Nanotubes have been used in golf shafts for a couple of years now...

nanotubes, or just carbon shafts? There's a big difference. I've used carbon-shaft arrows for years now but they're not nanotubes.

Edit: wikipedia says nanotubes have been used in mountain bike handlebars, but they're "bulk" nanotubes, kind of a mass of broken-up nanotubes held together with substrate. And they're just reinforcing conventional polymer, not forming the structure in its entirety. I don't think plastic, even with nanotubes in it, are gonna work inside a rotary.

carbon golf club shafts
carbon fiber wheels
bulk carbon nano-tubes as a stiffening additive in a number of applications, including polymers and alloys.

Unfortunately, carbon-nano-tubes (there are nano-tubes of other elements as well) increase thermal conductivity, which in an IC engine application would prove a detriment to BSFC. I don't think the rotary needs that.

Of course, a thermally reflective ceramic coating on a Ti-Al (cnt doped) rotor and housings would be really cool. ;)

I think you'd be better off using ceramics for the rotor housing and the seals, and superalloys for everything else. If you've ever seen some of the ceramics they have now, they're insane. They use them(and superalloys) in jet turbine engines to minimize creep, and their strength doesn't decline with heat until the last 10% or so before its melting point. If everything moving in that engine were ceramic or superalloy, I wouldn't be surprised to see 20k+ rpms coming out of that. Gear that down enough and you have a serious monster of an engine..

by the time nano technology is developed enough to make it practical to use such materials in an engine, we wont be driving internal combustion rotary engines

carbon fiber has been around since the 60's and only recently its appearing in consumer parts, soooo

so from what I can see. we all need flux capacitors?

P.S. they should make rotors out of diamonds.

Titanium, while ludicrously light, is far too brittle. There is a reason they don't make car wheels out of titanium. And it's not just because each wheel would cost $5,000 bucks.

^ although an alloy might work...

Diamond coated super titanium alloy mega super duper rotor!! yippeee. Now in the for sale section :).

I'd actually like to see the interior surface of the rotor and side housings, as well as the seals made from either vapor deposition synthesized diamond or laminates of vapor deposition synthesized diamond and flame sprayed sapphire. The coefficient of friction of diamond on diamond is equal to wet ice on wet ice while having a melting point around 5000F. If the seals and coating were sturdy enough, we might be able to do away with oil injection, further cleaning up the exhaust and allowing more latitude on air/fuel mixtures while still meeting emission targets.

As far as the rotors themselves, I'd like to see them made boron carbide/aluminum composite. The material was originally developed as potential armor for helicopters where weight is a critical issue; but conventional ceramic armor lacks second strike protection. The aluminum gives the ceramic a modicum of toughness that it would not otherwise achieve.

and yall though i was kidding around---ha!
OD

And to think, I nearly made an on topic reply to this old thread...