Don Dunbar wrote:

Hi Paul and group,
I have missed you all as my mail box has been empty.
Paul some time ago there where discussions on the pro's of drilling

the

ford E4D planetary gear carrier as per your design.

I have drilled this end plate and was surprised at how soft it is, I

have completed 3 dwgs of the PRSU unit using the series 5 auto bell

housing.

I am reviewing which one I will use and will post my desired version

for

your comment in the coming week.

Regards Don

I think you are referring to the planetary ring gear bulkhead.
Well I changed my mind about that. I decided the safe thing to do was

make

a new

4130 or 4340 bulkhead and drill that. Tracy cracked a stock powdered

metal

version by hitting it with a hammer and that kind of scared me.

Paul Lamar

Pual I can see from the photo that the bulkhead drive plate has cracked

but

can't see wether the outer planetry gear cracked also?
I am surprised that the bulkhead drive plate would crack as the test i

have

carried out indicate that they are verry soft.

My desired design would be to have a bulkhead drive with a press on

tapper

or a hydraulic press prop flange.
Regards Don

The outer planetary gear or properly known as the ring gear is steel and
is much tougher. I think cooling the 4130/4340 shaft with dry ice in
an acetone bath and heating the 4130/4340 prop flange will make a joint
that is un breakable.

Here is another picture of the powdered metal cracked bulkhead.
Tracy feels as long as you don't drill them and apply stresses
in places they were not designed for the stock bulkheads are OK.
Perhaps Ford varied the material the bulkheads are made from.

Paul Lamar

Yes, the ring gear bulkheads are made from powered metal and are *carefully*
designed for the application.  They work very well in their un-altered form
(I have found no reports of failures), but will fail very soon if modified.

Everett Hatch modified one for an early version of the Powersport drive and
it failed almost immediately.  This was one of two experiments that lead him
to the conclusion that automotive planetary gears were not suited to
aircraft reduction gears.  The other one was when he tried a  high priced
Allison transmission planetary gear set.  As luck would have it, he happened
to get a defective set and one of the pins backed out of a planet gear
during a test run.  I had a great deal of respect for him but I disagreed
with his conclusion.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

Now here is a picture of a cannon proof PSRU. It is the 3:1 drive that
Dave Garber is using and it comes from a Bell 47 helicopter rotor
gear box. Weighs only 43 pounds too. Dave paid about $300 for them
25 years ago. You can still get parts for Bell 47s in Trade A Plane.
I think this box would be good for about 1000 HP if anybody is thinking
of building a 1000 HP turbo 3 rotor race motor.

Paul Lamar
 
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