Flight Validation of a Rotary-Valved Four-Cylinder Pulse Detonation Rocket

A rotary-valved four-cylinder pulse detonation rocket engine system, Todoroki II, was developed, in which two novel techniques, the use of an inflow-driven motor and an inverted oxidizer cylinder, were introduced. The total length of the system was 1910 mm; its total weight when filled with ethylene–nitrous-oxide propellant and helium purge gas was 32.5 kg; and the engine weight was 9.6 kg. In a ground firing test with a duration of 1500 ms, a thrust-to-engine-weight ratio of 2.7 was achieved. Thus, it was demonstrated that a multicylinder pulse detonation rocket engine system can be used as a practical thrust mechanism. Using a launch and recovery system, a flight-simulating test was conducted to evaluate the features and viability of the engine design. The launch and recovery system operated perfectly, and Todoroki II reached a height of about 9.7 m. The operation of the pulse detonation rocket engine under conditions simulating real vertical flight without constraint forces with a duration of about 1200 ms and a thrust-to-engine-weight ratio of 2.5 was demonstrated. No serious impact of the vibration caused by the pulse detonation rocket engine operation or the rotation of the rotary valve on the flight was observed.