"Bass, Jerry" wrote:

No pictures with this copy, but I saw them on another. The input (sun)

shaft

looks shorter too.  Our units are about 14 inches from engine flange to

the

prop hub face.

..... SNIP

Everyone complains about blowing the rear seal.  And no one complains

about

the front near the prop hub.  Logic says the pressure behind the sun

gear

towards the back seal gets higher than we expect.  I added a drain from

the

back side of the bell housing near the seal to the pan.  this should get

oil

flow.

Jerry Bass

Jerry,

    I had the problem of oil leaks past the rear seal on my 2.17:1 Ross
drive. Finally got tired of coming back with oil covering bottom of aircraft
and canopy.    I tried everything from smaller oil flow restrictors (getting
down to 0.025" dia which is too small for good cooling of gears)  to
rerouting the drain line dump into the oil sump, to an expensive custom made
High Performance Oil seal - all with no success in stopping the leak.  I
finally drilled a 1/8" dia hole into the top of the gear box case right next
to where it bolts to the bell housing.  I installed a fitting, hooked up a
clear hose and ran it into a bottle.  I observed that anytime engine was
above 5000 rpm that oil would flow out this opening = about 10% to the total
oil flow to the gear box.  So I hooked a hose to this vent and vented it
back to the oil sump and have had no problem with any oil leaks since. And I
have since gone back to a 0.040" dia oil restrictor to get more oil flow
into the gear box.   I certainly don't understand what pressure mechanism
causes it to want to flow out the top of the gear box near the rear seal,
but this fix worked for me and was simple to do.  I made a point not to
drill into the area where the planetary spokes were.

Ed Anderson

The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org