YS .91ST4 Conversion to prop
 

I was wondering if there is a way to converted a YS .91ST4 so I can use it in a prop airplane if so what size prop mite it swing

Thanks

RE: YS .91ST4 Conversion to prop
 

No problem except that the shaft is short and you will need a reach through type nut. You can get the nut from Tru Turn, and you can get a drive washer from YS Parts at 775-782-4562.

Try a 13x8 prop for starters.

RE: YS .91ST4 Conversion to prop
 

Dave,
I found an old post of yours about using the YS91ST4 heli engine in airplanes. Did you ever give it a try? I'd like to know how it worked out.
Thanks. You may save me a lot of money and time, or make me happy.

RE: YS .91ST4 Conversion to prop
 

All the YS heli engines work fine in airplanes if you don't mind the short crank and reach thru prop nuts.

RE: YS .91ST4 Conversion to prop
 

Dave,
Thanks for replying to the question about the YS91. Would you please answer a couple of questions? I'd love to take advantage from your experience before spending the money.

1) Did the Tru-Turn nut and the washer from YS allow easy attachment of a spinner?
2) How did you find the performance compared to other 90 size engines?
3) Are the mounting lugs the same as on engines intended for fixed wing use?
4) What size props were you able to turn and at what RPM's?
5) How much did the entire package cost after you bought the drive washer and tru-Turn parts?
6) Would you do it again?

RE: YS .91ST4 Conversion to prop
 

1. Truturn makes them for with or without spinners. Check with them.

2. They are very powerful.

3. Same

4. Depends on what you want to do with the engine. You can run it anywhere from 12000 to 15000 without problems. That leaves almost any prop within reason open.

5. The additional parts cost is about $25 plus the engine.

6. Why should I, enough flyers have already done this to YS heli engines.