Will take readings next trip then am going to use the probes to test other ereas, ( back side of gen., coils, maybe fuel rail ) David
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, August 19, 2012 11:45:01 AM
Subject: [FlyRotary] Re: EM2 CHT ?
David, I suspect there will undoubtedly be a bit of lag before the heat of the coolant/oil inside the engine transferred to the outside of the aluminum housings - so I suspect the CHT temp would lag (just don't know how much). But, one would assume after a bit of engine operation they would stabilize at some temperature as they reach steady state condition.
However, I have doubts about the usefulness of a CHT for the rotary engine (or any liquid cooled engine). Here is my rational.
1. Air cooled aircraft engines transfer the heat directly from the combustion chamber to the cylinder walls and fins of the cylinder. So the CHT gives you a pretty direct indication of how things are going. One the other hand, the rotary (and any liquid cooled engine) has the coolant inside the engine transferring heat away. So, In contrast to the air cooled engine, relatively little heat is being transferred to the outside walls in the liquid cooled engine. Didn't say None, just a small amount compared to what you are getting rid of through your coolant.
2. So, I am not certain what a CHT reading will tell you that the coolant temp won't tell you sooner. In the air cooled aircraft engine, they of course do not have this option.
3. The CHT for the rotary could perhaps provide some useful information if it was mounted close to the sparkplug location as this is reportedly the hottest part of the chamber. But, on the other hand, its sort of is- what- it -is and I don't how you would affect temperature in that area much except by keeping your coolant flow cooler. So once again, it sort of boils (no pun intended) down to your coolant temps.
On the other hand, I certainly don't see any possible harm it would do to instrument it with CHTs.
Be interested in the results.
So keep us informed, David
Best Regards
Ed
Sent: Sunday, August 19, 2012 11:02 AM
Subject: [FlyRotary] Re: EM2 CHT ?
Sounds like a plan to me Ed, should have time Sun. to do. David
From: "Ed Anderson" <
eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <
flyrotary@lancaironline.net>
Sent: Saturday, August 18, 2012 6:54:35 AM
Subject: [FlyRotary] Re: EM2 CHT ?
I think I would run the engine at operational rpms (>5000) and watch the coolant/oil temperatures - when they got to my maximum limit, I would check the CHT reading and perhaps add 50 degrees for the limit (to start with). If I got a lot of false alarms at that margin I would try another 50 deg. Just a WAG.
Ed
Sent: Friday, August 17, 2012 10:20 PM
Subject: [FlyRotary] EM2 CHT ?
What are we using for high temp numbers from the CHT sensors on the 13B rotary, I have the under the spark plug style sensors bolted to each rotor housing in some factory threaded holes just above the spark plugs, not really the hottest spot but the holes were already in place so I KISSed it & moved on, now I need to set my high temp warning limit & do not know what to use. Possibly do an eng. run with upper cowl off & check bolt/sensor temp with a lazer temp gun at about 4000 RPM & go another 50 deg. higher? Ideas? David R. Cook RV6A Rotary
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