Good morning Paul

 I did a sketch with the Reno Program as evaluation but i can,t copy
 and paste  and i dont know if you can open it.

 The sketch showing both rotary located back to back behind the
 fire wall wich is about 50"wide, the left engine will be turned
 90 degres with the spark plugs upside so i can have all exhaust
 downward and away of the firewall.

 Both engine will have the second generation std transmission
 housing wich i will use to run a spline shaft to suit the proper
 lenght for the

 propeller clearance with the fuselage side.

 i tend to use a differential with a ratio about 3.15 to 3.25 ,
 i found some frombmw 1992 328i, to reduce differential weight i
 will have to get an aluminum housing and use the back cover in
 aluminum as already availble from the market also get rid of
 all gears and stuff i dont need but will reuse the existing
 trust bearing.

 I think to use a rubber coupling betwween the engine drive
 and differential input.

 the engine drive shaft and differential will be lubricated
 with the engine oil pressure system.

 Paul i want you to look at it and make your comments about
 my proprller drive project.

 I am looking this way to reduce drag,fire hasard safety because
 fuel will be located in the strake and center of gravity, the
 other differential ouput can be use to drive other equipment as
 desire.
 Also the adventage prop will turn on opposite way.

 see some differential i found may be you have some suggestions as
 per your great experience on car field


 Jean Prudhomme

 Certainly is unique.
 Running the engine up side down will require a dry sump and I still
 don't know if that will work. The oil drain backs are designed
 for up right running only.

 The weight penalty will be severe.

 This is complicated with a lot of unknowns.

 Just put the engines on the wings and run them both in the same
 direction.
 They are so close together that asymmetric thrust will not be serious.

 Paul Lamar

Paul, getting off topic here but I saw your picture of the transmission
and CV /drive shafts and I've got a question on these. Do you have any
rule of thumb numbers for what these should be run at [max speed] and
how far a person can deflect/bend them before running into
their limit's  or getting into vibration issues etc..[generally speaking]..

Curious is all...  :)

Jarrett

Not my my pictures. Jean's pictures.

That is a complicated subject. I just heard from a consulting engineer
working for Sikorsky wanting my advice on a tail rotor drive system.
I had no answers :) Props are big flywheels.

Helicopters are a loose collection of parts flying in formation
surrounded by and oil leak :)

One of the big problems is what happens when the gears wear
and you get back lash. Defies FEA I suspect.

Allison went through all this back in the eary 1930's for the
P39. It was not cheap or quick :)

As I told Jean it is a good idea to avoid that type of design
if possible and keep it short and simple :)

Like this 2D sketch.

Paul Lamar