Reciprocity Engine Demo
by jfrouleau
uploaded 2017-07-19
(updated 2017-12-26)
stock ship
#turboshaft #helicopter #demo


Built in the SPH in KSP version 1.3.1.

My KAH-2 has been used mostly for R&D lately and here is the latest experiment. We know that a jet engine can push a turbine wheel. We also know that a jet engine can push itself and the craft it is attached to in the opposite direction. Wait, I have an idea ! Let’s attach jet engines to a turbine wheel and aim them at the other wheel. This way, each engine push the wheel it is attached to AND the other wheel spinning in the opposite direction, dramatically increasing the engine output. The air intakes use the air speed of the rotor it is attached to so even if it is rotating the engines output is static thrust. To gain advantage of the air speed of the rotating engines, we would need them to be separate crafts held in a kind of cage attached to the rotor but all my attempts to do this ended with a boom.

The numbers

Here we have 8 junos that can lift 40t. It lift when the juno output is at 18kN so 18x8 = 144kN output from the junos.
The craft weight 40t so using rocket equations we need a thrust of 392.4 kN to lift this weight off the ground.
392.4 / 144 = 2.725 so the output from the rotor is about 2.7 times those of the engines.


Since throttle control is now on the rotor, I suggest using the deploy slider on the blades to control vertical speed.
Also the fuel is limited to the tanks on the rotor. A better way to do this would be to put the fuel tanks as the shaft, put the intakes at the center and leaving just the engines around the turbine wheels.
There is a limitation to the rotation speed because of the strength of the joints holding the rotating parts.

Update 07-19-2017: Corrected an error in my math.

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