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Excellent points, Ernest.
As far as the combustion chamber efficiency is concerned, the rotary is at a slight disadvanatage -- at least in theory. However, the piston engine has more friction and pumping losses. Think of just the power required to drive the camshaft and open the valves against the springs. The rotary doesn't have a cam, or valves. Also a lot less bearing surfaces to cause frictional losses. I agree with the opinion that the rotary is ideally suited for airplanes. I understand that with Tracy's controller the engine will happily run 200 degrees lean of peak. Try doing that with a Lycoming. Most important all, the thing is almost impossible to break, as Ernest pointed out. As long as the supporting systems are properly implemented -- and therein lies the rub -- the engine itself is practically bullet proof. Regards, Gordon. PS: Rusty, thanks for the info on the gearbox. That Hirth box or something similar sounds like a good way to go. 170 lbs is outstanding for a 100hp engine -- could be even more with peripheral porting. Best of luck with your Kolb project. I hope you will have some pictures available. "Ernest Christley" wrote in message . com... Corky Scott wrote: I don't quite understand how Tracy manages to get the kind of fuel burn he claims he reaches up and turns down that mixture button. The charge stratifies in a rotary, pushing the fuel charge out to the plugs. but I suspect he isn't running it very hard because the amount of surface area the rotors are exposed to as they rotate is much greater than that in a piston type engine. This much greater combustion chamber exposed surface area means much more fuel can condense on the surface. Running at 6000RPM vs 2500 doesn't leave much time for fuel condensing. It is true, though. The rotary doesn't get complete fuel burn, especially at the little pointy ends of the chamber. But the counterpoint is that most pilot run rich to keep from cooking their valves. No valves in a rotary. Besides, all that extra energy left in the exhaust need not be wasted in an airplane engine. It means it's going to get poorer gas milage inherently, unless you unleash the electronics engineers to do their magic with fuel injection and all the other gadgets that are used to emeliorate the situation. The problem is, you don't get that stuff when you put it in a homebuilt airplane unless you rip out all the sensors and the entire wiring harness to go along with it. Tracy is an electronics engineer 8*) I bought 42lb Ford injectors, still have to get LS1 (from GM I believe) coils. Tracy's controller is around $800. All the other sensor you need are attached to the engine when you pull it out of the car. You get them unless you go through a lot of trouble to leave them behind. So yes, it's a very very solid engine but like so many things in aviation, it has it's compromises. Have I mentioned in this thread that it will sacrifice itself to get you home. Even on one rotor, it will keep making enough power to keep most GA planes in the air until you shut it off. To me, it takes a lot to compromise away that much safety. -- This is by far the hardest lesson about freedom. It goes against instinct, and morality, to just sit back and watch people make mistakes. We want to help them, which means control them and their decisions, but in doing so we actually hurt them (and ourselves)." |
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