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bngbuck
SFN Addict
USA
2437 Posts |
Posted - 08/02/2010 : 17:43:13 [Permalink]
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Thin Air Designs......
| But other than that, not much as long as the tires etc can withstand spinning twice as fast as normal for a short time. |
What would the acceptable LDA be for such an aircraft landing?
Normal, shorter or longer than it would be on a ordinary runway?
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Randy
SFN Regular
USA
1990 Posts |
Posted - 08/02/2010 : 17:44:57 [Permalink]
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Brought to mind an older 'wing car' article from 1980 Popular Science. Hopefully the link will work...
http://www.popsci.com/archive-viewer?id=GgEAAAAAMBAJ&pg=102&query=wing+car |
"We are all connected; to each other biologically, to the earth chemically, to the rest of the universe atomically."
"So you're made of detritus [from exploded stars]. Get over it. Or better yet, celebrate it. After all, what nobler thought can one cherish than that the universe lives within us all?"
-Neil DeGrasse Tyson |
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sailingsoul
SFN Addict
2830 Posts |
 Posted - 08/02/2010 : 18:43:57 [Permalink]
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Originally posted by bngbuck
What would the acceptable LDA be for such an aircraft landing?
Normal, shorter or longer than it would be on a ordinary runway?
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I know if it's a Piper Cub and it crashed in a graveyard, in Poland. They'd be recovering bodies for days! SS |
There are only two types of religious people, the deceivers and the deceived. SS |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/02/2010 : 19:05:28 [Permalink]
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The video there brings it all together for me, even if it's taking forever to load. A much deeper understanding dawned as, from a dead stop, the blades started turning backwards compared to how they'd rotate if it were a wind turbine or the like. Nice.
Thank you, JB, for taking the time to post here (and everywhere else).
So... would the number of blades make a difference in performance (assuming you could put as many on as you want with the same total weight)?
I imagine that, at speed, if the driver turned 90° to the wind, the BUFC would just slow down and stop. What would happen if, at speed, you pulled a 180? The chain snaps and everyone goes home?
If you had a system which could dynamically pitch the blades, and a gimbal system to turn the whole propeller relative to the cart, could it work in almost any wind, or is this a one-trick pony (although it's a very cool trick!)? |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/02/2010 : 19:15:28 [Permalink]
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Originally posted by sailingsoul
I know if it's a Piper Cub and it crashed in a graveyard, in Poland. They'd be recovering bodies for days! |
What's the landspeed record for rubber-band powered craft? |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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ThinAirDesigns
New Member
13 Posts |
Posted - 08/02/2010 : 21:14:45 [Permalink]
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What would the acceptable LDA be for such an aircraft landing?
Normal, shorter or longer than it would be on a ordinary runway?
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If you are considering small things then "shorter" by a small amount because there will be more headwind than normal due to the movement of the belt against the air. This added headwind will work to slow the craft down above and beyond normal.
Also a slightly 'shorter' effect due to the slightly higher amount of airplane KE used to spin the tires up to 200mph rather than 100mph upon touchdown. This will knock a tiny bit more speed off the plane at touchdown than normal
There could be other tiny ones that I'm missing, but otherwise and for the most part ... normal LDA.
JB
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Dr. Mabuse
Septic Fiend
Sweden
9687 Posts |
Posted - 08/03/2010 : 06:18:59 [Permalink]
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It's a pretty neat balancing act, having the torque from the wheels almost out-balanced by the wind-induced counter-torque from the propeller, but only just.
I'm impressed.
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ThinAirDesigns
New Member
13 Posts |
Posted - 08/03/2010 : 06:23:02 [Permalink]
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Originally posted by Dr. Mabuse
It's a pretty neat balancing act, having the torque from the wheels almost out-balanced by the wind-induced counter-torque from the propeller, but only just.
I'm impressed.
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Thanks.
Yes, you can alter the gearing/pitch to favor one force over the other. If you favor the wind-induced force it of course becomes a directly upwind vehicle.
JB |
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ThinAirDesigns
New Member
13 Posts |
Posted - 08/03/2010 : 06:28:27 [Permalink]
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Dave:
| Thank you, JB, for taking the time to post here (and everywhere else). |
Thanks Dave.
| So... would the number of blades make a difference in performance (assuming you could put as many on as you want with the same total weight)? |
More blades in the same rotor size create more thrust, but less efficiency. In our application efficiency is king. More blades would lower performance.
| I imagine that, at speed, if the driver turned 90° to the wind, the BUFC would just slow down and stop. What would happen if, at speed, you pulled a 180? The chain snaps and everyone goes home? |
Yes to the first -- this vehicle performs *best* at DDW and degrades the further off the wind you get.
If you take a vehicle like ours and point it the other way, it still goes DDW, just not as fast since the camber of the airfoil isn't optimized.
| If you had a system which could dynamically pitch the blades, and a gimbal system to turn the whole propeller relative to the cart, could it work in almost any wind, or is this a one-trick pony (although it's a very cool trick!)? |
Ours is a one-trick-pony since it was optimized for record purposes -- there is no theoretical problem however with a vehicle built just as you describe being able to go faster than the wind in all directions.
JB |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 08/03/2010 : 08:14:01 [Permalink]
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Originally posted by ThinAirDesigns
Hi, I'm JB -- one of the two primary designer builders of the vehicle in question.
Originally posted by HalfMooner
I'd like to know whether, somewhere in that "massively heavy-duty transmission," there is a flywheel lurking. |
Journalists/bloggers always want to make something BIG or SUPER when doing a story. I have no idea why this one picked the transmission to 'super-size'. He of course never spoke to us nor did his research from our project blog (http://www.fasterthanthewind.org)
Our transmission consists of ordinary bicycle sprockets and chain.
http://www.fasterthanthewind.org/2010/01/next.html
http://www.fasterthanthewind.org/2010/02/last-circle-for-now.html
http://www.fasterthanthewind.org/2010/02/one-thrust-box-to-go.html
| I can envision such a wind-powered vehicle building up energy from harnessing a following wind's energy into potential in a flywheel while stopped or at speeds lower than the wind. |
The transmission is of the fixed ratio type -- we used the cassette to find the right ratio on the dyno, but there's no derailer and no shifting happens while on the run. (we haven't change ratios since we found the optimum one.
With a fixed ratio transmission, there is no way for any stored KE in the rotating parts of the drivetrain (prop, etc) to be used to accelerate the vehicle since slowing the prop also slows the wheels.
JB
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Thanks for the reply, and welcome to Skeptic Friends Network, ThinAirDesigns! I have to admit that I simply do not understand the way this car operates. Smarter people than myself are trying to explain it, but for me to no avail. But, unless someone convinces me otherwise, I will simply accept that this thing works as advertised.
Apparently you folks did some pretty fine engineering. Congrats! |
“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
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bngbuck
SFN Addict
USA
2437 Posts |
Posted - 08/03/2010 : 08:49:12 [Permalink]
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ThinAir.....
What happens? ... People on the internet argue about it for years. :-)
But other than that, not much as long as the tires etc can withstand spinning twice as fast as normal for a short time.
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There could be other tiny ones that I'm missing, but otherwise and for the most part ... normal LDA.
JB
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I have not the slightest doubt that you folks know exactly what you are doing and what you have done!
Congratulations on an elegant piece of engineering! It deserves to go down in history alongside the unknown Chinese Han Dynasty inventor of the Junk! I sincerely hope you can take this breakthrough innovation into practical fruition and make it a perpetual notion! |
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ThinAirDesigns
New Member
13 Posts |
Posted - 08/03/2010 : 10:38:10 [Permalink]
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I have to admit that I simply do not understand the way this car operates. Smarter people than myself are trying to explain it, but for me to no avail. But, unless someone convinces me otherwise, I will simply accept that this thing works as advertised.
Apparently you folks did some pretty fine engineering. Congrats!
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Thanks Halfmooner.
If you are willing to put up with me for a few posts I might be able to walk you through some of the basic principles involved and make the lightbulb go on.
I understand though it you don't have the time or are otherwise uninterested.
JB |
| Edited by - ThinAirDesigns on 08/03/2010 10:49:37 |
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ThinAirDesigns
New Member
13 Posts |
Posted - 08/03/2010 : 10:39:25 [Permalink]
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Thanks bngbuck.
JB |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/03/2010 : 13:20:27 [Permalink]
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Originally posted by ThinAirDesigns
More blades in the same rotor size create more thrust, but less efficiency. In our application efficiency is king. More blades would lower performance. |
Can't you guys get your equipment from the same place that used to sell my physics teacher his friction-free surfaces and immovable objects?| If you take a vehicle like ours and point it the other way, it still goes DDW, just not as fast since the camber of the airfoil isn't optimized. |
No, I was wondering what'd happen if you made a U-turn at speed. I imagine the turn radius of your particular BUFC isn't all that small, but what would happen if, say, the driver was capable of turning the cart directly upwind without losing more than, oh, 25% of the forward speed? The propeller would still be providing thrust, but it would be spinning the wrong way relative to the wind, yes?| Ours is a one-trick-pony since it was optimized for record purposes... |
Understood.| ...there is no theoretical problem however with a vehicle built just as you describe being able to go faster than the wind in all directions. |
So could the drive-train be "enhanced" with a battery-driven motor to get it up to speed, faster? And could "excess" power available from the wind (say the operator doesn't want to go as fast as he could go) be used to charge that battery? Really, I'm just wondering if the lack of theoretical problems could someday result in a practical vehicle that'd work better than sticking a wind turbine generator on the roof of an all-electric car.
Well, towards that practicality question: how much of a difference in performance of your actual BUFC does the mass of the driver make? |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/03/2010 : 13:22:32 [Permalink]
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Originally posted by ThinAirDesigns
If you are willing to put up with me for a few posts I might be able to walk you through some of the basic principles involved and make the lightbulb go on. |
Forget about whether HalfMooner would put up with it, I will happily put up with it, and I've got more clout another here than he.
In other words: please! |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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A most counter-intuitive feat!
