> Me too on the mold. I was thinking a spinning on the bell housing part

and welded aluminum tubing on the rest of it along with some machined
aluminum plate (ribs with draft). All tig welded up. I think a
six pinion ring gear held stationary with power out of the planet carrier
on a A4OD 2.17 gear set will yield a 3.15 over all gear reduction
for an RX8 based motor. 8500 takeoff RPM divided by 3.15 is 2700 RPM.

Lycoming should give up now.  Resistance is futile.

Paul Lamar

Paul do you think the EVOLV engine offers great advantages over the 13B in
aircraft application. The little I have read seems to indicates that most of
the HP increase comes from operating at a higher RPM. It is my understanding
that rebuilding a 13B for operation up to 8200 RPM is not that difficult or
expensive. Also could taking the exhaust through the sideplates increase the
cooling load in that area and the overall system.

Graydon Woods

I think you mean the RX8 or Renesis engine. Yes most of the HP increase
does exist from operating it at higher RPM. However we must get rid of the
subconscious bias against high RPM engendered in most of us by the fact that piston
engines blow up at high RPM. No such thing happens in a rotary. The 
minimum bearing load in the RX8 motor probably occurs somewhere around 
7000 RPM. This is where the centrifugal loads on the rotor bearings
are exactly balanced by the combustion loads. In the current 13B engines
this number is about 6000 RPM.

This point occurs in the majority of piston engines at 3600 RPM.

The rotor bearing loads are the limiting factor in the max RPM
of the rotary engine. The main bearing loads are only a function
of the combustion pressure.

How then do we get the potential power out of an RX8 engine? We use a 3:1 gear box
and run the engine at 8500 RPM (HP peak) for takeoff. Prop RPM is still only
2800 RPM. The other advantages of the RX8 engine are less fuel burn for
a given amount of power and a cooler and quieter exhaust.

Cruise RPM can be anything you want it to be. Particularly if you have
a variable pitch prop.

Paul Lamar
 
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