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Cozy MKIV - Nineteenth Flight Test

Date: September 26, 2002

So I started the 25 hour oil change yesterday after work, made a complete mess of the airplane and the ground underneath it (how DO you remove the oil filter from a B&C oil filter adapter without getting oil spilled all over the rear of the engine?), and went home.

This morning, I headed out before work, and talked to the A&P at the FBO before completing the oil change. I mentioned that my oil temps were high, and he said anything up to 260 F during break in is not a problem, and that the temps would naturally drop when I switched from straight mineral oil. Since I'm still burning a quart every 8 - 9 hours or so, he suggested using straight mineral oil until 50 hours, but NOT after 100 hours, and that I should see 10 - 15 hours/quart when everything has stabilized.

So, out to the plane, fill with 7 quarts of straight mineral oil, replace the filter, finish cleaning everything, and take it out for a spin to test the oil cooling. I now have the 4" long turbulators just in front of the NACA scoop at a 20 degree angle to the airflow, and I removed the oil cooler air scoop, plenum, and hose, so I'm back to my original oil cooler installation.

I took off and climbed up to 6500 ft, watching the oil temps the whole way. I leaned it out, but did not reduce the throttle until I got almost to Keene, NH - about 15 minutes. The oil temp never got over 200 degrees. I landed at Keene, then took off again, climbing back to 5500 ft. Another full throttle run (184 mph IAS, 200 mph TAS) at 2700 rpm for 15 minutes. Oil temp. never got above 220 F. So, it looks as though the turbulators make a large difference in the oil temperature - about 20 F degrees, I believe. Given my discussion with the A&P, I'm going to leave the oil cooling system alone - I think I've now got adequate cooling, especially if the temps will come down when I change to regular oil at the next oil change at 50 hours.

I did push the nose over to 200 mph IAS at one point (at 3500 ft.), although I did not do any flutter tests on this run. I also notices a very slight canard vibration at 190 IAS at 6500 ft. - the elevator was rock steady, with no vibratory feedback into the stick at all (don't think it was elevator flutter in any way), but the canard tips did look like they were vibrating a bit, just at that speed. I didn't go any faster at 6500 ft. to see what happens -).

25.5 hrs. and counting.......

End Date: September 26, 2002


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