2 Vertical Takeoff, Vertical Landing
3 Vertical Takeoff, Horizontal Landing
4 Horizontal Takeoff, Horizontal Landing
5 The ROTON was invented by Bevin McKinney, CEO of HMX, Inc. and is the subject of a patent application. Previously, elements of the concept, including rotor entry from orbit and tip-rockets on rotors, were independently developed by numerous entities, including Hiller Aircraft, Bell Helicopters, Kaman Aviation and Giravions Dorand of France (French Patent 1,430,178; 15 Dec. 1964)
6 LOX cooling at chamber pressures to 1500 psia was demonstrated by in-house testing at the NASA Lewis Research Center in the late 1980s. Chambers were fired with cracks to demonstrate wall integrity at elevated LOX mixture ratios. See AIAA paper 89-2739 or NASA TM 102113.
7 Rocket engines have even been test fired directly from tanker trucks. This was common practice at the NASA Lewis Research Center during the early years of the RL-10 engine program.