Human-Powered Helicopter: Straight Up Difficult
It's difficult to build a working four-rotor helicopter that spans 100 feet and only weighs 80 pounds. It's even harder when your engine is a 0.7-horsepower person. But one team of engineering students is trying to do just that.
![Human-Powered Helicopter: Straight Up Difficult](https://img.youtube.com/vi/emK-qIbuJ-k/0.jpg)