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

Yes Paul,
I am with you on this. I think the BE/AL rotor is a GOOD idea. The
machining of the material would be the only time that was worry some at
all. I need to re-read the alloy information. The beryllium was the
minor component of the alloy. Once alloyed the parts may pose no hazard
at all. Kind of like salt, a compound made from 2 poisons, that becomes
beneficial or even necessary for life!  Be assured I am not fighting the
idea.
Bill Jepson


Be is 62%

Paul Lamar