I did the maths and if I'm right (I'm terrible at maths) then a loop would be impractical for any reasonable G force anyway - the radius would have to be over 1

I did the maths and if I'm right (I'm terrible at maths) then a loop would be impractical for any reasonable G force anyway - the radius would have to be over 100km for even 50gs. I'm guessing they'd need some kind of linear acceleration, in which case they can just point upwards anyway.