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It might help to post a selection of those cases you`ve documented which you consider the most notable/important/interesting as a starting point. Otherwise nobody has anything to start from other than their general views on the topic.Please note that I'm not intending this discussion to become a wrangle about the wisdom of using auto/aero engines for other purposes, but
1) a historical listing of interesting applications (in other writings, I've managed to document many hundreds of crossovers) and
2) the clever and not-so clever engineering required to adapt for the new use.
... Plus whatever other blather the subject inspires.
Mercedes diesels certified for light aircraft use by Thielert
I agreed completely with oil system (go to dry sump, add a cooler maybe), reduction gear adapter I think needs complete thrust load decoupling always, and a full dynamics survey. But I'm curious about ignition. Magnetos are inherently reliable, but so can be classic distributors with electronic position sensor and the ignition module fully potted etc. to withstand vibration. The newer coil pans seem to be very reliable so long as kept cool. Are you making reference to high altitude flashover type failures? Just curious.Generally it never works well, and if the finances permit, its nearly always better to make something which is designed for purpose, except for the most basic civil, and training types where cost is almost everything and the performance required is so moderate that the compromises are made invisible.
People do it still because the cost of developing a totally new powerplant today is almost obscene, but from a performance perspective its very demode as a strategy.
It does also depend a little on the intended usage, as if you plan to fly about at very low altitudes many of the problems of adapting auto>aero go away.
Lots of people try this thinking its easy, then get all confused when the ignition system stops working, the fuel boils, the oil foams everywhere, the
engine mounts get fatigue cracks in a few hours, the propeller reduction gear adaptor causes unforeseen torsional vibration horrors and the bearings seize. By the time you fix all that, most people regret not using a purpose built engine. The duty cycles are also almost opposite, and this often causes a formerly reliable engine to turn into a horror which overheats and dies like clockwork.
Yes the dramatic reduction in the dielectric strength of air as you climb can cause a lot of problems. Even coil-over`s may not be immune here depending on howI agreed completely with oil system (go to dry sump, add a cooler maybe), reduction gear adapter I think needs complete thrust load decoupling always, and a full dynamics survey. But I'm curious about ignition. Magnetos are inherently reliable, but so can be classic distributors with electronic position sensor and the ignition module fully potted etc. to withstand vibration. The newer coil pans seem to be very reliable so long as kept cool. Are you making reference to high altitude flashover type failures? Just curious.