I have a Starlight, identical to the one Konstantin flys, and I will never, ever be able to fly it anywhere near its capabilities. But Konstantin can, and the repeatability of his flights on the "tracker" video is amazing. I believe he took 3d at the 2022 Worlds with it, and others have similar results all around the world. But all my other models, self-built with conventional design, have all moving surfaces sealed with clear tape. I have to since I see Brett at all our local contests and take his word as Gospel! As others have said, he is extremely generous with his time and the benefit of his decades of experience and experimentation.
And who's to say I am not a bot?
I am sorry if this came off dismissive, I have my bad days like everyone else.
But there is probably no other topic where we have tried absolutely every variant we can think of. Everything has been tried, because unlike most of the airfoil-type discussions, the hinge line treatment really does matter, it's critical, and even tiny gap differences can have very large effects on the performance. On a particular airplane, it is built how it is built, and unless you do something to alter it, it will have whatever effect it has. But .005" variation between one airplane and another, or from it absorbing water and swelling up in the morning and trying out in the afternoon, or getting a blade of grass stuck in it somewhere, can completely alter the trim of the airplane.
Same with a single airplane over the range of travel. Unless it is built to infeasibly tight tolerances, the gap always varies over the range of travel, and not the same on the inboard and outboard wing, and not the same on up and down. This has dramatic effect on things like the apparent need for tip weight and tabs, inside/outside turn differences, and all sort of strange frequently undiagnosable trim issues. Changing a .010 gap by .005 between up and down on the flap has more effect than putting on a 3/4"x 2" tab - and you can't have a tab on "up" that disappears on "down".
I also note that the Yatsenko "knuckle hinge" is far from consistent from airplane to airplane. I have seen them with the hinge perfectly centered in the pocket, and others with the flap poked up above the surface one way and below the surface the other. That seemed to have drastic effects on the inside/outside turn difference and the roll trim, not surprisingly the best and most honest were the one where it was close to center. I am not criticizing their workmanship because the worst one I have seen was something like 1/64" or so (.016-.020, I didn;t measure it) off. But for hinge lines .016 variation have very large effects due to differential leakage.
So people have experimented with hinge line design for years. My personal experience, and those gleaned from most of the people whose observational skill I trust, have led us to a more-or-less conventional hinge line design, with the harp corners knocked off, with seals. I am well aware of people thinking that they can leave a big gap and have it act like s a slotted flap (Al Rabe, for example) and those who like the "knuckle hinge" like on some of the Yatsenko airplanes, but having tried all that stuff, I still think that you get the most repeatable and consistent results, and probably the most effective flaps and elevators, using the regular hinges with seals. That's the best advice I can give.
Obviously, anyone can experiment with anything they want, I am not the hinge line police. I offer my (and many others) observation of what we wound up with at the end to maybe help people keep out of dead ends.
Brett
Topic: Imbedded Flaps (Read 1617 times)