marc wiese wrote:

How about a review of this design, Paul? Perhaps they would be interested
in a conversion to the Mazda using a straight thrust line and 3.x gear
reduction?
http://www.epi-eng.com/PSRU_Specs.htm

It obviously works as there are quite a few Engineair V8 conversions
flying. Ideal for an upright V8 as the six or so inches offset puts
the prop up near the top of the engine. For a rotary it would waste
a lot of valuable space in the cowl. Also it is quite heavy
at around 73 pounds. There is no beating a planetary in torque
capacity to weight ratio.
One nice feature is the separate gear box oil pump. Several
rotary engines have failed after a Ross
gear box has come apart due to gear box metal particles
contaminating the engine oil supply. It happened to Ken Welter
at least once. Ken suggest a screen filter from a motor cycle
engine to filter the oil from the gear box before it flows back
into the engine sump. He told me what kind to use but I forgot
the name. Ken? Help :-)
I would also devise a metal particle detector on the oil drain
plug wired to a light on the instrument panel.
Paul Lamar

ddunbar wrote:

Paul I agree with all your comments.
I find hard to believe that a manufacture of aircraft equipment can produce a PSRU being so heavy!  We are all looking for a PSRU that can handle the torque of a 13b at say 6500 rpm with an output of around 250hp . There seems to be many manufactures willing to sell their brand of PSRU to the home builder and they all seem to be over price except the unit offered by Tracy Cook.
In the marine industry I can buy a marine reduction gear with a higher duty cycle than an airplane  with oil lube pump, reverse gear and cooling for $1200.00US and weighting 35lbs.
Tracy Cooks unit looks to handle all we rotarians need and we should all work with a supplier of equipment to achieve a competitive product that we all can use and benefit from the results.
Don Dunbar

Charlie and Tupper England wrote:

73 lbs might not be that heavy when you consider that it's
bolted to an engine that can easily produce 400+ hp. A 2
stroke Rotax gearbox probably weighs far less than 20 lbs &
is very reliable on a Rotax 2 stroke making 65 hp, but I
wouldn't want it bolted to a 13b.

Charlie England

Its still heavy compared to a planetary Charlie. The Ford six pinion
planet set weighs about ten pounds less shafts and the total gear 
tooth width is 4.8 inches while the gear tooth width on this box 
is only about 1.5 inches.

Torque capacity is proportional to gear tooth width all other
things being equal. The trouble is... planetaria's don't work on
up right V engines.

The Ford  will probably take 400 HP or more as well. We have yet to
see a properly lubed example with more than  what ever the number of hours 
Tracy has on his box so far. The Ford truck it came out of can easily
generate 400 HP in some cases. Time will tell.

Paul Lamar
 
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