Sikorsky Prize Claimed
July 11, 2013 11:01 AM   Subscribe

Originally set forth in 1980, the Sikorsky Human Powered Helicopter Competition is deceptively simple: keep a human-powered helicopter aloft at 3 meters within a 10m by 10m square for 1 minute. The prize? $250,000. In the past 33 years, great progress has been made (Davinci III, Yuri I, Gamera I, Gamera II Previously), but no one has succeeded until Aerovelo's Atlas.
posted by Betelgeuse (53 comments total) 31 users marked this as a favorite
 
goddamn that gear ratio is MONSTER
posted by nathancaswell at 11:02 AM on July 11, 2013


He appears to be riding an inexplicably hovering unicycle surrounded by angels.
posted by justsomebodythatyouusedtoknow at 11:07 AM on July 11, 2013 [24 favorites]


Why does the bicycle have a rear wheel attached?
posted by Phredward at 11:09 AM on July 11, 2013


Wow. At first I was like, pretty cool but why'd they bring four of them.
posted by 2bucksplus at 11:11 AM on July 11, 2013


I'd like to know how many calories the pilot burned; maybe a pizza or two.

I'm also interested that the designers seem to have decided to take up nearly all the available 10m square with the helicopter itself.
posted by rongorongo at 11:16 AM on July 11, 2013


I'm not exactly going to be taking that down to the shop to get some milk any time soon, but that is a gorgeous piece of engineering.
posted by figurant at 11:16 AM on July 11, 2013 [2 favorites]


Why does the bicycle have a rear wheel attached?

I'm not sure, but my guess would be that it serves as a gyroscope to keep the pilot upright.
posted by Betelgeuse at 11:19 AM on July 11, 2013 [1 favorite]


This is a lot bulkier than the one in E.T. The Extra Terrestrial
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 11:19 AM on July 11, 2013 [4 favorites]


Very cool. The whole thing is almost 50 meters across - I guess they interpreted the rules to mean the center point could not drift outside a 10m square box.
posted by exogenous at 11:20 AM on July 11, 2013


The chain is still attached to the bike, so unless they created a different something in the back of the bike, the rear gears are generally attached to the rim of the wheel. So if they wanted/needed gears at the rear, they need to keep the rear wheel or re-engineer a whole thing.

Also, this is amazing and I applaud them!
posted by HermitDog at 11:29 AM on July 11, 2013


The chain is still attached to the bike, so unless they created a different something in the back of the bike, the rear gears are generally attached to the rim of the wheel. So if they wanted/needed gears at the rear, they need to keep the rear wheel or re-engineer a whole thing.

Nah, the gears attach to the hub. You wouldn't have to have a wheel to keep a gear at the back. So I think they must have some other reason for it.

I don't think the gearing moves the blades either - I think the cranks basically have like spools on them, that are taking up line, I'm guessing the line starts out wrapped around the propellor shafts and by winding it onto the bike, you unwind it from the propellors

(This is all just based off looking at the video)
posted by RustyBrooks at 11:35 AM on July 11, 2013


I wonder if the pilot can actually steer it? Is the leaning at ~1:18 part of a turn or is it just from fatigue?
posted by ceribus peribus at 11:40 AM on July 11, 2013


It looks to me like he's leaning to try to keep himself within the 10m square.
posted by etc. at 11:42 AM on July 11, 2013


That is one heck of a gear ratio from the front to back .. Makes this look like something a Tour de France rider could maybe keep aloft for a minute or two, but not a mere mortal.

Can someone explain what the "spinning basket" looking things under the rotors are ? Something to counter-balance rotational force ?
posted by k5.user at 11:43 AM on July 11, 2013


Todd Reichert is the pilot selected to fly the Atlas. Todd is a national-level speed skater and competitive athlete in the world of human-powered streamlined vehicles. His piloting background, as well as his experience flying the Snowbird human-powered ornithopter make him well suited for the job.

Okay, so not just some guy on a bike. I wonder how he compares compares to the pilot of Gamera II, and any other attempts. Not to downplay any novel engineering solutions employed here, but it looks like they got themselves a pretty nice engine.
posted by Kabanos at 11:45 AM on July 11, 2013 [6 favorites]


Ah, that makes sense, etc.

I think the spinning baskets are just landing points.
posted by ceribus peribus at 11:45 AM on July 11, 2013


Why does the bicycle have a rear wheel attached?

It's a flywheel to even out the power output of the pilot. See the team's world record application package here [zip file]
posted by Popular Ethics at 11:52 AM on July 11, 2013 [4 favorites]


Finally, a nice weekend DIY project for that old beach cruiser out in the garage!
posted by BigHeartedGuy at 11:53 AM on July 11, 2013 [5 favorites]


Makes this look like something a Tour de France rider could maybe keep aloft for a minute or two, but not a mere mortal.

The link that exogenous provided above gives more information, but Reichert specializes in this sort of thing — he's superior to a Tour de France cyclist within this timeframe (five minutes or less). He manages about 750 watts, or one horsepower, over a couple of minutes.
posted by Ivan Fyodorovich at 11:54 AM on July 11, 2013 [3 favorites]


Kabanos: "I wonder how he compares compares to the pilot of Gamera II, and any other attempts."

Yeah, he's a fucking stud. If you look at the tech info link in my comment earlier, they show some data comparing him favorably to Eddy Merckx, one of the top cyclists of all time, albeit noting "Todd’s is training is focused on efforts of 5 minutes or less, which is why his numbers exceed that of Merckx who was typically more of an endurance athlete." 772 Watts for 1 minute!

On preview, what Ivan said.
posted by exogenous at 11:55 AM on July 11, 2013 [2 favorites]


No arm power or recumbent seating? These guys haven't read their David Wilson?
posted by DU at 11:55 AM on July 11, 2013


I'd like to know how many calories the pilot burned; maybe a pizza or two.

The world record application I linked to above has a chart showing the power output vs time (you can get crank sensors to log this data nowadays). It looks like the pilot put out 900 Watts for 20s or so, and then 600 Watts from the remaining 40s, or roughly 10,000 calories in total.

I wonder if the pilot can actually steer it?

The design description and pictures of the ATLAS from a few months ago show a canard system on the end of the rotors for steering. These are completely missing from the video of the prize-winning flight, so maybe they decided to lose the steering and gun it :)
posted by Popular Ethics at 11:59 AM on July 11, 2013


I think the cranks basically have like spools on them, that are taking up line

That's a brilliant hack! I always look at these things and wonder how they manage to route the chain out to the rotors and back efficiently. But it's MUCH easier to just reel in a line, and the only problem is that the spool will run out eventually. But if you only have to reel in for 60 seconds, then you know exactly how much line you need to have on your spool. Piece o' cake!
posted by spacewrench at 11:59 AM on July 11, 2013 [3 favorites]


The document says the rear wheel acts as a flywheel for power smoothing.
posted by garlic at 12:00 PM on July 11, 2013


10,000 calories is only 10 food calories, though (kcals).

But also - when you produce X calories of output on a bike, it typically consumes about 4x calories of energy, because your body is about 25% efficient at producing power. So 40ish kcal burned.
posted by RustyBrooks at 12:01 PM on July 11, 2013 [6 favorites]


It also says the control system initially designed was changed to be based off of the pilot leaning pulling trusses and causing 'thrust vectoring' which sounds a whole lot like Wright brother wing warping to me.
posted by garlic at 12:02 PM on July 11, 2013 [1 favorite]


If you look at about 1:11 or 1:12 in the video you can see a closeup of the "spools"
posted by RustyBrooks at 12:06 PM on July 11, 2013


Yeah, I find my thrust vectoring is so much more precise now that I have a flywheel for power smoothing.
posted by Kabanos at 12:17 PM on July 11, 2013 [3 favorites]


Damn I want one of those! I could keep her aloft I bet, I was a hella good sprinter and still ride 25 mi. per day.

HUMAN POWERED VEHICLE NUTTERS PLEASE CALL ME!
posted by Mister_A at 12:22 PM on July 11, 2013 [1 favorite]


Yeah, I find my thrust vectoring is so much more precise now that I have a flywheel for power smoothing.

So now you own the sky, turn on a dime, macross zero style?
posted by radwolf76 at 12:22 PM on July 11, 2013


Is it wrong that I want to see this contraption filmed in black and white with an old-timey, undercranked camera and set to ragtime piano?
posted by usonian at 12:24 PM on July 11, 2013 [8 favorites]


usonian: "Is it wrong that I want to see this contraption filmed in black and white with an old-timey, undercranked camera and set to ragtime piano?"

Such a wish is never wrong.
posted by Mister_A at 12:29 PM on July 11, 2013 [1 favorite]


this is absolutely incredibly awesome! But, i really don't see any strings that are moving. Are they too small to see? What is the method by which the wheels move the propellers? Also, how come they didn't do a recumbent bike?
posted by rebent at 12:30 PM on July 11, 2013


Yay! I was curious whether this would go through when they started the Kickstarter project over a year ago. Good for them!
posted by BlackLeotardFront at 12:37 PM on July 11, 2013


I had always imagined a Human Powered Helicopter to more closely resemble a gasoline powered one: i.e. rotors on the top. The fact that none of these Sikorsky Prize contestants saw it the same way suggests one of two things about my engineering skills relative to theirs.

I will leave it to the hive to determine which is more likely.
posted by bluejayway at 12:51 PM on July 11, 2013


Having the rotors on the bottom, particularly with them being so large, lets them stay in ground effect which is more efficient.
posted by exogenous at 12:55 PM on July 11, 2013 [4 favorites]


Ivan Fyodorovich: He manages about 750 watts, or one horsepower, over a couple of minutes.
In case the one-horsepower comment doesn't drive it home (and of course horses don't all deliver 1.0 hp), the rough figure for heat output of a working human is about 300 W - which includes all the waste heat, which is most of our output.

This guy can beat that by a factor of two just in his useful work!
posted by IAmBroom at 1:04 PM on July 11, 2013 [1 favorite]


Congrats. I was rooting for my home team UofMD but gracefully accept Toronto strong like horse.
posted by stbalbach at 1:10 PM on July 11, 2013 [1 favorite]


In terms of steering, in this video it sounds like someone on a megaphone is shouting "more right more back" (and later, "more right") and the pilot is leaning in those directions, presumably in order to counteract the drift leftwards.
posted by chortly at 1:23 PM on July 11, 2013 [2 favorites]


I think the cranks basically have like spools on them, that are taking up line

If so, brilliant. Good on them for simplifying the drivetrain to the nth degree.
posted by RolandOfEld at 1:30 PM on July 11, 2013


I'm not sure, but my guess would be that it serves as a gyroscope to keep the pilot upright.

Interestingly enough, the gyroscopic effect of a rotating bike wheel is very subtle - it doesn't do much to increase stability of a moving bike. IIRC someone made a bike with wheels which somehow span in both directions to neutralize the effect and it was still rideable.
posted by Teakettle at 1:32 PM on July 11, 2013


it sounds like someone on a megaphone is shouting "more right more back" (and later, "more right")

What, was no one from the U of T curling team available?
HAAAAAAAAAAAAAAARD! HURRY HAAARD!
posted by Kabanos at 1:35 PM on July 11, 2013


Never before have I hated video production so much. I want a good look at the machine, proof that it works, some details about its operation, maybe some information or interviews with the people who made it. Not all that cutting and background music, dammit! If they had just had a guy with a video camera walking about taping it all and posted that to YouTube unedited I would be happy. They actually spent money to piss me off.
posted by JHarris at 1:39 PM on July 11, 2013 [3 favorites]


The design description and pictures of the ATLAS from a few months ago show a canard system on the end of the rotors for steering.

Are these trained ducks, who help steer by flapping on command?
posted by UbuRoivas at 1:59 PM on July 11, 2013 [1 favorite]


nterestingly enough, the gyroscopic effect of a rotating bike wheel is very subtle

A different kettle of fish, but I can tell you the gyroscopic effect of a motorcycle wheel at 135mph approaching the end of a straight is quite pronounced. Those pro riders are studs, it's a lot of work.
posted by maxwelton at 2:01 PM on July 11, 2013


Interestingly enough, the gyroscopic effect of a rotating bike wheel is very subtle

You think so? Whenever I've repacked my bearings and spun the wheel while holding the axle to test if it's smooth I'm always shocked at how strong the effect is.
posted by nathancaswell at 2:58 PM on July 11, 2013


So 40ish kcal burned.

So basically this guy burned off 2/5 of a Coors Light.
posted by gottabefunky at 3:00 PM on July 11, 2013


"You think so? Whenever I've repacked my bearings and spun the wheel while holding the axle to test if it's smooth I'm always shocked at how strong the effect is."

Yeah, but it's a bit of urban science folklore that it's what keeps a bicycle upright when it's actually only a small factor.
posted by Ivan Fyodorovich at 3:14 PM on July 11, 2013


More details about the team and the attempt here
posted by thecjm at 3:28 PM on July 11, 2013 [1 favorite]


In case the one-horsepower comment doesn't drive it home (and of course horses don't all deliver 1.0 hp), the rough figure for heat output of a working human is about 300 W - which includes all the waste heat, which is most of our output.

Todd Reichert also has a PhD and writes about the prize here (before it was claimed). He explains that the 3m height minimum was put in to prevent people from using ground-effect alone and he sums up the challenge of power to weight as follows:
The problem, of course, is that the human body can produce, at best, about 1 horsepower for a one-minute flight. This is about half the power that it takes to run a good hair dryer! Is it even possible to build a helicopter that can lift so much weight on so little power? It turns out that it is, but the aircraft will have to be absolutely enormous, possibly even bigger than 30 meters across. As far as the aerodynamics are concerned, it's more efficient to push very lightly on a large mass of air than to push hard on a very small mass of air. So bigger is better. But bigger means heavier, and with human-powered aircraft, weight is the biggest enemy. A viable Sikorsky Prize helicopter would have to be in the range of 100 pounds or less. For something the size of a Boeing 737, this is a pretty steep challenge!
posted by rongorongo at 4:26 PM on July 11, 2013 [4 favorites]


AH, that's the stuff thecjm! Thanks much!
posted by JHarris at 4:34 PM on July 11, 2013


>Why does the bicycle have a rear wheel attached?

>>I'm not sure, but my guess would be that it serves as a gyroscope to keep the pilot upright.


FYI the way the gyroscopic effect (for example, of a spinning bicycle wheel) works is this: Think of the wheel's three axes of rotation (image here). The wheel spins around one of the three axes. If you provide some movement into the 2nd axis then the gyroscope responds by moving in the 3rd axis (!).

In terms of a bicycle wheel, it works this way: If the bicycle is moving forward, and the wheel is leaned away from the vertical so that the top of the wheel moves to the left, the forward rim of the wheel also turns to the left.

So the reason this is potentially helpful for helping to keep balance on the bicycle, is that as you start to lean to the left, the wheel naturally steers to the left, steering you under the lean and straightening you back up. There are lots of other forces involved in balancing a bicycle--you can read all about them here--so the gyroscopic force certainly isn't the only thing keeping the bicycle balanced, but it certainly is a self-correcting factor.

In terms of the human-powered helicopter, however, this gyroscopic force isn't going to do anything helpful--because there isn't a front wheel to steer as there is with a bicycle. As the helicopter leans to the left, the gyroscopic force will cause a force rotating the entire helicopter towards the left (ie, counter-clockwise as seen from the top). And a right lean will rotate the entire helicopter towards the right (clockwise as seen from the top).

This isn't going to do anything to keep the pilot or helicopter upright, and anyway the helicopter is such a large object that its moment of inertia about that axis will be pretty large compared with this relatively small gyroscopic force. Meaning that the gyroscopic force of the bicycle wheel likely won't be noticed at all.

In short, the gyroscopic force of the rotating bicycle wheel definitely won't do anything to help the helicopter stay upright and probably won't do much of anything noticeable at all in terms of affecting control of the helicopter. (It certainly could be useful as a flywheel, as others have pointed out above.)
posted by flug at 5:21 PM on July 11, 2013 [2 favorites]


Happy to have been a KickStarter supporter of this effort.

I've been watching the closing gap of this prize as this team and the University of Maryland's team improve their devices. Both are amazing contraptions, and from what I gather it was the constraint of controlling the cyclist to a small square of horizontal moment that won the effort for the Atlas.
posted by grimjeer at 5:16 AM on July 12, 2013 [2 favorites]


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