Our cooling is generally fine, but on hot days when we stay in the pattern, the CHT’s get warmer than I would like. Luckily we know Terry Schubert, of CSA fame, and he’s just the guy to give us some tips. So, we setup for him to come down with some aquarium hose, air stones, and we hooked them up to our engine cooling plenum, top and bottom… and went out for some test runs. We took a bunch of data at 3,000′ pressure altitude (altimeter set to 29.92″) to see how much pressure recovery we’re getting from our NACAs. Ours is not as good as you might see on some well designed EZs, but for for reference here’s our data.

76F 30.16
delta P

in WC

100 .9″
110 1.1″
120 1.3″
130 2.8″
140 3.2″
150 3.6″

Basically it’s telling me that we should cruise climb at 130 because we get much better cooling there than even at 120. Yes, we won’t get the performance of Vy, but a cool engine is a happy engine. I won’t be obsessing over upgrades, but we did identify several places where we’re surely losing cooling air to leaks, and I’ll begin slowly addressing them and checking these numbers again to see if we’re making improvements. Some other captured data:

MT prop
100 110 120 130
76 76 76 76
357 355 344 341
CHT2 377 356 365 362
CHT3 349 325 336 335
CHT4 348 333 342 336
CHT5 384 355 371 370
CHT6 400 385 396 384
EGT1 1156 1132 1145 1147
EGT2 1184 1193 1182 1174
EGT3 1169 1157 1156 1154
EGT4 1234 1228 12321 1212
EGT5 1159 1163 1142 1148
EGT6 1195 1191 1187 1179


“The Legend’ Terry Schubert

The potentate’s magic carpet

We also hooked up to the rear oil cooler inlet and outlet but got no data… pressure side of the oil cooler

Low pressure side of the Oil Cooler

This is the plenum, pressure side connection

And the low pressure, outlet, side of the plenum


Posted By: Brett Ferrell
Saturday May 31st, 2014 at 1:34 PM

Categories: Cooling Flight Testing
Tags: Building Cooling Fuselage

One response to “Beginning a cooling study”

  1. Document says:

    […] At any event, he was good enough to get some aquarium hose and air stones and fly down to help me figure out where we should hook them up. Then he gave me his favorite test sheet and flight test parameters, and Beth and I went out and flew the test. We really should’ve done it earlier in the morning when it would’ve been easier to hold tight altitudes and speeds, but at least we got some baseline data that we can compare to in the future to see if our changes are helping or hurting. Check out the detailed page here. […]

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