China's DIY Aviators Take Flight 113
ScuttleMonkey writes "China’s emerging aviator class is spreading its wings with a plethora of approaches, from the ramshackle to the sophisticated to the potentially revolutionary. They’re using everything imaginable, from old motorcycle engines to electric motors to even their own legs, like Mao Yiqing and his human-powered airplane. You could easily plot these adventurous innovators on a graph, with the X axis showing their skill and the Y axis their financial means."
Re:Gotta say it... (Score:5, Informative)
But the technical sophistication of the effort and the wealth of the experimenter certainly *are* related.
The idea of a amateur homebrew helicopter is truly frightening, but *anybody* can dream, especially if he doesn't realize how incompetent he really is.
The minimum successful example is the guy with the autogyro. For that you need the kind of practical skills a farmer who maintained his own equipment would have. The most sophisticated component he'd need is the rotor, which *could* be manufactured from glued wood.
The next step up is the human powered guy. He needs a long carbon fiber boom as the main longitudinal structural component, and probably another one to carry the lift generated along the wings to the main boom. That's pretty expensive. Once he has that, then the drivetrain is bicycle technology.
The rest of the wings and pilot's nacelle are fairly sophisticated, but within the capability of a weekend tinkerer to construct. The key is the sophisticated materials you can buy. You make a basketwork out of lightweight wood and Kevlar tape, then heat shrink polyester sheeting on it to create a skin. Weekend boatmakers have been constructing ultralight boats this way for *years*. You can make a 17 foot canoe that weights under ten pounds this way, or a full sized rowboat that weights maybe fifteen pounds.
The guy who is working on a certifiable electric aircraft needs to have the most money. He needs a real machinist and sophisticated fabrication techniques. Batteries aren't really good enough for practical aviation yet, so for his demo he needs the best batteries and motor money can buy.
Each of these guys is designing the most practical aircraft possible within his financial means. Give the homebrew helicopter guy a million dollars, and he'll *probably* end up killing himself, but it would no doubt be in a more impressive aircraft.
Re:Gotta say it... (Score:4, Informative)
The idea of a amateur homebrew helicopter is truly frightening...
There are several flying examples in the U.S. of amateur-built helicopters. Granted, most of them are built from professionally manufactured kits (i.e., the manufacturer builds a prefab kit, and the "builder" assembles the parts), some of which are relatively sophisticated. Google Rotorway and Mini-500 (I think the Mini-500 is defunct now, but there were several built back in the '90s).
...but *anybody* can dream, especially if he doesn't realize how incompetent he really is.
I would argue that often times, those who don't realize how incompetent they really are are, in fact, the ones who make the biggest advancements. They don't know it's impossible before they try, therefore they are the ones who go ahead and do it anyway. "The Ark was built by amateurs; the Titanic was built by professionals." ;)
The next step up is the human powered guy. He needs a long carbon fiber boom as the main longitudinal structural component, and probably another one to carry the lift generated along the wings to the main boom. That's pretty expensive. Once he has that, then the drivetrain is bicycle technology.
Human powered flight is about as difficult as aviation gets, at least for right now. The problem is that it takes more energy than most people realize to lift a human body; we simply don't have the strength or endurance to generate that much power for very long. I believe the current record is 199km [gizmag.com] -- not too shabby, and much better than I thought before I looked it up just now. FWIW, building the carbon fiber boom isn't difficult (although the carbon fiber is relatively expensive -- but less so than most power plants for experimental aviation). I did the calculations for a carbon fiber wing spar about a decade ago, and estimated a ~1500 pound airplane stressed for a max G-loading of +6/-4 (plus reserve) would cost around $1000 - $2000. It isn't cheap, but it's certainly within the realm of possibility for someone of reasonable means. There was also a guy in Arizona about ten years ago who built a foot-launched sailplane called the Carbon Dragon, that would probably be worth studying if you were interested in trying to build a DIY human powered airplane. He sold plans for the airplane, but I believe he died a few years ago, so they might be a little hard to find now.
The rest of the wings and pilot's nacelle are fairly sophisticated, but within the capability of a weekend tinkerer to construct. The key is the sophisticated materials you can buy. You make a basketwork out of lightweight wood and Kevlar tape, then heat shrink polyester sheeting on it to create a skin.
That's not a bad way to do it. I remember reading magazines dating from the late '60s (I read them in the '90s, though) about people who had build entire airplanes with this method. My experimental airplane [google.com] uses a slightly different method, that also might work. The wing spar is an aluminum tube with foam ribs glued to it. The leading edge is 2024T3 aluminum wrapped over the ribs to make a stiff skin over the first 1/4 of the wing, then the entire wing is covered a material made by 3M for building greenhouses called Tedlar (as the story goes, 3M freaked and pulled Tedlar from the market after hearing people were building airplanes out of it; I haven't verified the story). It looks like a full-scale model airplane wing covered in clear Monokote ;) For human powered flight, I would probably replace the aluminum spar with carbon fiber, like you mentioned earlier, but the principle is the same.
The guy who is working on a certifiable electric aircraft needs to have the most money. He needs a real mach