Why Double Propellers are GENIUS!

Video Description

Why does this boat have two propellers, and what about this plane? These are called contra-rotating propellers, and their discovery was genius. What makes these contra-rotating propellers is that they are in front of each other and spin in opposite directions. One reason this is good is that it stops planes or torpedoes wanting to rotate against the direction of the propeller, due to the propellers torque. But, I think this next reason is even cooler. Behind a single propeller you get a cone shape of air, kind of like a cyclone. This is less efficient than it could be because not all the thrust is going straight backwards. The contra-rotating propellers fix this by counteracting the cyclone motion, resulting in a straight jet of air out the back. So why don’t we see these more often? Well, one reason is the complex gear systems required to get them to spin in opposite directions. Another reason is that these propellers mix up the air a lot, making them extremely loud. Subscribe for more efficient engineering. #engineering #animation #physics #automobile