On Thursday, May 29, 2003, at 11:15 AM, Pierce Nichols wrote:


At 10:37 AM 5/29/2003 -0400, Andrew Case wrote:

Unfortunately peak acceleration is probably substantially more. Also mean acceleration scales with the square of impact velocity. The good news is that 44 m/s is already pretty fast, so it ought to be possible to get down into that range with reasonable aerodynamic decelerators. Still, it's likely to be <accent = Russian>"worst experience of entire life"</accent>.

Still, it's injured, not dead. Both impact speed and crush length are likely quite a bit higher than your assumption; however, this is not a horrible thing. Race car drivers survive going into the wall at 100 m/s on a fairly regular basis, generally eyeballs out, with a meter or two of crush length.

The ones that take the full deceleration from 100 m/s to zero in 1-2m die, AFAIK. The survivable crashes tend to involve some sliding, or lower speeds. 100 m/s to zero in 2 meters is 250g average. Peak is probably quite a lot more.


In the case of a VTVL falling straight down at terminal velocity, that acceleration can easily be taken the same way the liftoff acceleration is -- on the back, legs up, in a cushion couch.

That's a big plus. Not a whole lot of fun, but probably survivable. Beats the alternative :-)


......Andrew

--
Dr. Andrew Case, PhD.
Institute for Research in Electronics and Applied Physics,
University of Maryland, College Park
"It is seldom that liberty of any kind is lost all at once."
 - David Hume

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