Monday, July 9, 2012
Flight Test Follies: Putting on my pants
Well, let's see now, heavy wing problem? Fixed. Oil leak? Fixed. Calibration of panel equipment? Done. Engine roughness? Cured.
It was time yesterday to begin adding wheel pants, gear leg fairings, and intersection fairings to reduce drag and allow the plane to zip along a little faster while using less fuel (please!). I spent many months, it seems, fitting the wheelpants with a laser level (with help from RV pal Chris Knauf), hoping that they wouldn't be off by as little as 1/4", which would adversely affect handling.
You see a lot of RVs with little pieces of balsa wood on the rudder. This is a "trim tab," designed to offset the effects of improperly installed wheelpants.
I've waited this long in the flight testing process because I want to solve each problem as it arises. Had I flown the first flight with wheel pants installed -- as some recommended -- it might disguise, say, a heavy wing problem (tendency to roll in one direction when you let go of the stick).
First I had to finish all of the problems I encountered on Saturday (see previous post) and as I was struggling with getting the brake lines bled, my friend Adam walked in. "Need a brake bleeding assistant?" he said. Adam is one of the people who pitched in when a year and a half ago when the plane seemed like it'd never get done. He shows up faithfully.
We got the brakes bled, the axle nut tightened and the wheel pants put on.
It was time to take it for a ride.
I started with just the wheelpants and made one high-speed run -- to be sure the brakes worked -- and then took off for a quick trip around the pattern. The "ball" on the Dynon D100 stayed centered, indicating the wheel pants were not acting like rudders. Yahtzee!
I landed and then put on the nose wheel fairing. This time I took off and headed southeast to the test area, landed in Dodge Center, then zipped off to Red Wing, 35 miles away.
I had no problem getting the plane -- traveling at 3020 feet -- to 140 knots (that's 161 mph) at about 65% power (2400 RPM and about 24 inches manifold pressure). I was able to also lean the engine back to under 7 gallons per hour, which makes flying a little more affordable than when I first started flight testing and was burning 14-15 gallons per hour.
I did detect what I think was a little nosewheel shimmy on landing at Dodge Center, but I'm not sure what that's all about. It's a pretty rough runway, the locals tell me, but I don't know that merely installing wheelpants would contribute to shimmy. I'll have to research that.
Back at Airlake, I cleaned the plexiglass canopy of all the bugs. I have to get some cleaner to clean up the aluminum. A lot of bugs have given their lives on the wing's leading edge...
It's funny how an obsession with cosmetics when you're building, tend to melt away once you're flying. There are oil stains and bugs on the cowling, and greasy fingerprints along the edges.
I'll have to sand that down and reprime at some point when I care. Plus, I've got to do some fiberglassing to close that gap anyway.
But I also found this problem yesterday...
At some point, things got so hot on the wingtip lens on the right side, that it started to melt. It's not from the NAV light, because I haven't used the nav light, and I don't think it's from the strobe. Given that it melted inward, I'm guessing it happened a week ago when the plane was sitting in the sun at Red Wing on a 100 degree day, and the sun beaming off the aluminum targeted the very soft plastic.
I'll order a new lens. Someday.
There are now 19 hours on the plane and I also passed 200 flight hours in my flying career.
This week I'll try to start doing some speed testing to establish best-climb, best rate-of-climb, and best-glide airspeeds. Then I'll need to change the oil on the plane and start making that final push which will allow the plane to come home to South Saint Paul.
I still have the gear leg fairings to do. They're mostly fabricated, but they're held in place by intersection fairings and I'll need to figure out how to secure them in place, and will probably need someone to help me install nutplates. That might be a job that'll wait until the plane is back at its home airport.