> >   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
> > Paul,
> > Why don't we get our new found friend Ted, from Russia to give us an
> estimate on how much titanium rotors would cost to cast.  He is correct
> that there is a huge titanium casting infrastructure, along with
> expertise available there at attractive costs compared to other
> countries.
> Titanium rotors have better properties in this application in any case as
> the alloy is an insulator, and would need little or no cooling at the
> face under the temperature it is expected to operate at.
> > Frankly I am surprised Mazda hasn't used titanium rotors before in their
> race engines.  The cost is  a drop in the bucket in the overall scheme
> of things.
> > Doug

  Hi Doug,
   It is possible to give such estimates. What we need is a drawing/3D model of what we want to cast. Than a little FEA study to optimize rotor geometry for this specific material (we will need mech. and therm. loads) - I can do it here.

  Thank You
  Ted

Great Ted. I'll work up a design in Rhino and send you a stp file. Do you have
Solid Works? In the mean time this is the temp data on the cast iron rotor.
I also have data on the phasing gear loads. The BMEP loads are not much over
such a large face. The other thing to worry about is the wear characteristics
of the apex seal slot. Perhaps a steel insert will work for that.

BTW what is the status of the Vaz rotary and why did they stop making them?

Paul Lamar

Hi Paul,
 I work with SolidWorks and Catia v5. Any standard file format should work reasonably. Wear characteristics of Ti alloys could be very good.

Thank You
Ted