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Date: Sat, 28 Jul 2007 12:55:41 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Gear redrives.com
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Marc Wiese wrote:
> All,
> http://www.geareddrives.com/Buds_philosophy.htm 
> Has a nice write up in the last Contact mag. I like the features of his
> psru----cs, separate lube, offset shaft. 
> He says "Build the PSRU so that anyone would be feel good about taking their
> grandchildren on a cross country flight. Safety being our first
> consideration, we do not advocate the use of belts, chains or planetary
> gears in something as important as a propeller drive. Belts break, chains
> stretch, and planetary gears are simply not designed to operate at high
> RPM's and under such a great load as they are under while in use in an
> airplane. Planetary gears do well in situations that only require high RPM
> for a very brief period of time, but are not designed to operate under
> consistent and continuous use at high RPMs. This is a recipe for disaster in
> our opinion. Spur gears, as we use in our PSRU, on the other hand, are
> designed to safely operate at a high RPMs and under continuously use. We
> chose to use what we know to be the most dependable and reliable technology
> for this application because our objective was to do what makes sense in
> terms of safety, reliability, and ease of maintenance. "
> Erstwhile comments on the planetary? What do you think Mistral makes of
> this? Of course his redrives are mostly made for V8's but I really like the
> clutch feature as he implements it!
> Marc Wiese
> 
> 
Something else he said was that the clutch was to compensate for burning 
up starters 'turning the gears & prop'. I'm no engineer, but if adding 
the load of the gearbox to the load of turning a 10/1 compression 400" 
V-8 burns up the starter, I'd take a long hard look at the gearbox. 
Looks like a lot of extra weight and complexity to compensate for 
something no one else seems to have trouble with.

(But being able to use an off the shelf c/s prop would be nice.)

Charlie