12 d
Been busting my buns for the last coupling of weeks re-engineering
and rebuilding the TTC dry sump system system. I did NOT do the
original design.
Last time we flew the original system we lost a gallon and a half of
oil over board. We got to 10,000 feet in one minute 47 seconds which
exceeds the record. The oil pressure dropped from 130 psi to 50 psi
at 10,000 feet. That worried me. I was not sure what was going on but
I suspected the oil pump was cavatating due to the long length of the
pick up line and the crank case pressure was blowing oil directly out
of the vent line.
I made some modification in the tank to move the vent line away from
the line coming in from the crankcase. The crank case collects all
the rotor cooling oil and any combustion gas leaking past the side
seals. It is a significant problem in most rotaries.
Here are the before and after pictures.
I had to cut the bottom of the tank off to mount it vertically in the
fuse. I lost about 3 to 4 quarts of capacity but we started with 4
gallons.
We ran it today but Dan did not fly it. It seems to be working. No
sign of any oil coming out of the radical long vent system. That long
vent is pressurized by the slip stream to about .2 to .4 psi.
It is also tilted up at a 45 degree angle during the climb so any
oil should run down hill back to the tank.
We will know for sure when Dan flies it again.
Paul Lamar
If it does start spitting oil, does that equate to reduced
visibility for the pilot?
Chris Cosman
Yes :-) Then I will have to change it.
We have had a lot of oil on the canopy in the past. I think it comes
out of the exhaust but I am not sure. The exhaust could be directed
more towards the bottom of the airplane.
The blow off valve spits only water and air so that cannot be it.
Could be the gear box vent. There is a lot of turbulence around the
engine so it could be coming from anywhere.
So far no oil with the new system but Dan only taxied.
When your primary direction of flight is more or less straight up all
things get more difficult :-)
Paul Lamar
Hi, in the early development of the P-39 Airacobra they had oil temp
problems to the point were they were calling it the "Airaducta" or
"Scoopacobra". The problem turned out to be a right angle fitting on
the suction line out of the oil tank. When replaced by a sweeping
bend the pressure pump stopped cavitating and the oil temp problem
went away.
Murry Rozansky
I'll keep that in mind. I do have a right angle fitting there.
Thanks.
Paul Lamar
That fitting coupled, with high (for a spur gear pump) rpm, could
easily
lead to cavitation. The pump speed alone could be causing a problem.
Gary Knutson
That is a possibility. We saw no signs of that when we ran it up sitting
on the ground.
Paul Lamar
------------------------------------------------------------------
Please add your questions or comments at the end of the thread.
Not the beginning.
I am going to enforce that rule. If people don't do that it will not be
forwarded.
My ISP changed the rules.
The Rotary Engine free News Letter. Powered by Linux. If you want off
the list PLEASE let me know and I will remove you. ACRE NL web
site.
http://www.rotaryeng.net You Tube
http://tinyurl.com/beqqxas
Copyright 1998-2017 All world wide rights reserved.