Can a simple craft (consisting of a fan geared up to a skateboard) go “directly down-wind faster than the wind” (without any additional power source, tricks nor wind fluctuation)?
Get a bowling ball.
Then get a really, REALLY, powerful leaf blower.
Push the bowling ball down the street with the leaf blower.(might take half an hour or so....)
When the camera is off, run in front of the bowling ball, throw leaves in front of the camera, turn on the leaf blower showing the bowling ball rolling down the street AGAINST the wind.(as indicated by the direction of the leaves)
It is true. Trust me. Things can go faster than the wind.
please don't ban me, please don't ban me, please don't ban me. ;)
Give me a break, I'm a physicist not an engineer.If you change skateboard to cart on wheels [..] I'd agree
His "My Way" isn't really a "discussion", is it?Russ has made it clear to me that he will only allow discussion in his thread only on this subject
I think that counts as "tricks or wind fluctuations", are you changing your vote?When the camera is off[.. suddenly move the leaf blower..] Things can go faster than the wind.
No it certainly is Not a discussion! I have had remarks taken badly out of context and it is very clear Russ is too biased in the matter to fairly moderate a controlled thread. I did open a new thread with links to my drawings but it was deleted and I was given an infraction (right across the wrist) ooooh that hurts. Seriously, I am glad you started this new thread but I doubt it will last long.His "My Way" isn't really a "discussion", is it?
I think that counts as "tricks or wind fluctuations", are you changing your vote?
In reference to your claim that the prop has somehow been switched during an edit, have a good look at this video, where it is very plain to see that the prop starts in a particular direction and powers the cart against the treadmill. As the cart is lifted and the prop slows down again, you can see that the prop is still turning in the same direction, and you can see the direction of the blades of the prop and that the wheels are fixed to the prop and all are turning the right way.Why is it, at the very end of the video, when the cart slows down and we can finally get a chance to see which way the fan is turning, the cart goes OFF CAMERA? The ONLY place in the entire video where this happens! Hell of an accident or coincidence? That video is a hoax and a very poor one at that.
I'm glad to hear that. I was really getting worried.Mender, a cart on the treadmill with a properly pitched propeller will advance. I agree with that.
Look very carefully at all the videos. It clearly is the same, which is why I went to all the trouble to find them for you.I am saying the pitch is not the same in each instance.
I was working with reference frames probably before Russ and you were born! If the prop pitch changes for any reason between frames the frames are not equivalent! You cannot fly a broad sail in one frame and a spinnaker in another! And since the frames are not equivalent, you cannot draw any conclusion about what will happen in one frame by makeing observations in the other. Are you willing to perform the demonstration as I delineated it or not?As I already asked, what are you basing that on? If it is because your logic dictates that because you have convinced yourself that this is impossible (which you have), you are presenting your case based on circular logic, not observation. You can prove anything with circular logic and a blind eye to what you don't want to see, and nothing will be proof enough for you.
What would convince you that the cart is now doing the impossible and moving faster than the wind that is powering it? Seriously. How would you prove beyond a shadow of a doubt that the cart reached and exceeded the wind speed?
I really hope Russ is able to clear up your problem with equivalent frames of reference.
Ok well this is a big change of heart. I thought this was the crux of the claim for DWFTTW. Are we now just discussing whether or not such a contraption can be self starting or not?Mender, a cart on the treadmill with a properly pitched propeller will advance. I agree with that.
There you go again! Why don't you answer my question for a change? What makes you think that the prop gets changed other than your circular logic?If the prop pitch changes for any reason between frames the frames are not equivalent!
And since the frames are not equivalent, ...
That IS the critical question Uart. Thank you for asking it. Yes it matters greatly how the cart is configured. Mender, Spork et all go to great pains to emphasize that the reference frames are equivalent. Indeed, the frames themselves are equivalent. But the cart or boat or whatever is IN the frame must also be exactly the same in both frames. You can’t have a sail boat in one frame and a motor boat in the other, for example. ALL the evidence for DDWFTTW is based on a cart advancing on a treadmill. Then that evidence is used to prove that a cart can advance DDWFTTW. There is no evidence to support that claim other than the treadmill evidence. As I said, with a prop of a certain pitch, a cart can advance on a treadmill. In order for anyone to use that evidence that it can also go down wind, the prop pitch must be exactly the same as on the treadmill. If the pitch is changed to go down wind, the treadmill evidence means nothing as you are essentially comparing two different machines. Please consider that carefully.Guys the argument seems to have shifted. Does it really matter if the device needs to have a variable pitch in order to self start and also to achieve DWFTTW (I'm not saying that it does need this, just that even if it does then it doesn't in any way invalidate that fact that DWFTTW is possible does it?)
I think he was getting at the situation where the cart is well below wind speed, in which case the prop acts as a bluff body (sail). Assuming the cart is geared properly for DDWFTTW, then the prop never acts as a turbine unless the driving wheels are sliding forwards.The prop on the back of the cart acts as a propeller at all times the cart is approaching, at or above TWS.
Well, I can't say for sure what he thinks, except that for some reason he thinks that the pitch is changed between treadmill and street -- something that just isn't true.I think he was getting at the situation where the cart is well below wind speed, in which case the prop acts as a bluff body (sail).