I am looking for a drive for my single. Tracy's drive is too heavy
for this application so I assume so would be all attempts at a
planetary drive. Does that leave only belt drives? Can anyone
recommend a drive? Perhaps someone on this list (Paul?) could
design a belt drive that I could build? Any guidance would be
appreciated. Jerry
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I can design one and they are pretty easy to build but I doubt you
would save much weight over Tracy's PSRU as the torque pulse
from a single rotor is severe. The big problem is getting a large
12" dia. cog belt pulley made out of aluminum. Ken machined his own.
Ken Welter can tell you what his belt PSRU weighs.
Weight can be gotten out of Tracy's
drive if you are willing to do a bit of machining on the housings.
A lot can be done with just a lathe.
Perhaps Richard Sohn can fill us in on the weight of the PSRU he is
planning on using.
-- Paul Lamar ...No rotor no motor.
I am using a Hirth psru G40. The weight is 20.25lb with a donut
coupler or
24.2 with a clutch. Ratio I am using is 3.3:3, however, there are
four more
lower ratios available with the lowest 2.03:1 .
I am a few days away from running mine with a prop on it.
Richard Sohn
Looking for the Hirth, I found Autoflight. This "Universal" (via
adaptor plates) gear box is good for 7500 rpm in put and 160 hp out
put. Weight is 19 lbs. Sounds perfect. Made in Australia, I
think. George, do you have any knowledge about this? Jerry
Beware Jerry. 160 HP at 7000 RPM is not a lot of average torque.
Particularly with a four cylinder engine.
HP = RPM X Torque /5252
HP X 5252 = RPM X Torque
HP X 5252 / RPM = Torque
Therefore:
Torque = HP X 5252 / RPM = 160 X 5252 / 7000 = 120 foot pounds.
The peak of the torque pulse out of the one rotor is about 35 Kg
per meter or
about 253 pound feet or foot pounds.
The question you want to ask is: What does the torque isolator look
like?
It is also not a planetary so you have mounting issues.
Paul Lamar
Thanks, I will beware. The company has both a Canadian and US
distributer. Maybe they will be at Oshkosh. If I get 110 hp 6700
rpm that would be fine. The gear ratio is 2.47.1 x 2750 ( max prop
rpm) = 6737 rpm
Jerry.
You are a good welder and you have a lathe and mill Jerry. I think you
could make your own out of thick wall 6061 tubing. If you do you could
lengthen the snout and move the engine back closer to the firewall for
better weight and balance. Here is one light weight design. I have others that use
telescoping thinner wall tubing so there is not so much lathe work.
This is a 2.17:1 design but I can redo it for 2.85:1. It will fit
Larry's bell housing. If you use that you won't need the steel tube braces.
The gear set and other parts are available from Slauson Transmission parts.
http://www.slauson.com/
Paul Lamar ...No rotor no motor.
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