Graviman,
I agree...doing Mach 2 without moving in my eyes!
I wonder also if there is a gearbox at the end of the boom for the pusher prop or if it is a direct driveshaft from the main box. It looks as if the latter is the case and if so that would put the driveshaft running right OVER the engine. I guess it isn't a big deal but just out of the ordinary.
Speaking of disc loading, how is it figured for a coaxial aircraft? Do you figure the disc area for both rotors or just one since they are acting on the same stream tube?
Max