- #1

Eagle9

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Imagine that the electro motor is rotating the blade in air at sea level:

http://img822.imageshack.us/img822/4655/222on.jpg

During this rotation the air impedes the blade’s rotation and if the blade rotates too quickly or if it is made of fragile material rod will be simply broken or bent. Can anybody tell me how can we calculate if the rod (with some certain mass, length, volume and rotational speed) withstands air’s resistance or not? Material’s which property should be taken into consideration when calculating this?

http://img822.imageshack.us/img822/4655/222on.jpg

During this rotation the air impedes the blade’s rotation and if the blade rotates too quickly or if it is made of fragile material rod will be simply broken or bent. Can anybody tell me how can we calculate if the rod (with some certain mass, length, volume and rotational speed) withstands air’s resistance or not? Material’s which property should be taken into consideration when calculating this?

*Specific strength*or*tensile strength*? :shy: This task was partially solved https://www.physicsforums.com/showthread.php?t=502817" where I learned to calculate the*Torque*(T) but what should be done now? I need somehow to connect*Torque’s*value and material’s strength and bending moments; could you please tell me how to do it?
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