I had no idea Curtis Wright investigated aluminum
 rotors. I was going over some old 1963 booklets and
 tech papers Don Sherman sent me awhile back (his complete
 collection. Thanks again Don.) and ran across this illustration.
 The booklet was written by Max Bentele and was called "Curtis-Wright's
 Experimental Rotating Combustion Engines". Here is an excerpt.

 "A rotor made from an aluminum forging offers the benefits of
 lightweight and
 high thermal conductivity, but requires adequate cooling.
 One of the most successful aluminum rotor designs is cooled by forced
 circulation of oil from the engine lubrication system. The cooling
 circuit is
 schematically illustrated in Figure 18. Oil is supplied from the
 hollow shaft,
 through radial feed holes in the eccentric, and then to the rotor
 bearing
 central annulus. The oil then divides, one part to lubricate the
 bearing and the
 other to cool the rotor.

 Integral fins in each rotor lobe provide adequate cooling surface
 and a small
 hydraulic diameter. A recess at each end of these finned passes acts
 as a
 manifold for distribution of the oil. The oil from the rotor exit,
 after
 passing the bearing end annulus, is discharged from timed shaft
 eccentric
 passages directly into the housing drain annulus.

 The oil entering temperature, temperature rise, and period of
 contact with the
 metal are controlled to avoid coking or other lubricant
 deterioration. To date,
 we have had no evidence of adverse effects in this regard. While the
 oil flow of
 this design is continuous, the velocity varies as a function of the
 system
 dynamics: shaft and rotor inertia pumping superpose a roughly
 sinusoidal
 pressure increment onto the oil supply pressure. The cooling oil is
 metered at
 the exit; in this way, the rotor cavities are maintained full. Cast
 iron rotors
 can be made very much simpler than aluminum rotors but at present,
 not quite as
 light. Their cooling system is, however, different; it is adjusted
 to the lower
 thermal conductivity of cast iron and the thinner rotor walls. It is
 expected
 that by further design and casting improvements, the weight of iron
 rotors will
 approach that of aluminum rotors."

 Curtis Wright failed to take advantage of this weight reduction not
 realizing
 that someday the RPM of the rotary would be limited to 11,000 RPM by
 the weight
 of the rotor. Modern material, like Beryllium aluminum alloy, would
 make
 aluminum rotors even better. Be/Al alloy is three quarters the
 weight of just
 aluminum. My guess is the RPM of a two Be/Al rotor rotary (weighing
 180 pounds)
 would double to around 22,000 RPM and the HP would also double to
 about 1600 HP
 for an all out p-port turbo charged racing version. That would be a
 power to
 weight ratio much better than a pure turbine with about 1/3rd the
 fuel burn and
 1/10th the cost in a turbo compound rotary configuration.

 http://www.berylliumproducts.com/Attributes.aspx?id=AlBeMet162

 When this happens it is going to be an earth shaking event.
 A 300 HP car engine could shrink to below the size of a soccer
 (foot) ball.
 The empty weight of the car would also decrease as it is largely a
 function of
 the engine weight. The light aircraft industry would never be the
 same if these
 super power to weight ratio rotary engines were used in VTOL designs.

 Paul Lamar

 Paul, isn't there a major toxicity issue with machining beryllium?
 This was to be the super metal of the late 40's and 50's and it
 didn't happen.

 best,

 George W

So? You want hi tech you deal with it. So is nuclear energy. Machining
magnesium is dangerous as well.

Paul Lamar

Paul,
Raw beryllium is dangerous, but alloyed much less so. The same reason so
much mag is in mag-al alloy form. Mag is of course a physical problem,
fire, rather than poisioning. Beryllium poisioning or berylliosis occurs
more with long term contact.
Bill Jepson

So you stay out of contact with it. This is the age of automation.
If you can reduce the weight of a car by 500 pounds what does that translated
into initial energy savings and pollution? Once it is in the engine you will not be in contact with it. There are beryllium springs already in the Mazda rotary engine.

Paul Lamar