davidstarlingm wrote:I mean, if movies and TV are to be believed, a blast wave is more than capable of flinging you across a room without much more than ringing in your ears. I'm guessing this is theoretically possible. One could then conceive of a Rapid Deceleration Gun that you pointed toward the ground while falling, then fired; it would have to measure the distance to the ground and the current airspeed, then fire a charge that would explode with the correct force to completely cushion your landing.
This is mostly pointless. Exploding stuff doesn't buy you anything physically. You still have the same distance over which to decrease your velocity. Now I know, you don't ever need a reason to blow things up, but I'm trying to use equations.
The most practical explosion would be just plain retro-rockets. If you limited the use to breaking your fall, it would actually be fairly practical although I don't know if it would be lighter than a normal parachute. It would certainly be more dangerous.
But that's ignoring the advantages. Just think about an entrance to a fight. If your opponent comes down from the sky in a parachute, you'll be like "alright, he looks pretty tough". But if the guy drops straight down, no deceleration, until the exact last moment when he fires rockets, then stands there and stares you in the eye, you're thinking "I'm going to die now". That's the kind of stuff that happens in Soviet Russia.
Actually, in Soviet Russia, not only do they drop in to a fight with retrorockets, they drop in with retrorockets on a tank.
You can easily calculate the time/distance needed to stop from terminal velocity. If you allow for pulling 7 g-s, then it only takes (200 mph)/(7*(9.8 m/s^2) = 1.3 seconds. But the distance taken is about 58 meters.
That's the real problem with the airbag approach. In order to prevent from dying, it would have to either be really really big, or you would have to sustain really really huge forces. I guess you could do a combination of both. That's the approach I would favor - in addition to some reduction of velocity due to the area of the balloon itself. You want to increase your drag dramatically, but with minimal equipment, then you could use the self-inflating balloon to take care of the rest.
Obviously retro-rockets are still cooler.