Bob Wilder owns the new world record for longest-duration indoor flight with a radio-controlled electric airplane. It stayed aloft for 4 hrs, 17 min, and 57 sec.
Wilder says it is important to perform tests to find the maximum thrust using the minimum current draw from the batteries. So he analyzed many combinations of motors, gear ratios, propellers, and batteries. "The real bottom line in producing an airplane that will fly inside for several hours is thrust versus current draw," he says. "That means the size of the battery and the size and efficiency of the motor are key."
Wilder uses a permanent magnet motor from Maxon Precision Motors (Burlingame, CA). He claims that the company's coreless motors provide the low-current consumption needed for extending battery life in competition. The motor's iron-less core eliminates cogging and provides smooth rotation even at the lower speeds required for landings.
For more information about motors from Maxon Precision Motors: Enter 539
The FDA has just released draft guidelines for using 3D printing in the design, development, and manufacture of regulated medical products. Although the recommendations are non-binding, they do set some much-needed parameters.
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