Hi Paul,

 I would be very interested in finding out the result of Will's mission to
 Mistral.  This is my largest concern with the idea of using a rotary
 engine.  To me, 10K for a competent purpose built PSRU with a 2000 hr tbo
 that I don't have to worry about is worth it.

 Kent Baxter

 Don't hold your breath. I doubt Mistral  have the money to build anything
 let alone one gear box. They won't be around to give you service anyway.

 BTW It is the communist system of new product development:)
 The poor dumb tax payers put up the venture capital :)

 Tracy's box is OK. It has 15 years of use and development
 with thousands of hours of accumulated use on dozens of airplanes.

 Apparently it only has one problem and I think we have that
 identified and solved. The problem was subtle and only showed up
 on less than a half dozen gear boxes. Pins were being sheared.
 Flex plates were being destroyed. Planet ring gear bolts sheared.
 You run the stress numbers and the parts LOOK strong enough on the face
 of it. The other hundred gear boxes are working OK.

 The answer was Tracy's rubber bushings were not working as
 rubber bushings. It was only recently that I figured that out.
 It was an easy mistake for Tracy to make. It looked OK to
 me 15 years OK. It wasn't until all these strange things
 began to happen in the last few years.

 There is no guarantee the same thing won't
 happen to the Mistral gear box. Relatively speaking it has zero
 hours compared to Tracy's design.

 The new rubber coupling can be retrofitted. I feel confident
 that will solve the torsional vibration problem. It is also tunable
 in the sense the rubber bushings can be easily changed. The design
 is used on just about every motorcycle rear wheel made. We are not
 reinventing the wheel here. Pardon the pun :)

 It was also widely used on Suburu belt drives and for the same reason.

 Paul Lamar

 Kent,

I will give you and update when I have it. Sometime in the next six weeks or so. I haven't had much luck talking to them on the phone so as I said earlier I will go to their facility. Sometimes face to face meetings are better.

I like you think 10G is a small price to pay for a reliable PSRU. For me it's the scariest part of the whole alternative engine. Like Paul said mistrals is largely unproven (in flight anyways) but it has spent thousands of hour on a test bench. And the coupling has been tested for vibrations.

For me also the hydraulic constant speed option is a plus. I work for a company and do alot of traveling. One of our spots to go is Genieva so I will be there sometime in the next 6 weeks. (Sooner rather than later I hope)

Will

They use the same spring clutch plate as Ross. That is old school.
No damping. Rubber is better. "An oz of rubber is worth a pound of engineering"
the brits used to say :)

Constant speed is over rated for a high power to weight ratio rotary
powered experimental. Choose a cruise fixed pitch prop and you will
still have adequate take off and climb performance.
A p-port has 50 more HP than a run of the mill aircraft engine.

Paul Lamar

The Rotary Engine News Letter. Powered by Linux. ACRE NL web site.
 http://www.rotaryeng.net You Tube http://tinyurl.com/beqqxas
 Copyright 1998-2013 All world wide rights reserved.