Oh yeh. I have in my mind that an effect of bang-seats is (always/sometimes?) crushed vertebrae – ie. you trade off a broken back for your life. Is that right – or yet another urban myth?
It’s much less of a problem with modern rocket powered seats compared with the old ballistic seats.
A rocket seat has a relatively smoother ‘push’ sustained over a longer time period, i.e. the time the rocket motor burns. The old ballistic seats used explosive charges to literally bang the seat out. Some seats had two charges which fired one after the other which meant that the jolt was about as gentle as it could be, but it was still similar to one big kick up the backside rather than the sustained push from a rocket seat. The firmness of the seat ‘cushion’ is also very important as it can affect the way in which the force of the ejection is transmitted to the pilot’s spine.
For example the Hunter seats were upgraded from using a 60 ft/sec gun to an 80 ft/sec gun and that was found to be about as far as the human body could go without very serious damage every time. There were still a lot of damaged backs, but if the correct posture was adopted (use of the overhead face-screen type of firing handle helped with that) then it could be kept to a minimum. Craig Penrice damaged his back very badly when he banged out of XF516 a few years back because he used the seat pan handle rather than the face-screen and so his posture was all wrong. His day job meant that he was used to modern rocket seats which often only have seat pan handles though so it’s understandable I suppose.
Remember to Mig mid-air collision at Fairford a few years back? If I remember correctly the pilot’s ejected, then calmly walked away uninjured from the carnage! Also the Harrier crash at Lowestoft – I believe the only injury the pilot sustained was a broken ankle when, after ejecting in the hover, the wind took him back over the aircraft and he landed back on top of it before it sank.
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