I have a suspicion that an all alloy rotor would have problems
 with keeping the fit of the pressed in e-shaft bearing with the rotor
 expansion and contraction due to temperature. I was considering using
 what I would call a flanged sleeve made of steel to mount the bearing
 and stationary gear. The stationary gear fits into the face of the
 flange, the bearing in the bore, and the alloy rotor fits over the
 outside of the sleeve with dowel pins into the back side of the
 flange.
 It doesn't appear too difficult to CNC the negative patterns to cast

 the
 wax as a left and right side with the wax sections keyed together.
 The
 difficult part is machining the side seal grooves which was a major
 stumbling block for rotamax. I was thinking of a router motor
 swinging
 in the proper arc over an indexing table but reading how much trouble
 others have had with this it is obviously not that easy. Useing 398
 for
 the rotor doesn't seem to be a problem as far as galling with side
 housings of the same material because the side inner and outer oil
 seals
 keep the parts separated. Temperature control of the rotor might
 require
 a modified control of an increased oil flow thru the rotor from the
 stock Mazda design although a prototype  of the stock type would be
 tried first. Alloy parts with different compression depressions would
 reuse the same flanged sleeve.


 george grimes

 There is a steel insert in Jeff's design for the rotor bearing.
 The side seal grooves are a piece of cake for an NC mill.
 Mazda mounts 3 rotors on a pallet and rotates the pallet to cut
 three groves at a time with a broach.

 Paul Lamar Graduate of a course in NC machining :)


 Yes, there needs to be a greatly increased oil spray directly on the
 inside of the rotor, accompanied with a powerful vacuum to draw it
 out.
 This should greatly reduce temps. I think a dual oil pump may need to
 be used.

 Does anyone think the Beryllium/alum cast rotor idea can't work?

 Ed Carver


 I am presently drilling into the issue of obtaining a small quantity of
 the beralcast 310 and the nasa 398. Starmet is the exclusive vendor for
 the beralcast, and a salesperson is kicking the ball back and forth
with
 me. I have contacted one of the nasa employees about a direct
vendor for
 the 398.

 Normal alloy vendors sort of give me the blank stare when I ask them
 about these materials. Never heard of them.

 George, have you found a vendor for the 398?

 Ed Carver

 OK guys some things to think about. First the rotary's problem isn't
 too much heat in the combustion chamber. Rather the problem is that the
 long and narrow chamber REMOVES too much heat for best efficiency. This
 is probably why Mazda hasn't made a aluminum rotor besides the cost.
 Second the rotor is a nice casting and the side plates are probably a
 better area to remove weight. Of course there isn't anything wrong with
 a lighter rotor, but heat transfer through the rotor wouldn't  be a big
 plus. The last concern is to be sure that the apex seal slots don't
 flex or wear too much. That can result in loss of a seal. The best
 material for the light weight rotor might be ceramic, or one of the
 cermet materials.
 Bill Jepson

 I want to point out to the many new guys that this is unnecessary.
 These guys just like to push the envelope :)

 The stock Mazda engine makes a great aircraft engine as is.

 Paul Lamar



Ed Carver, I really haven't tried to source 398 yet. I like it for the
mechanical properties and would use it if available. Possibly there are
things available as scrap the way that 390-17 can be found at the county
land fill. My next question is how to find out if the whole briggs
engine is 390 or just the cylinder block. I can use other alloys for the
back side of the housing where there are no wear surfaces and use the
rest of the scrap there. If it is all the same alloy it would be easier
to just pull off copper and plastic parts then melt the whole engine.

george grimes


I just spoke to a nasa admin about getting some 398, and was told they
have licensed a foundry in the Chicago area to produce and distribute
this material within 3 to 6 months; apparently to the general public,
for purposes such as ours. I would say this is much slower going than I
could imagine. The 398 alloy has barely seen use since it was patented
nearly 10 years ago.

Still waiting on beralcast corp to reply about availability of product.

Ed Carver

Ed, most people on here are looking to save money on aircraft
engines. One gets the price down by using mass produced products.
Automotive piston engines are not durable enough for aircraft.

Light weight rotors are only cost effective if you would like
to turn the engine at over 11,000 RPM.

The p-port 2 rotor's excellent power to weight ratio is hardly in the
class of a hunk of lead :)

The p-port exist because we need an intake  manifold of some sort anyway and
the P-port fits all versions of the Mazda rotary and gives an extra 50 HP.
The stock RX8 manifold is too high to fit under a cowl.

IMHO one should focus on real problems if any. I would say
high on the priority list is getting some weight out of the PSRU.
True getting the weight out of a one rotor is also up there.
Light weight rotors will not help much.

Probably the last thing a 2 rotor needs for aircraft use is aluminum rotors.
Are you talking one rotor engines. There you might save a little
weight.


Paul Lamar