b2run

Finally someone has won the Sikorsky prize. In the discussion, a commenter calculated that the biker would be putting out 730 watts. Pretty impressive.

https://www.popularmechanics.com/tech...prize-15682369

ThermionicScott 

Cool!

PlanoFuji

Yes cool, but why?

The goals for the prize seem too low to produce anything useful (3 meter height hovering for a minute)...

Given the estimated power it is clear the winner didn't produce anything with any long term use. Human device design goals that can be achieved with say 300 watts would start to be really interesting. As it stands, this is just another 'worlds biggest whatever' record...

ThermionicScott 

The benefits and applications of a breakthrough aren't always apparent at the time. Had you been at Kitty Hawk, would you have crossed your arms and said "Great, they didn't go anywhere and I'm not getting in one of those"?

PlanoFuji

No, because it would have been apparent at Kitty Hawk that the technology had potential. The short distance/flight time were simply the result of a first step to attain an actual goal.

This prize, which appears to have been the GOAL, has such a low ceiling, that its attainment doesn't represent any real advance. Considering that some individuals have had well more than 1,000 watts of power generation capability for similar time periods. Simply choosing the right athlete with the best power generation to weight ratio and even a basic design (though admittedly well engineered would be needed) was all that this goal required.

If this goal had simply lengthened the flight time enough to be able to demonstrate that a normal athlete power generation capability could achieve such flight (say 10-20 minutes) then it would mean a breakthrough in technology.

Without that kind of demonstration, this is like those rocket packs we have been seeing for 40+ years... A neat, but useless gimmick, because like those rocket packs, the fundamental designs require more power than can be supplied on the vehicle.

TromboneAl

What, no helmet?!

BlazingPedals

Au contraire. human-powered flight using fixed-wing aircraft was relatively easy. Achieving flight in a helicopter-type vehicle was monumentally hard. I honestly didn't think this would EVER be accomplished, even with unobtanium skin over carbon nanotube frames. Practical future applications were irrelevant to the project. This was purely to see if it could be done; and colleges across the country have been trying for, yes, 30 years.

Jeff Wills

The first Kremer Prize for human-powered aircraft was pretty modest, but people had been pursuing the goal for many years before the prize was established. The later prizes just raised the bar:

£50,000 for the first to fly a figure of eight around two markers half a mile apart.
Donated 1973, won August 23rd 1977 by Dr Paul MacCready Jr Kremer International Competition
£10,000 for the first non-US citizen, to fly the figure-of-eight course.
Donated 1979, won June 19th 1984 by Gunter Rochelt

Kremer International Competition
£100,000 for the first to fly from England to France
Donated 1977, won June 12th 1979, Pilot Bryan Allen, entrant Dr Paul MacCready Jr

And there's still more prizes out there:
https://aerosociety.com/About-Us/spec...Powered/Kremer

MichaelW

This was a proof of concept not proof of practicality as well as simply a very cool thing to do. Just as HP fixed wing may have spinoffs in the field of solar powered flight, we don't know what the spin offs from this may be in terms of new rotor layouts, materials, control mechanisms etc.
A close-up pic of the bike element seem to show some excess parts. What are the headset and rear wheel for? Do they take power off the rear rim ? Whoever took the photographs of the event either was not very good or was trying to hide the power transmission system.

Bikeforumuser0017

Look at all that flex in the down tube at 0:55! Although, that was quite impressive, they should've stiffened that area and I'm sure it would have been even more exciting.

PlanoFuji

I was thinking of the Kremer when I wrote my original post. While the original prize goal was modest, it still demonstrated a viable technology-the ability to fly a reasonable distance in controlled flight. The purpose of the Kremer was to design an aircraft that would operate successfully within the human power envelope. This competition seems to have a different goal, which is why it reminds me of the rocket packs... In forty years, there has been little improvement in those devices; despite all of the technological advances; largely because of the power to weight issue. If the goal of this competitition was to address that fundamental barrier to low powered helicopters then it would have been designed differently.

I am not saying this isn't an impressive engineering (and physical achievement), but I just don't think it is that important overall.

Jeff Wills

The Sikorsky prize was for a controlled hover at a specified height, for a specified time, within a specified "box". A review of the team's unsuccessful attempts (and crashes) shows a rapid evolution of controls and technique.

What's important here is an engineering lesson identical to the Gossamer Condor & Albatross: with a defined objective, simple designs that are easy to build, test, and repair are better than more complex designs that might be theoretically superior. "Git 'er done" needs to be tattooed on every engineering student's forehead.

PlanoFuji

The Kremer prize was for controlled flight over a span that dictated the flight was within a reasonable human power output capability (ie relatively useful or about 300W for still air). If the goal of the Sikorsky prize is to develop designs that permit useful flight (ultimately), then this stage seems to fail that objective. As I said both an amazing feat of human capability and engineering prowess; however, it still hasn't done anything to provide evidence that such technology might one day be useful or even possible. As I said, it appears very similar to the efforts toward rocket packs -- as opposed to solar powered aircraft.

If the sole goal of the Sikorsky prize was simply to provide a learning challenge for engineering students, then it served that purpose well...

If the goal is practical human powered helicopter like flight the best way to achieve that would be to require a stand electric motor and battery system that is capable of producing say 350 watts of mechanical power (and a minimum weight of say 150 lbs) and then use other requirements already in place. The replacement of a human with a mechanical power source would standardize the power requirements of the device into a potential human envelope and leave the students only concerned about the engineering. No worries about the pilots ability to momentarily generate extraordinary levels of power and a greater likelihood that any successful efforts would lead to real development in the area...

Bike Rat

Exactly! Now that we know it can be done, how can we make it better. This was done with $30k for the airframe (total not reported), now that proof of concept has been achieved, imagine what can be accomplished with more money put into it.

To speak of the need for known practical applications...then why study the aeronautics of the bumblebee? What impractical knowledge led to intentionally unstable aircraft?

He looked to be applying a bit of body english near the end, was the spinning of the rear wheel used for stability control (turning)?

Jeff Wills

I think the spinning "rear" wheel was used to modulate power applied to the cables that powered the rotors. The cables are pulled by the spools on the left crank. Without the wheel, tension on the power cables would vary quite a bit with the rider's pedaling, possibly putting too much stress on the "drivetrain" or causing the cables to go slack.

Bike Rat

Wish I was able to find more about the set-up. To me it appeared the cables were to support the bike and for "steering" via weight shift and the wheels kinetic energy...granted they weren't actually trying to steer anywhere, only stay in place.

It's not clear to me which of the cables actually powered it. I'm surprised by the sprocket/cog sizes...as I understand it a smaller cog is less efficient due to frictional energy loss.

Regardless, the most curious thing is why did he wear a cycling jersey...better aerodynamics, haha. Maybe he should've used drop bars.

Jeff Wills

OK- the chain and "rear" wheel have nothing to do with making the rotors go around. As I said, they are just there to modulate power input. The cables are spooled up at the rotors, travel through the truss, and down to the cranks mounted on the bike frame. When the rider pedals, the cables are pulled, which turns the rotors. Simple:

Bike Rat

Okay, thanks for restating it, Jeff.

Bike Rat

After reading more about this project, to me the most obvious practical application is heavy-lift transport. The most powerful helicopter ever built is the Mil Mi-26; with 22,798 hp and a maximum take off weight of 123,450 lbs, that's 1 hp for every 5.41 lbs.

The Atlas weighs 120 lbs, the rider/pilot maybe weighs 160 lbs(?), for a combined weight of 280 lbs, and he reportedly produced 1 hp.

Lifting a 280 lb payload with only 1 hp is extremely important!

PlanoFuji

It would seem that one of designers of this craft would agree with me;

So the machine itself is a gimmick. The purpose was a learning exercise for students. I have no issue with that, but it seemed to me that people were confusing the purpose of this prize with others like the X-prize that were intended to ultimately produce a useful technology...

PlanoFuji

I would suggest looking at some of the quad copter drone designs. It is already proven technology to be able to design a lifting craft for greater power to weight WHEN THE WEIGHT IS A FIXED AND KNOWN SIZE. The aircraft you mention is able to apply its lifting capability in a far more flexible way. And that is accomplished almost solely through the use of a light extremely efficient power source; something the human body is not.