From all this talk about about the Bell planetary and other
planetary designs one might get the false impression there
is something wrong with the Ford planetary used in Tracy Crooks
PSRU. Nothing could be further from the truth. It has been used
for the past 30 years as the core of several PSRU's. The most famous
being the Ross. Unfortunately towards the end of the Ross company
they shipped a few that were improperly machined.

The latest Ford's (actually manufactured by Toyota) have been
ungraded with 6 pinions and  are now used in the F250 Power Stroke
diesel pickup truck with 650 foot pounds of torque. That pales into
insignificance the puny 160 foot pounds from the Mazda 13B rotary.
The three rotor is only about 240 foot pounds.

Dozens of airplanes with Ford planetary have been flying for
years, some decades, with no trouble. One I know about had
over 2400 hours in a two place rotary powered gyro copter
used for training.

As far as I know no one has worn one out yet when properly
installed. The best part is the gear set cost less than a $100.

Paul Lamar

Agreed Paul - just looking at this for those with much higher HP
requirements. Also it is a special interest of mine, brought to life by
Doug's research.
George (down under)

Well lets see 650 ft pounds of torque for the Ford at 5000 RPM is
5000 X 650 / 5252 = 618 HP.

Paul Lamar ...No rotor no motor.

The Power Stroke is diesel Paul so the rpm's would probably 2000-3000 giving
247-371 hp. Tracy rates his for 300 hp which would seem to fit well.

John

Tracy is being a bit conservative IMHO.
Gear boxes are usually rated on torque and not HP.
Increasing the RPM and the HP in to such a gear box
assumes you are going to keep the oil cool.

IMHO the real limit is the RPM AND bearing load of the needle
bearing inside the planet gears. Needle bearings don't
like high RPM. This is a pretty good web site on the subject.

http://www.machinedesign.com/ASP/strArticleID/59055/strSite/MDSite/viewSelectedArticle.asp

Timken also publishes life factors as a function of load and RPM.

I think the Bell is going to have a needle bearing life problem
if run at 6000 RPM input for long.

The centrifugal load on the needles forces them out of contact
with the inner race at high RPM. The needles start to skid.
Silicone nitride rollers can up the RPM limit due to lower density.

BTW One of the reasons the Norton/Midwest/Diamond rotary engine
is limited to 7000 RPM is because of the needle bearings
in the rotor. A rotary engine this small should rev at 11,000
or more with at least 30% more HP.

Paul Lamar ...No rotor no motor.

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