Airbags for Enclosed Gyros?

If I want an airbag in my gyro, I just invite one of the local hangar-rats to go for a ride.
 
Heather Poe said:


Amsafe has sold those to some airplane OEMs and they are standard on Cirrus and optional (I think) on some single-engine Cessnas. They are also available on the Alarus and, I believe, the Symphony, but that product has been through more variations than Bach wrote....

The purpose of an airbag is to prevent the delicate parts of the human from coming into contact with the vehicle structure, and, secondarily, to absorb some of the deceleration forces. But the primary purpose is to prevent you from moving from your seat when your vehicle whacks something.

In a gyro, it wouldn't protect you from a high-energy event (for example, the rotor blade on Bill Ortmayer's gyro that sheared and killed his student, injuring Bill seriously at the same time; or a loss of control at anything above a few feet up). The forces unleashed in that kind of accident are too great.

A problem is that in many enclosed gyros the enclosure is not structural, and is not going to protect you in the way that the unibody of a car does. One exception is the Little Wing, which has a classic welded tube space frame, and which can sacrifice some of itself to absorb deceleration forces... in that particular airframe, an AmSafe airbag might be a good idea. In a more traditional enclosed gyro like the RAF 2000 or AAI Sparrowhawk, I'm not sure how much good it would do. The cabin is basically non structural and not designed with crashworthiness in mind. Crashes that don't destroy the cabin are usually survived at present.

Let's think about ultimate causes here. Things that can kill inhabitants of an aircraft in an accident:

1. Nonsurvivable deceleration forces.

2. Structural intrusion into pax space.

3. Ejection from craft and secondary impact with terrain.

4. Impact of unrestrained occupant on interior objects.

5. Post-crash fire

6. Exsanguination from wounds received in impact.

That's about it. Not much a pilot can do about 1 and 2, except, "not crash." The air bag helps with items 3 and 4 without creating any additional burden on the other items. Indeed, it might help with 5 and 6 because crash victims might be less concussed, more lucid, and more able to react.

cheers

-=K=-
 
I have an old EAA book on aircraft metalwork. It contains photos and descriptions of front-end crash tests done decades ago on Cub fuselages. 40 mph crashes produced minimal crushing of the passenger area and probably trivial injuries if the passenger were restrained properly. No reason why a Little Wing wouldn't fare just as well.

Much, much more could be done with the frames of pusher gyros, too. We face the disadvantage that the mass of the engine is behind us and cannot make its own separate peace with the ground as in a tractor. In a front-end crash, the force that stops the engine must travel through the frame that encloses the passengers, stressing it severely.

Even so, 4130 is a tougher material than aluminum alloy. "Toughness" in this sense refers to the ability of the material to absorb energy AFTER the load on it reaches the permanent-bending level. Standard window glass is an example of an extremely un-tough material. Aluminum alloys crack easily once they bend and aren't very tough, either.

A bit of progressive collapse can built into a 4130 tubing frame by using longer free spans in the tubes as you build forward beyond the passengers, and/or going to progressively thinner wall diameters in that area. Something like the Eagle's Perch frame (done in 4130) would be quite a bit more crash-worthy than our 6061-T6 lawn chairs and would help keep errant blades out of your face, too.

With that done, airbags would be icing on the cake.
 
English and German rules demand the mast to resist 15 G forward.
Strong demands on fuel tanks as well.
Its nice the frame ssurvives the crash when everything has burned awy.
On top of that the total weight for a two seater cannot be over 260kg empty.

JOS
 
exsanguination

exsanguination

"6. Exsanguination from wounds received in impact"

It is primarily a method of used to slaughter animals.

according to wikipedia.
 
Doug Riley said:
No reason why a Little Wing wouldn't fare just as well.

No disrespect to Ron's excellent design and well-built frames, but I think he'll agree that it's built a lot lighter than a proper Cub. However, that built-lighter has the dual effects of lowering strength, but also lowering mass... Ron is one of the guys who really thought hard and long about safety before he started cutting metal.

Much, much more could be done with the frames of pusher gyros, too.

Right, we can do better. To be fair to the designers of pushers, they've worked on other safety issues but have not addressed crashworthiness per se. After all, most of the crashes caused by PIO and PPO generate deceleration forces that are not survivable, full stop.

So of course crashworthiness is a facet of the design that hasn't been Job One. Still, it matters. Consider how much less serious Jamie's injuries might have been if the Marchetti he was in had been designed with a view to crash survival. He was racked up pretty good, from what was self-evidently a survivable (but still pretty violent) crash.

Even so, 4130 is a tougher material than aluminum alloy. "Toughness" in this sense refers to the ability of the material to absorb energy AFTER the load on it reaches the permanent-bending level.

It's a characteristic of most ferrous metals that there is a big range between the plastic yield point (where it bends) and the failure point (where it lets go). For mild steel, this is probably forty or fifty percent of the range. It's a characteristic of most aluminium alloys that they have scarcely any "plastic range". Also, aluminium is subject to fatigue much more than steel is.

Corrosion resistance is about a wash between the two. Pure aluminium is quite resistant, but common structural alloys are not. That's why aluminium sheet is customarily finished with a thin coat of elemental aluminium (that's what "AlClad" means).

I have wondered about Titanium alloy tubing as a possible construction material. You get the weight of aluminium (near enough) but the strength of steel, and it has an almost ferrous-metal-like plastic range: nice and wide. But it is costly and a bear to work.

David Holmes said:
exsanguination

Sorry, David and guys, technical term for "bleeding out." Below a certain blood pressure and volume (which will vary by individual), the organism cannot sustain life because not enough O2 is passing by the cells that need it. The organism is smart and involuntarily shuts down first the peripheries (through peripheral vasoconstriction) and then more and more of the other systems. Consciousness goes quite a ways before life does. They say it's not that bad a way to go, but then again no one who ever said that went all the way (obviously).

With modern trauma medicine and emergency medical transportation, this is increasingly rare. Still happens in some air crashes, though.

Yeah, animals can be slaughtered by bleeding them out, and in some cultures have to be (it's part of Kosher and Halal butchery, for example).

cheers

-=K=-
 
Good points all, and I will enjoy my kosher pastrami sandwich more knowing that tidbit about bleeding out the cow...
 
Crashworthiness is important in an airplane that contacts the ground at not much less than the stall speed.

A highspeed crash in a gyro is inexcusable. We at Sunstate used to have a saying; “If a crash is inevitable, crash as slowly as you can.”

An airplane that crashes at 60 mph has 16x as much kinetic energy to be absorbed by crumpling stuff as does a gyro that crashes at 15 mph.

All that’s needed to survive a 15-mph crash is helmet, seatbelt and a mast sturdy enough to provide rollover protection.

I have a fair amount of practical experience crashing gyros.
 
Chuck, there is the matter of errant rotorblades. I just about broke my arm the last time I got hit by a blade (in a simple crosswind tipover at zero mph). There's a nice scar and some permanent muscle damage... if a big dent is damage.

Every once in awhile someone gets hit in the head by a folding-up blade, with fatal results. That is what prompted my comment about the Eagle's Perch frame (though otherwise I think that a rotorcraft that can't autorotate is unacceptable). A rudimentary roll cage that includes a couple of stout tubes located ahead of the soft targets seems prudent, IMHO.
 
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