Ok Paul see attachement
 It will be similar to this photo with straight main spar


 Jean

 That is much better Jean.

 Paul Lamar

 Jean, The pcture was most helpful, and I just thought I might also ad some
random thoughts. Reguarding the automotive differenial an important thing to
remember is that in a car there is a tranmission ahead of it with something
like a 3.85 to 1 ratio and maybe a 2.85 ratio second gear multiplying
torque, the differential  has to be larger due to the resulting increase in
torque.Also torque  is related to horsepower such that the higher the RPM
the lower the torque for a given horsepower transmitted. The engine makes
the torque, we calculate horsepower moe like a conversion factor
horsepower =torque X RPM/ 5252     That is why torque equals horsepower at
5252 RPM

By transmitting your torque at 6000 rpm you are dealing with
less than 275 pound feet of torque. My Nissan titan pickup  is like 1100
pound feet into the differental and sized accoringly. As Paul indicated
weight in your sketch is a concern. I would be looking at shaft drive
motorcycle rear gearing such as BMW 1100cc or Honda gold wing or valkyrie.

These are a performance part built as light as possible for performance and
ow unsprung weight, and run without a cooling system. Also the driveshafts
are light and may be carbon fibre tubing as is used on som new cars. The
lower unit of a 250 horsepower mercury or evenrude outboard and sold
separately on 300 hp and 400 hp hydroplane powerheads have little or no gear
reduction and handle 400 pound feet.

The problem is that they rely on water
imersion for cooling and with tracy's 2.85 psru the torque capacity would be
exceeded. Motorcycle stuff loks like manna from heaven for your application.
I don't know a model but a type with a single sided swing arm would likely
have larger bearings and be easier to mount. You will still need a hollow
prop shaft with thrust bearings for the thrust load which coul be whateve
you intend to use on the auto diferntial since the halfshaft couplers didn.t
support a thrust load.

The corvette I had did take thrust loads since the
half shafts were the lower control arm.Please keep the newsletter posted on
what you design. Any ideas you come up with  may help other rotary people.
Did you do that twin engine velocity model  in the picture?

george grimes


You  are quite knowledgeable on this subject George so perhaps you
would be interested in these PSRU designs.


Paul Lamar