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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, 09:32:59 pm --- For Blackbird, the spinning prop adds some extra thrust, allowing the (force applied to vehicle) to be positive even when exceeding the wind speed. Therefore, Blackbird can reach a steady speed faster than the wind where it is still true that (power supplied) = (power consumed). --- End quote --- Do you read your own comments ? "extra thrust" ? You get that vehicle is only powered by wind ? There is no extra thrust and all the thrust as in the case of a sail is provided by the wind. Wind power supplied is zero when vehicle speed equal wind speed and even with your wrong equation you will get the same thing as force will be zero. |
| electrodacus:
--- Quote from: bdunham7 on December 28, 2021, 09:41:50 pm --- --- Quote from: electrodacus on December 28, 2021, 09:31:51 pm ---So each time a particle hits that area of the sail it will lose half of the kinetic energy since the other half will be transferred to sail. --- End quote --- Say what? Is this another gem that 'university professors' don't understand? --- End quote --- Alex the professor what lost 10K knows this and has never said anything wrong as far as I remember. He just failed to see that there is energy storage involved thus was unable to defend his position when Derek showed him the working treadmill model. |
| electrodacus:
--- Quote from: IanB on December 28, 2021, 09:42:21 pm ---Newton's first law of motion says that an object will not change its motion unless a force acts on it. If the sail boat is moving at the same speed as the wind there is no wind force: (w-v) = 0. If there is no friction, there is no friction force. Therefore no force at all. If there is no friction, the boat requires no power at all to continue moving at the same speed, so it neither needs nor gets any power from the wind. The wind power in this situation is zero, so the efficiency must be 0%. --- End quote --- Wind power drops as vehicle speed approaches wind speed thus efficiency is still 100% there is just no more wind power available when speeds are equal in an ideal system. |
| PlainName:
--- Quote ---As for direct down wind the ideal vehicle can get to same speed as wind speed but not above that without having some stored energy or an external energy source other than wind. --- End quote --- You are wrong. I was leading you gently to the realisation (and others are trying the more direct way), but you can't let yourself suffer the possibility that you might be wrong, so you keep diverting to this rubbish. --- Quote ---Blackbird is not using wind power when above wind speed --- End quote --- And I was on the way to showing you it could. But rather than learn you prefer to stick your head in the sand. |
| electrodacus:
OK lets compare the output of the two equations air density 1.2kg/m3 area 1m2 Wind speed 20m/s Vehicle speed a) 0m/s, b) 10m/s, c) 20m/s 0.5 * air density * area * (wind speed - vehicle speed)2 * (wind speed - vehicle speed) a) 4800W b) 600W c) 0W 0.5 * air density * area * (wind speed - vehicle speed)2 * (vehicle speed) a) 0W (how will your wind powered vehicle ever start) b) 600W c) 0W Any comments ? Seems even with your wrong equation there is no wind power available to any wind powered vehicle when at and above wind speed. |
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