They don't vibrate or require expensive fuel. They're great for training pilots.

So you'd think we'd have lots of battery-powered airplanes on the market by now, but we don't. The reason, according to industry insiders, is not because of technological issues or safety concerns.

It's because of a single phrase in the government's seemingly endless list of rules that must be followed to certify a new airplane design as safe to fly. The rule was written before electric powerplants for aviation were taken seriously, but the government won't change it.

In 2004, the Federal Aviation Administration created a new category of airplanes, called Light Sport Aircraft (LSA), to make it easier and cheaper for manufacturers to certify simple, fun-to-fly airplanes.