Any idea if it would be possible to make a type of 'co2' engine which ran on a mixture of co2 and n2o. Perhaps
1 part n2o to 2 parts co2. And in addition would it be possible to make it fourstroke so that during the compression phase the n2o decomposes to release heat and so boost the performance of the engine?
N20 and CO2 have very similar vapor pressure/temp characteristics so I don't see an advantage unless you do decompose the N20 as suggested. However, the conditions required to trigger N2O decomposition will probably negate any benefit due to hardware weight unless you have something in mind more grandiose than a model application. Typically a preheated ceramic bed at
200-300C is required to initiate decomposition which can then sekf-sustain, but how you could practically achieve that in a CO2 motor with a net gain in performance is beyond me. BTW our company manufacture N20 hybrid rocket motors. One could two-cycle the motor in theory I suppose, with the N2O continually decomposing into a gas reservoir between the supply tank and the cylinder. A similar scheme was proposed for a MARS aerial drone vehicle using hydrazine which I thought was quite intersting.