My new plane was flown for the first time yesterday. On the way home, I was thinking about the design concept behind it (apart from being silly with the styling and such) and was pretty pleased with myself. This is a brand new design.
About 600 square inches. 55 inch span. Could be a bit more than 600 because I didn't actually calculate when I was drawing it (OK, so I was silly, but hey, it looked right), but it's around 600, maybe 610. Something like that. About 50oz after adding some lead to balance it. It could be less if I give up the current engine (OS40VF) and go with the lighter one (PA40UL). I could then lose the 1.5oz in the tail. I'd probably have to put a half ounce back in the nose, but I could get that using a metal spinner instead of the current plastic one. Not sure it's worth it for an ounce savings. Not heavy, but not really light either. It's pretty much what I thought would be a good weight for the design. I had planned for a weight of 48 to 52oz and clearly it right in the middle.. The wing is my own airfoil. A bit sharper leading edge than I usually use. About 20% thickness with the high point back about 26%. Looks very like a NACA 0018 with just a bit more thickness. The idea behind this was a bit better wind penetration and perhaps a bit better groove. I often use very thick, very blunt airfoils with the high point well forward and while they can carry a lot of weight, they are somewhat harder to trim (at least for me) and, I feel, more susceptible to turbulence. I don't think they penetrate all that well but do have other benefits for those of us that tend to build porky planes. It's pretty overpowered with the OS40VF and on a pipe. Considering the size of the flaps (big), the size of the tailplane (also big at about 28% of the wing) and long moment arms (really long tail moment trying to accommodate the heavy engine in what is a pretty light design, the mechanical advantage in the thing is pretty huge. 4" bellcrank, very long flap and elevator horns (flap is 1.5" and 1" and the elevator is a slider that goes from 1.25 to .75) and quite a lot of handle spacing (right now about 4.25 inches).
Maiden flight was in 10mph winds with gusts to about 15. Zero problems. No wind up and no control issues after I got a bit of tail weight in it. Even in it's initially very nose heavy condition, if flew OK if a bit sluggish. The thing just flies and just goes where you point it. Good corner and very, very stable. Tracking seems pretty good so far. I'll be dinking with the fine trimming over the next 10 flights or so. But with just 4 flights on it, right this minute it flies better than any other plane I own.
Point is, the idea was to build a relatively light, smaller airframe and put a lot of very controllable power in the nose. For controllability, you don't get much better than the 40VF. It has a wing designed to be less bothered by wind and turbulence but generate enough lift to carry the weight easily. Large flaps that don't deflect a bunch but will generate additional lift when needed and enough authority in the tail to stop a turn quickly, again, in less than ideal conditions. The control system is limited (on purpose) to about 18° deflection and trust me, that's plenty. Hook up currently is about 1 to 1.
Nice to design something, actually built it to specs then have it perform pretty much as predicted when I was putting pencil to paper (in my case littorally). Makes a guy start to think he actually does have some idea of what he's doing. I was beginning to wonder.
Topic: Design thoughts - now, appearently, camera thoughts (Read 1374 times)