Ed, I believe that there will be more and more requests for such a system. All the reductions I suggested would allow a currently available governor to work. Tracy could do a new prop shaft housing to drive from helicals like Mistral, but it would be expensive. The biggest advantage of this drive is that the reduction is already built in. I think that is why Mistral went this way. Another fact is that you would be hard pressed to come up with anything that is lighter for doing this job than the current hyd/CS. I have seen a few inventive controls, but none that work even close to as well as current hydraulics.
Hey, Bill, I think it would be great if a light weight relatively inexpensive way could be found of providing the required hydraulic pressure and speed control (adapting a lycoming governor is one way). It wouldn't hurt my heavy RV-6A getting up quickly out of short grass strips either.
I think had there been a large demand for Tracy's gear box to have the provisions for it, it probably would have been incorporated in the design - but the old chicken and egg situation.
Perhaps the one that Lou referred to may be the answer as its hydraulic control is apparently internal to the prop hub - if I understood correctly. Wonder how much it weighs?
Ed
----- Original Message -----
Sent: Wednesday, December 20, 2006 12:19 AM
Subject: [FlyRotary] Re: hydraulic constant speed prop for rotarys
Guess I did, Bill. I know the governor has the pump to do this, its just I've not found a governor suitable for a rotary engine.
OK Ed,
I kind of figured you understood about the pump in the governor. As to the speed, I figured that the governor would require a reduction identical (or really close) to the PSRU. This could be a toothed belt/pulley system. With the reduction any standard governor would work. Mistral uses a helical right angle drive to a pad on the side of the prop shaft. I've also seen a v-belt driving off a pulley at the front similar to the O-360 Lyc alternator drive. Some movement is OK it needn't be timed. The reason I'm interested is the RV-10 will probably benefit from a CS.
As you mentioned the RV-4 hardly needs a CS. Just more complication. I am supprised Tracy didn't think about the other planes that would or could be using the drive when going into production though.
Bill Jepson