12 c
Do you have any data on the grade of steel for the prop Shaft?
Andrew Campbell. NZ
No not for sure. It was built seventy years ago. Probably 4130. It
is way over kill for the TTC as it was the main shaft for a
helicopter. 4130 has been around since the 1930's.
For the 2 rotor.... 2 inch dia, 3/16 wall 4130 tube is about right.
Paul Lamar
Thanks Paul. That was my first choice, some seem to think that EN 8
or similar medium carbon steels might be a good option.
Andrew Campbell.
Are you building your own gear box Andrew?
Here is an idea for a one rotor gear box.
Toyota's are sold in the millions around the world so you can
probably can get automatic transmission replacement parts in New
Zealand. Or you can just buy a Corrolla auto tx gear box in a junk
yard.
This page is from an automatic transmission replacement part
distributor and is for a 84 to 87 Corrolla. The planet carrier looks
much like the Ford planet carrier used in the two rotor gear boxes
but is probably smaller and lighter.
The sun gear is ideal as it has a long input shaft. If you don't have
Corrolla's let me know what you do have.
A gear box built with these parts should be good for 150 HP as long
as you have a good silicon rubber coupling. Very very important
with a one rotor.
The next trick is to abandon the traditional way of making aircraft
gear boxes. That is a long prop shaft in front of the planet carrier
with two widely spaced bearings. This is normally necessary to
take the bending loads on the prop shaft due to gyroscopic
reactions. It is even used on non geared piston aircraft engines.
If we put a flange on both side of the planet carrier and a bearing
on each flange we can do away with long prop shaft and save some
weight. The flanges will do double duty as a planet carrier. The
combined planet carrier will be ridged enough to do this and act as a
long prop shaft.
Don't bother with a traditional prop flanges as ground adjustable
prop blades are widely available.
Here are a bunch of pictures and a 3D
Paul Lamar
I did a bit more research on suitable gear boxes that are likely to
be found overseas.
The RX7 had a scaled down Ford automatic gear box built by Jatco in
Japan. A joint venture with Ford and Toyota.
That was also used by Nissan 200SX, 240ZX, 280ZX , 610,710, 810,
Pathfinder, and Pick up truck, Mazda Pickup and the RX3 and RX4.
All the work we have done so far on the Ford parts can be just scaled
down.
Paul Lamar
Thanks Paul I will see what i can find.
Andrew Campbell.
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