props
To be honest, the main limitation I've found with Pusher deisgns, is that only a few prop sizes are commercially available.
I came up with a 8 ft. long XB-70 Valkyrie, with 3 .60's in mind at the back, but had a really hard time finding the right pusher props for them. There only seems to be a few 1/2A and .40 size pusher props out there, or at least there were a year ago....
phil in austin