Down wind faster than the wind

[Brian-M]

Can a cart travel faster than winspeed? Possible I am sure. Orthodox science says that such a device cannot do so, if the only source of power is the wind, and that energy is consumed at that time. No storage is allowed, for example.
The wind does not have an absolute and constant speed, so "faster than" is indefinite term. That is a problem of measurement, of course.

Can a cart travel faster than winspeed? Possible I am sure. Orthodox science says that such a device cannot do so, if the only source of power is the wind, which is why the cart also uses the relative motion of the ground moving beneath it as a power source to achieve greater than wind speeds.

 

[Brian-M]

There is no ground power, The gears provide a pathway for the propellor's force to the ground. This may be advantageous when dispensing stored momentum, but there is no ground power.

You've got that backwards. The propeller is turned by the ground pushing at the wheels.

The wind does not turn the propeller.

All velocity is relative.
Relative to the cart, the ground is moving.
The cart harnesses power from the motion of the ground (like a windmill harnessing power from the motion of the air) to spin the propeller which pushes it along through the air.

 

[Brian-M]

<nonsense deleted>

Ah, screw it.
I'll just stop reading this thread, otherwise I'll be tempted to keep on responding to his garbage until the end of time.

 

[CORed]

I would like to throw out some ideas to move this thread away from arguing about whether the thing works or not. I'm satisfied that the propeller cart can move downwind faster than the wind.

What I would like to discuss is the relative merits of a propellercraft () vs. a sailcraft for wind powered transportation. It would seem that the propellercraft can do to things that a sailcraft can't: Travel downwind faster than the wind, operating in "wheel drives propeller" mode and travel directly upwind, in "propeller (or wind turbine, if you prefer) drives wheels" mode. As I understand it, for a single craft to do both, you need a means to either change the pitch of the probeller or change the gear ratio between the propeller and the wheels.

If we are going to operate in off-axis winds, if I am not mistaken for downwind (wheels drive propeller) mode, we would want to keep the axis of the propeller pointed forward, whereas for upwind (wind turbine drives wheels) mode, you would want the wind turbine to pivot so that it's aligned with the relative wind. So the question is, how would such a craft compare in cost and performance with a sailcraft. We could, of course, make a boat rather than a landcraft, substituting a propeller/water turbine for wheels. I'm not sure how well a downwind boat would perform, since the water turbine, propeller, paddlewheel, or whatever would be less efficient at transferring energy to/from the water than wheels are from the ground, and drag would be higher. I'm pretty sure upwind propeller boats have been built, but I don't know how well they perform compared to sailboats.

 

[ynot]

Have started a new thread for my turntable tests and have posted a video of the first quick test on YouTube - http://www.internationalskeptics.com/forums/showthread.php?t=130705

 

[Michael C]

Michael, that's not similar at all. Your ruler is acting as a springboard and the cottonreels are acting like interferometers and the real wind doesn't have little marks on it and the rubber on the big wheel is acting like a Van de Graaff generator that soaks up some of the electrical momentum of the table, although it does return some to keep things nicely in balance, but it's not doing what you think it's doing. Besides, your witnesses are only stuffed animals. You'll never do this in front of humans. (Sorry if you were having breakfast, JB)

Hihi! I haven't had breakfast yet.

​

 

[humber]

I read VERY little of what humber posts. While I've never seen him be right on anything at all (or even close), it stands to reason that he'd stumble onto something right with the reams he posts here.

Yes, when JB and I go to great pains to get the cart to exactly balance on an inclined treadmill, it is in fact in balance on an inclined treadmill. That seems obvious enough to me.

If we simply place it on our treadmill at max speed and max incline, the cart simply climbs the incline and heads straight off the front of the treadmill.

I have been telling you that you do not know how you own designs work and it appears from the above, that you are incapable of learning.
To have that confirmed was gratifying. However, to see you make such a lamentable excuse after all your hot air about admitting mistakes, is just the icing on the cake. I could not have insulted you more than you have just done.

 

[RossFW]

Got it.

Took a while but I understand the concept. I appologise to posters for suggesting the original video was a hoax.

It's a similar concept to Dynamic Soaring which utilises the difference in velocity between two airstreams and can produce airspeed WAY in excess of the velocity of either.

The world Model Aircraft speed record is in excess of 300kph and was gained with an unpowered glider dynamic soaring in the lea of a hill.

In this case, it's the difference in velocity between the air and the ground, with two different means (wheels and turbine/propellor) to harvest the energy from the two different media.

COOL!!

Dynamic Soaring record here available on UTUBE (I can't post urls yet).

 

[humber]

Umm... NO. The propeller literally pushes the air backwards. That's why the propeller is geared to the wheels, so it can push the air backwards.

As I said, Brian_M, we are talking about that wheeled cart and conveyor.
I do not agree they you are correct in your description of its application to the windcart. I do not agree that there is ground power. We will have to leave it at that.

Only if you're assuming that the force applied to the cart is the same.

If the medium pushing it has a constant velocity, and the cart is applying force to push back on the medium (in order to push itself forwards), then the medium is applying more force to the cart then it otherwise would.

Not that the rate of acceleration has any bearing on the matter, just the terminal velocity.

Yes, that is the purpose of the comparison. The differences betweend your cart and a 1/1 cart.
If you think that even though they use the same mount of energy to do the same thing, they remain different, then that is your choice.
To me, once that is established, then how that is broken down into velocity or force or acceleration, is a matter of design of the gears.

The amount of force applied to a regular cart by the wind diminishes to zero as it approaches wind speed.
The amount of force applied to a DDWFTTW diminishes to zero as it approaches (WindSpeed + BackwardSpeedOfPropeller).

Consequently, the DDWFTTW device recieves greater force from the wind over a longer distance than a regular cart.

As Work = Force x Distance, this means the DDWFTTW will have more kinetic energy than a regular cart.

If the carts are the same mass, and one has more kinetic energy, then it will be travelling faster. The wind supplies the cart with more kinetic energy than a 1/1 cart, which makes the cart go faster than a 1/1 cart. What's so confusing about that?
[\QUOTE]

You can say that, but it contradicts the laws of conservation of energy. If you introduce a new form of energy to explain the operation of the cart, then you will need to provide evidence to support that claim.

Please explain how these two ideas are different.
If the cart being pushed by the overhead conveyer had poor traction between the top wheel and the belt, how would this be any different than the propeller cart? What forces would be different?

It seems that there has been another misunderstanding Brian_M.
I though that we were discussing the -1/2 cart and the 1/1 cart, using a conveyor as shown in your animations, and according to Newtonian physics. I thought that you were making a claim for a difference under those rules. As I have said, I see no difference. They are geared version of the same thing, and the gearing will simply affect things as is normally expected.
I do not agree that the ideas of equivalence are applicable here, not with their interpretation outside of this thread. These ideas are not within orthodox science, so it is up to those who do hold these ideas to prove them. That's the way science works.

 

[humber]

Ah, screw it.
I'll just stop reading this thread, otherwise I'll be tempted to keep on responding to his garbage until the end of time.

OK Brian_M.

 

[H'ethetheth]

I do not agree that the ideas of equivalence are applicable here, not with their interpretation outside of this thread. These ideas are not within orthodox science, so it is up to those who do hold these ideas to prove them. That's the way science works.

Yes, but you have also made quite clear that your understanding of equivalence and its importance in modelling is limited. I'd still like you to answer this question:

My turn again: You want to know what happens aerodynamically when a F1 ferrari gets a 150 kph tailwind while travelling at 300 kph. The test track is booked full, and all you have at your disposal are a wind tunnel and a treadmill. Moreover, your boss wants to know the effects of the spinning wheels on aerodynamics.
How would you model this situation? Specifically: how fast is the treadmill running, and how fast is the wind blowing?


...and a 300 kph tailwind?

And a related question:

Say I want to model an aircraft in a windtunnel, yet all I have at my disposal is an aircraft and still air. How do I do this?

 

[humber]

Let's have a look at that. If you are standing on the walkway, the airport appears to be moving by. If you are standing on the floor, the walkway (and the people and luggage on it) appear to be moving by. Since you can't be in two places at once, you have to choose a frame of reference.

Which, perspective you mean. You are in the same frame of reference in both cases.

Which frame of reference allows you to easily read the tag on the luggage on the walkway? Right, the one that has the observer at rest with respect to the luggage. In either case, the luggage is moving with respect to the airport.

In high speed reading is often better it read the moving object so that a static scanner may be used. A technological and economic decision. Again, same frame, all the time

Let's reverse the situation and put the luggage on the floor, where you forgot it when you stepped onto the walkway. Someone sees what happened, grabs your luggage and runs ahead and stops, holding your luggage up so you can verify what the tag says. To stay stationary relative to your luggage and read the tag, either you have to walk in the opposite direction as the walkway is moving or the other person needs to walk in the same direction as the walkway. Both situations will satisfy the condition of having your luggage stationary relative to you.

Use RFID. Saves time and trouble.

But, you say, they are not equivalent, because the energy expended comes from different sources. That is right. But if you are saying that you can read the tag in one frame of reference and not in the other, that's wrong. You were able to achieve the same relative motion in both frames of reference between you and your baggage. Kinetic energy is not an issue either, because if either of you bump into a person that isn't walking, you still get a collision and the baggage is no longer at the same speed as you.

No, said nothing of the sort. If you choose to run around the block before picking up your luggage, add it to your energy bill, not mine.

Also, we've been assuming that in both cases, the person doing the walking is moving at the same speed as the walkway in order to cancel out the relative movement. What happens if the walking person moves faster than the walkway?

Yes, 100% assumption, I think.

Now let's address the small cart on the walkway. Let's use 10 mph for the walkway speed. Let's start with a person standing on the 10 mph walkway holding the cart, facing away from the direction of travel so that the still air in the airport feels like a tailwind.

Yes.

They set the cart down. The cart feels the air moving by at 10 mph. When the cart is released, the propeller is stationary and the air movement across the propeller and cart drags the cart along with the air. As the cart starts to move, the propeller turns against the direction of the air travel but the force required to turn the propeller forward is less than the force required to turn the wheels forward, so the cart moves forward.

Yes, I mentioned that in my last post for the nth time. The force of friction is the only thing that binds the belt to the cart. Once the force generated in opposition to that, be it via the propellor or simply air against the chassis, then the friction will break, and so limit the carts movement is that first direction.

This is a key point, and Michael C's ruler demonstration clearly shows that it does work
The cart continues to be pushed by the air movement and accelerates because of the unbalanced force.
Within a short time, the cart reaches 10 mph relative to the walkway and the person who released the cart, and is seen by people standing beside the walkway (in still air) to be stationary relative to them. However, the person on the walkway (who is still experiencing a 10 mph "tailwind") saw the cart move away from them after releasing, and unless their depth perception is quite acute will not be able to tell exactly when the cart reaches that 10 mph relative speed.

No, my balance explanation is correct, as you now know. The ruler explanation is not. Most of the above is not correct, so the remainder is therefore irrelevant

A bystander on the floor leans over and picks up the cart. The propeller, not having a power source anymore, slows down and stops. The bystander then places the cart back on the walkway, holds it for a few seconds to allow the propeller to get back to the speed it was at before and releases it again. The cart still has an unbalanced force on it and attempts to move forward relative to the person on the floor. They decide they want to look at it some more and poke it with a spork to hold it in place. Once they are finished, they allow the cart to continue on and the cart accelerates until the force generated by the spinning propeller is matched by the drag of the cart. That is at a finite speed, likely about 14mph relative to the walkway and 4 mph relative to the floor and still air of the airport.

No. Much slower than that. Roughly what you see in the videos.

When the cart gets to the end of the walkway, the cart wheels now encounter a surface that is stationary instead of moving and are forced to slow to 4 mph, the propeller transfers what little momentum it has to the cart, increasing the cart speed by a ratio equal to the difference in the momentum of the propeller and drive train and the entire mass of the cart. That causes a momentary spurt of speed, after which the cart immediately slows down and stops.

Maybe. Could happen.

If the carbon tube was a rubber band, the spurt of speed could be experienced over a longer time period but since it is carbon fiber and very rigid, it doesn't. The momentum transfer is essentially instantaneous and the cart jerks forward a little bit, then slows to a stop.

Perhaps. Details of a cart that is literally on an airport belt.

The question was. How does invoking this "equivalency" idea differ from not doing so? It seems from above, where you consistently take the local observer's view as being the reference ( or as I say the standard Newtonian frame that everybody else uses), then there is no difference as is expected, and yet again, none if you don't.

 

[humber]

Yes, but you have also made quite clear that your understanding of equivalence and its importance in modelling is limited. I'd still like you to answer this question:

It is not just me, H'ethetheth. Spork and JB have recently quoted academics that state that the treadmill is not as claimed, and not a frame of reference.

"Equivalency" plays no part in the treadmill or the cart. The 'relative' velocities and kinetic energies claimed to exist between these frames, is just another way of saying that Newton's laws are applicable to all objects. It follows that any object's velocity can be measured with reference to another, and that those same laws are independent of velocity, and that goes for kinetic energy and so forth.
This is the case for Newtonian space and time. Nothing more. Only the name has changed, to be mixed up with frames of reference.

Windtunnels are models. They are not "frames of reference", equivalent to the real world counterparts, but models ONLY. They come in all sorts of shapes and sizes according to need. Belts do not create wind in any windtunnel. Only Spork's treadmill claims to do that, but wrongly so.

What can I say that would change your mind? I mean that literally, H'ethetheth. Can you think of something that would falsify the idea for you? If so, perhaps I can address that, but otherwise, we are talking about F1 cars and second-guessing the application. The photo on the website is a publicity shot. Nowhere in the text does it say that the belt creates wind. There are no instruments attached to the car...

The belt may perform several functions according to its designed capacities.
1. A dyno. The belt drives a dummy load to absorb the engine's output. Variants could test braking and acceleration capacities.

2. A rolling road. The belt is independently driven, so as to drive the wheels. This allows observation of the mechanical components, yet keeps the car in place, perhaps also for cosmetic observation.

3. In combination with wind, allows the simulation of the moving ground below the car, whereas a tethered car does not allow for that interaction, which may be a consideration if ground effect is to being studied. It may not always be necessary to put the wheels on the belt if, for example, the underbelly profile is all that is being studied.
Instruments can monitor air velocity, pressure. Accelerometers may monitor the cars pitch or yaw etc.

4. Any combination of the above.


And a related question:

Say I want to model an aircraft in a windtunnel, yet all I have at my disposal is an aircraft and still air. How do I do this?

Well, a windtunnel that only has still air is perhaps a hanger, but anyway...

What would you model or measure? If it's thrust, then a tether would do, at least in a limited way, but then you need more than the above question allows.

I could make a scale model, and then use the propeller as a wind generator, scaling as appropriate. I could perhaps duct that air, and play it over the surfaces, using smoke or tags to observe the air flow. A jet aircraft may not be so useful in this regard.

I could put the plane on a sled, and then plot the power/drag curves to make some judgment upon that.

Take passengers, earn some money, and hire time in a working windtunnel?

 

[H'ethetheth]

It is not just me, H'ethetheth. Spork and JB have recently quoted academics that state that the treadmill is not as claimed, and not a frame of reference.

"Equivalency" plays no part in the treadmill or the cart. The 'relative' velocities ...[snip]...

Will you just answer the question?

...otherwise, we are talking about F1 cars and second-guessing the application. The photo on the website is a publicity shot. Nowhere in the text does it say that the belt creates wind. There are no instruments attached to the car...

The belt may perform several functions according to its designed capacities.
1. A dyno. The belt drives a dummy load to absorb the engine's output. Variants could test braking and acceleration capacities.

2. A rolling road. The belt is independently driven, so as to drive the wheels. This allows observation of the mechanical components, yet keeps the car in place, perhaps also for cosmetic observation.

3. In combination with wind, allows the simulation of the moving ground below the car, whereas a tethered car does not allow for that interaction, which may be a consideration if ground effect is to being studied. It may not always be necessary to put the wheels on the belt if, for example, the underbelly profile is all that is being studied.
Instruments can monitor air velocity, pressure. Accelerometers may monitor the cars pitch or yaw etc.

4. Any combination of the above.

This whole itemized list of yours has nothing whatsoever to do with my question. It's not a difficult question to answer! Now if you would, please?

Well, a windtunnel that only has still air is perhaps a hanger, but anyway...

Sigh. Seriously...

I'm talking about an operating windtunnel.

I'll rephrase the question below.

What can I say that would change your mind? I mean that literally, H'ethetheth. Can you think of something that would falsify the idea for you?

Yes. Was that supposed to make me think?

You could show evidence that aerodynamic forces differ more than say 10% between the two following scenarios, which, according to my books on physics are equivalent:

(1a) A car rolling on a treadmill in a wind tunnel where the wind speed is -10 m/s and the treadmill speed is -20 m/s.
(1b) The same car on a straight road driving along at 20 m/s in a 10 m/s tailwind.

(2a) An aircraft flying at 200 kph in a 50 kph headwind.
(2b) the same aircraft flying at 250 kph in still air.

(3a) A parachutist falling at 200 kph in still air.
(3b) the same parachutist hovering in a 200 kph vertical wind.

(4a) A wind sock on an aircraft carrier doing 30 kts in still air.
(4b) The same wind sock on an anchored aircraft carrier in a 30 kt wind.

(5a) A wind sock on an aircraft carrier doing 30 kts in a 30 kt tailwind.
(5b) The same wind sock on an anchored aircraft carrier in still air.

(6a) A DWFTTW cart on an aircraft carrier doing 30 kts in still air.
(6b) The same cart on an anchored aircraft carrier in a 30kt headwind.

There's more, if you like. Now, I've answered all of your questions. How about answering mine?Here they are again, rephrased a little to reduce uncertainty/wiggle room:

Question 1: You want to know what happens aerodynamically when a F1 ferrari gets a 150 kph tailwind while travelling at 300 kph. The test track is booked full, and all you have at your disposal are a wind tunnel and a treadmill. Moreover, your boss wants to know the effects of the spinning wheels on aerodynamics.
How would you model this situation? Specifically: how fast is the treadmill running, and how fast is the wind blowing?

Question2: I want to verify lift and drag measurements from the wind tunnel. The measurements featured a full-scale aircraft in various wind speeds. I have at my disposal the same aircraft and still air. How do I do this?

 

[mender]

No, my balance explanation is correct, as you now know. /QUOTE]

Actually, Humber, as you likely would know if you were able to put two and two together, I don't prescribe to your reality. I prefer the world as it really is. To use your own words, most of what you say is not correct, so the remainder is therefore irrelevant.

And having said that, I now join spork and Brian M (and likely others) in ignoring your somewhat amusing tirades. I congratulate you on your obtuse reasoning and hope that you seek professional help soon.

 

[humber]

No, my balance explanation is correct, as you now know. /QUOTE]

Actually, Humber, as you likely would know if you were able to put two and two together, I don't prescribe to your reality. I prefer the world as it really is. To use your own words, most of what you say is not correct, so the remainder is therefore irrelevant.

And having said that, I now join spork and Brian M (and likely others) in ignoring your somewhat amusing tirades. I congratulate you on your obtuse reasoning and hope that you seek professional help soon.

You don't agree with Dan_O, #1961 when he says it is?
I can also answer his question, can you?
ETA:
Sorry if I was flippant in that post, but reading labels?

 

[Dan O.]

It scares me that there are people like humber in the world making decisions that affect the rest of us. Even when everybody else is pointing out how wrong he is, showing the math, showing the physics, showing the video evidence, he sticks to his original decision.

On a forum it's not so bad and even entertaining at times. But when you find one as a manager (or heaven forbid, a president), their perverted reality impinges on our reality.

It's unfortunate that people are anonymous on this board because what I would really like to do is knock humber off his pedestal and send him back to school or at least insure that he isn't in a position to cause harm.


Humber is no longer answering my posts because I ask too many hard questions

Questions like in the equivalency test:

In situation A, we have a cart facing West traveling East to West at 10 m/s on the flat surface of a road and the air moving East to West at 10 m/s.

In situation B, we have a cart facing West on the flat surface of a treadmill where the surface is moving West to East at 10 m/s in a room with still air.

For each situation:

1. What is the speed of the cart relative to the surface?
2. What is the speed of the air relative to the surface?
3. What is the speed of the air relative to the cart?

Referencing only the surface, the cart and the air, what difference exists between situation A and situation B?

Why can't humber answer this?

 

[Christian Klippel]

Why can't humber answer this?

If he would answer that correctly, he automatically has to admit that his thinking was wrong from the start. So he avoids it as much as he can.

If he would answer that according to his stupid view of things, he would make it even more obvious that he has no clue at all.

My guess is that he already knows that he is wrong but doesn't have the balls to admit it. That would pretty well explain his ignorance as well as his avoidance of answering these questions.

Greetings,

Chris

 

[tsig]

You've got that backwards. The propeller is turned by the ground pushing at the wheels.

The wind does not turn the propeller.

All velocity is relative.
Relative to the cart, the ground is moving.
The cart harnesses power from the motion of the ground (like a windmill harnessing power from the motion of the air) to spin the propeller which pushes it along through the air.

So the motion of the cart spins the propeller. The propeller moves the cart that spins the propeller.

 

[H'ethetheth]

So the motion of the cart spins the propeller. The propeller moves the cart that spins the propeller.

Why would you leave out the wind?