No, this is not a continuation of the other thread so I'm not breaking my own forum rules.

But the original thread was quite interesting - if only to see other people's way of thinking in process.

So I pose to you the following problem, one that was presented to my class in high-school and that was cause for just as big a discussion as the "Will the plane fly" discussion. Maybe this problem is a bit simpeler and everybody will agree on the answer from the start. I hope not because that would take away all the fun! If so, sombody come up with a more interesting question. I kinda prefer these kinds of discussions over the usual "you,/he/the world/the universe sucks" threads.

Anyway, here it is:

A car uses a propellor attached to it's roof as it's engine. That is, a propellor driven by the wind is connected through a belt to the wheels of the car. Now suppose the propellor is aiming in the exact same direction as the nose of the car. In short, the car needs a head-wind to make the propellor turn. Is the car able to move forward? In other words, is the system able to use a force (and only this force) directly from ahead to overcome the same force (plus the drag)?

Are you actually refering to windmill power?

yes
it will move forward
and as it moves faster the wind powering it gets stronger

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Question wonder and be wierd
are you kind?

[This message has been edited by ray b (edited 12-05-2005).]

quote Originally posted by Wolfhound: Are you actually refering to windmill power?

The propeller is attached to the car (I've added that to the original question)

If you have a headwind ,with proper gearing yes. Acting as a windmill
If you are depending on the forward movement of the car, no.

If you are using the true definition of a propellor. No

[This message has been edited by Wolfhound (edited 12-05-2005).]

It will move farward as long as power can overcome drag.

quote Originally posted by 84Bill: It will move farward as long as power can overcome drag.

Correct. Also add that the motion of the car alone will not provide enough wind power to keep the car in motion indefinitly. This would make it a perpetual machine which to this date has not acknowledged by our government as existing.

Possibly, as long as the propellor is effecient enough to overcome ALL of the car's drag. An example of using a propellor this way (on a moving vehicle) is Ag spray planes often have the pumps driven by a small prop and they do just fine. The entire key is how much power do you need and how much can the prop system develop?

John Stricker

quote Originally posted by Cliff Pennock: No, this is not a continuation of the other thread so I'm not breaking my own forum rules. But the original thread was quite interesting - if only to see other people's way of thinking in process. So I pose to you the following problem, one that was presented to my class in high-school and that was cause for just as big a discussion as the "Will the plane fly" discussion. Maybe this problem is a bit simpeler and everybody will agree on the answer from the start. I hope not because that would take away all the fun! If so, sombody come up with a more interesting question. I kinda prefer these kinds of discussions over the usual "you,/he/the world/the universe sucks" threads. Anyway, here it is: A car uses a propellor attached to it's roof as it's engine. That is, a propellor driven by the wind is connected through a belt to the wheels of the car. Now suppose the propellor is aiming in the exact same direction as the nose of the car. In short, the car needs a head-wind to make the propellor turn. Is the car able to move forward? In other words, is the system able to use a force (and only this force) directly from ahead to overcome the same force (plus the drag)?

quote Originally posted by F-I-E-R-O: Correct. Also add that the motion of the car alone will not provide enough wind power to keep the car in motion indefinitly. This would make it a perpetual machine which to this date has not acknowledged by our government as existing.

Hummmmmm....

It does depend. This would fall under the catagory of "perpetual motion" which of course, in the real world, doesn't exist. If the propeller were geared so that the final drive force is sufficient to overcome the wind resistance against the car, the drag of the drive system, the tires on the road, the added force necessary to put the car in motion initially, then yeah, it *should* work. But in a 1:1 ratio, no. In a say, 3:1 in favor of the prop, then yeah, it might go.

I agree, its all about the gearing. if you have the prop geared all to hell, like 400:1 prop to wheels, the pitch of the blades would matter too, as not to create too much drag itself. The car would move REALLY slow in the forward direction due to the huge amount of torque a little breeze would provide. But the car would be slow. The more efficient you make it the faster it could go.

Now, if the gearing was something like one to one, and the prop blades are pitched close to perpendicular to the direction of the wind, odds are the car will move backwards because the wind is putting more force on the face of the car and prop, then the amount of force its delivering to the wheels.

Now the whole propetual motion thing, nah. We are counting on wind to provide engergy to move the car, so no wind, no movment.

Thats my summation. Now, for the stumper of a question:

Lets just say the same car with a prop, (or wind mill or whatever its called) had a TAILWIND pushing it; assuming flat level ground, can the car move faster then the wind that provides its forward movment?

[This message has been edited by Fierobsessed (edited 12-05-2005).]

I'll say yeah to that question. A sailboat can, so it's possible.

Oh oh! I have a question! This one has been known to stump even the best of scientists.....

I have placed a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer (me) cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. The question is - what should I put in my coffee?

quote Originally posted by ryan.hess: The question is - what should I put in my coffee?

Less sugar?

quote Originally posted by ryan.hess: The question is - what should I put in my coffee?

Less crack too.

hmm... well thanks for your input.

Let me ask the cat.

you have a one half dead cat

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Question wonder and be wierd
are you kind?

quote Originally posted by ray b: you have a one half dead cat

Don't change the subject. This is about my coffee.

Yes, given appropriate pulley ratios (Cliff stipulated belt drive), the car will move forward ... but we all will probably be disappointed by the maximum speed it can attain.

Related story: In the early '70s, I was actually retained by a guy named Rex Curtis (sp?) as a consulting engineer on a windmill powered electric car project. (Curtis's fundamental ... and fundamentally flawed ... idea was that a windmill mounted on top of the car would recharge the batteries while it was parked.) A few weeks after being retained I delivered my first and only report ... conclusively demonstrating that the concept was not feasible ... with my letter of resignation from the project attached. About two weeks later a big story about the car appeared in the local newspaper, complete with a humorous editorial cartoon for illustration, which prominently used my name (without permission, of course) and others to lend credibility the project. For weeks after that I received a lot of letters and phone calls for more information. The BBC even called requesting a radio interview; they must have been looking for a "What are those crazy Colonials up to now?" story. I declined all requests due to client confidentiality. About nine months later I received a telephone call from someone who identified himself as a clerk in the local Federal District Court. He asked if I had invested any money in the project and said, "I am preparing a pre-sentencing report on Mr. Curtis. ... The judge is deeply concerned that he can't seem to convince Mr. Curtis that he can't use the U.S. mail to defraud people."

[This message has been edited by Marvin McInnis (edited 12-08-2005).]

quote Originally posted by Taijiguy: It does depend. This would fall under the catagory of "perpetual motion" which of course, in the real world, doesn't exist. If the propeller were geared so that the final drive force is sufficient to overcome the wind resistance against the car, the drag of the drive system, the tires on the road, the added force necessary to put the car in motion initially, then yeah, it *should* work. But in a 1:1 ratio, no. In a say, 3:1 in favor of the prop, then yeah, it might go.

Is the entire universe a "perpetual motion" machine? Do we have some sort of cyclic rebirth type of deal (big bang, big squeeze, rinse, repeat?), and if so, do we lose a little energy each time it occurs? or was the big bang a "one time event"? will all matter get to a certain state, and then just end up with a general energy state of zero?

My brain hurts!

quote Originally posted by ryan.hess: Oh oh! I have a question! This one has been known to stump even the best of scientists..... I have placed a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer (me) cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. The question is - what should I put in my coffee?

Isn't that the "Schroedinger's (sp?) Cat" scenario? Or is it Schvansenschtecker?

quote Originally posted by fierobear: Isn't that the "Schroedinger's (sp?) Cat" scenario?

Yes, but ray b beat you to it.

I've had some real stumpers, but I can't remember them for the life of me... Ahh well.

There are too many unknown variable to answer the question. What is the design of the Prop? What is the gearing? what is the weight of the vehicle? Is it on a level surface, facing down-hill, or up-hill? What are the aerodynamic qualities of the vehicle (cd value)? etc etc etc.

In short, the answer would be...Yes, it's possible to create a wind powered vehicle that's form of locomotion is governed exclusively by the wind that would drive into the wind producing the energy assuming the variables above could be addressed.

first the wind would have to start teh prop and that could take a bit of force unless you had like 2409127349865972354:1 gearing and then you would have to overcome the amount of drag created by the headwind.... i know mr2's take soemthing like 13hp to go 60mph.... now take that and someone do the math required. also.... how big is this prop... its it 20feet across or 2 feet?

Let me say this. An air screw working as a propellor is pitched differently and the air foil is different than one working as a windmill or air turbine. You would always need real wind not movement generated apparent wind to move forward and it would never be more than a crawl.

A catamaran has been built that will ever so slightly make way directly into the wind. It uses a variable pitch three blade turbine that shaft drives a rather large fiberglass prop in the water. It works because of the density differential between the air and water.

A conventional sail boat can not sail faster than the wind downwind, but can on a beam reach or a close reach.

[This message has been edited by Wolfhound (edited 12-05-2005).]

I suppose it could be done. But it would take some heavy engineering. The windmill would need to be designed to generate more torque than the total drag of the vehicle (both aerodynamic and mechanical). And since aero drag increases exponentially with airspeed, the vehicle would only be operable within a specific airspeed range.

I agree with Wolfhound. If you were able to get it working, the vehicle's speed would be really slow.

But IMO, trying to make the wind fight itself is pointless. There are many other alternatives that are sooooo much more practical...

[This message has been edited by Blacktree (edited 12-05-2005).]

If you had say a 15 knot wind you could with a 15 to 1 ratio drive the wheels at 1 knot.
Don't make appointment with this as transportation.
This could only be done at some ideal area like the salt flats with a purpose designed vehicle.
maybe something resembling an ice boat with wheels

If a spring is compressed and then dropped into acid, what happens to the potential energy?

quote Originally posted by Cliff Pennock: A car uses a propellor attached to it's roof as it's engine. That is, a propellor driven by the wind is connected through a belt to the wheels of the car. Now suppose the propellor is aiming in the exact same direction as the nose of the car. In short, the car needs a head-wind to make the propellor turn. Is the car able to move forward? In other words, is the system able to use a force (and only this force) directly from ahead to overcome the same force (plus the drag)?

Now I figured on this for about ohh some time and I reckon this will work depending on if its headed uphill or down and if the car is in reverse or forward gear and I figure a lot of this has to do with the weather too. Seems if the sun is shinin' there be a better chance somebody might be out to see if it works cause if they ain't nobody out to see it then it don't make no difference anyway. Now to get the sun to be out and the wind to be up well then it must be a day in March cause that be fittin for that kind of weather bout then. Guess that leaves the other two problems of the gears and what kinda hill it be on. Well the gear thing ought to be perty simple. If you want to go forward put it in a forward gear unless the hill is too steep then you'll want to put it in reverse before you put it in forward so you can get a running start. Now I reckon that leaves the last problem about uphill or downhill. I figure it ain't gonna start going uphill as gravity be workin again ya and that is something you want on your side. Seems gravity is much more on my side when I go downhill cause it don't need no motor to take off that way.

So this contraption might just work if somebody done it sometime in March goin downhill in a forward gear. I just don't see much use for a car that is that limited!

If a sawdust rooster can lay an egg and a half in a day and a half,how long will it take a frog with a peg leg to kick a hole through a dill pickle?I'm sorry I couldn't help myself.
If the prop was connected through a torque convertor then hydraulic lines to a flywheel that could be disconnected from the wheels the flywheel could store energy that could be used to get the car moving when connected to the drive wheels.After that the torque convertor would be able to keep the flywheel turning,though at a much reduced speed.

If a 25ft long snake made the mistake of swallowing its own tail, and continued to swallow, would its tail end up inside its tail?
Nick

[This message has been edited by fierofetish (edited 12-05-2005).]

If you have a solar powered flash light and shine it on its solar collector would it charge itself?

quote Originally posted by Taijiguy: I'll say yeah to that question. A sailboat can, so it's possible.

Sailboats can't go faster than the wind downwind and neither would the car. If the boat were moving the speed of the wind, it wouldn't fill the sails, faster and the sails would work against it. Some sailboats can go crosswind faster than the wind speed, maybe that's what you're thinking of.

Good Luck!

quote Originally posted by Tugboat: Sailboats can't go faster than the wind downwind and neither would the car. If the boat were moving the speed of the wind, it wouldn't fill the sails, faster and the sails would work against it. Some sailboats can go crosswind faster than the wind speed, maybe that's what you're thinking of. Good Luck!

dead downwind no but a little off directly downwind and the apparent wind
goes up with boatspeed so net effict is faster then the wind
planing hulls and cats do this in races
you zig-zag around the strait down wind track and cover more ground
BUT go down wind faster then the true winds speed

BTW people have built windmill powered boats
it does work strait up wind
not real fast but it works
high cost, and complex

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Question wonder and be wierd
are you kind?

Like I said, going crosswind it works....

Good Luck!

quote Originally posted by Tugboat: <snip> Some sailboats can go crosswind faster than the wind speed, maybe that's what you're thinking of. Good Luck!

I was.
Fly the wire on a Hobie, nothing like it! ('cept for maybe a 505)

You can exceed hull speed in a hobie. It,s called pitch poleing.
Hell of an experience.

Flying a hull in 10 knot of wind, speed near 18 knots, Beam Reach

[This message has been edited by Wolfhound (edited 12-06-2005).]

Uh huh, dip the low hull. Better than any carnival ride! (except for the landing)

Just like falling on water skis, skip like a rock.
Forgot how much I loved sailing a Hobie.