looked to me like a high speed taxi test gone horribly wrong , it certainly didnt sound like that corvair was at full song . I would be very suprised if it was a rear C of G issue with a heavy corvair and psru up front .
I noticed the up elevator also and what sounded like 3/4 throttle which is why i thought it was a taxi test, but i couldnt work out why he wouldnt have got the tail up and angle of attack down and pinned the mains down with down elevator , rather than maintain the wing at pretty much climb angle of attack at marginal flying speed ?
Jason