Test flight
I made it out to the airport Friday evening after spending a good chunk of my afternoon looking at a new house. We’re thinking about moving to a place with a larger garage for a -10 project :). I think we found something that we’re going to make an offer on.
Time to flight test the recent changes; new prop governor and carburetor mixture modification. I leaned much more aggressively on the ground for taxi. That will become our SOP. I setup for takeoff, being prepared to carefully watch for prop overspeed and make adjustments. I also had my EGT display in running graph mode so I could easily see where they were during takeoff compared to before the mod. As I got full power in, the prop spun up to 2722 rpm for just a second (literally, by the captured data) then the governor stabilized it rock solid just under 2700. The max EGTs on takeoff were about 30 or so degrees cooler. The recorded fuel flow on takeoff didn’t go up very much at all. I only got two takeoffs in before it got too dark, but is sure didn’t go up anywhere near a full one gallon per hour. The max recorded fuel flow was 11.7gph. I think I was expecting to see something like 12.4gph. Although, that isn’t exactly a number that I’m inclined to chase too aggressively. Update: A later data set did show almost 13gph on takeoff for just a few seconds.
I went out and did some leaning tests. I’m now seeing about 30-40 degrees more EGT rise. I’m happy to see that. I’m comfortable that I didn’t overdo it. Runs great, and with this limited testing, it did have an effect on CHTs in climb, but the test data is too limited at this point to quantify. I also did a quick power off stall just to be sure that it wasn’t so sloppy rich in flight (full rich) that the engine would stop. It behaved fine. Cool, I’m happy with the carb mod.
So far as I can tell, the prop governor is totally rock solid. You set it at an rpm, and as long as you don’t make a major power or pitch change, it doesn’t flinch at all. So far it seems much more effective. The updated MT governor seemed like it was getting more and more lazy at holding an rpm. As I was finishing up my testing, the sun was almost fully down. I landed with lights and taxied to the pumps to top off the tanks, then back to the hangar to put it away. A good evening indeed.
Tanya and I are headed up to the Dallas area to have lunch with her parents tomorrow.