Power available to a wind powered vehicle traveling directly downwind

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Discussion Overview

The discussion revolves around the theoretical equation for calculating the wind power available to a wind-powered vehicle traveling directly downwind. Participants explore various factors that influence this power, including sail area, wind speed, vehicle speed, and the drag coefficient. The focus is on deriving the equation rather than obtaining a numerical solution.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants emphasize the importance of sail area in determining wind power.
  • One participant provides an equation: 0.5 * air density * area * (wind speed - vehicle speed)^3, but others challenge its accuracy.
  • There is a discussion about the definition of power in terms of force and velocity, with references to the drag coefficient being necessary for accurate calculations.
  • Participants express differing views on whether the provided data is sufficient to calculate wind power, with some insisting that the drag coefficient is essential.
  • One participant suggests using a specific example with defined parameters (sail area, wind speed, vehicle speed) to illustrate the calculation, while others question the assumptions made in the example.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct formulation of the wind power equation. There are competing views regarding the necessity of the drag coefficient and the interpretation of the variables involved in the calculations.

Contextual Notes

Limitations include potential misunderstandings about the role of the drag coefficient and the relative velocities involved in the power calculation. The discussion reflects various assumptions and interpretations that remain unresolved.

  • #61
electrodacus said:
What you describe is an overunity device like those electric generators powered by an electric motor and electric motor is supplied by the electric generator and on top of that you can also power a light bulb.
As I already mentioned not understanding energy conservation.
Incorrect. The power extracted never exceeds the power available per the equation. At this point I'm going to lock the thread since you seem to be uninterested in learning how these devices actually work and we're stuck in a loop where you just keep referring back to the wrong equation.
 
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