Well perhaps but there are plenty of them out there on 13B gyro
coptors running flat out at 7500 RPM with no mods to the lube
system.
Ian, did you mod the lube system on your Ross 2.85?
Paul Lamar
Yes, It appeared to me that the planet gears had inadequate
lubrication
and
my thrust bearing even less. I added a feed to the gears via an
existing
hole in the top of the stationary ring gear. 160hrs and still going
strong.
Ian.
Paul, most of my true rotor head friends have changed over to 2.85
drives,
and except for one guy, (Steve McGowan in Georgia) all of them (that I
know)
have an added oil tap to the sun gear area... the same is true for the
subie
guys as well... we all saw one trash the teeth and lock up once... it
was a
Chrysler gear set, but didn't have the oil galleys.......... the post
mortem
indicated a blueing from the heat!!
Gary Buster
Bridgeport, Texas
N263GB
Is that mod a recent development Gary? I did not notice that last year
at Bensen Days. I had heard about the Chrysler gear set failure but I
thought it was the one way clutch.
Paul Lamar
The failure mechanism was pretty straightforward... the sprag system
continues to work without a hitch... but it does take away your ability to
restart via the prop when airborne. The sprag system also has helped take a
lot of the vibrations out of the idle below 1800 [engine] rpm... it works down to
1100 and begins to chatter there... the engine doesn't like to idle that low
anyway... 1600-1800 is the normal idle. Most of the psru's are learning
from this and other experiences about needing the extra oil galley... the
2.85 ratios have had a remarkably minimal amount of failures... including
needing a thrust bearing... but the 2.17's and others, have learned about
needing the oil galleys the hard way..
The Chrysler failure was due to oil starvation, with resultant heating and
blueing of the gears... I talked them into using the Ford set up since then
and they haven't had a problem since... still flying wide open full throttle
for tandem flights.
I just got back my 12a from the Georgia guy... he didn't know how to "take
care of baby" and decided to use the subaru ej25 on his ship... that gave me
the opportunity to get the 12a back... now I gotta finish the divorce, then
I can build my next ship with "baby"!!!
Most of the gyro guys are sticking to the 2.85 with the 12a or 13b set ups
due to the engine rpms and prop sizes... 78" warp drives 4 bladed, and
usually cut tips to minimize the sonic pops
I'll send a pic of the cut tips if anyone is interested
Gary Buster
Bridgeport, Texas
N263GB
I think Tracy now claims his will idle down to 600 engine RPM with no problems.
Of course he uses a rubber based coupling of his own design instead
of the Ross spring clutch center. I have seen his idle and you can almost
count the blades as they go by :)
Paul Lamar
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