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NASA Tests Flying Airbag
coondoggie writes "NASA is looking to reduce the deadly impact of helicopter crashes on their pilots and passengers with what the agency calls a high-tech honeycomb airbag known as a deployable energy absorber. So in order to test out its technology NASA dropped a small helicopter from a height of 35 feet to see whether its deployable energy absorber, made up of an expandable honeycomb cushion, could handle the stress. The test crash hit the ground at about 54MPH at a 33 degree angle, what NASA called a relatively severe helicopter crash."
Thought you meant throwing a Senator out the window...
... when you strap my mother-in-law to a turbine engine. The rest of the plane is optional.
One of the main hindrances (the primary hindrance?) to adopting widespread flying cars or other airborne vehicles is safety, and helping to keep people from killing themselves in spectacularly Youtube-worthy ways. The development of an advanced "airbag" like this will really help accelerate the dawn of "highways in the sky", IMO. (Disclaimer: I work for NASA, albeit as an IT geek)
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2. ???
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I liked the system that they had in Demolition Man. When the car that Sylvester Stallone was driving crashed, it filled with foam. Initially, it came out like shaving cream, but by the time the crash had finished, it was like styrofoam. There are two problems I can see with it. The foam will suffocate you if it solidifies around (or even in) your mouth and nose. Also, it may be difficult to extract yourself from the foam.
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When I was young I used to wonder whether they couldn't wrap people in a stiff rubber like material that would just bounce off the ground if the plane crashed.
Of course, it would take some time to find you after your superball bounced around the country 23 times.
The thing hit the ground, and what happened? Worst. summary. ever. From nasa: "Engineers say the MD-500 survived relatively intact as a result of the honeycomb cushion. "
Isn't he a riot! Stop in often, tell your friends to come!
...from becoming a helicopter pilot. In fact, just last night my wife said, "sure honey, you can become a pilot just as soon as they invent the deployable energy absorber."
C'MON NASA!!!
I can't say I've studied helicopter accidents very much, but every one that I've seen video of involved a main rotor or tail rotor failure. The airbag seems like a good idea if the craft can autorotate down to the ground, but if the rotors are compromised you probably aren't going to hit belly first.
Perhaps there is a selection effect? I wouldn't likely see many successful autorotate landings of helicopters since they aren't sensational enough to make it onto the nightly news.
Helicopters can auto-rotate so crashing into the ground at 50-60mph like they say is a pretty severe crash.
Basic physics: the forces involved in a bouncy collision are *greater* than the forces involved in an identical "smooshy" collision. Why? Because the crash has to not just bring you to a stop, but throw you back away again.
What you want is a smooshy collision that takes place over a long time. Thus, airbags.
how many helicopters are generating zero lift when they hit the ground? What's important is not the height of helicopter crashes, but the speed. I can certainly imagine worse accidents than 53mph at 33 degrees, but I'm willing to take NASA's word for it that this is "relatively severe."
TFS didn't mention it, but the helicopter and "passengers" (excluding the skids) survived the crash.
On a related note, I think final car safety tests should be performed with the CEOs of the car company inside the car.
[sigh] Yes, but any helicopter that crashes from ABOVE 35 feet must also travel THROUGH 35 feet, thus a 35-foot test elevation should substitute for most helicopter crashes. One could certainly argue that a 5-foot test would effectively sample more scenarios than a 35-foot test, so perhaps they should test based upon that height instead. When will science learn that if you just use the right logic no one has to die.
The fact that it hit at a 33* angle suggests that the 54MPH was either groundspeed or total impact velocity, not just the vertical component.
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At 5 feet, the helicopter wouldn't reach the impact speed of a 35 foot helicopter crash. It also may be the case that most crashes below 35 feet tend to be less serious... and anything past 35 feet is going to kill you regardles
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how many helicopters are generating zero lift when they hit the ground?
All of them. As a matter of fact, that's one reason why helicopter crashes are so much more often fatal than regular fixed-wing airplane crashes. A plane gets most of its lift from the wing, and the engine merely provides the propulsion (which is needed to reach the speeds at which you get good lift, of course). An airplane that has all engines failing is still airworthy and will still glide to a degree -- quite frequently well enough such as to allow for an emergency landing. As you have seen many times on TV - plane encounters trouble, does an emergency landing on a field, street, river, anything. A helicopter, on the other hand, has no aerodynamic lift whatsoever. It is essentially a brick, held up in the air by sheer brute force. If/when the engine goes, there's not such thing as "gliding" back to the ground. A plane at non-zero speed always has a little lift left as long as there's any part of the lift surfaces (aka wings) still around. A helicopter doesn't have any lift surfaces other than the rotor/engine itself.
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This site has a video and some more information.
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"The test crash hit the ground at about 54MPH at a 33 degree angle, what NASA called a relatively severe helicopter crash."
I agree. Unless it hits at 300,000 Km/s, let's say a crash is 'relatively severe'.
http://en.wikipedia.org/wiki/Autorotation_(helicopter) Au contraire, mon bon sieur.
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wait... not that kind of sig.
Autorotation, look it up.
A helicopter produces lift as long as the rotor is spinning, do you think that all helicopter crashes result from main engine or rotor failure?
Helicopter crashes are more deadly than plane crashes because helicopters do more dangerous things, like flying around cities at a couple hundred feet.
wrong.
Unless the rotors are blown off somehow, they will continue to rotate and generate lift at any speed. Meanwhile, a fixed wing aircraft will stall at sufficiently low speeds and the only way to regain lift is to dive towards the ground at high speed, this places a high minimum velocity for fixed wing air crashes under most circumstances.
Wrong again. You can land a helicopter with a stalled engine. It is called "autorotation" and the parent mentioned it. The blades will continue to rotate and actually act as brakes while providing some lift.
This is why NASA is looking into airbags. People do walk away from helicopter crashes, but the forces are just right around the survivability limit. This is why a cushion makes sense.
Slashdot's rate-of-post filter: Preventing you from posting too many great ideas at once.
*double checks your math* Hun... That's funny.
Perhaps you need to go back and study some more physics. In earth gravity of 32ft/s^2 it would take about 2 seconds to hit the ground from 35 feet falling straight down. 2 seconds of earth acceleration has you moving at 64ft/s, which is just over 43mph. Even the lackluster summary states the impact was at 33 degrees, which implies the helicopter was guided in along a slope, rather than being dropped. So using a bit of trig, 35ft/Sine(33) = 64.26ft is the length of slope the helicopter descended, at 33 degrees to the ground, to impact at 54mph, which would then imply that it was actually falling slower than gravitational pull would account for, largely due to the friction of the guide cable. This is likely the same rig used to test reentry mechanisms for many other NASA vehicles, which has the ability to vary impact angle, while maintaining repeatability between each test in a given configuration.
It's close enough to the free-fall velocity in vacuum in km per hour, that I'm suspecting that someone at Networkworld just wasn't paying attention to units. Unfortunately NASA has been hobbled by all kinds of external contractors/suppliers/manufacturers/operators and, apparently, reporters who just aren't quite bright enough to get metric units. Of course any article about anything that NASA supposedly does/did/said that doesn't come with a link to an official souce might as well be considered a fabrication. There's certainly enough of those around on the net.
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Just put weights in it, duh.
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How was this modded "insightful" instead of "funny"? A 35 foot test only substitutes for greater height tests if in falling from a greater height, the helicopter pauses at 35 feet before continuing on to it's doom... as far as 33 mph, it's possible they accelerated it horizontally before they dropped it; they're simulating an auto-rotating 'copter coming in hard, not a 'copter falling from the sky like a brick.
I've abandoned my search for truth; now I'm just looking for some useful delusions.
Basic physics: the forces involved in a bouncy collision are *greater* than the forces involved in an identical "smooshy" collision. Why? Because the crash has to not just bring you to a stop, but throw you back away again.
What you want is a smooshy collision that takes place over a long time. Thus, airbags.
Reminds me of Hollywood physics, where it's the "ground" that kills, not the "stop". The protagonist is always saved by a safety rope, even if it stops him instantly 1m from the ground after a 1000m fall.
Yeah, that headline is the joke that keeps on giving. Just insert your favorite talking head: Michael Moore, Rush Limbaugh, Hillary Clinton, Sarah Palin, Sean Hannity, Bill O'Reilly, or whoever. . . the list goes on and on - and that's just the U.S. I'm sure people in any country on Earth can find someone to insert into the punchline.
Hopefully they find a way to make that deployable since I doubt anyone is going to put big blocks on the bottom of the helicopter that increase airframe drag.
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Table-ized A.I.
Yeah one killer is their very crap lift/drag ratio. In a fixed wing aircraft you can trade speed for altitude and look for a spot to land. In a helicopter you are going straight down into that junk yard or river, whatever is right below you.
Makes me wonder if a backup engine of sorts could be used to stretch autorotation. Possibly just something to give the rotors more momentum so you can better pull up in ground effect.
There are three helipads on the Yarra river close to where I work. A couple of years ago two people drowned when an engine failed while lifting from one of those pads. If airbags are to be used then you would need to look into ways of either keeping the aircraft afloat or making it easier to egress after a landing on water.
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Auto-rotation may not help if you are flying too low and slow. Or if you don't have a good place to land.
That depends on if you screw up the landing during an auto-rotation. Which may be beyond your control if you have limited landing sites. No point in keeping enough energy for a smooth landing if doing so will set you down on a forest canopy.
Yeah, I'm sure climbers and bungee jumpers never thought of that.
A safety rope DOESN'T stop you instantly. A good safety rope is designed to stretch and absorb much of the energy of your fall, and stop your fall over a comparatively long period of time.
I'm all for using science and research to improve safety, but this seems a little pointless to me. All helicopter crashes can be generally lumped into two categories: those in which control is lost at a relatively high altitude, and those in which control is lost only a short
distance from the ground.
In the former case, no one survives. Once a helicopter pilot loses control of the machine, it has all the aerodynamics of a grand piano and will collide with the ground with much the same effect.
In the latter case, the biggest threat to life and safety isn't the collision with the ground, it's the two giant rotors spinning at an ungodly rate. In a crash, the rotors inevitably strike the ground or a nearby structure and cause all manner of high-velocity objects, material, shrapnel, as well as the rotor blades themselves, to go flying in all directions.
This flying airbag is only going to be of much help in only the best-case crashes where the bird is only a short distance from the ground, perfectly level, and a good distance away from any structures. Go watch some YouTube videos of helicopter crashes. Those kinds of videos completely cured me of wanting to be a helicopter pilot some day. There are lots of ways a pilot can survive even the most severe problem with a normal airplane. In a helicopter, even the slightest mistake can kill you and a lot of other people before you even realize a mistake has been made.
As some know, cars are well equipped with something that is called a crumple zone. Airbags keep your seatbelt from breaking your neck, but the crumple zone is what absorbs most of the force of the crash. See this video for why your crumple zones make a big difference over the air bags.
Something witty.
I really don't know what the heck they mean by "Relatively Intact". In my 3300+ hours of piloting helicopters the only valid criteria was "Could you walk away from it?" That's the standard pilots (and I assume passengers) really care about.
you should keep reading http://en.wikipedia.org/wiki/Autorotation_(helicopter) Helicopter has the same capability of forward controlled flight with Auto-rotation, assuming you can still have control of the blade pitch, except it also has the additional ability of going straight down slowly, a plane doesn't.
Yeah, I'm sure climbers and bungee jumpers never thought of that.
A safety rope DOESN'T stop you instantly.
But in Hollywood they do. And don't just think ropes, think Spiderman plucking you from the air as you fall (thus not only causing an immediate upward acceleration to break your fall, but a sideways one so you swing away).
Even worse is when the rope instantly stops the person just before they hit the ground, but the rope isn't attached to a harness but around their ankle (so the near-hit is made even more dramatic by it being their *head* that is inches above the ground). With no ankle damage/amputation. And when someone falls off a tall object with a chain wrapped around their neck, they die of suffocation not a broken neck or decapitation (a short fall with a chain could result in suffocation, but I'm talking 30+ feet).
That's Hollywood physics.
A good safety rope is designed to stretch and absorb much of the energy of your fall, and stop your fall over a comparatively long period of time.
More to the point, to be a safety rope in situations where falling is possible, it has to be a dynamic line. Static lines are very dangerous even in short falls.
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Funny, but adding weight *would* increase the energy of the impact as an alternative to going faster. But as others have said, 54MPH is apparently appropriate for simulating a severe crash.
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It's not proper collisions testing unless MythBusters does it. Preferably with big explosions somewhere in the process.
Hmmm. Interesting.
Several factors affect the rate of descent in autorotation; density altitude, gross weight, rotor rpm, and airspeed. The pilot's primary control of the rate of descent is airspeed. Higher or lower airspeeds are obtained with the cyclic pitch control just as in normal flight. Rate of descent is high at zero airspeed and decreases to a minimum at approximately 50 to 60 knots, depending upon the particular helicopter and the factors previously mentioned. As the airspeed increases beyond that which gives minimum rate of descent, the rate of descent increases again.
...I expected the best sink rate to be at zero forward speed, which would make vertical landings easy. But if the rate of descent increases at low forward speed you might have to touch down with forward velocity, which doesn't sound good in a helo.
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Uhh, physics troll? h = gt^2/2; t = sqrt(2h/g); v = gt = g(sqrt(2h/g)) = sqrt(2gh) = 47 feet per sec = 32 mph. Not sure yet how you get more energy out of an inclined plane, but work it. Anyway, http://www.nasa.gov/topics/aeronautics/features/helo-droptest.html says: "We crash-tested the helicopter by suspending it about 35 feet (10.7 m) into the air using cables. Then, as it swung to the ground, we used pyrotechnics to remove the cables just before the helicopter hit so that it reacted like it would in a real accident," she explained. The test conditions imitated what would be a relatively severe helicopter crash. The flight path angle was about 33 degrees and the combined forward and vertical speeds were about 48 feet per second or 33 miles per hour (14.6 meters per second, 53.1 kph).
What you really want is something that absorbs the energy of the motion. You want something that collapses slowly, while arresting as much momentum as possible, and then also have a non-deflating portion as a final cushion. An airbag is not going to do this, at least not an airbag in the common understanding. Now an airbag that slowly deflates as you impact it would meet some of this requirement. I think NASA's honeycomb airbag, probably, is something like this. What I'm describing is used by Hollywood stuntmen to break falls.
If you're flying too slow and low to the ground, there is less time to recover and perform an autorotation. In a heli's flight envelope, this is often referred to as the dead man's curve.
Perhaps you need to go back and study some more physics.
(preferrably this time using the metric, international-except-some-countries-dontaskmewhy, system) .
In earth gravity of 32ft/s^2
, or equivalently 23.123 elbows/alittlewhiles^2.
I really appreciated when you translated the 64ft/s to 43mph, it really makes it much more intuitive for the rest of the world.
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http://www.nasa.gov/topics/aeronautics/features/helo-droptest.html
This could be incredible useful for automobiles. In order to increase efficiency you need to drop weight (as in, stop having SUV-like weight). The problem is that that weight creates a certain amount of crash safety (for the SUV driver to some extent - not so much thought, and not at all for anyone driving a smaller car). Given that, being able to use a light-weight energy absorption system like this could solve that problem and allow cars to have weights below 1000 lbs yet still have excellent crash safety.