Michael Emrys Posted March 23, 2013 Share Posted March 23, 2013 A combined look at both human injury and structural damage for the same overpressure values. Even 2 psi can be fatal. Remember, this is 2 lbs applied to every square inch of the target in the blast zone. John, Do you happen to recall the story of the test pilot who ejected at about Mach 1 back in the 1950s wearing only street clothes? He was not in great shape after his ordeal, but he did survive. Michael 0 Quote Link to comment Share on other sites More sharing options...
John Kettler Posted March 23, 2013 Share Posted March 23, 2013 The faster the pressure rises over some short unit of time, the greater the shattering or crushing force. For high explosive, as seen in blast overpressure plots in the FEMA doc, the peak occurs in a few milliseconds. It's that near instantaneous transition of conditions from standard atmospheric to that huge pressure spike that give HE what's called brisance. Low explosives, such as ANFO (ammonium nitrate mixed with diesel fuel) have great lifting power but not much shattering power because their detonation velocities are meager compared to the baseline HE, TNT, which destroys by tearing things apart--men, machines, bunkers, buildings. The human body can tolerate all kinds of abuses, but it doesn't handle blast very well. A supersonic shirtsleeve ejection at 3000 feet isn't the same as having conditions switch in two milliseconds from normal to enormous overpressure. Having read Udell's experience, I sure wouldn't want to eject at supersonic speed, but he did survive. His WSO didn't. http://www.ejectionsite.com/insaddle/insaddle.htm Let's take a better known case, even more miraculous. In Donald Burgett's CURRAHEE, he describes a life or death game of hot potato in the hedgerows with a German stick grenade. It came to him, he threw it back. It came again, so he picked it up and Boom! He was very fortunate that it was an offensive (blast) grenade, rather than a frag, but it blew off all his clothes and knocked him out until dark. Somehow, his body came through intact. That was a very small charge compared to what we're discussing here (.365 lb vs 100 lb--more than two orders of magnitude). Am going to post this now, lest my computer hiccup again and wipe out my second post attempt. Regards, John Kettler 0 Quote Link to comment Share on other sites More sharing options...
John Kettler Posted March 23, 2013 Share Posted March 23, 2013 Forgot! Here's a video interview with Supersonic Man. http://jalopnik.com/5894022/what-happens-when-you-eject-out-of-a-jet-at-800-mph Regards, John Kettler 0 Quote Link to comment Share on other sites More sharing options...
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