doctorow at July 12th, 2013 12:43 — #1
The Sikorsky prize for human-powered helicopters has been claimed by a Kickstarter-funded startup called Aerovelo. Aerovelo's founders, Canadians Todd Reichert and Cameron Robertson, won the $250,000 purse for the 30-second flight of Atlas, a huge quadrotor with a bike in the middle whose flight is an absolute marvel to behold. At that point, Reichert knew… READ THE REST
flugfrei_jones at July 12th, 2013 12:55 — #2
knoxblox at July 12th, 2013 13:12 — #3
So what's the next step now? Hoppers (short distances under varying conditions), or floaters (longer sustained flight under controlled conditions)?
digitalartform at July 12th, 2013 13:23 — #4
If only Leonardo were here to see this.
awjt at July 12th, 2013 13:24 — #5
I think the next step should be more controlled indoor flights and collecting data. They have had serious setbacks with bad descents, so they need to profile what a good flight looks like and give the cyclist a feedback mechanism (a tiny screen? led lights?) indicating how fast to pedal at a particular point, to have a controlled descent.
rusty_brooks at July 12th, 2013 15:29 — #6
This particular design will never be usable for anything but winning the contest.
The rotors start with a bunch of string wound around them. The bicycle has 4 spools, one for each rotor. As the cyclist pedals, the spools take up line and it unwinds from the rotors, turning them. When you run out of string, it stops.
Also, the cyclist has to put out an average of like 750 watts to keep it airborne - the guy doing the pedalling here is a badass and basically can't do this for more than a minute or two. No one in the world can do it for more than a few minutes.
There is much more of a problem here than just an engineering one - the human factor makes this all but impossible.
markdow at July 12th, 2013 15:53 — #7
The Wright Flyer was pretty disappointing too.
rusty_brooks at July 12th, 2013 16:13 — #8
Sure, ok. But this is a little like saying "they said we couldn't break the speed of sound, but we did. Now they say we can't break the speed of light, so they could be wrong". The airplanes we have now are mostly possible because of the enormous increases in power output that we've been able to apply to the problem (and in the case of some gliders, improvements in design and materials)
A few points:
this is not a disappointment, it's a marvel of engineering and human output
but even so, this particular design isn't a first step to a practical human powered helicopter. This is not me being a pessimist, it's just an analysis of the design.
The guy in the bicycle seat here was putting out 1HP on average, which is a LOT, for one minute. I'm a dedicated cyclist, I can put out, say, 250 watts for long periods of time, that's 1/3 as much power. Most people who don't do what I do (i.e. ride a few hundred miles/week) can't come close to that. So maybe we're talking 1/6 HP.
Forget the human powered part for a minute - is it possible to design a helicopter of any type, that can lift 200-ish pounds with a 1/6 HP engine? We're talking about an underpowered weedeater engine or an electric drill motor.
Propelling people forwards is easy which is why bicycles are fun and efficient. Propelling people upwards is extremely hard and I don't think there is a practical means of making a human powered helicopter that would be useful for much more than stunts like these.
tmburke at July 12th, 2013 16:37 — #9
It's taken ~500 years and incredible advances in science, materials, nutrition, fitness, etc for Leonardo's helicopter idea to be built and flown. A human probably was the best power to weight ratio 'engine' he had available at the time, and yet he likely knew he was a couple orders of magnitude away from having the power for his thing to fly. Incredible how he got many of the basics of flying right, and if 561 year old da Vinci saw this he'd crack a renaissance smile. Is this in any way practical? Of course not. Making 750 watts for this to fly is a feat in itself.
awjt at July 12th, 2013 16:50 — #10
Engineers relish the challenge. If they can do it with string, they can do it some other way, too. String? Unwinding large spools? I mean, that is weird but it got the job done. Like a mechanical capacitance. I am betting there are hundreds of other designs that could capitalize upon human power, perhaps store it and delay it in time and then unleash, and it would still be human-powered.
No matter how you slice this, it's friggin' amazing.
String? String??? Christ, that's awesome.
digitalartform at July 12th, 2013 16:56 — #11
The Flintstone Flyer did it best.
rusty_brooks at July 12th, 2013 17:13 — #12
I agree that there are other approaches that might be feasible. What I'm getting at, I suppose, is that if you drew a graph of advancements in human powered flight, this one is probably an offshoot branch, and not in the trunk between here and the end solution.
And really it's not so much that it's a technological problem as it is a pure physics problem. You can get more lift with less power by using larger and larger fan blades. But this thing is already the size of a 747. Making it larger probably wouldn't be considered an improvement.
If you stored a bunch of power (via a dynamo or whatever) I'm sure you could do much better. But if you did I wouldn't really consider it a "human powered helicopter" any more than I consider a tesla a human powered car (after all, you could charge the batteries by using an exercise bike)
The string thing is a brilliant hack, but it is one that is specifically designed to meet the contest requirements, not something that is even remotely practical for real flight.
rusty_brooks at July 12th, 2013 17:14 — #13
And FWIW I fully believe that this can be amazing and at the same time not be The Way Forward.
awjt at July 12th, 2013 17:48 — #14
Sure. The spools of string need to be converted to a lightweight drive mechanism. But I think what we're "arguing" about is if this is a first draft or a one-off. I see it as a rough sketch. Huge faults. Huge inadequacies. But a start. I don't see it as something that has no potential. I'm not suggesting that you do. I am just saying that the way forward starts with a contraption full of hard links (spools of string), bloated code (instead of iteration, blocks of code are repeated = the massive size), and serious stupidities (why is there a freakin spoked wheel and a bicycle frame on this thing?). Etc. But thru all of the madness I see brilliance here.
rusty_brooks at July 12th, 2013 18:03 — #15
The massive size isn't bloat, it's an emergent property of the physics. In order to make it smaller, you have to be able to put more (a lot more) power into the system.
Replacing the spools with a drive mechanism is not only not a trivial problem, it's going to add a lot of weight, and probably a lot of friction to the system. But that doesn't even matter because the thing is already too inefficient to fly with just a human's power output.
The wheel doesn't need spokes but they do need a wheel - they have a massive front gear and a small back one, they're basically using it for power-smoothing. They might get a better result with a faired wheel, but probably not much. The rest of the bike probably weighs less than any harness they were able to make to do the same job.
jsroberts at July 13th, 2013 02:07 — #16
How well would a recumbent bike work for the job? I realize a lot of the aerodynamic benefits wouldn't have an effect, but would there be other benefits from the positioning (i.e. being able to push against the seat)?
rusty_brooks at July 13th, 2013 15:05 — #17
Probably it wouldn't help. The guy is simply approaching the limits of how much power a human can put out, period.
steve_nordquist at July 13th, 2013 16:17 — #18
Holy PERL7 globs, Obviousman! Swapping out string and hub-torquing mechanisms for filament loops and edge drive will save enough efficiency to add a juice bar and a vacuum hull, plus microcontrollers to balance rotors and optimize stators, and ...let's see, a really good spare couch... [Blue Sky BG 'Pollyannerokee' hums a moment] ...grapple and chalk for elegantly dealing with multiple high-tension wires in the flightpath...radios and telemetry, emergency oxygen and soft-landing recovery bits...yeah, no reason a SOHO under a 6-mile-above-sea-level ceiling (with one non-obese tenant) should not have its own craft. Now roll your eyes and make teleportation awesome so I look absurd.
Or: That cyclist goes through that much dental floss since starting paleo diets anyhow. Ask him for a wildcrafted fennel steak and see if it isn't so.
awjt at July 14th, 2013 09:14 — #19
Nice. Also, he could be using his arms for something besides holding on, the lazy bastard.
doctorow at July 17th, 2013 12:43 — #20
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