I have not heard of an extraction system before this.  It sounds
interesting - less expensive, and lighter.  The question is, will it work??
Can you avoid the rotor blades? Just some thoughts on it...

Norm

Well there is another possible path and that is air bags. Big for the whole airplane or small for just the pilot.

Paul Lamar

A person in free fall reaches a speed of about 150 FPS. If he can stop
in only 15 feet that would be 47 G's If my math is correct.
Paul Lamar

Paul, from school and with the help of the Machinery’s Handbook I think
the math is like this:

t = 2S / Vf
t= 2* 15 ft / 150 fps = .2 sec

acc = 2S / t^2
acc = 2*15 / .2^2 = 750 f/s^2 / 32.2 = 23.3 g

Also:
acc = Vf^2 / 2S = 150^2 / (2* 15) = 750 f/s^2 = 23.3 g
acc = Vf / t = 150 / .2 = 750 f/s^2,

Just recall these relations:
1. S = 1/2*a*t^2;
2. Vf = a*t;
3. t = 2S/Vf;
from (1): a = 2S/t^2;

Hope that helps
Rolf

Wow only 23.3 G's perhaps all we need is an airbag.
Thanks Rolf I'll use these to write the program.
I'll put the human body aero drag in the program as it is too tedious to calculate
by hand. Looks like an airbag is better for low altitude pilot recovery :)
They inflate in a fraction of a second while a parachute takes several seconds.

I take it:
S is distance in feet
Vf is velocity in FPS
acc is acceleration in FPS per second.