George Lendich wrote:

Too HEAVY George. Cut the wall thickness down to 4 or 5 mm where ever

possible.

It would be useless for aircraft use unless you do that. Better to buy a

new bell housing

from Mazda that is high pressure die cast with walls as thin as 3 mm.
If your foundry can't do thin walls  send the pattern to me and I will

have my foundry cast them

for you.

Paul Lamar

Paul,
I hear what your saying, but even at 6mm it looks mighty thin for our
application.
I tell you what, I have the mould so I can do a thin wall one for
comparison - not so difficult now I have all the sizes.
The foundry can do the thin walls OK.
The 4 mm wouldn't be strong enough to bolt on engine mounts in my opinion,
that's why I made them thicker in the first place.- however I may be wrong,
I'm no engineer

All feed back welcome !!

However I'm thinking that the extra weight in the wall section can't make
much difference, but does add a lot of extra strength. The top arc section
is only 6 to 9mm.

So what will 3 sides 2.5' wide and 34" long add to the weight - probably
less than 3 lbs or 3 lbs including the top arc extra of about 4mm or less.

I made the mounting plate thick for machining to size, after shrinkage.
Seeing I've now almost complete this pattern, I will get one made - just for
the fun of it, not much cost involved.
That will be proof positive of weight etc.

What sort of target weight are we looking at ?

Make sure that 4mm is sufficient without the ears, as without the ears there
is no return to stiffen it up!!
BTW I originally made face plate 13mm all over as I have a bigger footprint
on my PSRU design with a bigger shaft access hole and the remainder didn't
seem to warrant the extra work on the pattern to keep it thinner on the
edges.

George (down under)

This is roughly what Butch was talking about. External fins. Common aircraft construction
practice. Thin 4 mm skins and ribs. Minimum 4 mm wall thickness everywhere except the 13 MM center

The side motor mounts are bolted on out near the extremes of the side box
sections picking up three or more skins. All bolt holes are beefed up
only to a 25 mm dia. and 13 mm thick.

Maybe you need to make two. One for your use and one that people can bolt
Tracy's redrive too. That would be the larger market.

Paul Lamar
 
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