Does gyro need anti-crash airbag?

[Timchick]

BRS chute on a gyro. Theory of operation: when it initially deploys it fires downward and is attached to the axle on one side so the gyro will hang from one side. After the rotor has slowed/stopped a release is pulled to release the first axle attachment point. The second attachment point is on the mast and this will allow the gyro to hit the ground on its' wheels. Never tested.

 

[Buccaneer]

Oh PS Welcome to the forum Buccaneer.

Thanks Joe !

 

[67november]

BRS chute on a gyro. Theory of operation: when it initially deploys it fires downward and is attached to the axle on one side so the gyro will hang from one side. After the rotor has slowed/stopped a release is pulled to release the first axle attachment point. The second attachment point is on the mast and this will allow the gyro to hit the ground on its' wheels. Never tested.

Your theory is sound, maybe I should submit it to BRS since they're only a few miles from my house.

 

[fiveboy]

BRS chute on a gyro. Theory of operation: when it initially deploys it fires downward and is attached to the axle on one side so the gyro will hang from one side. After the rotor has slowed/stopped a release is pulled to release the first axle attachment point. The second attachment point is on the mast and this will allow the gyro to hit the ground on its' wheels. Never tested.

What stops the chute line from wrapping into and around the rotor and/or the prop? What stops those from turning?

How high up do you need to be to have enough time to initiate all these actions?

I remember reading an analysis of the time lag from when a pilot realizes he has an engine out until he responds... it was a lot longer than one might like.

This solution would apply in what realistic situation?

I think an ejectable rotor/brs combo system might work but again it takes altitude and presence of mind to deploy. Not likely.

Occams Razor comes to mind here.

 

[Hognose]

I wonder if we should install some anti-crash airbag

Edward --

it is important to consider crashworthiness as a whole. Airbags protect only against some of the threats, not against others. Those threats include:

1. intrusion
a. of structure into the space of living occupants
b. of outside world (ground, tree, etc) into the space of living occupants
2. ejection of occupant
a. occupant unprotected by a/c structure
b. occupant suffers secondary impact against terrain etc.
3. Secondary impact
a. unrestrained or badly-restrained occupant impacts structure
4. deceleration forces
a. deceleration forces unsurvivable in absolute terms
b. deceleration forces unsurvivable due to design's not managing these forces.
c. deceleration forces along unexpected axis.
5. postcrash fire
a. fire not prevented or retarded
b. occupants can't escape due to design, damage to machine, or occupant injury
c. occupants not protected from fire.

As you can see, these multiple pathways of injury need multiple countermeasures. It is hard to do it all and still make a light and inexpensive machine.

You need at a minimum, to make a crashworthy machine:
1. to preserve the space for the humans inside and protect them from what's outside.
2. to restrain the humans so they don't get ejected.
3. to protect them from hitting things inside the machine, or suddenly hitting other parts of their own bodies, or snapping joints beyond what is survivable.
4. to manage deceleration forces (like the crumple zones in a car).
5. to keep fire from starting, especially in or near the crew compartment.

A solid rollover structure, good seat and shoulder straps, a helmet and possibly a HANS device, and some attention to fire management might do more than an airbag can. NASCAR and Formula 1 race drivers have no airbags but survive horrific impacts regularly.

Sorry for my long words, especially to those who are not native English speakers. But precision counts!

cheers

-=K=-

 

[EI-GYRO]

First you jettison the rotor, then deploy a suitable parachute.
I believe the Germans had this facility on the towed gyroglider
submarine observation system , "bachstalze".
If my interpretation of the photos taken by my wife in a museum are correct,
this was operated by a single lever, which jettisoned the rotor and extracted the
parachute from its container on the mast.
In any event, if I was given this task, that is what I'd do.
I suspect that is what BRS would do also.

Trouble is, most gyro pilots fly too low for any parachute to deploy
in time.
Also, the number of accidents to gyros flying within normal parameters at
a parachutable height is tiny.

 

[karlbamforth]

First you jettison the rotor, then deploy a suitable parachute.
I believe the Germans had this facility on the towed gyroglider
submarine observation system , "bachstalze".
If my interpretation of the photos taken by my wife in a museum are correct,
this was operated by a single lever, which jettisoned the rotor and extracted the
parachute from its container on the mast.
In any event, if I was given this task, that is what I'd do.
I suspect that is what BRS would do also.

Trouble is, most gyro pilots fly too low for any parachute to deploy
in time.
Also, the number of accidents to gyros flying within normal parameters at
a parachutable height is tiny.

I agree completely, and with what kevin has just said about the multiple possibilities of injuries from all manner of things then we have to go to F1 style cockpits which will be very expensive.

I still think education and training would be a more cost effective way of reducing deaths, not just in gyro's but in aviation as a whole.

Sadly in the gyro world we still have ppl who fly badly designed machines and others who think they can fly without any training at all, untill we get away from this mindset I doubt the statistics will improve very fast.

 

[Timchick]

Your theory is sound, maybe I should submit it to BRS since they're only a few miles from my house.

The guy in the photo already had a BRS on his gyro years ago. It's the white canister looking thing.

 

[Timchick]

What stops the chute line from wrapping into and around the rotor and/or the prop? What stops those from turning?

How high up do you need to be to have enough time to initiate all these actions?

I remember reading an analysis of the time lag from when a pilot realizes he has an engine out until he responds... it was a lot longer than one might like.

This solution would apply in what realistic situation?

I think an ejectable rotor/brs combo system might work but again it takes altitude and presence of mind to deploy. Not likely.

Occams Razor comes to mind here.

In theory you'd only use it for an extreme emergency. Some people theorized it could be used in case of a bunt over but since it was installed on a CLT machine that scenario seemed unlikely. If a gyro were to bunt over and the canister was fired the gyro would already be upside down at the start of a tumble so the chute would fire away from the rotors.

 

[Hognose]

The Fa 330 Bachstelze did indeed have a recovery chute, but it was meant for combat use. The gyrokite was towed behind submarines to expand their spotting range (in all the history of its use, they can document only one ship sunk, so it didn't work out all that well). If the sub had to crash dive, the drill was to cut the gyro loose, then the pilot pulled a single lever to shuck the blades and deploy his chute. Then he released his seat belt and the gyrokite frame dropped free. He had a small survival kit and the theory was that the sub would maybe come back for him. (Yeah, riiiiiight).

I have the German maintenance manual on the FA 330 thanks to a German reprint shop, and there is a lot of good info on it, including pilot interviews, in one of my books on German helicopters (in English). Can't remember which book, though.

It would be relatively easy to design a mast that was ejectable. Say, when you pulled a lever, it withdrew an internal block that pushed four large ball-bearings or rollers into place to lock the upper and lower mast together -- a similar lock holds HK rifles' bolts closed against 50-60,000 psi chamber pressures, and releases every time when it must. It would require more precision in manufacturing than the average gyro. You'd need to engineer it to at least +3.8G (and that, plus a safety factor of at least 1.5, so call it 5.7G, suddenly applied), and test it under all loads. Still there's a problem, unless you include a ballistic component, it would be dodgy in low-g to neg-g -- which is exactly when you are most likely to want it.

Recovery systems engineering is not easy, and recovery systems require (1) regular maintenance, and (2) operator training, to work effectively. Every year, military pilots die because they ejected out of envelope or didn't eject at all. There was just a crash in the RSA that killed a very experienced jet-warbird pilot -- news reports say he attempted to eject three times, and his last radio call was "ejection seat failure."

A wider deployment of ballistic chutes is, in my opinion, an unalloyed good. I have friends that are alive thanks to BRS, friends that are alive thanks to military ejection seats, a friend who's alive because of the reserve parachute on a military MC1-1 static line rig, and a friend who's alive because of one of the old hand-thrown emergency chutes from ultralight days.

In fact, I'm making an examination of the economics of recovery-systems certification the core of my capstone thesis in grad school. My hypothesis (or one of them) is that the strict type certification, TSO and STC rules that have kept BRS off of most light airplanes, actually costs lives, and works counter to the desires of those that made the policy. Unintended consequences.

The pilot (and pax) for whom recovery systems fail, like poor Dave Stock in ZA, is no better off than if there were no system at all, is he? Nor is the pilot who deploys it in a last hail-mary attempt, out of envelope. And there are risks that attach to having a recovery system. (I'm aware of unintended deployments -- quite a few of them -- of military seats, but haven't found one of a civilian airframe chute yet. I have not talked to the folks at BRS and Galaxy and so on yet either).

I welcome any pointers to research on inadvertent deployments or other hazards of recovery systems in most European languages (I'm stuck if it's in Greek or Finnish though). Also, any interesting cases, particularly in Europe or Africa... hit me at my private email, kevin at network impossible dot com, as my mailbox here has been full for months....

cheers

-=K=-

 

[Hognose]

Some gyro chute theory

Some thoughts --

1. Cut away the rotor head or rotor system (a la Fa330).
2. Deploy away from rotors -- may be a problem and adds a lot of altitude to your red (unsafe) deployment zone.
3. Pilot is under psychological overload and will take seconds he does not have to react. One answer is training (as realistic as feasible -- "stress inoculation" in psychological terms.
4. The unfamiliar sights and sensations of a bunt produce that overload, for example.
5. A chute could be entirely automatic and driven by accelerometers, with a human override.

Ballistic chutes don't save all lives. The advantage to them is they save lives in situations where nothing else can do it. From BRS alone, over 200 souls got extra life; and that doesn't count saves by Galaxy, Second Chantz (long defunct) and others.

We need to think about safety broadly. The most important ingredient is not design but training -- fatal accidents where pilot error is a cause still outnumber accidents where design is a cause, whether the problem is bunt resistance or crashworthiness. But in design, crashworthiness is a major factor.

Consider the friends our community has lost to post-crash fires. Post-crash fire is not inevitable, it is preventable. Some aircraft are noted for frequently having fires, and others seldom. What are the differences? In the fixed-wing world, consider the frequency of fatalities due to fire in crashes of Cessna fixed-gear singles (rare) or Piper Cherokees (more common). The Cherokee has (in most models) only one exit, and it has fuel tanks that form the leading edges of the inner wings. The Cessna 1-series has fuel tanks behind the spar, not before it, and there are doors on both sides. Simple design decisions that lead to survival... or lack of the same (overall, despite the differences in fire mortality, the planes' fatal crash incidence is pretty similar, telling me that the Cessna must have some hazards the Piper lacks).

How would you redesign the basic open-frame gyro so that it doesn't burn when crashed? How about an RAF or Sparrowhawk? What is the difference between accidents to these types that have had fires and that did not? Can we change something? And will it work? (The Russian Mi-8 and Mi-17 helicopters have their fuel tanks on the outside, and attached by straps, on the theory that they should break away in a crash and carry the fire away from the occupants. But instead, they seem to shatter and douse the broken fuselage in flaming fuel. The Mil designers are smart guys, have they thought about changing this?)

This kind of thing, as you see, fascinates me. How do we make things better and safer? I am encouraged by Rafael Celier's attention to crashworthiness in the design of Xenon, but discouraged by the regulatory impediments that keep this design out of the USA.

cheers

-=K=-

 

[Heron]

A bunt will probably mess up the pilots reaction, it is hard on the neck, helmet and all.
Altittude minimum 500 feet at the time of deployment for it to work.
The range of these accidents is so small that it is not feasable preparing for them.
Cost and results.
Heron

 

[Alan_Cheatham]

Your theory is sound, maybe I should submit it to BRS since they're only a few miles from my house.

Larry Neil developed the Ballistic parachute system for gyros years ago and there was a write-up about it in one of the PRA magazines, I assume it could still be purchased from Larry if one wanted one. As stated, it has never been tested in flight.

Except perhaps for a control system failure don't expect the rotor to separate cleanly from a gyro and pull a parachute out behind it, and in the case of the control system it would be better to use the weight that a ballistic parachute would add and reinforce the strength of the controls to preclude a failure in the first place.

.

 

[EI-GYRO]

I wonder if the Fa330 system was tested.?

It still probably would not work from unusual attitudes.

 

[Kingchocolate]

http://www.airbagsformyplane.com/HowDoes.html

 

[autogyro]

honeycomb cushion

honeycomb cushion

It is very interest that NASA use HoneyComb to absorber crash force.
please check.
NASA aeronautics researchers recently dropped a small helicopter from a height of 35 feet (10.7 m) to see whether an expandable honeycomb cushion called a deployable energy absorber could lessen the destructive force of a crash.

Chopper Drop Tests New Technology

 

[Hognose]

Fergus

-- sorry for late reply. Yes, the Fa330 release system was tested with dummies and volunteers.

-- Edward -- thanks for the interesting link to the NASA video. If they release the results I should like to see them.

A back of the envelope calculation suggests that a 10-m drop is borderline survivable in a crew seat, but not without injury.

The MD Helicopters (formerly Hughes) 500-series aircraft are noted for outstanding crashworthiness. In Vietnam, OH-6 pilots often survived shootdowns that would have killed H-1 or OH-58 crews. One way they did that was by the external bits breaking off and the round crew compartment actually rolling. It was very disorienting for the pilots, but they often survived. Fire did not normally penetrate the crew compartment.

The US Army (or perhaps it's a joint-services program now) actually publishes a magazine about survivability. It's largely focused on combat survivability, but there's a crashworthiness component to it also.

cheers

-=K=-

 

[Arnie Madsen]

.......Consider the friends our community has lost to post-crash fires. Post-crash fire is not inevitable, it is preventable. Some aircraft are noted for frequently having fires, and others seldom. What are the differences?

........How would you redesign the basic open-frame gyro so that it doesn't burn when crashed? How about an RAF or Sparrowhawk? What is the difference between accidents to these types that have had fires and that did not? Can we change something? And will it work? (The Russian Mi-8 and Mi-17 helicopters have their fuel tanks on the outside, and attached by straps, on the theory that they should break away in a crash and carry the fire away from the occupants. But instead, they seem to shatter and douse the broken fuselage in flaming fuel.
cheers

-=K=-

Thanks Kevin

Here are a few quick tidbits I know on the subject.....

I was at one time involved manufacturing (Aluminum) fuel tanks for certified automotive use. We also considered a poly type tank but went with aluminum because we were set up for it already.

The Department of Transport code manual for certified auto fuel standards is 2 inches thick and I studied it a lot at one time.

To save a lot of time and explanation I have a simple test I want everybody to do that will open a lot of eyes. It has mainly to do with poly type tanks often used in aviation.

Find an empty two liter coke bottle and fill it to the top with water. Leave the cap off. Take it outside to your driveway or sidewalk and drop it straight down from 3 feet. The split second of tremendous pressure will shoot water 20 to 30 feet in the air. The water will shoot out so fast you will repeat the test 2 or 3 times to see it properly. It will amaze you and give you an idea of the possible internal pressures inside a fuel tank during a hard landing or crash.

For a little more action try snugly pressing a cork into the bottle top and dropping it from 6 feet. If your eyes are quick enough to follow the cork I will send you a dollar.

The reality is most aviation and automotive fuel tanks will always have an airspace above the fuel to absorb the pressure. (part of the code) But to make sure the pressure remains contained in the tank comes down to having a sturdy gas cap and fuel line attachments.

The majority of crash and burn situations comes from failed fittings and caps , not tank failure. Most tanks are designed and tested to survive impact. You can test this by replacing the cap on the coke bottle and dropping it. Did you know a sealed coke bottle can withstand up to 175 psi and not burst? Like I said fittings and attachments are the weak spot. Sealed poly tanks are even tougher.

For this reason I would never use a push in type rubber grommet with a compression barb for a fuel line. An internal flange nut type fitting is the way to go when possible. Remember the internal pressure spike can be over 100psi during a hard landing. Some of these rubber grommets have been known to fall out just sitting in the hangar. One of our forum guys have had this happen. Rotorway helicopters have had them fall out in flight.

As far as the external breakaway tanks you mentioned , that is the system Bell went to on the 47. The early Bell had a tank mounted over the engine like the picture below of the one on floats . (I have two hours on this machine .... underpowered Franklin engine , draggy floats but I didn't complain)

After a couple of crash and burns Bell changed to side mounted "breakaway" tanks like the next picture. The theory was that the tanks broke off and rolled away upon impact. The metal fuel line would fold over and pinch shut before breaking. The fuel cap is a robust solid brass and positive locking.

It is nearly impossible to get data on how well the system works , investigators never mention it during post crash reports. I do know it works with full tanks , but not always with partial tanks (not enough weight to cause breakaway) I also know very few aircraft use external tanks anymore. Probably a streamlining issue. Hughes 500 uses a tough internal bladder in a well reinforced keel at the bottom of the cockpit. They survive quite well.

That's all I know and it ain't very much .....

Fly safe everybody and keep the fuel in the tanks where it belongs during a hard landing. If your landing gear collapses make sure your fuel lines and electric fuel pumps are not the next thing to absorb impact.

I also threw in a picture of a Bell delivering pizza to Chuck Ellsworth out in the water somewhere in beautiful BC. Where are you Chuck? Still retired? Need more pizza? Who ya gonna call?