"The pedaling of the pilot pulls on and reels in four Vectran cords, which are pre-spooled onto each of the four rotor hubs. The action of unspooling the cord and pulling on the rotor hub drives each rotor to overcome the drag force."
To put that into perspective, that's a chart[1] that some exercise scientists have put together that shows what power cyclists of varying levels tend to be able to produce. The data in the spreadsheet gives an average power of 708W for a minute, which equates to 10.1W/kg at 70kg, which puts him at the level of a category 1 racer or domestic pro.
Keep in mind that the ~1000W spike for 10s at the start of the ride probably harms the overall average, as a more constant power output generally leads to a higher overall average (or, higher power outputs are disproportionally harder).
Edit: according to the photo gallery in the article, Reichert is a nationally ranked speed skater in Canada, which is another one of the "big quads" sports.
Yes, there's a chart that shows power and height vs. time, and it certainly looks like that was the case. I bet it didn't feel like coasting though :-)
thanks for the link - I saw the big spools in the video and was trying to figure out what was going on. I presume that means that flight time is limited by cord length (rather than having a circulating loop like a bike chain)?
It would be interesting if they could get a version with six blades where (3) are required to provide lift and it oscillates between spooling/unspooling three of the six at a time such that you fly with 3 whilst spooling the other three - then "shift" between spools.
The shape of things to come I suspect. While folks talk about blimps and what not there is value to having "permanent" points of presence in the air above, be it a communications node, surveillance node, or early warning theatre defence. 'Human powered' is a good predictor of 'solar powered' since the total energy extractable from humans per pound payload is lower than solar. Thus if you're doing the calculus for keeping something up 24x7, this is a good indication you are close.
>the total energy extractable from humans per pound load is lower than solar
Whilst that may be true, don't forget that the energy output is in kinetic form, so for comparison you'd need to factor in the weight of motors, and for a "permanent" presence, some form of energy storage for night time use (and batteries are far from light!)
1 sq meter of monocrystalline cells (approximately 2kg) deriving about 166W/hr over a 6 hr solar "day" (1000 W.hrs)
stored in LiFePo batteries (about 1kG/100 W.hrs) so 10kg of betteries, with .5 kg of electronics (battery charger) and wires, delivered over 24hrs or 12.5kg/41watts continuous. Human athelete lets call it 165 lbs, so 75kg, or 6 * 12.5 or 246 continuous watts over a 24hr period, or a total of just over 5.9Kwh per 24hr period.
So basically anything a human can power, an equivalent mass of solar power infrastructure can power. The interesting bit is of course that you can use it all at once (like a human sprint) or spread it out over time. It will have more surface area however which often limits the ability to just swap solar cells for other forms of power.
Your batteries have to provide 600W continuous for 18 hours (actually more as that was the power needed for a controlled decent), and your solar panels have to provide that same energy in your 6 hour 'solar day'. In addition, the solar panels would need to provide another 600W for 6 hours in order to run the motors whilst charging the batteries.
So that's 10.8KWhrs of batteries, and 2400W/hr or 14.5sq m of solar panels.
That translates to 108KG of batteries and 29KG of solar panels using your weight to power ratios - 137KG in total, compared to the rider at 75KW, so your 24 hour solar bird is a sadly flightless before even adding motors, gearboxes electronics and cabling.
More considerations are the additional power needed for control inputs and to resist wind, and to compensate for thinner air at altitude, and the weight of a craft strong anough to operate outdoors.
The efficiency linking human motion to desired motion vs linking an electrical motor to the desired motion is pretty similar in my experience. Brushless motors are relatively light and pretty efficient (hence their use in models today). The human linkages (gears/chains/etc) are comparable in weight.
Bottom line connecting the human energy to motion is different but from a weight/volume standpoint similar in both cases.
Indeed, some others have mentioned the Gossamer Albatross, which was the result of progressive development of earlier fixed-wing human-powered flying machines. Long flying solar variants of this were made, so it is probably quite feasible to get there in a few years with the human copter.
I've often wondered if a balloon-based system might be the way that this is eventually achieved. As solar energy becomes more and more efficient every year (apparently it's on an expotential price/performance growth curve), you coat the balloon with a light-weight, flexible solar array, and either heat the air like a hot air balloon, or as it becomes cheaper and more efficient to extract hydrogen from water, fill the balloon with hydrogen, and constantly replace the hydrogen that leaks out with hydrogen extracted from water vapor in the air:
http://www.technologyreview.com/view/512996/a-cheaper-way-to...
You could use low powered propellers (like a blimp), and take advantage of weather patterns (like Google's Loon project) in order to maintain position or to slowly travel.
It was only a matter of time until the materials got good enough for this to happen.
I'm always surprised that these teams never seemed to try and recruit pro athletes for this kind of thing. I've got a friend who's a professional cyclist and his 30 second power rating is something like 1100 watts and I'm sure at a minute it's only degraded by 50-100 watts.
Bit of cycling geekery: if he can do 1100 watts for 30 seconds, he's probably around about 750-800 watts for 60 seconds. Power declines approximately with the inverse of time until it flattens out at your long-term sustainable power. A pro is probably somewhere in the 350 watts range of sustainable power, so doubling the duration would mean his power above the sustainable rate would be halved, putting his estimated 60 second power at 725 watts. In this particular range of power, the approximation tends to be a little low, so fudging upwards a bit puts him around 750-800 watts.
Those pro numbers are a little low. Although La Gazzetta's watt calculations have been somewhat questionable in the past, Tony Martin's wattage was given as 480 for the Mont Saint Michel TT on Tuesday.
Shane Perkins, and Aussie track rider who is probably the strongest cyclist in the world in terms of pure brute strength, has a maximum output of 2500 watts (my guess is that is a ten second effort, they don't give it, but his 60 second effort is certainly higher than 1100 watts).
An average pro (domestic and international) vs. the pro who just won a worldclass TT. An average weight pro vs. a big boy like Tony Martin or even more so Shane Perkins. I've seen quite a few pro wattage files, and 350 is fairly common for an average pro.
The more reliable measure is w/kg. Pros tend to range anywhere from high 4s (low-level sprinters or rouleurs) to mid 6s (world class TT'ers or climbers), with most being somewhere in the 5s. If la gazzetta's numbers are right, and if we believe Tony Martin's posted weight of 75kg, his 480 watts puts him at 6.4 w/kg.
I wasn't exactly thinking of Optum or Kenda, I was thinking of a Pro/WorldTour level rider. The numbers you mention are frightening close to these I found for Brian Vandborg: http://home.trainingpeaks.com/races/saxo-bank-sungard/2011-u... - not exactly known as a powerhouse (there he is finish 47 seconds down over a 8km TT, and here he is barely beating Chris Anker Sorenson in a 40km time trial a few months before those figures: http://cqranking.com/men/asp/gen/race.asp?raceid=20722). Sure, Domencio Pozzovizzio isn't putting out 400 watts sustained (he probably isn't putting out 300), but my feeling is that Siutsou, Chavanel, Tuft, Vanmarcke, Vaitkus, Malori and other riders of their ilk are creeping up towards the 375-400 range sustained.
Don't get me wrong, I'm nitpicking here, I was just noting those numbers feel slightly low.
On individual rides (e.g. http://app.strava.com/activities/66583736 ) there's a chart below the map which you can switch to show "Performance", check the "Power" checkbox and you'll see his watt output. Looks like today he cracked 1kw momentarily about ten times, and for an hour starting around ~1h30 in he never went below 200w.
From what I remember, pro cyclists are simply too expensive.
It's better to have an amateur who is 80-90% as good as a real pro, but is genuinely interested in the project and would be more dedicated than a hired pro.
It seems it would be possible to get a pro to work on the project pro bono provided you picked the right guy. I was assuming the projects would go that route. Any reasonably intelligent pro cyclist would love to be the guy who set a world record like that, it's a similar achievement to the Gossamer Albatross.
But that's a very good point you've made. I obviously didn't even factor in price.
Apart from price, would a pro be prepared to risk injuring himself in a malfunction? I'd guess a typical pro would put career above engineering glory. If the pro did it for free you'd probably still have to buy an insurance policy to cover him.
Pro cycalists already take risks; if their bike has an issue, or their path has an issue such that they fall they are potentially looking at serious injury. Not to mention the fact that prior to the test proper, the mechanism would be well tested to make sure it won't fall apart, and there would likely be many practice runs with additional safety percuasions until everyone was comftorable.
Also, how is powering the first human powers flying machine not good for a professional athlete's career?
Playing with semantics, if a pro agreed to power such a helicopter, he'd most likely be doing it as an amateur, since amateurs do things for the love of it!
Pros take risks, but I'd theorise that a part of the career would be managing those risks, to maximise the career. It would be very cool to power the first human powered helicopter, but I suspect we are not typical, in that the typical punter cares more about sport than a helicopter. From a professional point of view, the fame and returns from piloting a helicopter are negligible compared to the rewards of improving in the Tour or the Giro.
I'm descending into hot air production here, since I have no real evidence on which to base it!
It looks like Cervelo was sponsoring the team, based on the bike being used appearing to be an R5 and the kit he was wearing. Nowadays Garmin (for whom Cervelo is a major co-sponsor) only has one Canadian on the team, Ryder Hesdejal, but they do have a number of Americans, including Dave Zabriskie, a reasonably slim time-trial powerhouse (read: perfect for this), who is currently sitting on his couch in Colorado unable to ride due to his six-month suspension he received as part of admitting to doping and testifying against Lance regarding his time on the US Postal team. They could have made it happen...
"This attempt was made in accordance with the regulations of the FAI Sporting Code including the provisions of 5.2.2.3 on Unsporting Behavior."
and googling for that reveals:
'5.2.2.3 reads:
"Unsporting Behaviour. Cheating or unsporting behaviour, including deliberate attempts to deceive or mislead officials, wilful interference with other competitors, falsification of documents, use of forbidden equipment or prohibited drugs, violations of airspace, or repeated serious infringements of rules should, as a guide, result in disqualification from the sporting event."'
So I'd guess for official World Record attempts (and probably for the prize rules) doping is out. (Sounds like the pilot has enough other sporting pastimes that he'd be unlikely to dope just for this project too…)
Most top tier pro cyclists clock 25000-35000 miles a year on their bikes, and race 80-140 days a year. Other than that, the job is mainly sitting around recovering. Although cycling is an incredibly complex sport, on the level of gridiron football or basketball in terms of the number of calculations that have to be made as part of tactical decisions, the longer-term playout of actions (at least in long road races) means that riders and their sporting directors (think coaches) have time to think about their decisions, and that combined with how much of racing is done on feel means there isn't the same need for things like film study and in-depth tactical coaching on a daily basis.
Athletes have a lot of what might be called downtime in their schedule, but very little actual free time. downtime is a part of training, a good nap schedule and staying well rested between training sessions and races is very important. You can't just go off and pedal a helicopter because you've got a couple hours free.
this is surprising that they don't try to get world class cyclists.
I'd like to point out the distinction from professionally paid road racers and olympic-level track (velodrome) riders. Road riders are always travelling, generally pretty busy and would probably be hard to get for a project like this, but more to the point, don't train for this kind of maximal wattage output.
But in fact, the world record for the 1km time trial is right below 1 minute right now (58.875).... I read somewhere on the internet that world class kilo riders are doing <900 avg. watts to do a kilo. Not to mention the fact that these guys aren't really bothered by much outside an olympic year.
otoh, canada doesn't have any of these caliber of riders, afaik.
We have had, including Curt Harnett, Jocelyn Lovell and (on the female side of things) Clara Hughes. The "thunderthighs" crowd does tend towards speed skating, though, which tends to be more accessible in a large country with few velodromes.
Is there a good overview of materials improvements over, say, the past 150 years? It seems like one of the areas, along with IT and biotech, which has had huge gains even in the past 20 years, contrary to the "end of innovation" thesis of Thiel et al. You can get carbon fiber in everything now, ceramics are more used in things other than pottery, and companies like Crucible made a lot of awesome steels (including...cast stainless steels!) from the 1970s to now. Sure, the properties don't get 10x better, but a 1% improvement in strength-at-2000C for the blades makes a jet turbine a lot more efficient.
(i'm a material scientist by training and by trade (up till a month ago))
to me, the history of materials improvements is the history of materials characterization techniques.
so much of materials science is just trying to figure out the right lever to pull to control some property, and modern tools like electron microscopy, tga/dsc, xps, afm, bet, etc. all provide amazing insight that was simply unavailable 150 years ago.
but also, 150 years is a really long time frame. people were only just beginning to study material fatigue in the mid 1800s.
A standard intro materials science textbook wouldn't tell you exactly what you're looking for, but it would give you an idea of what the state of the art is and where different materials are used and also a little bit of potted history. I read Askeland, Fulay, and Wright's /The Science and Engineering of Materials/ a couple of months ago; it seemed like a mediocre book, but the material covered was fascinating (and reasonably clearly presented.)
Interesting that Aerovelo won this. As I recall, they were the only contender not using electronic assists which were set to become invalid this month:
'With the pilot using both hands and feet to power the aircraft, UMD faced a challenge developing a control system for the Gamera II. But an attempt to clarify the rule prohibiting energy-storage devices inadvertently opened the door to electronic controls being used on both the Gamera II and Upturn II.
AHS has closed the loophole, but both teams have until July to attempt winning the prize under previous rules.[0]
To me, this is really cool, since presumably it means the materials have gotten light enough for an electric helicopter to become a reality (beyond the crappy Firefly project). Imagine what it would be like if you could commute from the suburbs of NY to the downtown heliport without paying for fuel or expensive maintenance. It could transform the way people commute to work, eliminating traffic and the effect of accidents.
> It could transform the way people commute to work, eliminating traffic and the effect of accidents.
Hopefully, the same people who are causing the accidents in cars won't be able to directly control the helicopter.
A car wreck slowing traffic down to 10% on a freeway is preferable to death looming from the sky because someone really needs to check twitter right now.
I'd wager that on the evolutionary path to personal aircraft, the development of self-driving cars is as necessary a step as the development of manually-driven cars and manually-piloted aircraft. Or to say it a different way: there'll never be widespread manually-piloted consumer aircraft.
This is the ultimate reason for not having flying vehicles. You lose one and it's injury and death all the way down.
That said, gyro-copters have excellent fail safe properties (then can autorotate/glide to a landing without power) when controlled by someone, or something, committed to operating them safely.
The FAA requires that all helicopters be capable of autorotation. We actually design and test for this extensively, by adding mass to the blade tips to store inertia, pilots regularly practicing power-off flight etc.
Autogyros fly in constant autorotation (hence the name), the main rotor being unpowered.
It's a lot easier to avoid hitting anything in the air, because there's a lot more space up there, and a lot more directions in which to dodge. During the war we sent teenagers with <20 hours of training to fly in combat (and while many of them died it wasn't because they were crashing into each other or the ground).
It's not so simple. A worst-case scenario for a flying car might be nose-down terminal velocity into a crowded building. Or even faster, if the driver were deliberately accelerating into the building, trying to use the car as a kinetic weapon.
Scheduled commercial airline flights are quite safe, which makes people think "flying is safe", but general aviation, which lacks many of the strong controls that scheduled airlines have, is much worse[1]. I would expect flying cars under manual control of typical drivers over a crowded city to be much, much worse still.
Low power only works with incredibly large wings/blades. So large as to be highly impractical. The smaller your blades get the worse your efficiency. That means you need more batteries. But that adds more weight and means you need a bigger motor, which requires bigger batteries and so on.
I don't think we'll be seeing electric helicopters with any practicality until battery tech gets much, much better. I can't really even think about possibilities unless it gets at least 5x better with 10x being more interesting.
Things get a lot better when you do a ducted fan approach, preferably with variable geometry and/or counter-rotating rotors. Electrical engines also have the advantage of being more maneuverable, which means that creating an Osprey-like design with both VTOL and flight with wings will be mechanically much simpler. You need wings to have efficient forward flight, and I think a design like this will not be practical until we use a purely electrical design.
I don't know much about cars or helicopters, so I have an honest question: why would the maintenance for an electric helicopter be less expensive than the maintenance for an electric car?
The big money saver would be the engines. Most big helicopters run on turbines and they are not cheap. And they have a limited lifetime before you're legally required to overhaul or replace them. For the engines on business jets that a friend of mine used to charter pilot, that number was between $500 and $1500 per hour.
If you built electric motors for a chopper you could theoretically design so that it had 8 motor any one or two or three of which could fail and still fly. Make several different independent battery packs and you enjoy more robustness. If you engineered it right you could make the case to the FAA that the helicopter doesn't need any expensive preventative maintenance on the motors or batteries, just on the drivetrain. Which would save a lot of money.
EDIT: "most helicopters" to "most big helicopters"
Sorry, I should have been more clear - I meant the maintinence would be inexpensive compared to a gasoline piston helicopter. Given the requirement for safety in aviation, piston engines have to be inspected (and rebuilt, at a cost of ~$50k) every ~2000 hours the aircraft is flown. This cost essentially goes away with an electric engine, partially because they last 10x as long, and partially because they cost significantly less than a piston engine.
My inclination is more expensive. You'd probably have to deal with more vibration causing more mechanical wear, and tolerances would have to be might tighter since the stakes would be higher. On the plus side you'd have less road-wear related issues, but many (probably most) car owners are able to neglect those things for years.
Nobody literally goes over a pre-drive checklist before driving down to the grocery store.
for sustained power output of any duration, pedaling a fixed gear crank is about as good as it gets for getting power out of a human body. See Bicycling Science by David Wilson, MIT Press, for some interesting quantitative analysis. As an example to address your specific suggestion of rowing, compare a rowing scull with the Decavitator (MIT built pedal powered boat).
You should probably correct "skull" to "scull." Reading "rowing skull" then immediately mis-reading "Decavitator" as "Decapitator" was an interesting WTF?!? on my part ;-)
The huge speed difference with a single scull probably has more to do with inefficiencies in 'the drive train' (moving your weight around in a rowing shell introduces dipping, which loses energy; using oars is less efficient than using a propeller) than with inefficiencies of the rowing motion vs a cycling motion.
http://rowingbike.com/site/EN/ shows a bike operated using a rowing motion. That machine is competitive with 'normal' recumbent bikes, except in climbs. The main parts also could be fitted on that Decavitator. I would expect similar speeds.
Interesting point - it may be that rowing is comparable to biking in power, but the ease of building a cycling drivetrain generally wins out for projects like this, because the parts are readily available in any bike store (the cockpit of the copter here is an off-the-shelf bike frame and crankset attached to the spools).
Deadlifting is excellent for getting maximum force, but not power (powerlifting is misnamed!). The highest power lifts - the Olympic, explosive ones - aren't well suited to tapping to run a drivetrain.
Cycling is, among many things, very smooth, which helps when dealing with such delicate machines.
I would guess it is a pretty good compromise between smooth, efficient and powerful (a smoother motion presumably allows a less robust drive train). They pretty much need all the watts the pilot can supply just to get off the ground.
It is possible, perhaps through a clever arrangement of gears and what not, to create a human powered copter that can create sufficient lift with just one rotor?
Probably, but you'd need a tailrotor or tip props on the blade tips for countertorque. There was an unsuccessful HPH design with one tip-driven rotor. The negative is that you're generating aerodynamic force that is non-lifting, and thus wasting power. Four rotors were probably chosen for this design (and many past others) for stability; a helicopter in hover is about as stable as an air hockey puck, it needs constant control input to stay in one spot. Directional control is much easier with a vehicle resting on four legs than on one.
You lose weight in the external structure, but you'd gain some back in stiffening the blades to prevent excessive blade deflection (you'd have one big rotor instead of four small ones). You could also stiffen with external tension cables, but these rotate with the blades and would incur drag (streamlined wires were invented for this reason, also bicycle wheel disk covers) and disturb the axial flow. It's all about tradeoffs.
The claim that a 4-minute mile was once thought to be impossible by informed observers was and is a widely propagated myth created by sportswriters and debunked by Bannister himself in his memoir, The Four Minute Mile (1955). The reason the myth took hold was that four minutes was a nice round number which was slightly better (1.4 seconds) than the world record for nine years, longer than it probably otherwise would have been because of the effect of World War II in interrupting athletic progress in the combatant countries.
I would be willing to bet that this will never make its way into a consumer product or even a hardcore hobbyist product. Even human-powered winged flight is on the borders of what is anatomically and physically possible, and helicopters are even farther out on the feasibility scale. It's cool for a proof of concept, but you won't be able to improve this design by an order of magnitude even with weightless materials.
True, but my ~$120 quadcopter has about 80% of the power this thing needs to climb to 3m. There are people out there building human carrying scaled-up hobby quadcopters (well, hexa or duodec or hexadec copters).
I suspect there are (other) people out there now thinking things along the lines on "Hmmm, made from balsa and foam covered in poly film, prepreg carbon tube, kevlar tow, epoxy and cyano. All pretty common high-end but regularly homebuilt model plane techniques. 10m long rotor blades are big - but only 2 or 3 times longer than pretty common competition rc glider wings. There's a very reasonable chance that the right group of comp rc glider builders and quad rotor hobbyists could build something that weighs maybe only twice what this does, and has 5 or 10 times as much power available - probably for a budget of not much more that $10k."
I don't think "hardcore hobbyists" will be pedaling one of these anytime soon, but flying something similar electrically is certainly not an impossibility.
Pretty cool result. I'd wonder what the performance would be with ~150 lb of batteries, motors and electronic sensors/controllers instead of a human. I wonder if given the same mechanics of this system a human is the optimal motor just because of the built-in automation and control system (probably not).
For "What's next?" I would hope for something smaller. Impressive as this is, it's way to big to be practical. I suppose lighter materials could help reduce the size though.
Awesome! It's inspirational to see people attempt something they're not sure they can do, work hard for a good while, and finally do it. Just what I needed to start the afternoon!
Interesting tidbit:
"The pedaling of the pilot pulls on and reels in four Vectran cords, which are pre-spooled onto each of the four rotor hubs. The action of unspooling the cord and pulling on the rotor hub drives each rotor to overcome the drag force."