In regards to these Wankels as range extenders, did anyone ever see
Audi's work with Aluminum Rotors?

http://www.ipmd.net/articles/001927.html


I haven't been a fan of the 3D Printing technologies, I know enough
about metallurgy to make me dangerous and I couldn't see parts being
made that were robust enough via printing. My mind is changing after
hearing about GE making all sorts of parts via printing in their "Hot
Sections" of their turbine engines, and seeing the CEO of 3D systems
on one of the Financial channels.

I also saw the other day two articles about printing Titanium and how
cheap it may become, and printing it....

http://www.economist.com/news/science-and-technology/21571847-exotic-useful-metals-such-tantalum-and-titanium-are-about-become-cheap



http://www.domain-b.com/technology/engineering/20140101_titanium.html


So with that as a background, is a printed Titanium ( or Aluminum
Rotor ) a possibility?

Are at one of those rare junctures in history where material advances
and manufacturing techniques put us at a place of potential rapid
change aka a paradigm shift ?

My best,

John Smith ?

Won't work. Top workable temperature for aluminum is 500 F.

Paul Lamar


Paul, it seems like aluminum is used in situations where it sees much
more than 500 degrees. A piston crown for instance. Aluminum might
not be tough enough at the apex seal area but titanium would be.
Direct metal laser sintering has been used to make turbine blades, so
it is plenty tough.

Bill Jepson

The piston crown gets cooled by the incoming charge every other revolution.

400F is the absolute limit for aircraft cylinder heads.
The apex seal slot is high stress and wear area on the rotor.
Not to mention the phasing gear fixing.

Aluminum losses half it's strength at 500 F and melts about 1100 F.

Sintered metal is hard but brittle. It can be fractured with a hammer blow.

Paul Lamar

One very nice (unintended) feature of the Mazda Wankels in aviation use is that they will continue to run
even if they are overheated.  With heating, the iron rotor expands less than the AL rotor housings, so the
rotor doesn't bind up.  So, with a complete loss of coolant the engine will often still generate a considerable
amount of power even though it will be damaged (seals and o-rings melted, etc), and 10-15 minutes of
"emergency" powered flight can make a very important contribution to safety.  This wouldn't be the case
if we used an AL rotor.  It's not something I'd be willing to give up in a liquid-cooled aircraft engine.

Mark W.


The Rotary Engine News Letter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net.
You Tube http://tinyurl.com/beqqxas.
Copyright 1998-2013 All world wide rights reserved.