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Human-powered Gamera helicopter hovers its way into the record books

By

August 19, 2011

Hovering for 11.4 seconds has secured a place in the record books for the Gamera team, and...

Hovering for 11.4 seconds has secured a place in the record books for the Gamera team, and for its pilot Judy Wexler, who made the longest human-powered flight by a female U.S. pilot

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A biology student has just hovered her way into the record books in a four-rotor, human-powered helicopter named after a giant flying turtle from Japanese kaiju movies. Gamera was built to try and claim the American Helicopter Society's Sikorsky Prize, that was set up in 1980 and has yet to be claimed. The team's first flights in May resulted in a 4.2-second U.S. national record, and now the record page has had to be rewritten again after the young pilot's frantic combination of hand and foot pedaling action kept Gamera in the air for nearly three times longer, during the recent summer flight sessions.

For the last two years, a team of 50 graduate and undergraduate students from the Alfred Gessow Rotorcraft Center at the University of Maryland's Department of Aerospace Engineering has been designing, building and tweaking a lightweight, four-rotor helicopter that's powered by the human pilot suspended at its center. The hope is to build a craft capable of walking away with the American Helicopter Society's Sikorsky Prize of US$250,000.

Diagram of Gamera - each crossbar of the frame is 60 feet long, and has a 42-foot rotor at...

The rules of this challenge - named in honor of helicopter pioneer Igor Sikorsky - state that the craft should get all of its power from the human pilot and that it should thus be capable of hovering for 60 seconds within a 10-meter (32.8-foot) square area. During this time, the lowest part of the machine must reach an altitude of 3 meters (9.84 feet) above the ground - if only momentarily. As of August 2011, no-one has claimed the prize.

The closest so far was 1994's Yuri I (19.46 seconds at an altitude of 0.2 meters/0.65 feet) designed by the Nihon University Aero Student Group. Gamera sports a similar design - with a 42-foot (12.8-meter) rotor at the end of each of the four points of a cross, and the pilot sat in the middle. Each crossbar of the frame is 60 feet (18.2 meters) long.

"The similarities are more a result of convergent evolution than direct inspiration," the team's Joe Schmaus told Gizmag. "Helicopters are notoriously challenging to control and human powered flight has only ever been possible with the aid of ground effect. A quad rotor is the only configuration we have identified that is passively stable and allows the rotors to be as deep in ground effect as possible."

Final checks on the structure of Gamera, which had to undergo emergency repair the night b...

Gamera's main structure is made from carbon fiber using a specially-developed truss construction method, that allows highly optimized composite trusses to be created very quickly. The team also developed a novel method to minimize buckling, where airframe trusses at critical points have been reinforced with so-called baby trusses. Elsewhere, the craft is made of balsa, foam, mylar, and other lightweight materials to help keep its weight down - the entire weight is just 210 pounds (95.25 kg), including the weight of the pilot - while also offering structural strength.

The lightweight pilots used throughout the project have also been experienced cyclists, and were free to design their own training regimes based on their specialist knowledge. The team "became aware through our testing that a more focused training plan that optimized for muscular endurance rather than cardiovascular endurance, and one which trained the motion that is unique to Gamera, would produce even better results," said Schmaus. "Moving forward we are working with specialists in Biomechanics to develop a targeted training plan."

On the eve of the most recent record attempt inside the University's Reckord Armory, Gamera crashed during testing - forcing an emergency all-night repair. However, the next day a few bleary-eyed team members watched as pilot Judy Wexler powered aloft for 12.4 seconds in the presence of officials from the National Aeronautic Association (NAA). However, it's a time of 11.4 seconds from a subsequent flight that's just been confirmed as a new national record by the NAA and submitted to the Fédération Aéronautique International in Switzerland for consideration as a world record. The flights also represent the longest human-powered flight by a female U.S. pilot.

Judy Wexler straps in for the record-breaking flight

Even though the team members believe that Gamera is capable of longer duration flights, they are now faced with something of a dilemma.

"The Sikorsky Prize has the very ambitious target of 10 feet and 60 seconds that we do not think our current vehicle can achieve," said Schmaus. "Through the development of Gamera we have learned many things about extreme ground effect aerodynamic design and also about lightweight structural design. At this point we are combining these two knowledge bases to determine whether to go for another record setting, but not prize-winning, flight with Gamera or put all our energy into designing a vehicle capable of the Sikorsky Prize."

The next phase of the Gamera project will be decided shortly. Updates will appear on the project's website.

In the meantime, you can watch all 12.4 exhilarating seconds of human-powered flight in the following video:

About the Author
Paul Ridden While Paul is loath to reveal his age, he will admit to cutting his IT teeth on a TRS-80 (although he won't say which version). An obsessive fascination with computer technology blossomed from hobby into career before the desire for sunnier climes saw him wave a fond farewell to his native Blighty in favor of Bordeaux, France. He's now a dedicated newshound pursuing the latest bleeding edge tech for Gizmag.   All articles by Paul Ridden
20 Comments

So it's capable of lifting a lot of weight while being quite light itself. Replace the human being with small gasoline motors and... no... still wouldn't work outside and there's no way to steer the thing.

Beyond being neat I can't see any practical applications. Nor can I envision any spinoff technologies that could come from this. But maybe I'm wrong, feel free to correct me. Sure you could claim this is driving up research on lighter materials but it really isn't, there are a million other and bigger things driving up demand for lighter materials. I think this is all about getting some attention for the university. Or maybe it's not really for anything.

Samantha Renault
21st August, 2011 @ 04:29 pm PDT

They need to get a world class sprinter for the pilot. It should not make the craft twice as heavy to make it support two pilots, but that would depend on the rules allowing it.

Slowburn
21st August, 2011 @ 06:50 pm PDT

RE Samantha Renault

They are teaching problem solving, and outside the box thinking. And ultra-lightweight structures translate into ultra-strong structures very well.

Slowburn
22nd August, 2011 @ 12:55 am PDT

How clever on one side and "primitively unforseing " are they to try this in such a space restraining area.

Vic Vicarious
22nd August, 2011 @ 08:01 am PDT

DIdn't it say it had to go like 10 feet in the air?

Paul Anthony
22nd August, 2011 @ 11:28 am PDT

Icharyus and DaVinci were right.

Jess Atwell
22nd August, 2011 @ 12:25 pm PDT

For a better power to weight ratio they should use a man. I agree with Slowburn they need a sprinter. Using a cyclist is half right, most have pathetic upper body strength. Yes, you need some endurance but only for 60sec. A wrestler would be better, can get very lean and better upper body strength.

Phileaux
22nd August, 2011 @ 05:03 pm PDT

Watts per/kilois what they need...and a woman is far inferior @ that. I was a former track cyclist with over a 20watt/kilo power output. To cover your 60 seconds you need a kilo specialist. A kilo specialist can generate over 1000watts for a 60 sec duration. I wonder if they had an ergometer on the bike.

Ryan Mertens
22nd August, 2011 @ 05:12 pm PDT

I think it is way cool I think it is a great attempt. Perhaps they add control in a future version. :)

BigWarpGuy
22nd August, 2011 @ 05:24 pm PDT

That design will never achieve controllable lift even with a electric motor attached. The rotor designs are some of the worst I have ever seen, The lag and energy required to overcome the drag, forget it.

Hilary Albutt
22nd August, 2011 @ 05:54 pm PDT

In High-school I learned That humans do'nt have sufficient Horsepower for personal flight. I have great sympathy for all efforts that push against physical constraints like the speed of light and absolute zero.

jochair
22nd August, 2011 @ 10:31 pm PDT

@jochair The human powered airplane, Gossamer Albatross, flew across the English Channel in 1979. MIT Daedalus is the current human powered flight distance record holder at 74 miles, which it did in 1988.

The problem with a human powered helicopter is it must lift 100% of the machine and the human powerplant solely by the power output of the human. A human powered airplane relies on normal aerodynamics for lift while the human only has to provide enough power for thrust.

Gregg Eshelman
23rd August, 2011 @ 12:16 am PDT

The efficiency problem of helicopters is that going forward is a side affect of generating lift, were as with an airplane lift is a side affect of going forward.

If I were trying for the prize, I would design a tandem rotor with blades similar to the wings of the MIT Daedalus.

Slowburn
23rd August, 2011 @ 03:28 am PDT

A committee must have planned the test. With no one in charge, no one noticed the room was way too small. What could have been a longer flight was ended abruptly by a chair. All that work fouled up by a silly mistake.

voluntaryist
23rd August, 2011 @ 10:00 am PDT

There is no advantage of 4 rotors over one, has more friction, weight, and are mounted too low.

Rigby5
23rd August, 2011 @ 12:06 pm PDT

Re Rigby5

They chose for inherent stability, rather that absolute mechanical efficiency. A single rotor design would require an energy eating counter-torque system of some sort, which is why I would go with a tandem design. The closer the rotors are to the ground the more use they get from ground effects, which improve efficiency for this application.

Slowburn
23rd August, 2011 @ 10:00 pm PDT

You guys are completely missing the point. It is a SCHOOL so this project was a teaching opportunity for the team. They came away knowing more about advanced materials, CAD, how to actually BUILD what they designed. It's one thing to draw something, it's another to BUILD it - some people can't do both yet collect a big paycheck.

It was also an opportunity to BRAG a little which is important for a school. It's resume material for the students. It's experience which is important for students today who are faced with a tough job market who often demand experience to back up the academic studies.

How is applicable? Learn from the mistakes and go on to advance helicopter technologies - noise control, power requirements, durability, advanced materials, etc.

A school can't afford to build a $5M machine so they teach with less expensive projects. It doesn't matter if science is or isn't advanced. The knowledge of the student team is and that is the goal of any university. Let the next student team try to further the design and achievements of the last. Everyone enters the adult workforce smarter for it.

JoeAverage
24th August, 2011 @ 08:42 am PDT

That's awesome. Now get it to an airplane maintanace hangar to have some space to work with and break your own record again! :)

TM80
25th August, 2011 @ 02:54 am PDT

While I've never participated in designing a human-powered aircraft, I worked on another human-powered vehicle. I am EXTREMELY skeptical that any 100% rotary human-power collection configuration is closely approaches optimal net-power/weight ratio. Opposing muscle sets produce non-linear force curves. Those are applied through pivoted bone attachments. This isn't tough to model. While these student's machine design dual 100% rotary power-collection configuration may be appealingly simple, I believe they can do better by testing differently-configured human-power collection strategies.

Excellent work! Great "mind candy."

LoveLearn
25th August, 2011 @ 03:51 am PDT

I'm real conflicted on this one. Their accomplishment is remarkable, yet as many of my fellow monday morning quarterbacks here have observed, they seem to have done it with extreme handicaps built into their design.

1. A different pilot, women's leg strength is as strong as men's, but commonly in a comparison of equaly fit people the men are going to have more upper body stength.

Surely there are plenty of women that could arm wrestle most men without a sweat, but in a comparison of elite's the upper body strength is going to be way more in the men than the women.

2. BIG DOUBLE DITTO ON THEIR HORRIBLE AIR FOIL, they need to find out fast how lousy their airfoil is. Seems like that would have been the primary feature of their design.

I offer up this as a place they could get an idea of how they should design their

airfoil for greater lift and LESS DRAG:

Jack Norris himself may be tickled pink to advise on this project.

Ref: Jack Norris self publised book "Propellers Explained"

http://www.vansairforce.com/community/showthread.php?t=23721

http://www.propellersexplained.com/

Betz Goldstein Theodorsen BGT

I'm aware of a propeller efficiency idea that may not be mentioned in Jack's Book, I'll be asking him about it if I don't run across it in his book, goes back to about 1910. Horten Brothers "Hawk" propeller of WWII looks to have been based on this 1910 or so idea.

I've only just recently recieved a copy of Propellers Explained, for me it's been a bit of a slog going through the introduction "... It's so simple ... overlooked for 138 years ... should have been written 50 years ago ... I'm writing both for people with advanced knowledge and no knowledge ..." Others love that, somehow snuck in there the idea the chord length must decrease to a point at the tip is something I have gotten.

Obvious to anyone that's ever thought a moment about propellers:

The airspeed at the tips is far higher than closer to the hub, why is the wing one uniform section & angle from hub to tip, terrible, and yes that's how they look on most helicopters, that a feature is common among many different craft does not allways follow that it's a good thing to do.

http://www.agrc.umd.edu/gamera/rotor-blades.html

3. Ergonomics & drive - there's obvious slipage or jerking when the pilot starts, sure sign some pilot strength is going to waste.

Take a look at snek bicycle for; ergonomics, drive, and possibly control.

http://rowingbike.com/site/EN/Home/Introduction/

That's if you want to put as many possible muscles into powering the gadget.

So far as I know bicycle speed records are held by leg-power only machines, and it's not a matter of rules, just performance. Please let me know if I've got this wrong.

4. Control! Put up a freaking pendulum near the pilot that projects some sort of drag pin out the tips of the wings for trim. Pilot could tilt head, wiggle butt or do something to influence hover direction. In the gizmag video I see no control. Over the lack of control issue, I'm sure Wilbur & Orville Wright and Igor Sikorsky are all spinning in their graves, and generating lift with greater efficiency, just not much of it.

Dave B13
16th September, 2011 @ 11:05 am PDT
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