View Full Version : Prop Torque Question
08-06-2005, 09:37 AM
My 912S engine has a lot of torque which twists the gyro hard to the right if I ever give it full power, which I avoid as a result.
If I put a 68" long piece of a light (Dragon Wing) rotor blade about 6" or so behind the prop, running horizontally and centered of the prop, would this stop the torque twist of the gyro? Kind of like a vertical tall tail but only 7" or 8" chord and running horizontally.
Would it be better closer to or farther away from the prop?
08-06-2005, 09:44 AM
I doubt it. My S-H conversion still had enormous torque roll, especially with the IVO prop when set for full take-off rpm, around 5500. Left stick seems to be the only way to counteract it, even with a tall tail like mine had.
08-06-2005, 10:15 AM
The Autogiros of the 1930s had a real torque challenge.
An engine producing 300 hp at 1600 rpm results in 985 ft-lb of torque.
Many things were experimented with but the most practical solution was the use of an inverted airfoil on half of the tailplane. One side had an upright sort of Clark Y, the other side had an upside down one.
Ron Heron uses differential tailplane incidence to balance torque. Set the main wheels on bathroom scales and adjusted tailplanes for equal readings.
08-06-2005, 10:30 AM
Do you think I could add small angles on the trailing edge of my horizontal stabilizer - turned up on one side and down on the other to create the twist required to offset the torque? I could use the bathroom scales to determine the amount of angles to use on each side.
If the HS was centered on the prop this should work.
My present HS is not at the center of the prop but not at the bottom either. It is well within the prop disk area. It might still help but add some side load to the tail. Right?
08-06-2005, 11:12 AM
Probably, Ken R., if the tabs were big enough. But to counteract propeller torque, the torque load transmitted back to the airframe is equal to propeller torque.
Torque = HP x 5252/propeller rpm
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