What is a 'Counter-rotating' propeller?

Question

What is a 'Counter-rotating' propeller?

Answer 1

On most twin screw boats, the starboard propeller turns in a clockwise direction. The port propeller turns in a counter-clockwise direction and is called a counter rotating propeller.

Answer 2

Counter-rotating propellers, are found on twin-engine, propeller-driven aircraft and have propellers that spin in opposite directions.

Counter-rotating propellers generally spin clockwise on the left engine, and counter-clockwise on the right. The advantage of counter-rotating propellers is to balance out the effects of torque and p-factor, eliminating the problem of the critical engine.Counter-rotating propellers should not be confused with Contra-rotating propellers.

Answer 3

Counter rotating propellors are indeed two on the same shaft rotating in opposite directions. Among the advantages are smaller prop for the same horse power.

Try to find a picture of a Tupolev Tu 95 Bear bomber. 4 pairs of eighteen foot 4 bladed conterrotating props. The problem with this beast is that at top speed it is incredibly noisy as it is producing 32 sonic booms constantly.

Answer 4

Technically, counter-rotation propellers are two propellers mounted one behind the other on the same shaft in front of the engine, one turning clockwise and the other counter-clockwise. This arrangement can be found on the 'Fairey Gannet', Shackletons and other similar aircraft. This system negates the torque generated by a single propeller.

Answer 5

the counsel of the propellers blades coming at the same time on the brink of the fuselage might desire to have led to a short-term develop in air tension, which will have had some consequence on the path of bullets. they might have chanced on in a wind tunnel that it labored greater effective for the propeller blades to return at the same time below than above. i'm merely guessing. I study someplace that the RAF ordered various P-38s, yet they wanted the engines and propellers to the two rotate interior the comparable direction, for ease of upkeep. those planes, they got here across, have been plenty greater good to fly, distinctly in takeoffs and landings, as a results of fact the torque of the propellers further quite than cancelling one yet another.

Answer 6

The prop rotates counter clockwise relitive to the pilot looking out the window

Answer 7

To answer your question correctly you have to know what P-Factor is it will cancel it out (force acting on the aircraft).



Asymmetric Propeller Loading ("P" Factor)



The effects of "P" factor or asymmetric propeller loading usually occur when the airplane is flown at a high angle of attack.



The downward moving blade, which is on the right side of the propeller arc, as seen from the rear, has a higher angle of attack, greater action and reaction, and therefore higher thrust than the upward moving blade on the left. This results in a tendency for the airplane to yaw around the vertical axis to the left. Again this is most pronounced when the engine is operating at a high power setting and the airplane is flown at a high angle of attack.



Since the airplane is flown in cruising flight most of the time, airplane manufacturers design the airplane with certain built-in corrections that counteract the left-turning tendency or torque effect during straight- and-level cruising flight only. This correction eliminates the necessity of applying constant rudder pressure. Because the effect of torque varies to such an extent during climbs and changes in angle of attack, it is impractical for airplane designers to correct for the effect of torque except during straight-and-level flight. Consequently, the pilot is provided other means such as rudder and trim controls to counteract the turning effect during conditions other than straight-and-level flight.



Many manufacturers "cant" the airplane engine slightly so that the thrust line of the propeller points slightly to the right. This counteracts much of the left-turning tendency of the airplane during various conditions of flight.



Other manufacturers, when designing the airplane, increase the angle of incidence of the left wing slightly, which increases the angle of attack and therefore increases the lift on this wing. The increased lift counteracts left-turning tendency in cruising flight. The increase in lift will, however, increase drag on the left wing and, to compensate for this, the vertical stabilizer is offset slightly to the left.



Torque corrections for flight conditions other than cruising flight must be accomplished by the pilot. This is done by applying sufficient rudder to overcome the left-turning tendency. For example, in a straight climb, right rudder pressure is necessary to keep the airplane climbing straight.



When thinking of "torque" such things as reactive force, spiraling slipstream, gyroscopic precession, and asymmetric propeller loading ("P" factor) must be included, as well as any other power-induced forces that tend to turn the airplane.

Answer 8

That's correct. same for aircraft, the props rotate in opposite direction. Can't remember what the exact benefit is, I think make the aircraft easier to control (torque roll and what's called the P factor).

Answer 9

at the same /dual/ shaft are two propellers one turning clockwise, one turning counterclockwise. they have the same mass, thus the same but opposite torque effect /due to the opposite rotation/ - this helps to fight the torque effect of large proppellers of the turboprop airliners and of some helicopters - Kamov family.

Answer 10

just a guess

If the piston engine crankshaft rotates one way,

then threw a geared transmittion

the prop turns the other way.

....sorry but I am unable to remember an example,

...look for an old aircraft with Twin row Radial engines !

like a DC4 or Bi-wing crop duster.?