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Old 2nd January 2013, 08:01 PM   #41
quarky
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Originally Posted by ynot View Post
Well thatís an unusual about-face attitude given your previous posts in other threads where you claimed to be a ďcheerleader" and wanted to be kept up with future developments etc.

Not everything has to be done to impact our world, provide a novel approach or save the whales. Some things are fun to do merely because they are. Sorta why crosswords, sudoku and jigsaw puzzles are so popular with many people.
I know, I know. I shouldn't have said that, and I'm still totally a cheer-leader.

Its coolness rests on its own laurels. I'm totally into it.
It's simply way beyond my abilities.
This is one tough challenge.
I'm sure you all get that.
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Old 2nd January 2013, 08:14 PM   #42
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I suggest not discounting the control aspect. It is very hard to effectively control these vehicles given the very slow rotor speed, or so I have been told by an aeronautical engineer that is friends with a former competitor in this competition.
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Old 2nd January 2013, 08:14 PM   #43
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Hmm, why not try 3 initial pedalers that all turn (via a cluster gear) a central wheel, that gives lots of initial power. then have 2 drop off, one by one as the gearing changes to minimize the jolt on the other two, then single pedaler?

Generally speaking, getting things started burns more energy than keeping it moving....

I am not an engineer (though I used to have a train drivers hat when I was a kid!)
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Old 2nd January 2013, 08:17 PM   #44
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Originally Posted by StankApe View Post
Hmm, why not try 3 initial pedalers that all turn (via a cluster gear) a central wheel, that gives lots of initial power. then have 2 drop off, one by one as the gearing changes to minimize the jolt on the other two, then single pedaler?
Why would you have 2 pedalers stop?

Starting is not so bad because you have ground effect. The 10 meter height requirement is difficult because you no longer have ground effect helping you.
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Old 2nd January 2013, 08:47 PM   #45
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I was thinking you might have the other 2 stop (and their two pedaling stations drop off) so as to save weight. and the diminishing return of their pedaling energy vs their weight.

maybe?
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Old 2nd January 2013, 09:51 PM   #46
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Originally Posted by StankApe View Post
Hmm, why not try 3 initial pedalers that all turn (via a cluster gear) a central wheel, that gives lots of initial power. then have 2 drop off, one by one as the gearing changes to minimize the jolt on the other two, then single pedaler?

Generally speaking, getting things started burns more energy than keeping it moving....

I am not an engineer (though I used to have a train drivers hat when I was a kid!)
Always pays to read the rules . . .

4.1.3 The machine shall be powered and controlled by the crew during the entire flight, including accelerating the rotor up to takeoff speed.
4.2.2 No member of the crew shall be permitted to leave or enter the aircraft at any time during takeoff or flight
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Old 2nd January 2013, 09:51 PM   #47
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Originally Posted by ynot View Post
Wouldnít dream of asking for any form of sponsorship until Iím sure Iíve got something worthy of sponsoring.
You could at least talk to organisations. Get them interested. The important thing is to have a relationship. Work out which companies would be willing to sponsor you and which ones are a waste of time. Then concentrate your efforts on the ones that might sponsor you.

Maybe have a free on-line newsletter with photos showing your progress. You get your potential sponsors to read the newsletters. They might come and inspect your progress.
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Old 2nd January 2013, 09:55 PM   #48
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Originally Posted by rjh01 View Post
You could at least talk to organisations. Get them interested. The important thing is to have a relationship. Work out which companies would be willing to sponsor you and which ones are a waste of time. Then concentrate your efforts on the ones that might sponsor you.

Maybe have a free on-line newsletter with photos showing your progress. You get your potential sponsors to read the newsletters. They might come and inspect your progress.
Sure, but only after I know that's it's not completely a flight of fancy.
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Old 2nd January 2013, 10:00 PM   #49
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Originally Posted by StankApe View Post
Hmm, why not try 3 initial pedalers that all turn (via a cluster gear) a central wheel, that gives lots of initial power. then have 2 drop off, one by one as the gearing changes to minimize the jolt on the other two, then single pedaler?

Generally speaking, getting things started burns more energy than keeping it moving....

I am not an engineer (though I used to have a train drivers hat when I was a kid!)
Ynot's first post contains a link to the rules, which unfortunately specify that nobody can get on or off during takeoff and flight, and ground crew cannot help with propulsion.
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Old 2nd January 2013, 10:02 PM   #50
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yeah, that sucks...........

Ummm, could try and go a different route than the other groups, tons of small propellers moving very quickly versus the 3 or 4 giant ones moving slowly
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Old 2nd January 2013, 10:40 PM   #51
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Originally Posted by StankApe View Post
yeah, that sucks...........

Ummm, could try and go a different route than the other groups, tons of small propellers moving very quickly versus the 3 or 4 giant ones moving slowly
I think from the little information granted that this or something like it is what Amishman Dan is aiming at. He speaks of a jetpack type of device, which would, obviously, have to move a whole lot of air in a hurry.

I think most HP flight designers have sacrificed velocity for higher volume, finding that you can't get both within the horsepower range, and you get more lift from a big slow fan than a little fast one. Of course we await new results here.

Don't forget bearing losses here. Mechanical efficiency becomes hugely important when human power gets to its outer limits. Bearing designs and refinements that are blue-sky silly on a road bicycle might well make a vital difference here, and I think it's going to be a challenge to overcome mechanical losses and weight in any system that seriously gears up.
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Old 3rd January 2013, 12:25 AM   #52
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Originally Posted by bruto View Post

I think most HP flight designers have sacrificed velocity for higher volume, finding that you can't get both within the horsepower range, and you get more lift from a big slow fan than a little fast one. Of course we await new results here.
Rotors (large radius) have a better lift/horsepower ratio than propellers (small radius). Rotor drag increases by the cube of the speed. Divide the RPM by 3, and you've cut drag 27 times. To reduce the speed, you need to increase the radius. Surface area increases by the square of rotor radius, so you also gain efficiency due to weight. It's pretty basic math at this level.
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Old 3rd January 2013, 12:47 AM   #53
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My method is slow and powerful.
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Old 3rd January 2013, 01:14 AM   #54
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Originally Posted by roger View Post
I suggest not discounting the control aspect. It is very hard to effectively control these vehicles given the very slow rotor speed, or so I have been told by an aeronautical engineer that is friends with a former competitor in this competition.
Seems to be one of the main problems for the Gamera that they're trying to solve. Will be interesting to see what they come up with.
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Old 3rd January 2013, 01:25 AM   #55
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I'm working on a "transmission" for my one pilot designs and a feature of what I've developed would be a really good improvement for my two pilot design. This is why I like to design as I build as sometimes I make things I hadn't previously thought of and maybe never would have thought of.
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Old 3rd January 2013, 10:41 AM   #56
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Tossing out some thoughts, just for fun, as though I were approaching the problem-

A useful approach might be a 2-pilot pedal driven design where the pilots use the same 2 pedals, so each pedal has a foot on each side, that eliminates a bunch of weight and mechanical losses, and if they lie opposing it smooths the power pulses, or maybe since with clips each could push and pull you'd want them at some V angle so they weren't both between pulling or pushing at the same moment (use twins so it can be called a 'V-twin and get sponsorship from harley davidson, heh).

You'd still need separate arm cranks, but those would be much lighter as the power transferred would be much less.

Perhaps some efficiency would be gained with the arm cranks geared to a different ratio than the leg cranks.

If separate rotors didn't lead to duplicative losses I'd think about having each pilots arm crank power a rotor that would do some lifting, and since the rotor speed could be varied one could control pitch and the other yaw.

How to control the craft with legs and arms pumping is an interesting question, weight shift might work but if the pilots are secured so that they can maximize their leg effort on the pull stroke even shifting just their butts wouldn't work. The head is free for this purpose, though, and a clever design would set it up such that if the craft leaned 'left' the corrective action would be towards keeping the head level, ditto for pitch.

Counter-rotating or contra-rotating rotors will waste energy as will a 'tail'-rotor, I would investigate a high angular momentum design (about the rotor shaft axis) with stabilizing fins, let the whole thing rotate, who cares as long as it is slowly enough that it can be kept in the box with pitch and roll. The fins could be very large and very light.
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Old 3rd January 2013, 12:47 PM   #57
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Originally Posted by CNY_Dave View Post
Tossing out some thoughts, just for fun, as though I were approaching the problem-
Fun thoughts can sometimes be the best.
Originally Posted by CNY_Dave View Post
A useful approach might be a 2-pilot pedal driven design where the pilots use the same 2 pedals, so each pedal has a foot on each side, that eliminates a bunch of weight and mechanical losses, and if they lie opposing it smooths the power pulses, or maybe since with clips each could push and pull you'd want them at some V angle so they weren't both between pulling or pushing at the same moment (use twins so it can be called a 'V-twin and get sponsorship from harley davidson, heh).
Or you could have four pilots and call it a V8 (legs)
Originally Posted by CNY_Dave View Post
You'd still need separate arm cranks, but those would be much lighter as the power transferred would be much less.
Perhaps some efficiency would be gained with the arm cranks geared to a different ratio than the leg cranks.
If separate rotors didn't lead to duplicative losses I'd think about having each pilots arm crank power a rotor that would do some lifting, and since the rotor speed could be varied one could control pitch and the other yaw.
How to control the craft with legs and arms pumping is an interesting question, weight shift might work but if the pilots are secured so that they can maximize their leg effort on the pull stroke even shifting just their butts wouldn't work. The head is free for this purpose, though, and a clever design would set it up such that if the craft leaned 'left' the corrective action would be towards keeping the head level, ditto for pitch.
I had thought of using the head for steering as itís pretty much the only movable thing left if youĎre using both legs and arms for power. In my designs I think it would be possible to momentarily use a hand to adjust steering which I think would be better.
Originally Posted by CNY_Dave View Post
Counter-rotating or contra-rotating rotors will waste energy as will a 'tail'-rotor,
I agree that a tail rotor would be a waste of energy as it doesnít contribute to lift but counter-rotating rotors would so I donít know why you say they would waste energy.
Originally Posted by CNY_Dave View Post
I would investigate a high angular momentum design (about the rotor shaft axis) with stabilizing fins, let the whole thing rotate, who cares as long as it is slowly enough that it can be kept in the box with pitch and roll. The fins could be very large and very light.
Not sure that large fins would be effective enough at preventing counter-rotation to comply with this rule . . .
.1.2 The machine shall be a rotary wing configuration capable of vertical takeoff and landing in still air, and at least one member of the crew shall be non-rotating.
 
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Old 3rd January 2013, 05:43 PM   #58
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Originally Posted by bruto View Post
I can sort of understand Quarky's point, but some challenges are fun for the person meeting the challenge. Human powered vehicles and land speed records and 50 knot sailboats and the like may never have any technology that trickles down to us, but it's fun to see if you can do something. I am guessing that Ynot and Amishman Dan are getting some fun out of it, but so, in their own way, may be the teams figuring out how to get a half ounce off a wing and get another inch off the ground.

But it's true that the hovering vehicles we see in the videos are very serious and very impractical, expensive and involved. Not the same kind of fun we had putting together odd bicycles and water pumps and diesel lawnmowers and stuff. We're definitely out of the back yard here.
It has been one of the one of the greatest things that I have ever undertaken. What a challenge, to work towards achieving what some have called impossible.
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Old 4th January 2013, 07:39 AM   #59
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I think if you use multiple rotors you can't get them far enough apart to prevent each from seeing disturbed air from the other.

That part about having a non-rotating crewmember could do with clarification, could be that was intended for not having all the crewmembers rotate with the rotor.

Now fins could be used that would capture the downwash (although more vortices than downwash) and create an opposing torque, some energy would be wasted but at least the parts would not have to be rotating.
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Old 4th January 2013, 08:54 AM   #60
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Originally Posted by CNY_Dave View Post
I think if you use multiple rotors you can't get them far enough apart to prevent each from seeing disturbed air from the other.

That part about having a non-rotating crewmember could do with clarification, could be that was intended for not having all the crewmembers rotate with the rotor.

Now fins could be used that would capture the downwash (although more vortices than downwash) and create an opposing torque, some energy would be wasted but at least the parts would not have to be rotating.
I am guessing that the rule for a non rotating crewmember comes from someone envisioning a ganged set of human powered airplanes tied together. Since we know that human powered airplanes can fly, it's not hard to imagine that, say, three identical ones, pinned together at a wingtip so they rotate, would lift up like a helicopter, but this would involve no really new technology.
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Old 4th January 2013, 02:23 PM   #61
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Originally Posted by bruto View Post
I am guessing that the rule for a non rotating crewmember comes from someone envisioning a ganged set of human powered airplanes tied together. Since we know that human powered airplanes can fly, it's not hard to imagine that, say, three identical ones, pinned together at a wingtip so they rotate, would lift up like a helicopter, but this would involve no really new technology.
You're nearly there. Take the pilots and cockpits from each plane and put them together at the pinned centre so they don't rotate with the wings. No rule requires there to be any new technology.
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Old 4th January 2013, 02:34 PM   #62
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Originally Posted by ynot View Post
You're nearly there. Take the pilots from each plane and put them together at the pinned centre so they don't rotate with the wings. No rule requires there to be any new technology.
But that changes the structural issues. If it's two planes tied together, the forces look like this:

Code:
lift     lift lift     lift
    pilot         pilot
    weight        weight
And there's not much bending force on the wings.

If you "put the pilots together" it looks like this

Code:
lift lift        lift lift
        pilot pilot
       weight weight
and the lifting force is exerted rather far from the weight, so the wings now need to be stronger to resist bending.
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Old 4th January 2013, 02:48 PM   #63
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Originally Posted by ben m View Post
But that changes the structural issues. If it's two planes tied together, the forces look like this:

Code:
lift     lift lift     lift
    pilot         pilot
    weight        weight
And there's not much bending force on the wings.

If you "put the pilots together" it looks like this

Code:
 
lift lift        lift lift
        pilot pilot
       weight weight
and the lifting force is exerted rather far from the weight, so the wings now need to be stronger to resist bending.
Although I’m not at the wing stage yet I’ve considered long wing problems. What about having more wings of a shorter length? I’ve done some model size experiments at prestressing and cable-staying wings and the results seem to be promising. I shook my head in disbelief when I saw how the Upturn team used poles and a cobweb of lines on their wings.

ETA - This sort of thing . . .

wing.jpg
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Old 4th January 2013, 05:02 PM   #64
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The other difference I could envision between rotating and non rotating pilots is the drivetrains. In the 'separate planes joined at the hip' scenario, each plane will have its own propeller to provide rotation and a short drivetrain to run it. Moving propellers powered by a non moving source become forbiddingly complex, and the problem (including the structure at the common hub) immediately becomes technologically different if the rotational power comes from some source other than individual propellers.
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Old 4th January 2013, 05:12 PM   #65
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Originally Posted by bruto View Post
The other difference I could envision between rotating and non rotating pilots is the drivetrains. In the 'separate planes joined at the hip' scenario, each plane will have its own propeller to provide rotation and a short drivetrain to run it. Moving propellers powered by a non moving source become forbiddingly complex, and the problem (including the structure at the common hub) immediately becomes technologically different if the rotational power comes from some source other than individual propellers.
Not forbiddingly complex at all if lines are pulled from propeller spools down through a centre hole and twisted onto a drive spool (as the Upturn does).

It’s important to remember that the flight time only has to last for 60 seconds.
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Old 4th January 2013, 05:39 PM   #66
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It's hard to dodge the relative wind speed/resistance/lift connection.

All the contenders in the early hpv flight contests had huge wing spans, and moved at slow speeds, near the ground, or water.

I'm open to the idea of smaller blades, moving faster, but the math doesn't add up.
AFAIK, the choppers that have managed to leave the ground, have been enormous, ungainly structures, of just-barely structural integrity. Protected form outside wind gusts, as well.

In some ways, I should think that wining the prize inside a huge building, essentially, is cheating. None of the other big hpv contests allowed this.

At any rate, it takes some connections to secure a huge indoor space.
This is what separates the back yard tinkerers from M.I.T.s engineering department.
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Old 4th January 2013, 05:50 PM   #67
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Iíve been considering three different HPH design options and I think Iíve now done enough reading, thinking and playing to settle on pursuing with the two coaxial, counter-rotating rotor/wing-sets with two pilots design that I thought of 30+ years ago. Not looking forward to having to make twice the number of wings as I would if I was making a single pilot design but Iím more confident that this design could/would/will work than I am with the other designs.

I think the biggest problems to be faced are the balancing of the overall craft and the balancing of the push/pulling of the pilots so they can control their rotation well enough. Iím reasonable confident these potential problems can both be solved. Before worrying about balance however I will put my efforts into designing and building the bestest two pilot ďtransmissionĒ system in the Universe . . . . Geronimooooo (now thereís a name).

Silly joke - What does Geronimo yell when jumping out of an airplane? . . . Meeeeee
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Old 4th January 2013, 05:55 PM   #68
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Originally Posted by quarky View Post
It's hard to dodge the relative wind speed/resistance/lift connection.

All the contenders in the early hpv flight contests had huge wing spans, and moved at slow speeds, near the ground, or water.

I'm open to the idea of smaller blades, moving faster, but the math doesn't add up.
AFAIK, the choppers that have managed to leave the ground, have been enormous, ungainly structures, of just-barely structural integrity. Protected form outside wind gusts, as well.

In some ways, I should think that wining the prize inside a huge building, essentially, is cheating. None of the other big hpv contests allowed this.

At any rate, it takes some connections to secure a huge indoor space.
This is what separates the back yard tinkerers from M.I.T.s engineering department.
Big slow wings with a big slow prop.
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Old 4th January 2013, 06:05 PM   #69
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Originally Posted by quarky View Post

In some ways, I should think that wining the prize inside a huge building, essentially, is cheating. None of the other big hpv contests allowed this.
Wind crossing a rotor provides lift. This is supposed to be human powered, not 'get lucky with steady, not too strong prevailing winds' flight. That's my take on the rule.
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Old 4th January 2013, 06:14 PM   #70
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Originally Posted by roger View Post
Wind crossing a rotor provides lift. This is supposed to be human powered, not 'get lucky with steady, not too strong prevailing winds' flight. That's my take on the rule.
I think being allowed to use ground effect is more cheating the concept of a helicopter. Makes it more like a hovercraft that can get momentarily to a height of 3 metres competition.
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Old 4th January 2013, 06:26 PM   #71
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Originally Posted by roger View Post
Wind crossing a rotor provides lift. This is supposed to be human powered, not 'get lucky with steady, not too strong prevailing winds' flight. That's my take on the rule.
Funny you say that.

My take on the outdoors situation, is mostly about getting unlucky.

I can't even imagine an optimal exterior wind flow impacting this even in a positive manner...unless you designed for it, and knew its speed, and the direction it was coming from.

I'm all ears if you see this differently.
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Old 4th January 2013, 06:31 PM   #72
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Originally Posted by quarky View Post
Funny you say that.

My take on the outdoors situation, is mostly about getting unlucky.

I can't even imagine an optimal exterior wind flow impacting this even in a positive manner...unless you designed for it, and knew its speed, and the direction it was coming from.

I'm all ears if you see this differently.
I could surely be wrong. Certainly (thinking about it) it would make staying in the 10 meter square harder. I think that pretty much demonstrates that I am wrong and you are right.
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Old 4th January 2013, 06:33 PM   #73
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Originally Posted by ynot View Post
I think being allowed to use ground effect is more cheating the concept of a helicopter. Makes it more like a hovercraft that can get momentarily to a height of 3 metres competition.
Perversely, when you wrote that, I had to wonder about the 60 seconds required.
What if the team spent many minutes filling a bag with H2, via electrolysis, and electrical out-put.

Once the chopper is floating, it should be easy to keep it up there for 60 seconds.

Cheating?
HPV?

Storing energy?

It's all about storing energy...a matter of how long.
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Old 4th January 2013, 06:46 PM   #74
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Originally Posted by roger View Post
I could surely be wrong. Certainly (thinking about it) it would make staying in the 10 meter square harder. I think that pretty much demonstrates that I am wrong and you are right.
If they didn't have a "must be in still air" rule you could construct a level and open launch platform in an updraft on the side of a steep hill. Think they might have employed a cheat to help them with the rules.
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Old 4th January 2013, 06:51 PM   #75
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Originally Posted by quarky View Post
What if the team spent many minutes filling a bag with H2, via electrolysis, and electrical out-put
No lighter than air materials are allowed.
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Old 4th January 2013, 07:03 PM   #76
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Originally Posted by ynot View Post
If they didn't have a "must be in still air" rule you could construct a level and open launch platform in an updraft on the side of a steep hill. Think they might have employed a cheat to help them with the rules.
Apologies for not pouring over the rules enough...but do the rules imply indoors only?

If you can't use the wind to help in this, which is really hard to imagine, for me, and the judges deem any potential up-drafts as illegal...well, doesn't this necessarily have to be done inside a really large, empty building?

And doesn't that imply serious pockets?

Or, possibly, your brother-in-law owns a big indoor skating rink, and he's willing to let you use it, after midnight on Tuesday and Wednesday?

I cheer lead for David, over Goliath.
I can't help it. It's not religious for me.
It's more about digging the napkin math.

Honestly,

Where would we be without the napkin math?
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Old 4th January 2013, 07:13 PM   #77
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This is the rule . . .

4.3.2 All attempts shall be made in still air, which shall be defined as a wind not exceeding a mean speed of approximately one meter per second (3.6 kilometers per hour, 2.24 miles per hour, 1.94 nautical miles per hour) over the period of flight.

Doesn't seem to be any requirement to be indoors but there''s obviously advantages from the competitors point of view to be indoors.

I would be happy to do my testing outdoors in calm air but there's no way I would want to attempt to win the competition outdoors.
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Old 4th January 2013, 07:21 PM   #78
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Originally Posted by ynot View Post
Before worrying about balance however I will put my efforts into designing and building the bestest two pilot ďtransmissionĒ system in the Universe . . . .
Chain/pedaals/sprockets provide almost 99% energy transfer efficiency, so it will be interesting to see what you are thinking. Your only path seems to be to bring more of the human's muscles into play in a sustainable way with a minimum of impulse spikes.
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Old 4th January 2013, 07:22 PM   #79
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Originally Posted by ynot View Post
This is the rule . . .

4.3.2 All attempts shall be made in still air, which shall be defined as a wind not exceeding a mean speed of approximately one meter per second (3.6 kilometers per hour, 2.24 miles per hour, 1.94 nautical miles per hour) over the period of flight.

Doesn't seem to be any requirement to be indoors but there''s obviously advantages from the competitors point of view to be indoors.
I'll say.

But how does Amish Dan, or you, for example, gain access to such environs?
To my limited knowledge, all credible efforts, so far, have been indoors.
I'm delighted to be corrected on this.

You remember the hell of spork's efforts and claim?
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Old 4th January 2013, 07:47 PM   #80
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Originally Posted by roger View Post
Chain/pedaals/sprockets provide almost 99% energy transfer efficiency, so it will be interesting to see what you are thinking. Your only path seems to be to bring more of the human's muscles into play in a sustainable way with a minimum of impulse spikes.
What helped me finally decide what design to use was when I took my granddaughter to a playground yesterday. There was a large multi-level merry-go-round that would have been quite a weight in itself not even considering my granddaughter and many other kids being onboard. I was able to plant my feet firmly on the ground, and using only one arm, was able to spin the whole structure to a ""flight speed" very quickly and easily. I was able to do this because I was applying my energy directly to the structure and had a firm anchor surface in the ground to push against. With my design human energy is applied directly to the wings but obviously I can't take the ground up with the craft. But I don't need to. As each pilot push/pulls direct against the push/pull of the other it's essentially like pushing against the ground. It's like arm wrestlers opposing each other's force.

I don't care how efficient pedaled cranks are claimed to be or are, there's no way I could have achieved the same acceleration and speed with a pedaled crank. Neither could I have by spinning props by pulling a line off a spool.
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