flyrotary@lancaironline.net Mailing List Archive

Randy,

If you are trying to check the EM3 airspeed indication, it would be good to connect your manometer to the EM3 pitot connection right on the EM3 and leave the other EM3 ports unconnected. The manometer would be connected to nothing else. From your description, it is possible that you were connected to the static system instead of the pitot port of the EM3. The static system is probably connected to several locations including the static ports on the outside of the airframe which would act as leaks. If you are trying to check the overall installation, it would be best to connect the manometer to the pitot or static ports on the outside of the airframe without changing anything anywhere in the plumbing of the system.

Concerning the radiator questions, the location of the radiator 4 inches (or more) below anything else in the system would not be a problem. Four inches of water column generates less than 0.2 psi of pressure. I would expect that the EM3 is indicating pressure in psi, not inches of water (or Hg). A 15 psi radiator cap would hold 416 inches of water column if it is working correctly.

If you have a 14-15 psi radiator cap on the radiator and the pressure sensor for the EM3 is located where it indicates the pressure on the inlet to the radiator, then the pressure reading of 17 and the radiator cap venting makes sense. This may be the result of the restriction of the radiator causing a build up of pressure in excess of the radiator cap capability. The water pump in my 13B is capable of pressures in excess of 40 psi at cruise RPM if the flow is restricted. If there is a radiator cap somewhere else in the system other than between the water pump outlet and the radiator, then the cap on the radiator can be replaced with a non-venting cap rather than trying to increase the venting pressure of the one installed there now.

FWIW

Steve Boese

RV6A, 1986 13B NA, RD1A, EC2

From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Randolph [randolph7714@comcast.net]
Sent: Sunday, April 15, 2012 7:36 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Just basic questions here

I'm finishing up ground runs on my 1988 13B using the EM3 EC3 before closing everything up to install the biplane wings..

Wanted to be sure the 5/32" ID silicon tube was connected to the right place in the AQM. I configured a manometer to the steam gages in the front and rear cockpits

an observed about 3.3 inches of water gives a reading of 80 mph. So far so good. Then I tried to check what this pressure would do with the aqm (EM3) and found no change in

the near zero true air speed EM3 reading. In fact there seems to be a bleed-off of pressure so I cannot hold a steady 3.3" pressure on the EM3 to measure anything. Did I spend $ 28 to get this silicon tube for naught or am I confused about the one pitot and two static ports on this AQM?

And then again..the water temp was about 165 without the cowl, but on the latest ground run the temp ran 188 degrees and climbing..gurss ya have to fly in to know...problem is the three pass19" X 20" X 2" radiator is some four inches below the steam chamber and water fill cap so at 17 inches of pressure indicated (EM3) coolent spewes out liberally from the radiator cap.. Can I add rubber washers to this cap or should I toss it away and weld up that racing radiator cap location? The water after radiator temp registered 30 degrees below the engine out water.. is this enough?

Wishing you all had problems so basic as mine!

Randy

__________ Information from ESET NOD32 Antivirus, version of virus signature database 7056 (20120415) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com