Test Flight #1

I started blogging about building my Bede BD-4C airplane back in 2011 because I wanted to keep my friends and relatives up to date on my progress. I have been delighted (and thoroughly surprised) to find that many people beyond my close circle are also interested. I was even more surprised to have several people ask me to keep them posted on the flight testing.

This article is long and detailed. For a shorter overview, see my gleeful First Flight! post.

OK, you asked for it; here we go.

Test Flight Planning

A few months before my homebuilt airplane was ready to fly, the Experimental Aircraft Association released the first edition of the EAA Flight Test Manual. I jumped on the website so fast that I may well have placed the first preorder. The book arrived and I am using it as a basis for my own flight test program. It is just a basis, though, because the EAA Flight Test Manual is written for testing a wholly new airplane, with unknown flight characteristics. I am testing a Bede BD-4C, the latest iteration of a kit which was introduced to the market in 1968. There are several hundred flying BD-4 airplanes and its flight characteristics are well known and pretty benign.

Before each test flight, I write down the goals of the flight and the specific procedure that I will follow. After each flight, I write down and analyze the results. My first flight was actually my fifth formally planned and documented operation of the airplane. The first four were taxi tests.

Here is my plan for the first flight. Flight test card: 05: First Flight

Startup & Taxi

The engine started easily but there was a cold wind on me as soon as I began to taxi to the runway. I could see that the passenger side fresh air vent had popped open. With my seat belt on, I cannot reach that vent. Had it opened in flight, it would have been a real nuisance. I taxied back the hangar, shut down the engine, and taped the vent shut. Candy and Bill and David drove back to see why I had returned to the hangar. They were relieved to learn that it was a minor issue.

With blue “aviation grade” masking tape installed, I restarted the engine and taxied to the runway. After waiting for a couple of airplanes to land, it was my turn. I taxied into position, lined up for takeoff. I took a moment to collect my thoughts, made a last check that everything seemed OK, and pushed the throttle all the way in. 200 horsepower pulling a lightly loaded airplane on a cold day makes for some impressive acceleration and I was airborne in a few hundred feet.

Bill and I had briefed the takeoff. I had intended to stop climbing just a bit above the runway and do a quick check of the controls. Had anything been horribly wrong, I could have pulled the power back to idle and land straight ahead. No fuss, no muss.

Takeoff

It did not work out that way. Being the first flight, I had only been able to guess where to set the pitch trim. It turned out that I had set the trim for a pretty nose-high attitude and the plane shot skyward. It was about a hundred feet in the air before I found the right amount of forward pressure on the control stick for level flight. I knew that the left wing would be heavier than the right, since I had 24 gallons of fuel in the left tank and only 6 gallons in the right tank, but I did not anticipate just how much heavier it would be. It took more work to keep the wings level than to keep the nose down. I had to move the control stick about 1/3 of the way to the right (which increases lift on the left side of the airplane) and then stomp hard on the left rudder pedal (to keep the nose from swinging to the right) to keep the airplane from banking hard to the left and making tight circles to the left.

By the time I got that sorted out, I was satisfied that the airplane’s controls were operating properly and that I could continue the flight. I resumed climbing.

I took a look at the engine instruments and confirmed that the oil pressure and temperature were both in the green. The engine RPM was above redline, though, at about 3000. Redline on my Lycoming IO-360 is 2700. While I was climbing, I dialed back the propeller control to reduce RPM. Nothing happened. I dialed back some more. Nothing changed.

Problems Controlling Engine RPM

By this time I was past the end of the runway, less than 1000 feet in the air, and super busy trying to maintain level flight and get the engine speed below the redline. I decided to reduce my workload so that I could attend to the engine RPM issue. I made a left turn, following the traffic pattern for the airport. This put me track to land, should I not be able to tame the engine speed issue.

I pushed the nose down to level flight and adjusted the pitch trim so that I did not need to hold a bunch of forward pressure on the stick. I reduced power to a middle setting, giving me a slow cruise speed of about 100 knots. I still needed to haul the stick to the right and to press down on the left rudder pedal but, with the airplane now needed a lot less attention simply to keep the shiny side up and the wheels down. I made a second left turn, onto the downwind leg of the traffic pattern, parallel to the runway. From this point, I could fly straight and level for about a mile before I would need to make a decision and do something, either turn left and begin to land or turn left and begin to climb to orbit the airport. (Had I not turned, I would have flown north into Illinois, away from the airport, not something that I was ready to do.)

While flying downwind, I fiddled with the propeller control a little more, Pulling the knob out (toward me) is supposed to reduce engine RPM; pushing the knob forward (away from me) is supposed to increase RPM. It was not working. The airplane was flying well, though, and I decided that the right place to continue my experiments was near the airport but farther from the ground, reasoning being that if something funky happened with the engine, more altitude equals more time to deal with the situation.

I was flying straight and level at about 95 knots. I left the propeller control alone and push the throttle in, adding power. The airplane began a gentle climb. I made a left turn north of the airport to begin orbiting. I climbed up to 2500 feet MSL (feet above mean sea level, the way that pilots measure altitude), which is about 2000 feet AGL (above ground level) at my airport. The climb gave me time to get a feel for flying the plane and catch my breath.

Ideally, I would have climbed higher but the St. Louis Class B airspace overlays St. Charles County Smartt Airport (KSET) so I had to stay below 3000 feet.

Once I leveled off, I returned to experimenting with the propeller controller. At my reduced throttle setting, the engine was turning at 2600 RPM. Small adjustments of the prop control did nothing. If I made large adjustments, nothing happened until all of a sudden, the RPM dropped from full to 1400 RPM and still falling. The engine was trying to go all the way from full power to idle. I pushed the prop control back in and the RPMs returned to 2600. I repeated the experiment, got the same results, and shoved the prop control back in. 2600 RPM was much better than idle!

Landing Early

I gave this a few seconds of thought, disappointed that continuing to fly the plane in this state was clearly untenable, and decided to cut the flight short. I radioed Bill on the ground to let him know the situation and that I was returning to land. I pulled the throttle back some so that the airplane descended as I continued to orbit the airport. By the time I was flying the upwind leg of the traffic pattern (parallel to the runway and into the wind), I had leveled off at traffic pattern altitude.

I flew a normal approach and landing, with the only difference being that I did not use the flaps. Avoiding flaps on the first flight was part of my test plan.

I flew final approach at 90 knots, crossed the runway threshold at 85, touched down smoothly within the first 500 feet of pavement, and easily made the turn-off at 1400 feet down the runway.

I taxied back to the hangar, shut down, grinned like an absolute fool, and toasted success with Candy and David and Bill and a nice glass of Glenfiddich.

Summary & Video

Takeoff: 13.02.19 14:14
Flight time: 00.25
Max altitude: 2448ft
Max airspeed: 118kts
Max/Min vertical speed: -1160/+1780fpm

Here is the video of the first flight. If you just want to watch the good parts, the takeoff is at 2:45 and the final approach begins at 6:35.