" planetary gears are simply not designed to operate at high
RPM's "
You mean like in all those turboprop engines spinning at 30,000+ rpm? (PT6 etc)
"and under such a great load as they are under while in use in an
airplane."
Like all those radial engines on most WWII era aircraft?
Statements like these quotes undermine whatever credibility people like this may or may not have. As for warm fuzzy stuff like "feel good about taking their grandchildren on a cross country flight."
well, that just doesn't do anything for me as an engineer.
Any prop reduction drive whether it be belt, planetary or spur gear might be good as gold or a POS depending on the design. To make blanket statements about any of them is just blowing smoke. I suspect that Mistral made about as much of this as I did. (You can probably guess about me : )
These things withstanding, the clutch is a neat piece of work but I'm not sure it pays for itself weight-wise. The company owner's plane is the only one I've seen with this drive.
I did notice the company was for sale when I checked their website about 3 months ago.
Tracy Crook
On 7/28/07, Marc Wiese <cardmarc@charter.net> 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
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