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Author Topic: Directorly Downwind Faster than the Wind  (Read 148426 times)

magnetmotorman

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Re: Directorly Downwind Faster than the Wind
« Reply #195 on: October 25, 2010, 08:37:53 PM »
OOOHHHHHHH.....................

I'm sorry MISS PRINT

                      SMART FELLER
GEESE
sorry about that!!
All this bandwith for a few silly letters!
HOW EMBARRASSING!!

Chet

HAHAHAHA, very funny!

Anyway, there is no overunity in a windmill mounted on a cart.

spinn_MP

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Re: Directorly Downwind Faster than the Wind
« Reply #196 on: October 26, 2010, 03:33:07 PM »
WOW
Some really Fart smellers !!
You two should right a book !

I could use some more toilet tissue!!

Chet

Hey Ramses, cannot help yourself, can you?

Sure, you can use "some more toilet tissue".... But don't exaggerate... The misuse is already showing in your brilliant contributions...

"The Boss" is watching you...  :o

magnetmotorman

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Re: Directorly Downwind Faster than the Wind
« Reply #197 on: October 26, 2010, 03:38:51 PM »
OK, that's enough, I unsubscribe from this thread, bye.

ramset

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Re: Directorly Downwind Faster than the Wind
« Reply #198 on: October 26, 2010, 03:40:32 PM »
                                    Spinner

                                      :-*
                                      MY
                                    HIGH
                                    KNEE
  EDIT
Emmanux
Please !! This thing with Spinner is an old thing!
He happens to be one of the lucky souls that God shared all his knowledge with!
            He knows everything about everything!
                     I'm JUST JEALOUS!!
Chet

spinn_MP

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Re: Directorly Downwind Faster than the Wind
« Reply #199 on: October 26, 2010, 04:23:32 PM »
Hey, guys, don't be silly... No need to abandon this serious discussion!

I come here just occasionally, and I, frankly, have no intentions to insult anybody... Even if I "slip" occasionally... Sorry, but ramset is so ..._____... ;D


I'll stay out of the "serious" threads in the future... I swear!
Cheers!

Mike Furness

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Re: Directorly Downwind Faster than the Wind
« Reply #200 on: December 27, 2010, 11:25:23 PM »
Some of you (with respect) must be mad! consider firstly a sailboat running directly downwind; and let's say we don't want to be drifting about, so we start the engine, at the exact speed of the wind the sails fall in the water, because there IS NO WIND, therefore no power; similarly, put the little machine on a road, with no wind, does it rush off into the distance, of course not! Stretch your minds a ,little, and then you'd have aeroplanes without fuel, Hmmmmmmm!
FYI, any force, be it mechanical , electrical, or wind can be considered as the resolution of two vectors at right angles, and is the underlying knowledge and manipulation involved in such diverse applications from automotive wheel balancing to SSB radio transmitters.

For a boat to sail fastest, one starts with the wind on the beam (90 degrees or less than, NEVER more), as the boat accelerates, the 'apparent wind' heads the boat and gets stronger by a simple vector addition of the boat's speed, therefore the vector pushing the boat declines as the vector pushing sideways increases dramatically, hence boat is held laterally by the keel and heels over more.

The limit of course is when the angle to apparent wind becomes so small that it equals the losses of sail efficiency and friction. in any case, normal displacement hulls make waves which limit the top speed, which is approximately 1.4 x the square root of the waterline length unless the vessel is light enough to plane.
Land yachts and ice yachts are not limited by such factors and with extremely low friction can obtain quite phenomenal speeds, and close windedness somewhat similar to aircraft wings.
i have not posted here for some time, as I see these groups as a forum to scientifically challenge any 'misguided' information.

Sadly, I mostly see 'camp followers' and total acceptance of outlandish statements, with of course the inevitable utube video, usually high on pictures and music, and devoid of any technical information!

Firstly I challenge the originator to produce 'Proper drawings,' & 'Bill of materials' which includes the pitch and diameter of the propeller, and the number of rotations per foot of wheel travel, so ANY can 'build exactly as shown.'

Next, as a simulation of travelling at wind speed, place on a flat road when no wind; will the propeller turn all on it's own? NO sir, it won't, maybe a concession, push it with a stick at walking speed, will it accelerate away from you NO sir!

Finally, in a real situation where the machine starts off with a following wind and the wind turns the propeller (as it will) to accelerate the machine downwind; and assume for one moment that it does actually exceed the wind speed, the wind now comes from ahead and will REVERSE the propeller direction and stop the machine!
Unless the inventor's plans show automatic pitch reversal at wind speed, then this post has truly exposed a scam! (Or lack of experimental correctness)

Sensible comment welcome,

Mike.

Mike, J. Furness.


ramset

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Re: Directorly Downwind Faster than the Wind
« Reply #201 on: December 28, 2010, 01:04:54 AM »
Mike,
Are you saying that Google [their sponser]
Is running a scam?  Hoax?
And all the fellows that sanction these events and validate them,They are in on it too?

http://www.nalsa.org/DownWind.html

Perhaps I'm missing your point??

Chet

tbird

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Re: Directorly Downwind Faster than the Wind
« Reply #202 on: December 28, 2010, 04:23:25 PM »
Mike, J. Furness

Quote
Some of you (with respect) must be mad!

this statement, coming from you, sounds like "the pot calling the kettle black".

your overall post has a lot of holes in it.  i won't address them each at this time.  it should be enough to just point out you have based everything on the wrong concept.

the wind doesn't drive the blade that turns the wheels that moves the device (car, cart, etc.).  it's just the opposite.  the wheels drive the blades that create thrust that pushes the device.

if you take the time to go (and read) to this link...

http://www.wired.com/autopia/2010/08/ddwfttw/all/1

you will find a very detailed article on the subject.

enjoy!!

tom

tagor

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Re: Directorly Downwind Faster than the Wind
« Reply #203 on: December 28, 2010, 05:14:31 PM »

Sensible comment welcome,

Mike.

Mike, J. Furness.

are you serious ?
 
is it a joke ?
 
if you want to built it look at this forum
 
http://www.econologie.com/forums/post183525.html#183525
 
 
http://www.youtube.com/watch?v=nBm6DU_t9i0&feature=player_embedded

Cloxxki

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Re: Directorly Downwind Faster than the Wind
« Reply #204 on: December 29, 2010, 01:02:54 AM »
Are people applying for the award "last person to understand DDWFTTW"?

It's not a debate anymore. It's an open question how to best apply what's been proven, for betterment of mankind. Better wind turbines, better fuel efficiency transport.

TinselKoala

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Re: Directorly Downwind Faster than the Wind
« Reply #205 on: December 29, 2010, 06:45:25 PM »
Mike, unfortunately your analysis is incorrect, as experiment has shown. There are plenty of links to explanations and illustrations above, so I won't add more.
But don't feel too badly; at first, due to similar errors on my part, I didn't believe it either.

WilbyInebriated

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Re: Directorly Downwind Faster than the Wind
« Reply #206 on: December 29, 2010, 08:57:31 PM »
But don't feel too badly; at first, due to similar errors on my part, I didn't believe it either.

that's par for your course...  ;)

Mike Furness

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Re: Directorly Downwind Faster than the Wind
« Reply #207 on: January 02, 2011, 11:36:10 PM »
Thank you for the information, which I have studied at length.
I did indeed misunderstand the principle originally; however, having studied carefully, the answer is still NOT POSSIBLE!
To elaborate, sure, a wind generator produces power, and it's not a large step of imagination to see that if this power (velocity) is transfered to a drive motor, then SOME progress directly into wind is indeed possible. As the wind resistance increases as the square of the velocity, it's quite apparent that DIRECTLY into wind can only have a very limited velocity increase.
The walking road and sloping ramps merely confuse as the moving road furnishes the velocity which otherwise would need power to attain.
The desert scene behaved absolutely as predictable UNTIL the wind headed the machine, only then did it begin to move, and obviously could derive some very limited power from the headwind
one has to consider the very low drag and low friction wheels to see just how little energy is available to drive the machine, probably not even 100 watts.
To obtain some forward velocity from say a 30MPH DIRECT headwind is indeed possible, but accellerating to 3oMPH when there is no headwind (same as wind excess downwind) is clearly imposible, sorry (any other than directly into or directly downwind excludxed, for obvious reasons).

I return once agaiin to my original statement, no wind, no propeller turning, hence no movement; push it along a road with a stick, and it will surely stop under the same circumstances of totally self generated wind.
consider a very simple analogy, you propel a vehicle which then takes the power vested by way of it's speed; to make it even simpler for you, drive an alternator from the car's wheels, at the instant you stop external pushing, at 100% efficiency you would retrieve exactly the same energy back as you put in, NEVER more; unfortunately wind and rolling resistance would exceed the input and you would come to a standstill quite quickly!
just don't be confused by a propellor instead of an alternator, principle exactly the same!

Mike.

Mike. J. Furness

ramset

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Re: Directorly Downwind Faster than the Wind
« Reply #208 on: January 02, 2011, 11:43:45 PM »
Mike,
"no wind no propeller turning"?

You did see the part where the telltales go slack [the no wind part],and the machine continues to accelerate ?

Chet

helicalred

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Re: Directorly Downwind Faster than the Wind
« Reply #209 on: January 03, 2011, 02:11:37 PM »
The directly downwind, faster than the wind crowd http://www.fasterthanthewind.org/ say they have established a world record http://www.nalsa.org/DownWind.html, exceeding the wind speed by a factor of 2.8. Although they claim it is not a hoax, I think that's playing with semantics. My thought is that the whole thing is a bit of a swizz - a well stage-managed extravaganza although for what purpose other than some ego building I can't imagine as the machine doesn’t appear to have any practical value.

There are seemingly endless forums on this thing (see http://forum.mythbustersfanclub.com/index.php/topic,12948.0.html, http://forums.randi.org/showthread.php?t=128483 and http://skepticblog.org/2010/05/27/sailing-directly-downwind%E2%80%A6-faster-than-the-wind/#more-8353 if you can spare the time) the main protagonist in all the discussions being someone called "Spork" who presumably is Rick Cavallaro - the person who seems to be the "owner" of the project. Nowhere, that I can find, does he give a clear and concise explanation of how the thing works, even on the record submission http://www.nalsa.org/BlackBirdDDWSR/NALSA%20Submision%20report.pdf. Plenty of photos, video clips (some very well made and convincing), hand-waving, diversions and distractions but nothing conclusive. I'm put in mind of a stage magician. In an attempt to lend credence or authenticity or whatever to the performance there are the Major Sponsors: Joby Energy and Google, support from some obscure university and, in pride of place, a video shot by Richard Jenkins - holder of the world land speed record (Wow!). All very impressive but absolutely meaningless. And note that the speed wasn't actually measured by The North American Land Sailing Association (NALSA)  people, they were merely observers who reckoned that everything looked above board and OK.

That was four months ago. Since then nothing new on the web-site – no revelling in the glory of it all or cashing in on their success, they’ve just turned out the lights and gone home, it seems. Strange.

Now, for how long was this faster-than-the-wind speed sustained? Ten seconds!  I'm not convinced. Before a 10mph wind their speed was 27.7mph. In that 10 seconds they would have covered approximately 124 metres. why not go for a longer distance at a lower speed? That would look more impressive to me and would still be a record.

I don't doubt that they did reach the speed they say, but I think it is rather telling that the graphs of the velocity profile etc only show the recordings for that ten seconds; I'd be most interested to see recordings of the same measurements in the minutes before and after.

How I think it works:
As Spork says, the propeller makes no contribution in getting up to wind speed, the wheels always drive the propeller and never vice versa.
While getting up to wind speed, the propeller is 'feathered' i.e. not producing any power. However the wheels still spin it and it acts as a flywheel storing kinetic energy. I would say that the purpose of the gears seen in some of the photos is to get it spinning as fast as possible.
When wind speed is reached, this kinetic energy is tapped allowing a brief period of acceleration to an over-ground velocity greater than the wind speed by either a) disengaging the propeller from the drive chain and giving it some pitch (and consequently some thrust) or b) leaving it feathered but changing the gearing relative to the wheels so that for a short time they are driven.   

All of Spork's banter seems to me a collection of truths, half-truths and waffle with a hefty dose of obfuscation.

Cheers,
Bill