Quote:
Originally Posted by BigWhiteYeti
I've only seen two robots with fans and both were pointed horizontal, so they add thrust but not traction. If I remember right, one of the updates had a clause outlawing "mass manipulation" to gain a traction advantage. I guess it is up to the inspector to judge whether a fan is mass manipulation.
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The point he was trying to raise is that if the fan isn't transmitting force directly through the center of mass of the robot then it will create a torque (rotational force) on the robot as a whole. This torque will apply additional force to one set of wheels (the front if the fan is above the center of mass) and lessen the force on the other set. He was asking if this change in force distribution would be considered to be changing the traction properties of the robot.
Think of a car. When it accelerates the weight of the car shifts towards the rear wheels. When it brakes it shifts towards the front. Same reason motorcyclists do wheelies while they're accelerating and decelerate to bring the front wheel back down.
Now, I don't think this violates the rule, because the total normal force does not change. It is just shifted. Beyond that, if this violates that rule, so do any drivetrains where they don't apply force through the directly through the center of mass, which is likely every single team in FIRST.