Peter Cowan/Lexi Cameron wrote:

My impression is it is well engineered for an internal spur gear drive.
It is also true that internal spur gear drives are heavier than a
planetary drive of the same torque capacity and cost more.
They also have an undesirable thrust line offset for most aircraft
installations. They lower the engine relative to the thrust line taking
up valuable room needed for a cooling radiator. I don't see the advantage.
Why bother?

1: 2.4 reduction. Some slow planes need big props
2: Same rotation as other aircraft engines so more access to props
3: Offset shaft also gives more room for the longer prop mentioned above
4: Weight and price differences are not a significant percentage.
5: Made in CANADA.

Don't get me wrong. I like and respect Tracy and his drive and would buy one
in a minute but for these factors.
Peter.

1: 2.4:1 is a slight advantage over 2.17:1 but if we can get Tracy to
build 2.85:1 that is even better.

2: OK

3: I don't see this. The engine can be mounted anywhere.  If you mount
the engine higher the prop will be higher and you will have just as much
trouble seeing over the cowl. There is no visibility advantage to
a internal spur gear box with the thrust line higher than the Mazda
engine center line because the gear box itself sticks up above the engine.

4: OK If a 10 pounds or 15 pounds does not bother you.

5: AhHa! Now I understand! Got to keep them Canucks employed :-)

Good thing most Americans are willing to buy Canadian products :-)

Paul Lamar
 
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