The idea of a human-powered helicopter has intrigued many engineers and pilots. Although a practical application really does not exist, it is a good exercise in the development of highly efficient airfoils and light weight structures. As such, many colleges and universities have put together teams of engineering students to develop and build a human-powered helicopter.
A human-powered aircraft is defined as a vehicle that can carry at least one person using only what power is provided by the person(s) on board, usually by pedaling. Early attempts mainly involved airplanes. For example, the best known human-powered airplane is the Gossamer Albatross, which flew across the English Channel in 1979. Helicopters which require much more power to hover present a much bigger challenge. The two biggest problems are weight reduction and designing a highly efficient rotor system. Efficiency means that the rotors must generate a lot of lift with very little drag.
In 1980, to help further and support the idea of a human powered helicopter, the American Helicopter Society established the Igor I. Sikorsky human-powered helicopter competition. A prize of $20,000 was offered for a successful controlled flight lasting for 60 seconds and reaching an altitude of 3 meters while remaining in an area 10 meters square.
The first vehicle that actually got airborne was the Da Vinci III in 1989, designed and built by students at Cal Poly San Luis Obispo in California. For high rotor efficiency, the students knew that it would be important for the blades to work with as much air as possible. A big rotor handles a large amount of air and thus requires less energy to produce lift. The Da Vinci III had a 100-foot rotor diameter and a tip speed of 50 feet per second. In order to reduce weight, rotor tip propellers provided thrust. This eliminated the need for a transmission and anti torque system. The approximate weight of the aircraft with pilot was 230 lbs. It flew for 7.1 seconds and reached a height of 8 inches. However, the helicopter was unstable and required students on the ground to assist with control. No attempt was ever made to correct the instability.
The current world record for human-powered helicopters is held by an aircraft named Yuri I, built by a team from the Nihon Aero Student Group (NASG). It used four two-blade rotor systems (10 meter diameter each) operating at 20 rpm. In 1994, it achieved a height of 20 cm for 19.46 seconds unassisted and unofficially reached 70 cm during a flight lasting 24 seconds.
As far as I can tell, the most recent attempt, although unsuccessful, at a human-powered helicopter was on August 10, 2004, by a group of engineering students at the University of British Columbia. Although their project seems to be on hold, their Web site is still up.
Many have attempted to fly human-powered helicopters both before and after the creation of the Sikorsky Prize. So far no one has met all of the Sikorsky prize’s requirements.
Tags: Tim McAdams