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| Naej:
--- Quote from: electrodacus on July 14, 2022, 12:29:06 am --- --- Quote from: Naej on July 14, 2022, 12:05:15 am ---Yes. Completely and utterly irrelevant. Wind mills provide more power that you put in (0W). You're trying to disprove what thousands of physicists understand, and what was experimentally proven. Obviously you're just making mistakes. So stop lying to yourself about your understanding of energy and start learning. --- End quote --- If you think treadmill powers the vehicle explain to me how it will do so. It will push against what ? --- End quote --- Air. Can't you see the propeller? --- Quote from: electrodacus on July 14, 2022, 12:29:06 am ---Why is the fact that a wind turbine traveling at wind speed produces nothing ? It just shows that there is zero wind power when vehicle speed equals wind speed direct down wind. --- End quote --- No. See if I burn 1L of gasoline it won't propel anything. It doesn't mean there's no energy in it, it means that the device is inefficient for a conversion to kinetic energy. And if you replace the turbine by a prop, it works, a proof that 1/2*m*v² continues to work. --- Quote from: electrodacus on July 14, 2022, 12:29:06 am ---If thousands of physicist think that a direct downwind vehicle is powered by wind while above wind speed they should find a different job. --- End quote --- Yeah they don't care about your advice. --- Quote from: electrodacus on July 14, 2022, 12:29:06 am ---I can consider myself and expert in energy generation and energy storage so I have a very good idea of what energy is. Your only understanding is based on the results on some incomplete experiments. The blackbird excuse was that it was running out of road and needed to stop and the treadmill is way to short to see the vehicle slow down fully. But you can see in any video how the rate of acceleration slows down. --- End quote --- Yes the rate of acceleration slows down. Not the speed. --- Quote from: electrodacus on July 14, 2022, 12:29:06 am ---You still did not provided a mathematical proof (nobody did). You showed an equation that was not only wrong but also predicted zero wind power when vehicle speed equals wind speed. Not to mention that equation was your invention as nobody ever uses that equation for anything. --- End quote --- It is correct, and an approximation as I already explained. Also it is easily derived and you found no problem either with the mass flow or with the kinetic energy part. I also provided you a mechanical example (since you're confused by hydrodynamics), and you found no problem either. --- Quote from: electrodacus on July 14, 2022, 12:29:06 am ---While the wind power equation I provided is used by basically everybody in a large range of applications. Want to know how much wind power a sail vehicle has to be able to calculate how fast it accelerates you use that equation. Want to know how much a wind turbine will produce again the same exact equation. Want to know the power needed to overcome drag for any vehicle you use the exact same equation. The range of applications is huge and it includes both versions of blackbird. All you have is words and you are unable to make any sort of predictions. --- End quote --- As I said what you call your equation is true, however it is in the car reference frame. And in the car reference frame, ground has kinetic energy, which is obvious but you refuse to admit it. I can make the following prediction: if you build the blackbird, or the treadmill model (without supercapacitors) you'll be able to go faster than the wind/treadmill. Also, all physicists who looked at it understand this. All you have is your wrong conceptions about a very abstract concept called energy, which presumably come from looking at batteries. It's hardly convincing. |
| electrodacus:
--- Quote from: Nominal Animal on July 14, 2022, 12:39:30 am ---No, that's just what I know when trying to model physical phenomena. My own scientific field is molecular dynamics modelling software and their development –– i.e., I'm a toolmaker more than I use those tools to do research ––, and this sort of thing, or oversimplified models and trying to find the correct complexity level where things are still understandable and simulatable, but not so simple that they no longer reflect reality, is a daily encountered problem. Like I said, I am not interested in the equilibrium case. To me, it's like investigating automobile fuel consumption by assuming that all roads are straight without intersections and all travel at the posted speed exactly. In the real life, different types of vehicles' fuel consumption varies very differently due to repeated accelerations and decelerations, which is the reason why fuel mileage is usually reported separately for "city driving" and "long-distance driving": one being constant acceleration and deceleration, the latter with relatively stable speeds. Those who teach economical driving, always emphasize how big of a beneficial impact keeping to a constant speed makes. To put it more simply, the case where the vehicle is traveling at exactly the speed of wind is not interesting. Instead, divide the examination into two: One, when the vehicle is traveling slower than the speed of wind. Parametrise the scenario, and especially examine how acceleration changes as the vehicle speed approaches wind speed. Two, do the same examination, but in the case where the vehicle is already traveling faster than the speed of wind. Next, using the parameters (coefficients and such) you established, find out if and when the vehicle already traveling faster than the speed of wind can keep a nonnegative acceleration (ie., zero or positive). The equilibrium case, where the vehicle has exactly the same speed as the wind, has zero acceleration, and has no exploitable energy storage, just doesn't happen in nature: it is an unstable state, and will always fall into one of the above two cases, sooner or later. If, and only if, it turns out that the vehicle has always nonpositive acceleration when already traveling faster than wind, will that unstable state always fall to the lower speed side, and only then is it impossible for that vehicle to travel directly downwind faster that the wind. If you can find a mechanism or model and parameters, where the vehicle can keep a nonnegative acceleration while already traveling faster than wind, then that vehicle can keep traveling faster than wind almost indefinitely (barring similar unstable points, possibly an infinite number of them, as the exactly-same-speed-as-wind case). So, as unintuitive as it might seem, the entire scenario seems to depend on exactly how the vehicle behaves when it is already traveling faster than wind directly downwind. In my mind, this is well in the realm of fluid dynamics; and indeed if a simple propeller-like arrangement can achieve that, the actual underlying mechanism is almost certainly more interesting than just flywheel-like energy storage. I wouldn't trust a treadmill (either way!), because the static charge buildup in the belt can cause all kinds of wonky stuff. Depending on the materials, it can act like a big but not very good Van De Graaff generator, for example. I'm not making any such claims, for or against. I am saying you are looking at the issue from the completely wrong angle. The exact point where the vehicle speed matches wind speed is an unstable point state, which will immediately change. It is not interesting or useful to examine it, at least not before you have some kind of models that describe the two different situations around that state, depending on the speed. I'm not saying anyone is cheating, either, but it would be easy to do, even unwittingly. You might make a very lightweight vehicle, but use heavy natural rubber wheels, which would definitely behave like an energy storage (flywheels, literally). A model that can describe multiple different such vehicles is the way to go. Note that since the faster-than-wind-speed case is critical, it is not sufficient to show one model that works that shows it cannot be done; that only proves that that vehicle cannot do it. Considering sail boats (that can jig faster than wind nearly-downwind), I suspect it is possible, certainly possible enough to do research on, but I wouldn't be overly surprised to find out it would be unfeasible somehow either, say requiring a 1m long but 100m wide vehicle, for example. Some kind of vertically rotating wane system would be what I'd look into myself, simply based on existing sailing techniques. --- End quote --- The vehicle speed = wind speed is just the ideal case with no friction and can not be demonstrated in real life for any wind powered only vehicle. To me all is very simple as I work with energy all the time. Equation for available wind power is independent on the vehicle design other than the equivalent are of the vehicle hit by air particles as that is the only way wind will transfer energy to a vehicle (air particles colliding with vehicle). Pw = 0.5 * air density * area * (wind speed - vehicle speed)3 The equation is the ideal case so of course friction will not allow any wind powered vehicle to exceed wind speed directly downwind as a few particles will still need to collide with the vehicle body in order to cover the vehicle friction losses thus vehicle speed will be significantly lower that wind speed. That (wind speed - vehicle speed) is there to show that the wind speed relative to vehicle is what important so for example if vehicle travels perpendicular to wind direction then wind speed relative to vehicle will always be the same no matter the vehicle speed and so vehicle always has access to max amount of wind power as air particles will hit the vehicle from the side. Of course as soon as you add any sort of energy storage device can be a rechargeable battery or what is actually used in this case pressure differential the vehicle can store energy while below wind speed and use that stored energy to significantly exceed wind speed but only for a limited amount of time until stored energy is used up. The flywheel effect plays no role in allowing the vehicle to exceed wind speed but it is used to allow spending more time above wind speed as that will cover friction losses when the deceleration phase starts. Nobody demonstrated faster than wind indefinitely but that is what they claim. The real world is way to messy with the huge variation in wind speed and the much more controlled environment like the treadmill indoors is way to short maybe 1m before the vehicle will fall down. Still if measurement were made they will see how acceleration rate decreases during that 1m or so it travels on the treadmill showing that it is powered by stored energy. |
| Nominal Animal:
--- Quote from: electrodacus on July 14, 2022, 01:06:53 am ---The vehicle speed = wind speed is just the ideal case with no friction and can not be demonstrated in real life for any wind powered only vehicle. To me all is very simple as I work with energy all the time. --- End quote --- Don't be surprised, then, when the results you get differ from the real world. A lot of "laws" in physics only apply to equilibrium conditions. For an example, go compare non-equilibrium thermodynamics to (normal, equilibrium) thermodynamics. If you used your approach to investigate sailing, you'd conclude that it is impossible to tack upwind, or jig downwind faster than wind speed. |
| electrodacus:
--- Quote from: Naej on July 14, 2022, 12:57:30 am ---Yes the rate of acceleration slows down. Not the speed. --- End quote --- So what happens when the acceleration rate is zero ? Real vehicle will start to decelerate due to friction losses. --- Quote from: Naej on July 14, 2022, 12:57:30 am ---As I said what you call your equation is true, however it is in the car reference frame. And in the car reference frame, ground has kinetic energy, which is obvious but you refuse to admit it. I can make the following prediction: if you build the blackbird, or the treadmill model (without supercapacitors) you'll be able to go faster than the wind/treadmill. Also, all physicists who looked at it understand this. All you have is your wrong conceptions about a very abstract concept called energy, which presumably come from looking at batteries. It's hardly convincing. --- End quote --- Reference frames do not change the results or conclusions if you are careful when you look from a different reference frame. If you consider the vehicle stationary and earth moving then yes now the vehicle will have zero kinetic energy and the earth will have the vehicle kinetic energy as they were swapped. That is not a prediction. You seen that treadmill model moves against treadmill direction but you have no idea why. I looked at all (at least many) energy storage versions including thermal, chemical, mechanical and electrical. There are multiple things that you do not understand. - conservation of energy (first law of thermodynamics) thus you claim 300% efficiency is not a problem. - Newton's 3'rd law of motion This are absolutely essential else I have no chance to convince you that you are wrong. Even if I demonstrate that blackbird slows down below wind speed after stored energy is used up you will find excuses as in your world energy conservation is not real. |
| electrodacus:
--- Quote from: Nominal Animal on July 14, 2022, 01:12:11 am ---Don't be surprised, then, when the results you get differ from the real world. A lot of "laws" in physics only apply to equilibrium conditions. For an example, go compare non-equilibrium thermodynamics to (normal, equilibrium) thermodynamics. If you used your approach to investigate sailing, you'd conclude that it is impossible to tack upwind, or jig downwind faster than wind speed. --- End quote --- The results will not differ. Yes the results may be slightly off as you rounded things off or ignored things with small influence but the results are correct within the accuracy with which you made the calculation. It does not change the fact that equation predicts it is impossible for a vehicle to exceed wind speed directly down wind powered only by wind without energy storage. And this also means when energy storage is use since it is finite the vehicle will slowed down after the stored energy is used up. In fact I can bet my life (and I love life more than anyone) on this being correct. I never observed that to be incorrect at least for normal speeds not approaching speed of light where equation may need corrections but even then nobody ever proved that conservation of energy is not true. |
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