On The Issue Of Survivability

[giroplano]

I will start by stating that I am a former gyroplane enthusiast.The accident statistics in my country are horrendous,five or six fatalities in probably no more than 20 or 30 people that have practiced the sport in about 30 years. After the accident reported by Caribean_gyro(see GYROPLANE DOWN) I have given this matter a lot of thought.I have examined the photos posted and had the opportunity to talk to one of the witnesses that day and from the nature of the injuries observed ,it looks as if a helmet and perhaps some form of body restraint besides the lap belt might,...just might,... have saved his life.We have seen cases where,for example ,a race car going 200+ mph crashes and literally disintegrates around the pilot and he survives to race again.Since with rotorcraft the only way to get rid of the energy is precisely with the whirling rotor,when it stops doing its precisely balanced act and gravity takes over,the only thing that might keep you from buying the farm is bodily protection.

QUESTIONS:

How many of you out there fly without head protection? Motorciclists and bikers do.

Have y'all considered the feasibility of a shoulder harness on your machine?

How difficult would it be to come up with some sort of protective cage for the pilot?

Finally,when will somebody come up with a recovery system (parachute) for rotorcrafts?I have an idea. Anyone interested?

[tadgyro]

I preach in my Club , shoulders harness for years.. Not every body fill comfortable in harness but my opinion harness save people life. I see in my pass very bad injury because gyro was equip only with just seat belt.
Good questions.
Don't let you stop from flying Gyro ,because some people are stupid
Teddy
Ps. Helmet is mandatory just for one reason to kips you face look good after crash

[Timchick]

A lot of people already do use shoulder belts and most do wear helmets. Air Command, for awhile, was putting a BRS chute on their tandem gyros. The line of thinking on it's use was to use it only if something happened to the main rotor. Otherwise it would get tangled up in the rotor. A cage would add more weight and drag but maybe some sort of frame could be adapted to act as a roll bar.

Sport Copter designs their seats to collapse and absorb the energy of a hard crash.

[Rehan K.Janjua]

Yes the Air Command did come up with the recovery system.

Thanks to Larry Neil, it was a progressive hanging system where the left wheel tube was attached to the chute and would hang on its side till the rotor stopped and then the pilot can dis engage, enabling the gyro to hang
up right from the mast.

It is the most effective way to have a survival system.

Thank You.
Rehan

[Timchick]

Rehan,
Thanks. I didn't know about the 2-stage part.

[mcbirdman]

Tim, you mean some sort of a frame that actually doubles as a cage? Hmmmm function and form that is TRUE beauty. Not just what you see but what you get.

Thing is ..... The function and form has been there from the beginning but designers of the last few years have been using only one or those factors while all but ignoring the other in recent configurations.

Funny how new ideas are not as new as they seem or how strange it is to find out that our parents most often actually new what they were talking about back when it seemed like they didn't.......

The answers to the safety of autogyros really go back to the the original designs. Time has proven that ignoring many of these "features" to get a better looking or a better view has affected much more than was originally thought..... Now as then it is still worth consideration of Form over function vs Function over form.....

[scott heger]

I will keep it short and simple; it is not the speed or altitude that gets gyro pilots, it is the SUDDEN STOP. I wear a full face helmet and 4 point racing style seatbelts. This *may* help in a accident 50 feet or under and low speed. The rest of the time, I don't plan on much help in the survival department. That is why this sport is not for everyone, actually very few. There is alot of downside to flying a gyro, and we must not forget that, but oh boy, it is some of the best flying around also.




Scott Heger,Laguna Niguel,Ca N86SH

[karlbamforth]

We have seen cases where,for example ,a race car going 200+ mph crashes and literally disintegrates around the pilot and he survives to race again.

A race car crash is completely different thing to a gyro or aircraft crash.
To start with millions of dollars have been spent on crash survival for race car drivers. Pour a few million into gyro's and the statistics will almost certainly improve.

Secondly race cars are generally moving across the surface of the earth, so any impact tends to be a glancing blow. The reason we see race cars spinning during an accident isn't always "just the way it happens" race drivers know that spinning a car dissipates energy and makes any impact with barriers at a tangent. The reason the car dissintegrates around him is again by design. Anything torn off the car dissipates energy.

Aircraft and gyro accidents that kill are normally at a much more extreme angle and impact with the earth, the greatest mass for quite a few miles around. Barriers and other race cars move, the planet does not (well not much).

As the earth is not going to move, almost all the crash energy is dissipated into the gyro and pilot. By default in most common gyros, assuming you survive the first impact there is an engine following you down.

Ohh well flying is still the safest form of transport.

The trick is don't crash, wear the best protection you can afford, harness and helmet.

I seem to remember Cessna designing a harness with an airbag installed.

Have you seen a military style life raft that fits snugly to a jet pilot when inflated? maybe something like this that can be inflated during those few seconds you are diving out of control would provide a few inches of air bag protection round the torso and head making survival chances better.

Another question to ask is "what kills most gyro pilots?" I know you gonna say the sudden stop. But you will see that over recent years race car drivers have started to wear a HANS device on their shoulders. For many years it was thought that the sudden stop killed drivers, then an investigation showed that most died from a broken neck due to the weight of the helmet. During an accident the HANS device transfers some of the load from the helmet down to the shoulder straps.

Just my thoughts on the subject.

[John Stahl]

Too truly address the crash survivability the gyro community need to admit that the gyros we fly and love are not as safe as they could be. The gyro community then needs to be more excepting of new or old safety improvements. It took years to get gyro pilots on board of the HS wagon. RAF still hasn’t gotten on the HS wagon.

Preventing a crash should be our first and foremost effort.
Training Has saved many lives.

Stability is still an issue. I would like to see a Pitch Stability Augmented System used on a gyro. These systems are used in aircraft from jumbo jets to RC helicopters, why not on Gyros?

There appears to me to be some control linkage problems that have caused some crashes. We may need to have safety cables in key places on our control linkage. These cables may buy us some time to get to the ground.

Then we need to look at how to survive a crash.
The engine on a pusher gyro appears to be killing pilots on impact. Just think what 200 lbs of metal would do to you if it fell on you. It would take one hell of a roll cage to stop the engine from crushing you.
Tractor gyros have the advantage in gyro designs that improve your crash survivability.
Engine in front, stable, good roll cage.

Using racing helmet technology is a great idea.

The military has tried to find ways to use parachutes on there helicopters but hasn’t found a way to do it yet. So if you do then let the military know.

[Ga6riel]

QUESTIONS:
How many of you out there fly without head protection? Motorciclists and bikers do.


hard to answer isnt it, better yet, how many fly with the best quality helmets they can find


Have y'all considered the feasibility of a shoulder harness on your machine?


shoulder harness isnt nearly enough, the absolute basline is a four point harness, the fivepoint is the most desirable and effective. The harness needs to be adequately framed in, off the rack 1/4" bolts will not suffice anything like a 20G impact. A shoulder harness will likely just leave unsightly marks on your body for the undertakers to clean up, no doubt thats expensive and its hard to argue with the bill.


How difficult would it be to come up with some sort of protective cage for the pilot?


the genesis of these machines seems to favour open frame zero protection, I think if someone was serious about safety it would be possible to make radical improvements. Instead of this, there seems to be more interest in how pretty the thing is, whether or not wheel spats look good, etc etc. One of the most dangerous machines is politely fitted with a 'nice' cabin.

While a tube framed or CF tub/chassis would add a good deal of weight I would contend that it weighed less than a coffin. Trailing gear and a long flat keel, ample stroke room in the cockpit for belt stretch in an impact. A more unified construction be it a tube frame or carbonfibre tub. The pilot needs to be protected within the tub and obvious impact areas need additional bolster.


Finally,when will somebody come up with a recovery system (parachute) for rotorcrafts?I have an idea. Anyone interested?

this is exceptionaly difficult, while ballistic chutes are an advantage to FW cousins, the very presence of the rotor makes it difficult to have an effective hitch. There have been helos with exploding bolts at the rotor roots, but this technology is way beyond home use. I cant think of anything that improves on that except to hitch from the tailboom which is hardly ideal

one can assume the AH64s below came down hard, notice despite glass, covers and panels being lost hull integrity is maintained. note the gear has collapsed absorbing much impact. The AH64 may not be pretty like those girls on the street corners, but she hides a special beauty within

[Racer]

I am glad this subject has come up. To answer an earlier question I for one wear a snell sa 2005 rated full faced helmet, Same one I wear in my racecar when racing as well as a five point seat harness. When indy cars first started racing they did not have any protection whatsoever, No roll bars, no fire protection , nothing. Now they are very safe and keep in mind that they as well have there engine behind them. Those cars are actually designed to break apart in a crash separating the energy from being attached from the driver, the front end are designed to calaps and absorbe energy, the only part of the car that you do not want to come apart in a crash is the cockpit the driver sits in. Keep in mind that even to this day even these cars still only have a roll bar, no need to carry the weight of a full roll cage. We can learn alot from there millions of dollars of there reaserch and development and make our sport safer as well. The biggest problem I think we need to figure out is how to keep that motor behind us from pushing us 6 feet under the daiseys in the event of a crash. Lets all put our minds together and make our addiction to flying a safer experience.

[brett s]

Scott summed it up pretty good - the sudden stop is what gets you, and on a simple open gyro there's not much you can do about it. There's not much available to absorb the force, unlike the Apache shown above which has both carefully designed crumple zones & seats that stroke vertically.

I've seen a UH-60 that fell vertically (with no blades, after a low speed wirestrike) about 180' - 3 out of 4 crew survived, it landed almost upright. All the glass was gone & every panel on it was bent but it did a pretty amazing job of protecting the crew.

[Ga6riel]

indeed, but i think that is the reason for my comparison
im sure there are a wide variety of accidents, the stats of which are unavailable to me

not a lot is going to save you from that chandelle at 12,000 ft
but we hear stories here of rollovers on the taxiway
of accidently coming in too hot
simply clipping the deck with the rotor
many of them are very low alt events you deserve to survive

safety is not a black art, or an indivisible science or a mystery of the universe
but it is a subject that doesnt win much in the way of applause
just ask ralph nader

[Heather Poe]

it is not the speed or altitude that gets gyro pilots, it is the SUDDEN STOP.
Hi-Tech Foams (http://www.seatfoam.com/) sells ConforTM Foam, which has been recognized as the best seat cushion available for comfort and impact safety since the Apollo Space Program. I understand that SportCopter uses this material in the seats they purchase from Oregon Aero (http://www.oregonaero.com/). In a crash the foam compresses in a way to dissipate much of the shock to the occupant. Also, airbags might be available soon (http://www.amsafeaviation.com/inflatablega.htm).

[PW_Plack]

When this topic comes up, I can't help but conclude that the way to make a pusher gyro more crashworthy is (1) design it without a bias to fail in a nose-down mode and (2) make sure training programs stress bringing it down vertical or tail-low.

Obviously, if you fly a machine prone to PPO, you're tossing most of the possible effective crash strategies overboard from the start. If you're at 1,000 AGL and chop off the tail, slow and damage the rotor, options become very limited.

Ballistic recovery systems on small pusher gyros to me seem ridiculous. How often do properly built, maintained and inspected rotors fail?

Ever?

The rotor system will handle many times the weight of the machine, and as long as it's turning, you can descend at a survivable rate. If you can't maintain or fly it well enough to keep it turning, you're probably not a good candidate to successfully maintain or operate a parachute system, either.

You can practice vertical descents as often and as many times as you like. Are you honestly going to practice 'chute deployments?

The hinge point on the Sport Copter folding mast has proven to be reliable in its role as a failure point in a rotor strike. I'm sure there are also other ways to design such a "weak link" in a mast to ensure it breaks above belt attachment points. Do that, get a good four- or five-point harness and a helmet, fly a design that's not known for constantly trying to become a dart, maintain your rotorhead so it keeps turning, and train to bring it straight down to a vertical impact if needed.

The safe breakaway point for the mast and four-point harness may be the most important of any of these precautions, given the number of people injured when they strike blades against the ground.

It does seem reasonable to me to add some sort of redundancy to control linkages.

[Gyro-nut]

I'm with you Paul... I'm still a rookie to the gyro community compared to some of you out there, but I practice my engine outs and vertical descents every time I fly. In fact, I prefer a vertical descent with a small transition to forward flight right over the numbers... it's a lot more fun than the traditional glide slope approach :)

I wear a full face helmet and shoulder harness; but I'm looking for a better shoulder harness (not the looped harness but the kind that actually slides onto the latching mechanism - like sportcopters). If anyone has one available, let me know.

[Cobra Doc]

A couple of notes on the Apache accident. There is no doubt the landing gear saved the crew. Add in the seats and those guys got down in good shape. There is a little clue that tells you what condition they were in. Everybody noticed the left side windows are gone. Who noticed the right side windows are still in tact? The doors on an Apache, as opposed to Cobra, are both on the right. The cockpit frames are twisted and the doors can not be opened. The crew blew the left side windows and clibed out normally. Look close at the top of the cheek pods. Depending on what caused the accident, the pilot was in good shape, at least until the gunner got his hands on him!!
Larry's gear has a lot in common with the Apache and Black Hawk gear. Energy absorbing seats aren't particularly hard to make. NOt everybody needs 26g seats. Mounting a seat on a pogo stick would be better than nothing. Even some of the seat foams sold by Oregon Aero would help.
the Apache pilots were also wearing a four-point harness. Five-points bother me. As my favorite comic book hero, Wolverine, said in X-men 3 "Let's see you grow those back!".
If I can wear a DOT/Snell helmet and riding jacket on the bike during a Phoenix summer, I can't think of any valid excuses to not use them in an open frame aircraft.

[GyroDoug]

One subject that hasn't been brought up here yet is the new landing gear technology that has been developed by companies like "Carter Copter" and Larry Neal with his "Monarch Butterfly" Gyro. They have developed landing gear that can absorb the impact of a 25 ft. vertical drop and still let you walk away instead of being hauled away in an ambulance. I am not sure why everyone in the aviation world isn't moving in that direction as fast as they can go. In my opinion that technology will increase the survivability of a large percentage of Gyro accidents, and is something we should all be taking advantage of. Just my thoughts!!!

[rtfm]

I am not sure why everyone in the aviation world isn't moving in that direction as fast as they can go. In my opinion that technology will increase the survivability of a large percentage of Gyro accidents, and is something we should all be taking advantage of. Just my thoughts!!!
Hi,
My guess is expense. Larry's not going to give that technology away. I'd love to incorporate his landing gear on my gyro, (and I'm going to contact him regarding doing so) but I expect the price will be way out of my league, even if he were actually willing to sell (or licence) the technology to me.

As far as my reading of this thread goes, it seems to me that a combination of the following safety features would be considered 'best practice'.

4-point harnass
Break-away mast at point above pilot or harnass anchors
Built-in crumple zones
Energy absorbing landing gear
Confor foam on seats (at least)
Some sort of roll-cage or roll-bar
Wearing of high-quality helmet in open frame gyros


To this maybe I could add the following:

Fuel as well away from engine as possible
Thorough pre-flight checks


I'm in the happy position of designing a gyro from a blank piece of paper, and so am free to incorporate as many of these safety best practice items as possible, thank goodness. All except perhaps item (4) above are in the plans.

Regards,
Duncan

[PW_Plack]

Doug says,

I am not sure why everyone in the aviation world isn't moving in that direction...

(1) Cost (2) Weight (3) Drag (4) Complexity/Maintenance (5) Center of mass and center of pressure both drift downward for several seconds after takeoff.

In other words, evaluating benefit to downside, many designers and builders will consider the G-Force gear to be inelegant engineering.

Doug, if a vertical landing can be accomplished without injury in a Bensen with no suspension at all, many builders will have a difficult time adding something like G-Force to a low-cost, recreational gyro if the only advantage is avoiding bending some aluminum.

The full benefit of the G-Force gear still requires attention to the proper attitude on touchdown. If you're a little off in pitch, and hit the tail or nosewheel before the gear is through its entire stroke, you haven't received the entire benefit, and may create a suddent pitching on touchdown.

I am impressed with what Larry and the guys at Carter have achieved, but I'm just as impressed with the engineering of the gear on Cessnas.

A simple spring axle, using tire scrub on landing to dissipate energy and avoid rebound, is crude to some, elegant to others, depending on your perspective. It wears the tires faster, but ditching shock absorbers sheds extra weight that affects performance 100 per cent of the time, while benefitting the pilot only for a few seconds on every flight. That simplicity seems appropriate in the paradigm of a light, cheap, reacreational gyro.

(Isn't that how both Twinstar and Magni are set up?)

[giroplano]

Thanks to all of you who replied to my post. Frankly,I was not expecting many replies.After all who likes to talk about unpleasant realities?
Almost four decades have gone by since the day I was charmed by that article in Popular Mechanics,about a do it yourself flying machine.It lands in 25 feet,does not stall,can fly at 25mph.Upon power loss, it floats down in autorotation like a maple seed........so it said.
Along with my son we built and taught ourselves and flew,first a training trailer(for those who remember what that is)then a gyroglider and finally a B8M with a 90Mac.Mind you,not without its share of scares.

I am now into UL's ,however my presence on this forum attests to the fact that there is something about Mary...err...gyros that you just can't shake of .Guess it's the nature of the crowd you hang with or perhaps that they are plain fun to fly little machines .

Your replies show that the issues of the the inherent risks in the sport and survivability in it have not faded away with time and are really in the back of a lot of peoples minds.

The idea I mentioned that I have is for a disc shaped, rotor mounted parachute.The BRS I have on my UL weighs around 15 lbs,has a volume of 509 cu. in. and is rated for 900 lbs.An equal volume disc would be 2 in. thick with an 18 in. diameter or other possible combinations of thickness and diameter.Bonus benefits from this placement are;higher CG from the thrust line,added inertia on the rotor and it might even add a little lift in forward flight

Yeah!,I know,easier said than done.What about mounting? activation? deployment? etc.,etc.Anyone interested,drop me a priv message to discuss it further.I've got a couple of ideas if not solutions.

About the cage I suggested,I did not mean an enclosure.I meant a simple frame around and over the pilot's body.I think,15 or 20 lbs.of chromoly added weight is worth it.

[iconnary]

Doug says,

I am not sure why everyone in the aviation world isn't moving in that direction...

(1) Cost (2) Weight (3) Drag (4) Complexity/Maintenance (5) Center of mass and center of pressure both drift downward for several seconds after takeoff.



I fly a Monarch and feel obliged to comment on my experiences so far with the machine. My machine runs a 582, and is comparable in weight and price to other similar machines (340lbs/$17k).

Larry Neal's implementation of this landing gear concept employs simple automotive shocks, which are neither expensive nor high-maintenance. The G-Force gear provide 18" of dampened (not spring loaded) travel on the main gear. The only real additional complexity is that a dual swing arm suspension needs to be used to keep the wheels oriented perpendicular to the ground throughout the entire suspension travel. The key concept here is that the gear have no spring loading - they simply absorb the impact energy and settle into the fully up position. IMO this is better suited to gyro-style landings than a more conventional aircraft gear. The downside of course is that there is zero shock absorption when on the ground for taxi/takeoff.

I often wondered about the drag and CG implications of having the gear drop so low below the gyro. I have no quantitative way of measuring what effect this is having. According to Larry the machine is designed to be CLT with the gear dropped, not raised. My experience is also that no significant trim changes are needed between gear raised or lowered (I have flown with the gear tied off in the raised position).

I can say with certainty that the gear have saved me at least a few times from bending metal. I have had a couple landings that I'm pretty sure would have otherwise broken an axle and rolled me over. The gear provide an enormous margin of error, perhaps too much. I worry sometimes that they may be encouraging sloppy habits in my landing style.

[Ga6riel]

interesting post Iven
of course, it ought be possible to add a pinion snubber or some other sort of rubber at the end of the travel, rubber suspension is no longer common but was used successfully in the isigonis Mini. and it wouldnt make any difference to the shock qualities.

[Hognose]

Rafael -- GREAT questions. I will be brief in my comments, though, because it's 0300 and bed calls!

1. The Puerto Rico crash where the rotorblade threw its d-section rod is the one you're talking about. I can't recall what altitude he went in from, but I did the math at the time and the deceleration forces were probably nonsurvivable. You can find the Naval Flight Surgeon's guide to accident investigation online and it contains the formulae you need. Which brings us to...

2. Crashworthiness in general, means you have to consider what kills people in gyroplane mishaps.

a. unsurvivable deceleration forces.
b. intrusion of aircraft structure into the pilot/pax body
c. secondary impact (person hits aircraft structure or is ejected and hits something besides the initial point of impact).
d. postcrash fire-related injuries (thermal, smoke inhalation)
e. death due to complications of injury, i.e. exsanguination (bleeding out).

The is not a complete reduction of the issue; for example, the exact mechanisms by which deceleration forces kill are highly variable.

Most of our bro's who die in gyros are killed by deceleration forces. That is why the ballistic chute is a tempting piece of safety gear. OTOH, the AmSafe seatbelts, which work wonders in fixed-wing, aren't much help in an open-frame gyro (they exist primarily to protect you against secondary impact on cockpit structure).

I'd also like to mention that chutes for gyros are not new (althout Larry Neal does deserve great credit for researching and promoting them). Indeed, I'm surprised that Rob (Ga6riel) missed this detail, cause he seems to know his gyro history coming and going. I'm referring, of course, the German WWII gyro-kite, the FA330. A handle cut away the rotor system and deployed a round rescue parachute.

cheers

-=K=-

[Ga6riel]

many thanks Kevin, no I didnt know that
but now that you mention it (Fa330)
I do recall reading about how the pilot was equiped with a chute
and I have seen the chute attached to the mast of the glider
but stupidly didnt put the facts together correctly
I mean, can you imagine a pilot putting the chute on while seated, and in the hurried moments of a crash diving U-Boat doublessly under attack, clearly not

so thats more than interesting, and its apparently to the German Kriegsmarine and Fieseler Flugzeugbau GmBh to illustrate the cleverness of the art of the possible. And to Kevins sleeping habits and ability to recall the facts

Blending the technologies might see the rotor released from the mast and a momentary deployment of a ballistic parachute. The protection of the cockpit and the integrity of the gear does the rest. but what to do about the control linkages ...... rotor most be released from above the gimbal

Focke Achgelis Fa 330, aka Bachstelze - sandpiper; aka water wagtail

below are some images from my database, note attached parachute, and further note it has a stab

[Cobra Doc]

Everytime this comes up, I think about the instrumentation packs on the Kiowa Scout and the Apache Longbow. Yes it would require a redesign of the gycopter head, but it's not an impossible situation. Unlike helicopters, the gyro mast doesn't spin. That takes the hardest part out of the equation. I have yet to see a steerable recovery 'chute. Problem #2 is solved, pop it and hope for the best. Problem 3, staying out of the rotor: Well, since it would be mounted above the rotor and deployed by a single long cable, problem 3 doesn't exist and really wouldn't matter anyway. Once the 'chute is deployed, who cares what happens to rotor speed?
A surviveable gyro isn't that hard to do. Now that I break it down, even I could put a BRS on a gyro. Trailing link gear with El Rancho off-road resevoir shocks. Shock mounted seats. Composite cockpit tub. Maybe I should break out the Etch-a-Sketch and crayons?

[Hognose]

The emergency drill seemed to be this:

1. Pilot reaches overhead and pulls the lever (which I believe was marked "abstellen" -- but my best Fa330 reference is lent out to my brother right now).

2. the blades are released and centrifugal force carries them safely away from the craft, which begins to fall ballistically.

3. meanwhile, the chute is deploying. The chute container is attached to the frame of the gyro, but the risers are attached only to the pilot's harness. When he has a chute, he releases his safety belt and the frame of the gyro falls free.

They did this several times in terrestrial-based tests but I am unaware of a test of this over water. Of course, they were deployed in U-Boats, and most U-Boats were sunk by Allied forces, so I don't believe any report of operational use exists anywhere.

The wheeled-skid undercarriage in one of your photos is a v-model in testing.

This and the conceptually similar Hafner Rotachute were, I believe, the inspirations for Dr Bensen's gyroglider and gyrocopter. His contribution was to adapt Arthur Young's teetering rotor in place of the Cierva-inspired fully-articulated rotor used by Fieseler's designers and Dr Hafner. (Speaking of learned doctors, where's Dr Bruce Charnov when we need him? He studies this stuff professionally).

I would like to get my hands on any more detailed FA 330 drawings. Hmmm... I haven't asked Udo Hafner of Luftarchiv Hafner (no relation to the British Siegfried(? I think) Hafner) if he has them. He got me an assembly and maintenance manual for the Me 163 that's a gorgeous, hardbound reproduction, and studying that answered many questions about 163 structure and systems.

cheers

-=K=-

[Ga6riel]

there are some rather nice images of Fa 330

http://www.aircraftresourcecenter.com/AWA1/301-400/walk330_Fa-330/walk330.htm

just click for enlargements

Ive emailed someone from Kockums (submarine designers) as to operational use

and some more detail

http://www.nasm.si.edu/research/aero/aircraft/focke_achgelis.htm

Should the U-boat came under attack and need to 'crash' dive, the pilot pulled a large red lever above the seat. This started a chain of events designed to save the submarine without sacrificing the pilot. The towline disconnected from the aircraft, freeing the submarine to dive immediately, and the spinning rotor simultaneously departed from the airframe rotor mast. As the rotors flew up and away, they pulled a cable that deployed the pilot's parachute. When parachute blossomed, the pilot popped his seat harness and the remainder of the gyrocopter fell into the sea. After the submarine evaded the threat, it could return to the surface to pick up the pilot. If time and circumstances permitted, the pilot could release the towline without triggering the entire emergency sequence. The flyer could then ditch his Fa 330 near the submarine, or attempt to land back aboard the ship. The type of threat and the speed of its approach dictated the pilot's actions.

[Ga6riel]

some history of U 852 mentioned in the above page
Laid down 15 Apr, 1942 AG Weser, Bremen
Commissioned 15 Jun, 1943 Kptlt. Heinz-Wilhelm Eck
Commanders
15 Jun, 1943 - 3 May, 1944 Kptlt. Heinz-Wilhelm Eck
Career 1 patrol 15 Jun, 1943 - 31 Jan, 1944 4. Flottille (training)
1 Feb, 1944 - 3 May, 1944 12. Flottille (front boat)
Successes 2 ships sunk for a total of 9.972 GRT

Scuttled on 3 May, 1944 in the Arabian Sea off the east coast of Somalia, in position 09.32N, 50.59E, after running aground during a British air attack by 6 Wellington aircraft (Sqdn 621 and 8). 7 dead and 59 survivors.

The boat was heading for the Indian Ocean to join the Monsoon wolfpack operating there.

This boat got famous for all the wrong reasons when Kptlt. Heinz Eck had survivors of the Greek steamer Peleus machine-gunned in the water to erase all signs of his sinking. Eck and 2 of his crew were executed after the war, the only U-boat commander to be even tried for war crimes.

On 3 May 1944 the Allies captured intact the Fa330 "Bachstelze" aircraft carried by the U-boat, thus getting the first news of its existence. Impressed by its simplicity and easiness to fold and unfold, they began to test it.

[Ga6riel]

composite image made in paint shop pro
sharpened and tidyed up a bit