Mailing List flyrotary@lancaironline.net Message #21668
From: Jerry Hey <jerryhey@earthlink.net>
Subject: Re: [FlyRotary] Re: To Lynn Hanover re: windage trays
Date: Mon, 9 May 2005 15:36:17 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

On Friday, May 6, 2005, at 09:07 PM, Lehanover@aol.com wrote:

In a message dated 05/06/2005 06:44 Central Daylight Time, jerryhey@earthlink.net writes:

Lynn, I would appreciate your advice.  I am starting out to build
wedge oil pans and wonder about the advisability of having a windage
tray at all since they are not used stock 13-B or Renesis.   The
Renesis oil pan has a sub floor about .75 inches above the actual real
bottom where oil can be trapped and presumably de-frothed.   This
might only be necessary because the pan is so shallow.  I don't know
and am looking forward to hearing your comments.   The wedge oil pans
would be much deeper toward rear and that is where I hope to place the
pick up.    Thanks,  Jerry


 
The primary reason for the windage tray in rotary racing with the internal pump, is to keep the entire oil supply from filling up the front cover and uncovering the pickup under hard braking. 
 
I have thought about the problem of keeping the pickup covered during climb and descent.
How much of a climb angle would be tolerated before a problem develops. Riding down to Sun&Fun in the Bonanza I decided the angles involved were just too shallow to be a factor.
 
That only leaves the defoaming as a benefit. We were racing without a tray for years before adding one. During a race (40 minutes) the oil pressure would drop from 85-90 PSI to 70 PSI.
 
Some of that from oil temps going up, and some from oil foaming. We were putting it up into the front cover under braking and foaming the crap out of it with the front counter weight. This is with a stock pan with a quart of oil extra added.
 
A conical shaped pan with the pickup at the inverted apex would seem close to the ideal if you maintain the internal pump. If you want the tray for defoaming I would suggest a flat plate with a 5/8" gap around the edges the full size of the pan. Or try the deep pan without any tray at all. If you don't use steep climb angles the oil will stay off of the front counter weight and little foaming will occur. Most foaming in the straight line is cooling oil from the rotors, and that exits at an angle before it gets to the pan and is just below the breather port.
 
Lynn E. Hanover 

Thanks Lynn, I always learn a lot from your comments. Consider a tractor config climbing vertically. If a windage tray covered the back 1/3 of the pan, the pick up would probably remained covered and little oil would be able to enter the front cover. As you said, at more normal angles, it would not be a problem with or without the tray. Those engines using Tracy's old pan plate and also the CC pan plate are in the windage tray plus stock pan category. No problems have ever been mentioned as far as I know.

Considering the Wedge pan, the way I built mine was to first make a .125 thick aluminum windage tray that I used as a foundation to weld up the pan. Thus the tray and pan became a single unit. The problem I have experienced with this is that it is difficult when installing the pan to feed it over the pick up tube. I think it would be better after welding up the pan to completely cut out the center of the tray leaving only the bolt flange very similar to the stock pan. A separate windage tray, quite thin, could be added if desired.

The wedge oil pan is Paul Lamar's idea. For those unfamiliar with it, it is intended to save space under the engine for the belly radiator and plenum. I modified the pan shape to make it deepest at the pick up tube. Perhaps I should have moved the pick up to the rear of he pan instead. I would appreciate anyone's thoughts on this. BTW, the wedge pan capacity as I built it is the same as the stock pan and the full length wedge is a little larger. Jerry
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