<< Now from momentum considerations you can show that the tip speed should be equal to the exhaust velocity- in this case ~200 m/s >>
I may be missing part of this scenario, but there seems no reason for rotor tip speed to equal exhaust velocity. I would think rotor tip speed would increase until the torque of the overall drag forces on the rotor equaled the torque produced by the engines. IF this "terminal velocity" HAPPENS to equal the exhaust velocity of rocket, then additional energy from the rocket propellant would go mainly into the kinetic energy of the air moved by the rotor (downwash, shock waves, etc.), less an allowance for inefficiencies. In ordinary rockets, the classic rocket equation does link exhaust velocity to final vehicle velocity through total propellant mass. For instance, the burnout velocity of an ideal, free space, single stage is equal to its exhaust velocity when the propellant mass is "e-1" (1.718..) times the mass of everything else. But I would think a rotor would reach its drag-limited "terminal velocity" long before fuel consumption becomes an issue. --Best, Gerald _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
