| Power Planes |
Ken Willard Drake |
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This was my first scratch built plane. A Ken Willard design, it was built from an article in Model Aviation. The plane in the magazine was rudder-elevator only and powered by a .15. Construction was a balsa fuse with a built up wing. I decided to use a foam core wing, sheeted with 1/16" balsa. Rather then just rudder-elevator, I added flaperons. The fuse on mine is glassed with light FG and painted. My Drake was originally powered with a Magnum .25, but I later switched to an O.S. .28 heli engine. As a result of all this stuff, plus lots of paint, mine came out at about 4lbs, probably 1lb overweight!
The first flights...
As you can imagine, my Drake sits very low in the water. In fact, the front deck is nearly level with the water line. On take off, the nose briefly submerges. With full up elevator on the application of throttle, the nose will pop out and the Drake will get on plane and accelerate fairly quickly.
Once in the air, the Drake does not show any bad habits, except that it tends to fall through a turn if banked to steeply. This is high drag design, so it's not going to win any races, but it seems to move around fairly well. Climbing performance is not very good, probably because the nose deck clarence restricts me to using an 8" max prop. With the .28, the plane climbs a bit better, but not much. Top speed seems to be about the same.
The Drake is mildly aerobatic, with moderate rolls being possible. I'm a bit afraid to loop it, though, because I don't think the tail will survive too much stress.
Landings are straight forward, though the sink rate is a somewhat high. The flat bottom hull ensures that the Drake will bounce or skip a few times unless set down perfectly. As you might expect, water taxiing is, well, taxing. The nose goes under water at anything over idle throttle, causing huge blasts of prop spray. This means I have to taxi very slowly, which means that there is very little directional control if there's any wind. The plane has no water rudder. Instead, I installed a large tail wheel, as shown on the plans (it was supposed to be amphibious). I don't think it hangs down low enough to be effective, though.
Here's a report from my second day of flying the Drake....
Before the next flights, I added some down and right thrust, and this really seemed to solve any serious trim problems. The lake was fairly glassy and there was little wind so take off went smoothly. One thing I've learned is that it's best to appy full throttle immediately. When I tried gradually advancing the throttle, the nose would start porposing before the engine speed built enough to set the tail down. If I just jam on full power right away, along with full up elevator, the tail sets down and the plane plows forward in a nose high position. After about 20 feet, it picks up enough speed to begin planing. Once it's on step, I neutralize the elevator and then just let it pick up speed and fly off the water by itself.
Any other problems I was experiencing are defintley from the weight. The plane will want to descend though almost anything but a gentle turn, even at full throttle. Still, it flies smoothly and seems to have no bad habits, aside from a rather high sink rate. There seems to be no tendancy to tip stall or do anyting suprising. Eventually, I tried lowering the flaps, and I found that I could manuver around at about 1/3 throttle, even at low altitude. I just had to be sure to add a bit of power in the turns.
I did quite a few landings and splash n' go's. It was easy because the water reflected the plane very well. It's fun to do a splash, lift off, then immediately do a 180 and do it again from the other direction.
Eventually, after flying around a bit I let my friend try it. I suggested that he try a landing. He did, but he didn't appreciate the high sink rate the plane has before it gets into the ground effect. He ended up thacking it down in sort of a carrier style landing. It must have boucned about 10 feet! Anyway, no damage, and I took the controls and landed it. Taxing in, the engine died, so we took the boat out to go get it. It sure looked pretty just sitting out there by itself in the middle of the glassy lake. I wish I'd had a camera.
The only real problem I've experienced is with the new Hitec micro servo that I'm using for the throttle. It was acting up the night before and would only move in one direction. This was mounted exposed on the plyon, so I thougt maybe some water or exaust residue might have gottem into it. I first checked the wiring (it was ok), then opened it up. Every thing was perfectly dry. I put it back together, and suddenly, it worked. Everything was fine during the day's flights, but when I brought it in, it was not moving again! I don't know what's going on, but I'm replacing it with another servo.
I don't think I'll be adding any foam to the fuse unless my paint job is startiong to degrade anyway. Flotation really isn't a problem, except when I'm taxing in and the plane is nose heavy. A new, lighter wing is still a possibility, though.
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