I'm looking for the standard weights of the major
components in a 13b engine to do a weight analysis.

My goal is to lighten the engine by at least 30% and
at the same time strengthen the parts.

AM-SC1 is a new magnesium alloy (mg matrix) with a
32%
weight reduction from aluminum. Temperatures can run
higher as well so cooling may be adjusted.

The rotor assembly cannot be lightened significantly
just yet. Custom shop has taken only 0.2 pounds off
the rotor.

The casings are the prime target.

Fuel injected or carburated, I'm looking at the full
aircraft engine without the prop. So if you have a
special exhaust manifold that is lightweight let me
know.

David Mathes

From Don Dunbar.

Paul Lamar ...No rotor no motor.

Wow. Thanks!!!

David Mathes

Hi David;

Have you looked at Al-SiC to replace the iron bits:
http://www.mc21inc.com/
or foamed metals using ceramic microballoons?

Cheers
Cary

Cary

I wonder about the toughness of this material.  Wouldn't a non
homogeneous
material like this be prone to create stress risers in an engine housing
application?  I'll send the info on to our Tokyo office and see what the
engineers think.


DougFir

Hi Doug;

Homogeneity is an issue with foamed plastics, it would depend on the
process. You are essentially dealing with a "new" material whose
(reduced) physical properties must be determined.  Products may need to
be re-engineered to take full advantage, with say thicker skins to take
the same load, but the thicker, lower density, skins are stiffer and
reduce local buckling...
High stress regions such as bolt holes may need hard point inserts.

The nice thing is some of these materials can now be cast.  Al-SiC has
properties that are looking more like cast iron.  I'll have to look at
AM-SC1.

As a teaser for David, a physicist friend (whose specialty is coatings)
discussed the possibility of foamed Al at 10% of the weight, it would of
course be uber expensive...

Cheers
Cary

Cary,


Thanks for the info.  Yes light weight castings would help our aircraft
situation out.  Who will be brave enough to try the first bell housing cast
in them.  If an auto maker was using the material then that is a good start
for us.  I would think racers would be interested in saving weight.

I might have mentioned to ACRE newsletter that my company has a 1 kW output
wind turbine generator in production now and it's body is all made from high
pressure die cast Al. Our shells are only a few mm thick, are strong and
ring like a bell. Even then the casting company says they are a pain to
make. The temperature control of the mold is critical to get a good flow.
With that in mind I can't imagine how they would mix something with less
density like micro ceramic in with molten metal and prevent the migration of
the ceramic media during the injection.  Of course if the balls were the
same density of the alloy then it would probably work.  Surface tension is
another factor they deal with.

Pressure injection seems to be a little more complicated then in college we
just melted some aluminum cans and poured it in a breakable mold:)  I have a
good relationship with the company that does the casting work.  If you can
get some information or specs on Al-SiC I can forward it to them and see
what their opinion is.



Doug



The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.