Late Saturday morning I headed out to FIT to perform a once over of the aircraft. I removed both cowlings and the nose doors so that I could poke and prod everything, looking for leaks, loose fittings and screws/bolts, or anything else amiss. While I didn't find anything like that, I did discover why there was just a BIT of a "catch" in the carb heat cable in one direction - the arm on the air filter that moved when the cable was pulled just ticked the lower angled baffle in the lower cowl. 30 seconds with a dremel tool fixed that, and the carb heat cable now actuates very smoothly. All else was clean and tight, so I buttoned it up and prepared for test flight five.
This flight measures temperature rises of CHT and oil during climb. I chose to measure at 120 mph, 100 mph, and 80 mph, as this will pretty much bracket the full climb regime. At first, I was going to measure climbs at 1, 2, 3, 4 and 5 minutes at each of these speeds, with a 5 minute cruise stabilization between each climb. After cogitating on that for a few minutes the night before, I quickly realized that would take about a week and a half. I chucked the 2 and 4 minute climbs.
Once I took off and climbed to 2500 ft, I realized that every dang time I had taken off, I had climbed for at least one minute, and the CHT's and oil temps were always reasonable. There goes the 1 minute climb test. So, I'm down to 3 and 5. After the first 150 mph stabilization period, I performed the 3 minute climb at 120 mph. No problems - data taken. Then another 5 minute stabilization period at 2500 ft. and a 120 minute climb for 5 minutes. Dang, 8000 ft. - this is pretty high. No problems - data taken.
As I started the 3 minute climb at 100 mph, I realized that 3 minutes is less than 5 minutes (thank MIT for those advanced calculus for engineers classes, eh?). If I take the data at the 3 minute mark, but keep climbing, I'll be able to take data at the 5 minute mark and not have to descend or stabilize that extra time. What a genius!! Once again, data taken twice with no problems.
The last round was a 80 mph climb. This is a bit nerve wracking, as the nose is WAY up there - the only forward view (at full throttle) is UNDER the canard. Every 30 seconds or so I'd drop the nose so that I see where the heck I was going and look for traffic. On the other hand, this got me up to about 9000 ft. That's the highest I've ever been on the east coast. In this climb, the CHT's were still fine, but after 5 minutes, the oil temperature was up to 240 degrees F. Still "legal", according to the oil specs, but definitely a lot higher than I want to run on a regular basis.
Anyway, data successfully taken, I descended for a 10 mph crosswind landing on runway 32 at FIT - no issue. This was the longest flight yet at 1.3 hours - just imagine how long it would have been if I wasn't so brilliant and hadn't figured out how to get rid of about 3/4 of the flight -).
You can read the Flight Test Protocol for Flight 5.
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