One of the oldest prizes in aviation is one step closer to being claimed after a team from the University of Maryland flew a human-powered helicopter for 50 seconds yesterday. The students managed the tenuous indoor flight with the Gamera II, beating the team's previous record of 11 seconds set last summer.

The flight came at the end of two action-filled days of flying, fixing and flying again with numerous hops above the University of Maryland's basketball court heli-pad.

The prize is the Igor I. Sikorsky Human-Powered Helicopter Competition from the American Helicopter Society and a win earns $250,000. In order to claim the prize a human powered helicopter must lift off the ground, hover for at least 60 seconds, reach an altitude of 3 meters during the flight and stay within a 10-square-meter area.

Yesterday's 50-second flight was one of more than a dozen over the past two days, including a 35-second flight on Wednesday and a 40-second flight earlier Thursday (video below).

The Gamera II is a far cry from its robust spinning terrapin namesake. Like its fixed wing, human powered cousins, the delicate helicopter is a rather large, yet extremely lightweight aircraft. The entire craft has a width of 105 feet and each of the four rotors has a span of just over 42 feet, 7 inches. But despite the size of the Gamera II, it weighs just 71 pounds. That's more than 30 pounds lighter than the original Gamera that flew last year, thanks largely to redesigned rotors and an improved truss design.

The design is delicate and an incident on Wednesday had them making repairs and delaying further flights.

Photo: Univeristy of Maryland

Carbon fiber rods and thread are used to create small trusses that in turn make the four large trusses that spread from the cockpit. At the end of each truss is a rotor that is perched just above the ground. With the rotors located close to the ground, the team can take advantage of ground effect, an aerodynamic condition where there's a reduction in induced drag from the lift generated by the rotors. With the rotors spinning at just 20 revolutions per minute, less than one horsepower is needed to hover at 2 feet above the ground.

Gamera II is piloted and powered by a pair of students at the University of Maryland. Unlike its predecessor, Gamera II uses both pedals to power with the legs, and a hand crank to add a bit of extra power. The team estimates they gain around 20 percent with the arms over using legs alone.

The University of Maryland team is one of only three groups that have ever achieved human-powered helicopter flight. A Japanese team held the previous record with a 19-second flight back in 1994.

More flights are expected today and the team hopes to crack the 60-second barrier. A live stream of the Gamera II in action can be seen on the team's website.

https://www.youtube.com/watch?v=S-k-3efasOk