SPR Ltd.



Feasibility Study

Demonstrator Engine

Flight Programme

Dynamic Tests

The engine was mounted on a dynamic test rig enabling it to be “flown” on a rotary bearing, as shown in fig 3. The tests simulated the engine moving a 100Kg spacecraft in weightless conditions. The programme included acceleration and deceleration runs in both directions, and confirmed the thrust levels measured in the static tests. The dynamic operation also conclusively proved that the engine obeys all Newton’s laws, and that although no reaction mass is required, the engine is not a reactionless machine. Reaction occurs between the EM wave and the reflector surfaces of the resonator, and the law of conservation of momentum is maintained with the transfer of the momentum of the EM wave to the engine.

Fig 3. Demonstrator engine mounted on dynamic test rig.

A video clip of the initial part of an acceleration test run can be downloaded here:

Notes on Test video:

  1. The field strengths within the thruster equate to a power level of 17MW. Signal leakage causes EMC effects within the fixed video camera. This leads to the apparent vertical movements.

  2. The engine only starts to accelerate when the magnetron frequency locks to the resonant frequency of the thruster, following an initial warm up period. This test operation eliminates possible spurious forces.

  3. The rotary air bearing supports a total load of 100kg, with a friction torque resulting in a calibrated resistance force of 8.2 gm at the engine centre of thrust.

  4. For this test a thrust of 96 mN was recorded for an input power of 334 W.