X-Mozilla-Keys:                                                                                 

Emmett, Eric @ WAU wrote:

Tracy,
Would you care to comment on why you are developing a PSRU for the 13B
engine?  What advantage does it have over the Ross unit?  What's its wt.
compared to the Ross unit?  Have you been having problems with the Ross
unit?

Eric E.

Tracy Crook wrote:
No single reason and any of them would take a lengthy conversation to
explain but I'll try to give a thumnail sketch.

First, I wanted control of my own destiny.  There were changes I felt were
needed and Ross was not going to get them done on any schedule I would be
happy with.  Don't know when you joined this newsletter group but I have
posted the problems I've had with the Ross here before.  They were:

1.  Oil seal leaks.
2.  Floating planet carrier mount causing wear and increase in drive play.
3.  Galling of the sun and planet gears due to inadequate lubrication.
4.   Failure of the prop shaft thrust bearing.
5.  Engine crankshaft end "mushroomed" due to pounding of the Ross input
shaft (caused by lack of input shaft thrust bearing in the Ross drive).
6.  Excessive wear of the engine crank thrust bearing. (same cause as 5.)
7.  Excessive noise & vibration due to wobble of the propeller shaft.
(caused by play in needle bearings)

These problems occured over the course of 856 hours of flying.

My design was an attempt to address these problems and at the same time come
up with a design which could be produced at a significantly lower price.  I
would have liked to reduce the weight at the same time but this was not
possible if I was to meet the other goals.  The weight is essentially the
same as the Ross.

Is it a success?  Can't say now because I only have about 37 (flying) hours
on it but I'm very pleased with the "feel" of this drive.  Even my wife
noticed the improvement in noise and vibration within minutes on her first
flight after the change.

Tracy Crook
www.rotaryaviation.com

 
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