Gregorie
> gregorie. | Essex, UK
> org |