Calculate RPM of Fan
 . The fan rotates 25 times for every single turn of the crankshaft. observe one leg and measure the time it takes to complete one cycle. One cycle is a single rotation of the crankshaft. It is possible to calculate fan RPM with this information. I am using a video editor (30 fps) to do the timing, but you could use the elapsed time indicator on your video player or an accurate stopwatch.  Note the leg starting to lift at 14:15, thats 14.5 seconds (15 represents .5 of 30 frames) In the picture below the strandbeest has moved.  The strandbeest has now moved through one cycle, the leg we are watching is about to lift again, it is at the same spot in the cycle.  This single cycle is completed at 17.3 seconds (10 frames = .3 seconds) subtracting, 17.3 - 14.5 = 2.8 seconds One rotation of the crankshaft takes 2.8 seconds. Because the gear ratio is 1:25, this means the fan makes 25 rotations in 2.8 seconds. Here is how we calculate the RPM of the fan: (60/2.8) x 25 = 536 We estimate the fan to be rotating at 536 RPM. |