Larry Childs has agreed to produce a new bell housing at reasonable
cost in his NC machine shop if there is a demand. It can be retro fitted to
most
existing aircraft for a more professional look. It is based on Al Gietzen's
brilliant idea of mounting the starter using the Mazda stock bolt positions
on the cool side of the engine. Last jpg.
Weight will be low as Larry can take weight out in the final
NC machining step. Jarrett Johnson did the Solid Works design.
This greatly simplified the bell housing design and lowered the cost.
We have been trying to get this done for the last 8 years or so.
Finally looks like it is going to happen. If you order a new gear box
from Tracy ask about deleting the adapter plate, spacers and long 10 mm
bolts. Use this bell housing instead. I am sure Larry would be
glad to wholesale them to Tracy if Tracy wanted them.
Larry needs to know how many would be interested. If you want one
please let us know.
--
Paul Lamar ...No rotor no motor.
No doubt that it would be more professional looking; and I'd like that.
One thing to consider is the critical alignment of re-drive input shaft, and
the fit into the pilot bearing recess in the eccentric shaft. Secondary to
that is alignment of the damper plate and the oil seal in the housing. It
would be worth reviewing Tracy's installation procedure where things are
tightened in a sequence to insure alignment; and requires access to the
damper plate bolts with the drive in place. I'm sure that can be dealt
with; but needs to be considered.
I also think that air circulation around the flywheel/damper-plate area is a
good - maybe necessary - thing. There is some energy being absorbed in the
damper bushings, and there is heat transferred from the input shaft
(friction heating from gear friction) to the damper plate. A closed housing
may result in excessive temps for the elastomer bushings.
As I recall, the weight of the mounting plate, spacers and bolts on the
RD-1B is 8.5 lbs (although I did cut a bit off the bottom where the normal
starter position is); so not likely any significant weight saving. I'm
guessing the flat plate part of the housing may need a bit heavier webbing
and thickness for a cast material.
And it remains to be seen what the "reasonable cost" comes out to be. A
mounting plate from Tracy is $75 (plate with seal only).
Unfortunately it will not work on my installation because of my engine mount
plate that bolts between the spacer blocks and the rear housing.
FWIW,
Al
Two inch dia. cooling holes are no problem.
Easily fixed in the final NC machining Al. Just mill a custom slot to fit
your unique engine mounting system. A custom longer hollow dowel pin can be made
for the lower right 10 mm bolt hole that aligns the bell housing with
the engine.
Here is a picture.
Pocketed center plate load is not a problem Al. Been there and done that. Jerry Hey
tested it for deflection. Middle pictures. Larry is going to FEA it anyway.
Your airplane would look as good or better than Buly's with one of these bell housings :)
Last pictures.
Paul Lamar ...No rotor no motor.
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