Mailing List flyrotary@lancaironline.net Message #38262
From: Richard Sohn <unicorn@gdsys.net>
Subject: Re: [FlyRotary] Re: OMP flow rate
Date: Fri, 6 Jul 2007 07:42:29 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
 
----- Original Message -----
From: Al Gietzen
Sent: Friday, July 06, 2007 1:20 AM
Subject: [FlyRotary] Re: OMP flow rate

 

 

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

From: Al Gietzen

Sent: Thursday, July 05, 2007 7:12 PM

Subject: [FlyRotary] OMP flow rate

 

Does anyone know what the flow rate is from the OMP?

Unfortunately, I don’t know what year the pump is from.  It is on my 20B which has a 12A front cover.  It is a 4-port, likely from a 13B, in which one port has been blocked and the other three go one to each rotor housing.

 

The only data I have on hand is what Richard measured some years ago, running the pump at 6000 rpm.  This could useful if I knew the ratio of pump speed to eccentric shaft speed.

 

Thanks,

 

Al

The OMP drive gear is the same size as the distributor gear. So it runs half as fast as the E-shaft. In my tests I referred to the E-shaft speed.

 

Richard Sohn
N2071U

 

Thanks; Richard.  I wasn’t sure because what I have in my file ends with some open question about the speed:

 

> At 6000RPM crank speed and 48deg. control lever opening angle, the flow rate is 498cc or .498Liter/hour.
> Opening the control lever to 90deg.resulted in a flow rate of .688Liter/hour.
> The 90deg. position seems to be the maximum for the pump. A run with the lever at 180deg. did not change the flow rate.
>
> Richard.

> Richard. Your oil flow rate seems very high. Fuel consumption off 30
> litres/hour at 6000 rpm and .5l of oil gives a ratio of 60 to one. Most of
> us run around 120 - 150 to one. Does the pump actually run at crank(e shaft)
> speed?
>
Ian Beadle RV6A W. Australia

Good point Ian. I don't think it does.

 

Al

This test was at maximum condition setting. This condition only exists in a 6000RPM/WOT situation. This rarely happens in a car. In addition, the flow adjusted by the control lever does not seem to have a linear characteristc, it is more like a snap at one point. I never investigated that. I fully agree with the 120 - 150 to one as an average.

 

Richard Sohn
N2071U

 

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