Down wind faster than the wind

[CORed]

This question has been answered, but here it is:

(1) It's very difficult to control the circumstances, and

Yes, outdoors, the wind gusts, and the ground is rarely perfectly level.

(2) it's virtually impossible to do it in such a way that a video will satisfy skeptics.
For instance, I would guess you weren't satisfied with the video of the big radio-controlled cart outside with the wind sock.

You can never rule out the possibility that a video was faked in some way. One of the few things that Humber has gotten right was when he said that the wind sock on the outdoor cart was too close to the propeller. It was hard to tell whether the sock was blowing backwards (relative to the cart) because the cart was moving faster than the wind, or because the backwash from the propeller was blowing it back. Besides with the outdoor test, even assuming no deliberate fakery is going on, you can't rule out the possibility that the cart is going downhill, or coasting on momentum from a gust. Nonetheless, I would like to see somebody build one of these things that's big enough to carrry a rider. Then give Humber a ride on it. I'm guessing he still won't believe it's moving faster than the wind.

(3) The treadmill is equivalent to the point of being identical, plus it's easy to control, and easy to present.
The only problem is that not everyone understands that (3) is true.

[/quote]

That is the one thing about this discussion I just don't get. I really don't think Humber is deliberately trolling, though it's impossible to know without reading his mind -- something I wouldn't want to do even if I could -- but it just blows me away that he can't grasp the (to me) obvious concept that the treadmill belt moving relative to the air is equivalent to the air moving relative to the ground. A longer treadmill would be nice: you could demonstrate self-starting, and make a more convincing demonstration of going downwind faster than the wind, but the only way to do it would be to build your own or buy some sort of industrial conveyor belt. Either way could get kind of expensive for a hobbyist. A turntable really doesn't work that well, as it is non-inertial, and moves at different speeds depending on radius, introducing a whole lot of complications.

Actually, I find the thing a lot easier to understand from the treadmill frame of reference: Belt drives wheels, wheels drive prop, prop generates thrust to pull cart in the opposite direction of belt movement. When I think of it as wind driven, it gets a bit confusing to me (although the parachute and yo-yo models, and the chain and cogwheel models help). But unlike some, I do understand that if the cart can move "upbelt" on the treadmill, it can move downwind faster than the wind on the ground.

If I ever have enough spare cash, and (more difficult) time I'd love to build one that would carry a rider. Then I'd find the guy I've seen in the park near me with a sailboard on wheels and race him. If I can catch the day when the wind is blowing in exactly the right direction, I'll win.

 

[Christian Klippel]

If I can catch the day when the wind is blowing in exactly the right direction, I'll win.

Hello CORed,

that's a nice comment which reminds me of a question that i wanted to ask quite some while ago:

Actually, how "direct downwind" must the wind be? That is, what angles not directly in-line with the cart's movement are allowed to still have it work properly?

I'm really thinking about to build such a cart and put it outside to film it, preferably from several angles at the same time. We have quite some big abandoned industrial places here which have big, flat areas in them. So i'm curious about how much tolerance the cart allows with respect to the direction of the wind. It's quite hard to find a situation outside where the wind always blows in the exact same direction.

Maybe Spork or TAD have an idea/suggestion for this?

Michael C., if i may ask, in what area of Germany are you located? If not too far away, maybe we can put our efforts together to get a nice video done showing the cart in "real action" outside? Or anyone else here from Germany who lives roundabout in my area?

Greetings,

Chris

 

[CNY_Dave]

OK, have been following this fairly closely but with the 2341+ replies have lost track of the consensus- does it or doesn't it? (Looks like a no as far as I can track it)

I know that whenever you have a system, and add energy to that system, you can get some counter-intuitive things to happen, but for a cart going DWFTTW, directly downwind, I'm not seeing a mechanism to allow it.

Cart's going downwind at windspeed, prop geared 'up' or geared 'down', prop blades pitched steeply or not much (that is, prop is producing thrust or is spinning too slowly to do so), I can imagine optimizing this to get the cart pretty darn close to windspeed, but at cart-speed = windspeed I just don't see how energy is being added to the cart.

Am I looking at this just too bloody simplistically?


Treadmill, interesting case, but I think I want to consider that as separate and non-equivalent for the time being.


Has everyone had a look at scienceblogs.com /goodmath/2008/12 /the_real_bozo_attempts_to_aton.php ?

In a way a fetching and persuasive explanation, but I think it goes off the rails in there somewhere.



Background- Electrical engineer, aced physics and 2 classes of thermodynamics (long ago in a classroom fairly far away).


Dave

 

[Michael C]

Why are you so reluctant to test your wind device in the wind?

All tests are done in the wind, as can be seen in the videos.

 

[Michael C]

OK, have been following this fairly closely but with the 2341+ replies have lost track of the consensus- does it or doesn't it? (Looks like a no as far as I can track it)

I know that whenever you have a system, and add energy to that system, you can get some counter-intuitive things to happen, but for a cart going DWFTTW, directly downwind, I'm not seeing a mechanism to allow it.

Cart's going downwind at windspeed, prop geared 'up' or geared 'down', prop blades pitched steeply or not much (that is, prop is producing thrust or is spinning too slowly to do so), I can imagine optimizing this to get the cart pretty darn close to windspeed, but at cart-speed = windspeed I just don't see how energy is being added to the cart.

Am I looking at this just too bloody simplistically?

Yes. Remember, the relevant law is Conservation of Energy. There is no law of Conservation of Velocity!

Note that the wheels of the cart are geared to the prop so that it is extracting energy from a mass of air moving relative to the ground. As long as the cart has contact with both air and ground, this energy is available, no matter at what speed and in which direction the cart is moving.

Has everyone had a look at scienceblogs.com /goodmath/2008/12 /the_real_bozo_attempts_to_aton.php ?

In a way a fetching and persuasive explanation, but I think it goes off the rails in there somewhere.

The bozo got the mechanical cart completely wrong. Afterwards he has a good "intuitive" grasp of the wind cart, but doesn't actually give a solid mathematical analysis. Have a look at Thabiguy's posts here and here for some maths, or this page for a good explanation

 

[Michael C]

Michael C., if i may ask, in what area of Germany are you located? If not too far away, maybe we can put our efforts together to get a nice video done showing the cart in "real action" outside? Or anyone else here from Germany who lives roundabout in my area?

I'm in Mannheim, so the Ruhrgebiet isn't too far away: if you make a DDWFTTW cart I'd be very interested to see it in action and collaborate on a video.

Have you seen Spork's parts list? I've no idea how easy it is to find the corresponding bits and pieces here in Germany.

As to the wind direction, I understand that the cart is designed to work best when it's really travelling directly down wind.

 

[ThinAirDesigns]

Cored:

One of the few things that Humber has gotten right was when he said that the wind sock on the outdoor cart was too close to the propeller. It was hard to tell whether the sock was blowing backwards (relative to the cart) because the cart was moving faster than the wind, or because the backwash from the propeller was blowing it back.

Nope, you're both wrong there. If you watch the early portion of the Goodman video (with his wife in the frame and other early footage), it's easy to see that the streamer is directly off to the side and far away from any potential prop wash.

If you look at that footage and don't agree, I will post screen shots to show it.

JB

 

[H'ethetheth]

Hi Dave. Welcome to the forum!

Treadmill, interesting case, but I think I want to consider that as separate and non-equivalent for the time being.

Why?

 

[CNY_Dave]

Hi Dave. Welcome to the forum!Why?

Haven't convinced myself its equivalent, so just want to focus on the primary case.


Dave

 

[Michael C]

Haven't convinced myself its equivalent, so just want to focus on the primary case.

In order to grasp how the cart works, it's essential to look at the relative motions between cart, air and ground. Understanding the treadmill situation can help in understanding how the cart works on the open road.

 

[CNY_Dave]

In order to grasp how the cart works, it's essential to look at the relative motions between cart, air and ground. Understanding the treadmill situation can help in understanding how the cart works on the open road.

OK, I think I have my head wrapped around the cart in the open OK at this point (rolling ferris wheel was a good example), haven't translated that to the treadmill example to my satisfaction.

So in the open air case its all about air coming in from the back and hitting the prop (so to speak), as opposed to the prop spinning fast enough to suck air in from the front (to speak grossly).

I think then there's a simpler analogy to use for the cart in the open- that of a sail near the front of the cart, cart is going at just about windspeed, and then some mechanism on the cart just moves that sail towards the rear of the cart fast enough that the sail 'sees' some wind from behind the cart. The sail 'sees wind' from the rear, and the mechanism pushing the sail rearwards of course pushes the cart forwards. Get 2 of these sails on a moving belt driven by the wheels, fold 'em down or shield them from the air as they move forwards on the bottom part of the belt and I think the analogy holds nicely.

(I'm deliberately not phrasing this very scientifically because then it wouldn't help to explain it to someone else)

You can then think of the surface of the propeller (let the 'point' where an individual bit of wind hitting the propeller slide across the propeller, the wind doesn't care) of as a sail that's moving backwards. Look at it this way- if you spin the prop, and shine a laser pointer on the prop, it looks like the red dot is moving backwards relative to the cart.


Now hopefully I don't have that completely backwards.


Dave

 

[CNY_Dave]

Having just read the 'tumbleweed' paper, I see I've just re-invented the basic principle of his tumbleweed..

Ah well, I just have to remember, I'm unique just like everybody else

Would a tumbleweed go forwards on a treadmill, though?


Dave

 

[HighRiser]

I tested my Lego cart on the treadmill this evening. No advance with this 12-06 prop at any speed up to 12 mph. Hopefully my hobby shop will have a 12-04 tomorrow.

 

[John Freestone]

Hello John,

would be quite some fun to compile a "best of humberphysics" and put it online somewhere together with the original quotes from humber, quotes of the messages they refer to, and an explanation in what these humberphysics would actually result in the real world, if they were true.

You know, like this thing with the bullet, props that do no work anyways, stiff propshafts that act as a torsion spring, lightweight plastic props that seem to store heavy amounts of momentum like a big flywheel, gravity working on something to actually make it go upwards faster, brakes that improve the performance of car(t)s, etc.

That would surely make a darn good "book of jokes" to make every sincere person laugh. Some kind of geek-jokes, you know...

I would contribute web-space for that. Any takers?

Greetings,

Chris

Edit: Lets not forget the thing that wheels that slip on a surface can transfer enough energy into the heavy prop-flywheel to make the cart climb against the moving and inclined treadmill using the same slippy wheels.

Hi Christian

I know what you mean, but I don't want to do anything like that, at least not outside the forum. Despite being angry with Humber because of his obtuseness, and being motivated to push him to see if I can get actual answers to some of those humberphysics problems, and attacking him quite remorselessly at times because I think he is being dishonest, wasting people's time and trolling, I am also not out to hurt him, and even feel quite sorry for him. I have no desire to mock him publicly any more than I feel he brings on himself, and in this thread that feels acceptable (and only just acceptable) for me to do.

In saying that, I don't mean to criticise you or have a holier than thou attitude. Only a few days ago I wanted to collect his stupid physics together into one post too. Maybe we're all on different paths here - some have written him off earlier and now have him on ignore - I may get there later myself. Others are still trying to have sensible conversations with him, like H'ethetheth, and fair play to you H. I'm just going through the angry stage, or just did. Now maybe I'm just giving up. I'm also a bit concerned that his mental health might be more delicate than I imagined, and wondering if he might be more genuinely stupid than I thought, and less deliberately deceitful.

Still, if he's dug a hole for himself and is now suffering terrible angst as he tries to save face, he could just stop coming here and forget about it. He could just be a sociopath, just chuckling as he makes up his next piece of nonsense, not meaning any of it. He could be clinically insane. He could be incredibly badly educated (and yet he seems to be able to sketch reasonable diagrams of force vectors when he wants to - better than I'd know how to do). I have to keep at least a tiny crack of my mind open to the possibility that somehow all his ideas will be proved right in the fullness of time, or I'm not a sceptic. I also have to admit that without his distractions I'd find a lot less of interest here - Humber's pathology, whatever it is, is almost as interesting as the cart. But then I feel apologetic towards those who want to deal only with the cart.

Britnney Spears? Grow up.

Humber, it doesn't really matter whether I have a roomful of britnney posters or play horses with my friends in my bedroom. Once again you are not addressing the logical consequences of your strange imaginings, unclear expressions and infantile physical understanding of the world. My "Oh my God!" was just an arbitrary expression of disbelief and exasperation that you could criticise spork for suggesting that scenario of the bullet, off-hand, as if you genuinely had no idea of relative speeds.

And once again, if I am to try to divine any meaning from your response, it seems that you are suggesting that you did know about relative velocities (although, again, you fail to be specific).

If you understood the point, you would not have said that tsig pushed spork into making such a stupid statement about the bullet.

Or if I have misunderstood, and you weren't saying that spork's statement was stupid, then it is odd that you fail to clarify my mistake, and focus instead on telling me that you did know what you demonstrated you didn't, as well as the suggestion that I'm a teenage girl.

Your descent into more and more childish forms of argument mean that at some point I have to just back off, not because I'm wrong or have anything to hide, but because I don't want to contribute to your meltdown or unnecessary humiliation.

On the other hand...

It appears that you hold the position that for a given speed, the cart advances faster when the treadmill is placed in an inclined position.

Correct?

JB

It would be gratifying for those you have criticised, sidetracked, insulted, irritated, angered, worried, confused and generally caused problems, if you would actually put your cards on the table, make a clear prediction, agree to a test of it, and then be shown to be utterly and completely wrong, even if you refuse to accept the validity of the result, which I imagine you would. Nice one JB, I'm all for that.

 

[Christian Klippel]

Hi Christian

I know what you mean, but I don't want to do anything like that, at least not outside the forum.

Hello John,

that's fair enough and i have to agree with what you said. It's just that it occurred to me that it would make a good example of "If you don't know what you are talking about, don't talk at all. Otherwise people will have a lot of fun about you."

But i admit that i might have "overshot" a bit.

Time will tell what happens in the end.

Greetings,

Chris

 

[John Freestone]

Oh, Christian, if you're compiling a Humbertronics manual anytime, don't forget the one about the clockwise-anticlockwise rotation! From an uninformed mortal's reading of Humber's text, he seemed not to realise that clockwise-ness or CCW-ness does not specify unambiguously the direction of rotation of a wheel. Obviously he would know that. Once again it must be our mistake to think he could be so thick. Several attempts were made by me and others to explain this point to him, and I don't think he ever commented on it. He has, however, not bothered to describe wheels' motion as clockwise or counterclockwise since.

You know, it would be fascinating to catalogue as you suggested, and a lot of fun. I just wouldn't want to export it to somewhere else. I'll keep pointing out how ridiculous his ideas are in this thread anyway, and if you want to turn it into a Broadway Musical, I'll book tickets.

Greetings
John

 

[Christian Klippel]

I'm in Mannheim, so the Ruhrgebiet isn't too far away: if you make a DDWFTTW cart I'd be very interested to see it in action and collaborate on a video.

Have you seen Spork's parts list? I've no idea how easy it is to find the corresponding bits and pieces here in Germany.

As to the wind direction, I understand that the cart is designed to work best when it's really travelling directly down wind.

Hello Michael,

ah, i see. Yes, i have already seen the part list, build plans, and so on. This happens "autmagically" once you search the net for this topic. Also, i guess i have completely read almost every thread about this topic, and also wrote a few replies at places other than this forum.

I have a "Modellbauladen" a few streets away that i'm going to visit next week or so. I will ask Spork to send me the parts if they can not be found easily. After all it's only ~40$ plus shipping, and as we know the Dollar is quite low compared to the Euro these times.

Yes, the wind direction would be best if it is the same as the cart moving. But alas, this is a somewhat dense populated area, and buildings will have an impact on the airflow. I have a horse-racing track around the corner which also has a big parking lot. Finally, i know of some quite long "streets" which are pretty flat and open, but have no car traffic. In any case, i would prefer an industrial site if possible, because they are _huge_, no traffic and also make for an interresting background in the video. Look up "Zeche Zollverein", i'm an 20 minute walk away from that one. If you take a look on Google Maps, you can see that it is really, really huge.

After all i think the only way to settle this case is to really make a bullet-proof video, together with cart- and wind-speed measurements. Since my work is designing electronic circuits and programming, it would be easy for me to make the tools to collect the relevant data myself. They need to be small and lightweight, since the cart is small and i'm not sure if it's performance would suffer if there is too much payload. Using an pressure sensor (MPXV7002) that can do positive and negative air pressure (it has two ports), it would be easy to record the wind and how it's direction changes relative to the cart if it transitions from slower-than to faster-than the speed of the wind. Also, using an encoder disc on a wheel (doesn't need to be disc, markings on the wheel are just fine) and a reflective sensor makes speed-measuring of the cart easy.

I'll think about all that more next week when i have more time for that, since i'm quite busy currently. If you want we can start a private e-mail exchange on this then, maybe together with Spork and JB.

So long,

Chris

Edit: It might be possible to use one of the old mining-shafts at Zollverein to conduct the test. That would guarantee a steady, uniform wind since in fact it is something like a wind tunnel. But i would have to ask the people there first, since the shaft's are closed to the public because of safety concerns. Also i think they have some rather steep inclination, but i have to check.

 

[Christian Klippel]

Oh, Christian, if you're compiling a Humbertronics manual anytime, don't forget the one about the clockwise-anticlockwise rotation! From an uninformed mortal's reading of Humber's text, he seemed not to realise that clockwise-ness or CCW-ness does not specify unambiguously the direction of rotation of a wheel. Obviously he would know that. Once again it must be our mistake to think he could be so thick. Several attempts were made by me and others to explain this point to him, and I don't think he ever commented on it. He has, however, not bothered to describe wheels' motion as clockwise or counterclockwise since.

You know, it would be fascinating to catalogue as you suggested, and a lot of fun. I just wouldn't want to export it to somewhere else. I'll keep pointing out how ridiculous his ideas are in this thread anyway, and if you want to turn it into a Broadway Musical, I'll book tickets.

Greetings
John

Hello John,

yes, indeed he avoids to comment on things that point out his obviously flawed thinking. In any case, for now i will try to find some time to prepare a real-world cart test, and as it seems Michael C. is interested as well. However, i'll sure as hell will collect the proper quotes and stuff to make a compilation some day.

Have fun, greetings,

Chris

Edit: Also worth noting is that initially, he talked about the wheels slipping and skidding, saying that this would be a somewhat integral part of the cart doing what it does. However, in a recent post he said that "(2) Wheels are slipping ( probably not)..." after it has pointed out to him in various ways and various people that the wheels do not slip. But indeed he never actually answered any direct comments to that effect, saying that he might be wrong. About the prop acting as a flywheel he didn't said much recently either. Oh well, the wonderfull world of the humberverse, where prop airplanes could never start, gravity helps to make things move faster upward, etc, etc....

 

[Dan O.]

Humber, where is your testable model?
Everybody else, please don't feed the trolls.

 

[John Freestone]

Humber, where is your testable model?
Everybody else, please don't feed the trolls.

Sorry, Dan, but maybe you should think about those sentences again.

ETA: Sorry if that was a bit curt, but what I mean is that I don't think that asking for Humber's testable model is any less feeding the troll than a longer analysis of his writings here, a thorough criticism, trying to have a conversation with him, as H'ethetheth does, or asking him to provide answers to qute a number of questions raised by his assertions that he hasn't answered.

I also think it is fair, given the controversy around the issue and the number of newcomers to mechanics who happen upon this, to keep up the pressure on him. I'm open to the idea of us all ignoring him, but even then there's no certainty he won't respond to that by posting more.

Probably someone should nail him to a large treadmill and ask him if he's enjoying the breeze.