Human-powered aircraft

A human powered aircraft is an aircraft that is powered entirely or partly by the pilot(s). Several human powered aircraft have been constructed in the past 30 years for recreation or to win prizes.
Designing a successful human-powered aircraft is difficult because a very large power to weight ratio must be achieved. This has been the reason why many of these aircraft use advanced composite materials in their construction.
There are human-powered aircraft being designed and made now. One aircraft is being built by Virginia Tech University named the Iron Butterfly. Another one is being built by the Pennsylvania State University named the Zephyrus.