I can answer that on by experience! You better make damn sure you injection oil to the apex seals! I've had a metering oil pump failure before, and the friction heat is enough to warp the apex seals. And it will do it every time. The good news is it doesnt loose enough compression to stop the motor from running, but it aint gonna start again after you kill it. It may not even idle. Thats just 1/4 mile experience. The problem may be much worse in a plane trying going further than a 1/4 mile!

Bob Mears

----- Original Message -----

From: Al Gietzen

To: Rotary motors in aircraft

Sent: Wednesday, May 17, 2006 6:20 AM

Subject: [FlyRotary] Re:

 

Richard, are you saying that the metering oil nozzles that inject oil into the combustion chamber should have a vacuum line attached to the top opening of the injector nozzle?  I recall a discussion some time ago where I thought you said that it was OK for those connections to be open to the atmosphere.

 

I would say that it is OK for them to be open to the atmosphere.  The reason to connect them to the manifold is to get filtered air, and to modulate the differential pressure across the valve. At low throttle there would be low pressure in both manifold and rotor housing. I have no idea of the full story of the pressure dynamics over the throttle range.

 

If the vacuum line is disconnected, the oil being pumped into the rotor housing drop by drop is not spread cross wise along the apex seal. Therefore, the oil will do next to nothing in regard to cooling or lubricating the apex seal.

 

Based on experience of others, this appears to be an overstatement.  Rotories have run thousands of hours with no air to the nozzles.  There may be some evidence of wear patterns indicating that the tip seal travels some distance (maybe 4-5”) from the point of injection before the oil spreads to the ends of the seals, but I’m not aware of any direct comparison wear with and without the air flow.  Maybe some of our racing friends can have some input on this.

 

Al

 

Certainly, Al, nobody seems to know how much good that top lube does, if any.

 

 

Richard Sohn
N-2071U