Ever wonder how the single driveshaft in your car manages to power two (or more) wheels simultaneously? The answer is the differential, a device capable of splitting torque dynamically. There are a variety of different types of diffs, from fully unlocked to more pricey limited-slip models, but none are quite like the one created by Harvard
graduate student Pratheev S. Sreetharan and professor Robert J. Wood. Dubbed the PARITy (Passive Aeromechanical Regulation of Imbalanced Torques), it's only five millimeters long and, while such a tiny thing would evaporate if mounted between the rear wheels on a Mustang GT, it's destined for rather smaller applications: tiny, winged micro air vehicles
. The scientists proved its effectiveness by clipping one wing on a PARITy-equipped drone and, despite the imbalance in lift surface, the robo-bee maintained level flight -- differential automatically flapping the tinier wing more quickly to compensate. You know what that means: keeping our robot overlord's spies grounded just got a little bit harder.
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