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Direct Drive Rotary?

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PTAirco

Well-Known Member
Joined
Sep 20, 2003
Messages
4,006
Location
Corona CA
Ok - I am pretty ignorant as far as these engines go, compared to the usual piston things out there, but here are some thoughts people might like to comment on.

The basic engine is inherently light, simple and (theoretically) reliable due to its few moving parts. Most issues in making it fly have been with the usual PSRU problems and its torsional vibation characteristics which apparently occur just at the kind of RPM you'd run it at , like 4500 or so.

Now if a two-rotor engine can put out around 180 hp at 5000 rpm (is this realistic?), then a 4 rotor version of the same engine should be able to produce the same power at about half the RPM, 2500 or thereabouts, which is normal for the size prop you'd use on this.

Now, if one could find/build/modify such a 4 rotor engine, would the extra two housings weigh so much more than the PSRU (say40-60 lbs depending on design) ? I doubt there can be a lot of difference. Of course, with the PSRU the sky is the limit as far as power goes since these things seem to be capable of indecent amount of revs, but in terms of this kind of hp (say 160-180) I would rather have the direct drive version. (I'm sure it would need a little thought put into the prop drive and bearing, but that would certainly be do-able.) I'm talking about getting the ultimate in hp/weight ratio, just a simple reliable engine in thepower range described.

Now I know there are 4 rotor engines out there and I have looked around the net a bit, but perhaps we have a resident guru here in the forum who can tell me what is available and maybe poke holes in my argument above?
 
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