First Fully Electric Manned Helicopter Flight 86
cylonlover writes "On August 12, electrical/aerospace engineer and helicopter pilot Pascal Chretien took to the sky in the world's first untethered, fully electric manned helicopter flight in a prototype machine that he designed and built almost entirely by himself within a 12-month development period. In his 2-minute, 10-second test flight, Chretien beat aviation giant Sikorsky into the record books — but it was not without significant risk. As the man himself puts it: 'in case of crash I stand good chances to end up in kebab form.'"
Ground effect (Score:5, Insightful)
Re:Wow.... (Score:4, Insightful)
I haven't read TFA yet, but there's probably a difference in goals here: a fully-electric helicopter at the lowest possible cost, vs. a fully-electric helicopter that's actually somewhat usable for the things you'd normally use a helicopter for.
With enough time, I could put together a homebrew electric helicopter that lifts me up in a lawn chair, but what good is that? All it does is prove a concept, but I could have told you before that such a thing is perfectly possible, and you don't need to actually go to any effort to prove it. Unless you can actually lift a significant amount of weight, and have an airframe that meets various regulations, has all the required instruments, has the required measure of crash protection (normal helicopters actually do have a certain amount of crashworthiness, to prevent needless deaths from low-speed crashes near the ground, such as from "hard landings" and other accidents that occur before the craft has reached any altitude), has all the required lights, and can perform within a sufficient envelope, then it's fairly pointless to build something like this.
Converting any fossil-fuel-powered vehicle to electric power isn't rocket science. There really isn't that much to it: you get rid of the piston/turbine engine, stick an electric motor in its place (there's a lot of different kinds of motors however and I'll avoid getting into that), and then most importantly, you put in enough batteries to hold the power you'll need for that motor. That last part is the hard one, because right now we simply don't have batteries capable of coming close to the energy density offered by a fuel tank full of gasoline, diesel, or kerosene. The motor part is easy; we've had great electric motors for a long time, and the brushless-DC motor technology we have now is simply fantastic, but without a way of storing enough electricity to make them usable, it's all for naught.
It's worse in a helicopter however than in a car. In a car, weight isn't that much of a factor (since it doesn't have to lift itself off the ground, after all), so a few hundred pounds of batteries can be a perfectly acceptable tradeoff in light of the fact that gas engines waste a lot of fuel by being oversized for their applications (a car engine has to be sized for its peak load, not its average load, and accelerating from a stoplight requires much more power than simply cruising at 55, but the bigger the engine, the bigger the frictional and pumping losses). In an aircraft, engines aren't oversized for peak loads; in helicopters, they're always run at 100% of their rated rpm. So with converting a car to electric drive, you get to improve your efficiency by the fact that most of the time, you only need 10-20 HP or so to maintain your speed, and you only drain that much energy from your batteries and don't suffer any significant loss of efficiency by having an electric motor that can deliver 150 HP when it needs to. But with a helicopter, you have to run it at 200HP (or whatever; that's what a small 2-seat training helicopter would need; something that can hold 6 people would need more like 1000+) constantly, from the time you lift off until you touch down. That's a LOT of energy to store in batteries, and is quite frankly beyond our technology.