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| Mess with your minds: A wind powered craft going faster than a tail wind speed. |
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| fourfathom:
--- Quote from: electrodacus on December 25, 2021, 06:57:33 pm --- --- Quote from: dunkemhigh on December 25, 2021, 10:11:00 am ---* There is no wind * The propeller is powered by a battery If the speed of the propeller wash is 1m/s, do you agree that the vehicle will move forward at around 1m/s? --- End quote --- Replacing the moving sail with a propeller will not be the same thing if the propeller is not powered by something. --- End quote --- This is a thought-experiment, OK? The propeller is powered by a battery in this experiment. The question is what will happen in this experiment. |
| Labrat101:
--- Quote from: electrodacus on December 25, 2021, 06:57:33 pm --- So propeller will still rotate but slower and slower same thing that actually happens after the vehicle used all the pressure differential and vehicle starts to slow down. --- End quote --- You keep forgetting 1 thing . This type of propeller has an integral clutch . Which means it can spin Free with just wind force . only . so it can be used as a sail .(kind of ) When the clutch engages it can ether give power to the wheels or from . Depending on the setting of the pitch angle of the Blades . |
| fourfathom:
--- Quote from: Labrat101 on December 25, 2021, 07:23:02 pm ---You keep forgetting 1 thing . This type of propeller has an integral clutch . Which means it can spin Free with just wind force . only . so it can be used as a sail .(kind of ) When the clutch engages it can ether give power to the wheels or from . Depending on the setting of the pitch angle of the Blades . --- End quote --- I believe we can analyze, or at least demonstrate this with a fixed-pitch, fixed-gearing propeller. That's how the treadmill model is built. I don't know if this model can start from a full-stop, but it does accelerate once past windspeed. |
| electrodacus:
--- Quote from: fourfathom on December 25, 2021, 07:46:46 pm --- I believe we can analyze, or at least demonstrate this with a fixed-pitch, fixed-gearing propeller. That's how the treadmill model is built. I don't know if this model can start from a full-stop, but it does accelerate once past windspeed. --- End quote --- That model will be able to start from a full stop assuming high enough wind speed so that power based on vehicle equivalent back area can overcome vehicle friction. The thing you (all) seems to be ignoring is that air speed relative to vehicle is what can power the vehicle and so when air speed / wind is equal with vehicle speed in exact same direction then there is no way for the air to push the vehicle. And somehow you imagine that propeller can push air backwards but that will require an energy source and wind is no longer there to help when vehicle is at or above wind speed. You just think that you can take energy from the wheel but the problem with that is that when above wind speed that wheel no longer takes energy from the wind but will need to take energy from the vehicle kinetic energy and so vehicle will just slow down if you ignore a energy storage device like the pressure differential witch continues to push the vehicle basically taking the role of the wind for a few seconds or minutes depending on the design. |
| Labrat101:
--- Quote from: fourfathom on December 25, 2021, 07:46:46 pm --- --- Quote from: Labrat101 on December 25, 2021, 07:23:02 pm ---You keep forgetting 1 thing . This type of propeller has an integral clutch . Which means it can spin Free with just wind force . only . so it can be used as a sail .(kind of ) When the clutch engages it can ether give power to the wheels or from . Depending on the setting of the pitch angle of the Blades . --- End quote --- I believe we can analyze, or at least demonstrate this with a fixed-pitch, fixed-gearing propeller. That's how the treadmill model is built. I don't know if this model can start from a full-stop, but it does accelerate once past windspeed. --- End quote --- I am not sure how this can be done as both these propellers have totally different properties .Your know about boats . It would be like saying a life raft is the same as a boat or worse still a Ship . They both travel or go in water . (spot the difference) . |
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