Bicycle Helicopter Hovers Closer to Reality

A while back we posted on a pedal-powered helicopter concept built on a fat bike base.

Now, the concept gets a less bicycle-looking form factor but actually flies. Students from the University of Maryland are chasing the Sikorsky Prize, one pedal stroke at a time. They’re doing it aboard a pedal-powered helicoptor made of carbon fiber, styrofoam and string. It has a 100ft span and weighs just 80 pounds without the rider. All they have to do to win the $250,000 prize (unclaimed for more than 30 years) is hover for one minute, top 10 feet and not drift more than 10 feet horizontally.

The video tells the story and plenty of background from NPR is here.

Comments

Chris Ames - 10/22/12 - 3:48pm

Why the recumbent position? Upright would be more efficient when trying to put out that kind of wattage, would it not?

Eric - 10/22/12 - 4:41pm

Maybe, but I don’t think you can use your arms very effectively. From a physics standpoint, it’s clearly much harder than pedaling a bicycle uphill. To compute the power required to hover an 80 pound quadcopter and 140 pound pilot/rider (about 100kg), you have to factor in the mass of air being accelerated downward and the rate that the air is being accelerated at. I can’t remember offhand but I have done this computation once for fun. Long story short, those kids are working hard.

Hoping they make it to their goal! Would be a great accomplishment for them!

hollywood - 10/22/12 - 5:29pm

where’s his helmet mirror?

kidding, kidding…super cool.

diehipsterdie - 10/22/12 - 8:13pm

maybe lance should try this

qrim - 10/22/12 - 9:59pm

@Eric, one of the biggest things to take into account is “ground effect”. Basically, the higher you go the less the ground pushes back up at you. Another words, Power needed for maintaining flight @ 1m is much less than at 3m.

dumbjer - 10/22/12 - 11:23pm

watching their cadence increase after lifting off the ground, i would pay a weight penalty in order to impliment some sort of gear system. A schlumpf bottom bracket would at least a second higher gear to keep them from over revving their legs. too many rpms kill the pilot quickly.

dougie - 10/23/12 - 10:58am

I agree with dumbjer, the weight of adding gears well worth it. adding 3lbs is very small relative to the overall weight

Eric - 10/23/12 - 1:36pm

Dougie, adding 3lbs is close to a 4% increase it weight. Not to say that a gear system isn’t a good idea, but 3lbs isn’t anything to scoff at in a project like this.

@ Chris, studies have shown that the recumbent position can give higher power outputs. The real trick is finding a very strong cyclist who is used to pedaling a recumbent since the seated position uses your leg muscles differently.

science - 10/23/12 - 5:14pm

Yea, seems that the odd position is limiting power and making it hard for the legs to perform 100%. A light-weight recumbent rider would be better than weekend cyclist kids. Lose the arm pedals and you lose weight and gain power imo.
Just like an airliner can not fly any closer than about 50 feet to the ground at typical speeds (not landing/stalling) because the ground effect so the opposite is a problem. Faster wings/propellers would raise the ground effect, but also take more power.
Enclosing the propellers in a short cylinder would increase power, but also add weight.
This is a cool project nonetheless.

science - 10/23/12 - 5:16pm

A pro cyclist could double those guys power and probably weigh about the same too.

Walter - 10/23/12 - 6:16pm

@Chris @Eric With the right technique & training, recumbent position does give quite a lot more aerobic power than traditional position. Lungs get more room.
In this construction the position is not recumbent, just a traditional position tilted backwards. See the angle between upper body and legs.

MB - 10/23/12 - 8:15pm

Recumbent position with hands in static position would seem to be better? Pulling against the push so to speak?

Topmounter - 10/24/12 - 11:12am

I’d guess that position has some benefits with regards to lowering the center of gravity and increasing stability.

raphael sonstein - 10/27/12 - 2:56pm

your pedal cadence is too high. a lower gear ratio or gears (different speeds) would get this bicylcopter flying!

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