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| Mess with your minds: A wind powered craft going faster than a tail wind speed. |
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| electrodacus:
--- Quote from: IanB on December 28, 2021, 12:56:38 am --- --- Quote from: electrodacus on December 28, 2021, 12:51:02 am ---I saw a better example but here is one. Notice the non constant vehicle movement ? --- End quote --- No. Every frame, the vehicle moves forward by the same amount. --- End quote --- Can you not see the vehicle stopping while the propeller still rotates ? Meaning power stored and then released. If vehicle was to be directly powered by the propeller/wind turbine then there will be a smooth constant movement forward. |
| gnuarm:
--- Quote from: electrodacus on December 28, 2021, 12:51:02 am ---I saw a better example but here is one. Notice the non constant vehicle movement ? and another one a bit better but still not the one I was searching for. --- End quote --- The first video doesn't seem to show much in the way of speed variation. The second video shows the gear driving the track slipping from time to time and I'm not sure, but I think the fan is being turned on and off so it doesn't blow so hard. If it blows too hard the gear slips and the vehicle goes nowhere. Either way, the storage has nothing to do with nothing. You just provided two examples of vehicles moving INTO the wind being powered by the wind. The first one even goes up a 30 or 40 degree ramp! When are you going to respond to my prior post about the power to hold a vehicle stationary? You've already said the power was zero if the bike rider simply puts his weight on the pedal into a 20 km/s wind. So doesn't the rest follow, the equations are as I've shown them? Quote from: electrodacus on Today at 07:33:23 pm A rider with sufficient weight standing on the pedal will still be a form of brake. It is a gravitational based one but still a brake. Let's just deal with one detail at a time. So do you acknowledge that the correct equation for the power at the wheels to move the vehicle into the wind must contain a factor which is just the velocity of the vehicle relative to the ground the wheel is pushing against? The force from the wind is Fd = 1/2 · Cd · A · p · (vw + vo)^2 The power required at the vehicle wheels to maintain a speed into the wind is Pv = 1/2 · Cd · A · p · (vw + vo)^2 · vo Correct? |
| electrodacus:
--- Quote from: gnuarm on December 28, 2021, 01:07:19 am --- The first video doesn't seem to show much in the way of speed variation. The second video shows the gear driving the track slipping from time to time and I'm not sure, but I think the fan is being turned on and off so it doesn't blow so hard. If it blows too hard the gear slips and the vehicle goes nowhere. Either way, the storage has nothing to do with nothing. You just provided two examples of vehicles moving INTO the wind being powered by the wind. The first one even goes up a 30 or 40 degree ramp! When are you going to respond to my prior post about the power to hold a vehicle stationary? You've already said the power was zero if the bike rider simply puts his weight on the pedal into a 20 km/s wind. So doesn't the rest follow, the equations are as I've shown them? Quote from: electrodacus on Today at 07:33:23 pm A rider with sufficient weight standing on the pedal will still be a form of brake. It is a gravitational based one but still a brake. Let's just deal with one detail at a time. So do you acknowledge that the correct equation for the power at the wheels to move the vehicle into the wind must contain a factor which is just the velocity of the vehicle relative to the ground the wheel is pushing against? The force from the wind is Fd = 1/2 · Cd · A · p · (vw + vo)^2 The power required at the vehicle wheels to maintain a speed into the wind is Pv = 1/2 · Cd · A · p · (vw + vo)^2 · vo Correct? --- End quote --- I think is fairly clear to see the stop start movement in both videos while second video is better quality and easier to see. You just try to find some other non existent reasons but the reason it moves that way is due to energy storage charge and discharge. Like I mentioned even presenting clear evidence you will try to find some other reasons to exclude the energy storage witch is essential. Evacuation for force is correct for power it is not and correct one is below. Pv = 1/2 · Cd · A · p · (vw + vo)^2 · (vo+vw) |
| gnuarm:
--- Quote from: electrodacus on December 28, 2021, 01:01:16 am --- --- Quote from: IanB on December 28, 2021, 12:56:38 am --- --- Quote from: electrodacus on December 28, 2021, 12:51:02 am ---I saw a better example but here is one. Notice the non constant vehicle movement ? --- End quote --- No. Every frame, the vehicle moves forward by the same amount. --- End quote --- Can you not see the vehicle stopping while the propeller still rotates ? Meaning power stored and then released. If vehicle was to be directly powered by the propeller/wind turbine then there will be a smooth constant movement forward. --- End quote --- The stopping is irrelevant. It is moving INTO the wind. You were trying to argue that when moving downwind it was on average moving slower than the wind because of some speed variation that no one else thought was relevant. Moving into the wind the only requirement is that the speed must be greater than zero. The first video clearly shows the vehicle moving with a positive velocity at all times. So clearly any energy storage is incidental. The second video clearly shows the gear slipping on the belt rather than energy storage. Even so, why does that matter? Both vehicles move INTO the wind. Energy storage is not relevant. They do what we are talking about - moving into the wind while powered by the wind. If you want to use a river example, how about we use a sailboat on the water sailing into the wind? This happens all the time... literally! |
| electrodacus:
--- Quote from: gnuarm on December 28, 2021, 01:16:17 am --- The stopping is irrelevant. It is moving INTO the wind. You were trying to argue that when moving downwind it was on average moving slower than the wind because of some speed variation that no one else thought was relevant. Moving into the wind the only requirement is that the speed must be greater than zero. The first video clearly shows the vehicle moving with a positive velocity at all times. So clearly any energy storage is incidental. The second video clearly shows the gear slipping on the belt rather than energy storage. Even so, why does that matter? Both vehicles move INTO the wind. Energy storage is not relevant. They do what we are talking about - moving into the wind while powered by the wind. If you want to use a river example, how about we use a sailboat on the water sailing into the wind? This happens all the time... literally! --- End quote --- The stopping is relevant as it confirms my energy storage theory. The video shows a upwind version not sure why you include the downwind in discussion as that is competently different. For upwind as shown in the video there is a small capacity energy storage that charges and discharges even a few times a second and that is what allows the vehicle to move against the wind direction for unlimited amount of time. For the down wind version energy storage is the pressure differential much, much larger energy storage capacity and so the vehicle will move above wind speed for a few minutes before staring to slow down below wind speed. Without energy storage neither upwind at any speed or down wind at higher than wind speed will be possible. |
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