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Bill, I certainly do not question the likelihood of
demand for a rotary C/S increasing. Not having any experience with a
C/S prop other than a few hours behind one early (real early) in my flying
career, I'll certainly defer to those with more experience/knowledge with the
prop. For Lycoming and other big displacement piston engines, I agree that
the current arrangement is likely the best that could be developed - at the time
- and perhaps even now.
I am not as certain that technology in many
areas has not advanced considerably since the early 1950s that might lend
themselves to lighter C/S props for the rotary without the need for the current
incarnation of the prop governor. But, if I study the problem, I might
easily change that assessment.
My bird simple could not stand 50 lbs or so
stuck out on the end of the nose. 15 lbs additional -
perhaps.
Again, not knocking C/S props, just not certain
adopting the current configuration for Lycomings/Continentals is what we need -
just my opinion of course.
Ed
----- Original Message -----
Sent: Wednesday, December 20, 2006 10:37
AM
Subject: [FlyRotary] Re: hydraulic
constant speed prop for rotarys
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.
Bill
-----Original Message-----
From:
eanderson@carolina.rr.com
To: flyrotary@lancaironline.net
Sent: Wed, 20
Dec 2006 5:37 AM
Subject: [FlyRotary] Re: hydraulic constant speed prop for
rotarys
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
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