Why do the proppellers rotate in the same direction?

Question

I have noticed that in twin turbo prop fixed wing aircraft, the proppellers rotate in the same direction thus on both the port and starboard wing (engine) . What effect would be experienced if they were to rotate in opposing direction and why?

Answer 1

If you look at the blades, mainly the angle they turn to force air behind the engine. Forcing the aircraft to move.

Answer 2

It makes the engine capable of being installed in any location.  If the right engine HAD to turn CCW, and all you had were CW engines, you would be SOL.  Also, imagine all the individual components that would be specific to the engines that turn different directions.  (Just count the compressor blades alone and you'll get it.)

Answer 3

it wont fly. they have to turn in the same direction

Answer 4

They don't all rotate in the same direction. Many aircraft are designed with counter rotating props. Did somebody say it wouldn't fly like that? hahahahahahahahahahaaaaa

And changing direction would produce reverse thrust? Think maybe also reversing the pitch of the blades might get the thrust headed the right way.? hahahahahahahahahaha

Answer 5

Lots of multi-engine aircraft have counter-rotating props.

The difference between the two types of airplanes would be in the way the rest of the airplane is designed to work with the rotation of the props.

Answer 6

Props on a fixed wing aircraft rotate the same way as the pitch on the propellers are designed to rotate in one direction for thrust and changing the rotational direction would produce reverse thrust.

Answer 7

There are many airplanes with counter-rotating propellers (one clockwise and the other counter clockwise). The Wright Flyer, P-38 Lightning and the Piper Twin Comanche are all examples of counter-rotating propeller aircraft. With props that are rotating in the same direction you have what is referred to as a critical engine (usually the left). If you lose the critical engine, the airplane becomes much harder to control because of the inability to overcome the left turning tendencies created by asymmetrical thrust coming from the right engine. The counter-rotating propellers eliminate the critical engine and vastly improves the chances of a successful landing on one engine. Most airplanes don't have counter-rotating propellers because of the cost and complexity of manufacturing one engine and another of it's mirror image, this is especially true of turboprops.

An interesting side note, the P-38 actually had two critical engines as both of the descending blades were on the outside of the propeller arc. Apparently it improved accuracy in gunnery.

Answer 8

Don't give me a P-38

With props that counter-rotate.

They'll loop and they'll spin

And they'll auger you in.

Don't give me a P-38.

Give me operations

Out on some lonely atoll...