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| Mess with your minds: A wind powered craft going faster than a tail wind speed. |
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| Kleinstein:
It is a false assumption that one can not extract emergy from the wind when moving faster. It may be against intuition of a simple mind, but it works. The blckbird vehicle demonstartes it and the in the video there is a an explaination on how it works. The explaination does not need energy storage. The concepts with energy storage does not work, there is just no significant energy storage. The litter energy storrage that may be there is good for a few ms to maybe 1/10 s a second, but that's it. So the idea does not work to explain the observation. Just claiming that the vehicle can not harness the energy from the wind when going faster is not a valid argument. Relative to the vehicle the air around it will move in the opposite direction, not just from the speed of the vehicle, but also from the prop. Energy is used to move the wind that way even faster than just from the difference in velocity. So just looking in the reference system of the vehicle, the prop does not get energy from the wind, but it creates force or thrust in the forward direction. In the vehicles reference system the wheeels are harnessing power from the ground moving relative to the vehicle. The surprising point is that the wheels can generate more power than is needed to drive the prop. It may help to understand the concept of force for this. |
| electrodacus:
--- Quote from: dunkemhigh on September 17, 2021, 03:03:09 pm --- --- Quote ---since the wheels are connected (by an elastic rubber band) --- End quote --- Don't use an elastic band - it is introducing something that's not necessary and just confuses things (such as, allowing you to claim energy storage). Ideally use a toothed belt, but failing that a tight piece of string would be better. --- End quote --- The rubber band just shows the effect more pronounced and I tried to build one using gears only but due to the toy nature of my cart there was still significant amount of energy storage in the vehicle body flex that can be seen in the video I just posted. Not sure how low the energy storage capacity will need to be for the vehicle not to advance forward but if energy storage will be zero then is guaranteed that vehicle could not move in the opposite direction of the paper road. So basically the back wheels are in locked and the front wheel will start to store energy until they slip and in that moment because of the stick-slip hysteresis the vehicle can advance a bit forward then front wheel can start storing energy again and process continues. So the movement is not smooth it is start/stop multiple times much more visible in a vehicle with a soft and long rubber band and less visible the stiffer the belt is as the start/stop frequency will be much higher and could only be seen by a high speed camera. If there was no storage at all then front wheel could not move without the back wheel moving so then either the front of the back wheels will just slip continuously and there will be no forward movement of the vehicle. https://odysee.com/@dacustemp:8/wheel-cart-energy-storage:3 |
| PlainName:
--- Quote ---still significant amount of energy storage in the vehicle body flex that can be seen in the video I just posted. --- End quote --- Well done for posting the experiment. The lack of wheel grip was expected. I wouldn't have called it energy storage, but I suppose you could get away with that, despite the amount being trivial. --- Quote ---So the movement is not smooth it is start/stop --- End quote --- Can you point to any part of this discussion that demands the progress be actually smooth rather than having the appearance of same? AFAIA, the requirement was simply that the vehicle moves left to right, something you insisted was impossible. More importantly, whether or not it does that in a hop, skip or jump, it will continue to do so for as long as the paper lasts (or forever if on a treadmill). Your supposition, as I understood it, was that such effects would be temporary and last only as long as the initial energy storage could give a boost. |
| electrodacus:
--- Quote from: dunkemhigh on September 17, 2021, 05:04:53 pm --- --- Quote ---still significant amount of energy storage in the vehicle body flex that can be seen in the video I just posted. --- End quote --- Well done for posting the experiment. The lack of wheel grip was expected. I wouldn't have called it energy storage, but I suppose you could get away with that, despite the amount being trivial. --- End quote --- Energy storage is done in yellow rubber band for first vehicle and in frame torsion in the second vehicle. --- Quote from: dunkemhigh on September 17, 2021, 05:04:53 pm --- --- Quote ---So the movement is not smooth it is start/stop --- End quote --- Can you point to any part of this discussion that demands the progress be actually smooth rather than having the appearance of same? AFAIA, the requirement was simply that the vehicle moves left to right, something you insisted was impossible. More importantly, whether or not it does that in a hop, skip or jump, it will continue to do so for as long as the paper lasts (or forever if on a treadmill). Your supposition, as I understood it, was that such effects would be temporary and last only as long as the initial energy storage could give a boost. --- End quote --- I was pointing out the non smooth nature of the movement so that you can see that energy is stored then released so there are micro cycles of storing energy then releasing. Of course being able to break the back wheels (even if that if from friction only) and then produce energy on the front wheel and store that energy then latter release that to move a bit forward will not brake any laws. What you (most of you) where saying is that an ideal vehicle with no friction and no energy storage can advance forward and that is not the case. This combination of friction (back wheel locked) and the energy storage device allows you to store energy then use that to advance a bit forward. Is fairly similar to how blackbird will work is just that energy storage is order of magnitude larger so to see that store then hop to above wind speed then drop below wind speed and charge again are at a much larger time scale. So is like you had seen just a small fraction of my video in super slow motion and then you will think the same as you think about the blackbird. As most of you say the blackbird will stay above wind speed indefinitely (incorrect) while I say blackbird will stay above wind speed only as long as there is still stored energy so depending on vehicle construction (amount of energy that can be stored and vehicle friction losses) from a few seconds to a few minutes. |
| electrodacus:
Here is a slow down version of the first belt type vehicle to best observe what happens and you can even slow down to 0.25x from the video player menu. https://odysee.com/@dacustemp:8/wheel-cart-energy-storage-slow:8 Is fairly clear that vehicle stores energy and when that is large enough the vehicle will use it to advance forward. Motion seems smoother the smaller the storage capacity is since charge discharge cycles happen faster than our brain can perceive. Without any amount of energy storage the vehicle will not be able to move forward left to right. |
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