To: tgrendl and Shy Torque
tgrendl wrote;
>If the blade on the left reached the point of maximum pitch at the exact 90 degree mark wouldn't that force developed take some amount of time to transmit to the fuselage? <
No. In the case of an absolutely rigid rotor I don't believe this so. In the case of this totally rigid (and hypothetical) rotor, there is no flapping or teetering. This rotor is rigidly coupled to the fuselage, perhaps by what is called a static mast. Therefore, any movement of the rotor, other than rotation about the mast, will cause an immediate and identical movement in the fuselage.
You must consider this really rigid rotor as if it was a large variable pitch propeller mounted vertically. The only movement is rotation about the mast and pitch change. No blade flex. No nothing. No kidding!
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The following may help to clarify the activity;
We are looking down upon the rotor disks of Shy Torques two helicopters.
On both helicopters;
0-degrees azimuth is straight back.
90-degrees azimuth is the mid-point of the advancing side.
180-degrees azimuth is straight ahead.
270-degrees azimuth is the mid-point of the retreating side.
The X-axis is the longitudinal one.
The Y-axis is the lateral one.
The Z-axis is the vertical one.
Both helicopters are hovering.
Let's consider that by applying the same cyclic to both helicopters, the greatest blade pitch is at azimuth 90, the least pitch is at azimuth 270 and the mean (average) pitch is at azimuths 0 and 180.
We know that the blade pitch and thrust at azimuth 45 is the same as it is at azimuth 135. We also know that the blade pitch and thrust at azimuth 225 is the same as it is at azimuth 315.. We also know that the blade pitches and thrusts at 45 and 135 are greater than they are at 225 and 315.
So far everything has been the same for the two helicopters.
Now, in the case of the helicopter with the teetering rotor, the blades will climb from azimuth 0 to azimuth 180 and descend from azimuth 180 to azimuth 0. The disk will be tipped back. The helicopter will 'eventually' pitch up and fly backwards.
OK so far?
Now for the helicopter with the totally rigid rotor.
Remember that the rotor and fuselage are totally interconnected, except for the rotors rotation about the Z-axis.
The combined thrust at 45 and 135 EXCEEDS the combined thrust at 225 and 315, The rotor and the firmly attached fuselage must therefore roll about the X-axis and sideslip toward the retreating blade side of the craft.
The combined thrust at 45 and 225 EQUALS the combined thrust at 135 and 315, The rotor and the firmly attached fuselage will therefore NOT pitch about the Y-axis nor will the craft move forward or backward.
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We have give both rotors the same amount of blade pitch at the same azimuths but one helicopter is flying backwards and the other is flying sideways.
The only way to get them to fly in the same direction, is by giving the teetering rotor helicopter a 90-degree phase angle and the totally rigid rotor helicopter a 0-degree phase angle.
Hope this makes sense.
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Lu;
Thanks for the information on the V-22 rotor.