我想做一个[乒乓球风速计][1]估计或近似的测量表面风和气流速度低到中度。我现在没有一个风速计,但我估计利息之间的速度为零,最高的10年或15英里(感觉类似于骑自行车(非rac)山原本无风的一天)。如果我理解正确的话,乒乓球风速计可能指的是使用一个乒乓球或者其他[显示][17]通常用于指示风向*也尝试用*来估计风的速度。如果这是一个问题,我建立了力量和平衡方程分别垂直和水平部队,假设风是水平的。水平力,我使用一个简单的方程阻力的函数速度从[维基百科][10]:$ $ F_D (v) = \压裂{1}{2}\ρv ^ 2重金属镉的$ $(在低海拔高度和中等温度的空气密度][15]大概是1.2公斤/ m ^ 3美元一个的横截面积是乒乓球美元\πR_ {p-pb} ^ 2美元和重金属镉的美元[阻力系数][11],这是所有的现实和空气动力学的并发症实际上是隐藏在实践中。重金属镉美元并不是一个常数,通常是[谋害速度][14]和其他参数。然而,对于一些范围(雷诺数)[12],一个完美的球体就会约常数重金属镉美元[0.47][11]。但[2.7克,直径40毫米乒乓球][16]风速计,或类似的设备是一个真实的设备。也许我应该用一个重球,但我认为球的平滑度是至关重要的,如果我想用一个理论重金属镉和估计的速度使用方程而不是美元做一个真正的校准与一个已知的风速计或乘坐/在一个已知的车辆速度。有说明如何构建,使用,和校准或解释结果这种简单的风速计吗? Ideally some dimensions and a suggested scale would be great! Or if this has been actually measured for a pingpong ball or another object, that would also be a great answer as well. ---- ---- If [the concept][18] is good enough for a [Mars lander weather station][13], then it's good enough for me! [![enter image description here][4]][4] **above:** GIF from images transmitted from Mars. From the [The Telltale project][5] page on the [Mars Simulation Laboratory][6]. Also [archived here][7]. [![enter image description here][8]][8] **above:** Instrument as delivered to NASA. From the [The Telltale project][5] page on the [Mars Simulation Laboratory][6]. Also [archived here][7]. That's a 45 degree mirror below the telltale providing a simultaneous view from below. [1]: https://en.wikipedia.org/wiki/Anemometer#Ping-pong_ball_anemometers [2]: https://en.wikipedia.org/wiki/Phoenix_(spacecraft)#Meteorological_station [3]: https://en.wikipedia.org/wiki/Anemometer#Hot-wire_anemometers [4]: https://i.stack.imgur.com/FJbPa.gif [5]: http://marslab.au.dk/research/instrument-development/the-telltale-project/ [6]: http://marslab.au.dk/ [7]: https://web.archive.org/web/20120220080017/http://www.marslab.dk/TelltaleProject.html [8]: https://i.stack.imgur.com/xCWAk.jpg [9]: https://space.stackexchange.com/q/21680/12102 [10]: https://en.wikipedia.org/wiki/Drag_(physics) [11]: https://en.wikipedia.org/wiki/Drag_coefficient [12]: https://en.wikipedia.org/wiki/Reynolds_number [13]: https://space.stackexchange.com/q/21680/12102 [14]: https://commons.wikimedia.org/wiki/File:Drag_coefficient_on_a_sphere_vs._Reynolds_number_-_main_trends.svg [15]: https://en.wikipedia.org/wiki/Density_of_air [16]: https://en.wikipedia.org/wiki/Table_tennis#Ball [17]: https://en.wikipedia.org/wiki/Tell-tale [18]: https://en.wikipedia.org/wiki/Tell-tale#Space