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From: "Monty Roberts" <montyr2157@alltel.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1693889@logan.com>
Subject: Re: EM2 Data Logger pix
Date: Tue, 2 Jan 2007 22:16:19 -0600
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Tracy,

Thanks for the data.

Wow! The inertia in this system is much greater than I thought it would be. 
The Lag time between the maximum fuel burn and the max rad inlet temp is 
almost 1 min. Really brings the duty cycle thing home! Anybody wanting to 
make really big power continuously should study this very carefully.


I would solely attribute the difference in rise time to the exhaust inserts 
in the Renesis side housings. Not too surprising considering the additional 
cooling problems you had with this engine. The lower EGT had to go 
somewhere. Some to expansion and work; the rest to the coolant.


Transient data is no good for doing heat balance work. If you already have 
steady state data it can be useful to give you the thermal mass/resistance 
of the engine/coolers etc, but otherwise is pretty useless. Too many things 
going on. Metal heating up in the block and the coolers. That is why all the 
lags in the various temps. A big gulp of fuel makes heat. Heat conducts 
through rotor housings, rotors, side housings etc, finally makes it to 
coolant. Coolant begins to heat rad. Rad begins to heat air. A large portion 
of that fuel heats the coolant more directly through the side port exhaust 
than the al rotor housing apparently. Seems a little strange.....but must be 
less resistance there.

To really get a good comparison here you are going to have to get some 
steady state data. The best approach is probably to see what the max fuel 
burn you can get at some egt at 15Kft is. Fly in this condition long enough 
for the transients to stabilize in a reasonable fashion. Then repeat at the 
same fuel burn at 2000 ft or so and maybe one intermediate altitude like 6K 
with the egt in the same approximate place (Peak EGT is probably the 
easiest). From that I can figure out some things.....hopefully.

If you send me raw data in Excel or some sort of delimited format I can even 
crunch on it a little and see what shakes out.

Monty