Subject: Advice/source needed for high Si Al

From: [email-masked] (Bill Webster)
Date: Wed, 25 Jan 1995 08:55:51 -0500

I'm building a small model airplane motor of .049 ci.  This size is 
available from many different manufacturers, but I want to have a try
at building my own.

After looking at many of the other high performance model airplane engines,
they all have one thing in common - high silicon content aluminum pistons
riding in a chrome plated brass sleeve.

The sleeve I can handle, it's the piston material which I'm seeking.
Just for some background information, the engine fuel is alcohol, castor
oil, and nitro-methane.  The RPM is in the range of 28kto 34k.

So, I guess my question is, what would be a reasonable aluminum for the task
and where could I purchase a really small quantity?

As an aside, I have some 2024 and 7075 (off-hand I can't remember the 'T'
series) from which I'll make the connecting rod.   This should be strong
enough as the bigger engines use 7071.  I'm reusing a crankshaft
>from  another .049 engine.  And the crankcase is in the works thanks to many
who helped me square up a block of Al.

So, any suggestions on high Si Al?  Maybe an old Volkswagon piston?

Thanks in advance.

-- 
Bill Webster ([email-masked])

---

From: [email-masked] (Mike Rehmus)
Date: 25 Jan 1995 17:16:46 GMT

In <[email-masked]> [email-masked] (Bill 

>So, any suggestions on high Si Al?  Maybe an old Volkswagon 
piston?

Bill,

Don't know about the metal question but did you know that the 
"Testor" brand of 0.049 (and their other engines) are machined to 
an accuracy of 50 millionths.  That is why they run so well with 
no gaskets or rings and cost so little.  Interesting, IMHO.

Best,

Mike