To: SouthXross
First of all if you have flapping capability and the blade flaps upward and there is an increase in the pitch setting made by the pilot then there is a major flaw in the design. If I understand your description, the pitch link is not inline with the cone axis but lies ahead of it in relation to the blade. So that when the R-44 blade flaps up it will have a higher increase in pitch than the R-22 if it flapped to the same angle.
The whole purpose of the flapping is to equalize the lift on the disc. So, when the blade flaps up pitch will decrease and the aerodynamics will bring the blade into the rotational plane. The opposite is true when the blade flaps down the pitch will increase. This is called pitch coupling and it is exactly like on the tail rotor. When the tail rotor teeters the advancing blade depending on the design will flap inward and the retreating blade flaps outward. The advancing blade looses pitch and the retreating blade gains pitch thus equalizing the aerodynamic forces on the tail rotor.
The further outward the pitch link is relative to the cone axis the greater the pitch coupling. Understand this one point on the Robinson rotorhead the pitch link can never be mounted so that it is behind the cone axis. If this were true then your thoughts would be correct in that when the blade flaps up the pitch would increase.
If what you observed is true then Frank and his designers wanted the difference between the two rotorheads as he needed the extra pitch coupling +/- on the R-44 head for aerodynamic reasons. What those reasons are, I don’t have a clue.
Here is another point. Go out to your R-22 and R-44 and check if the R-44 pitch link is at an angle relative to the swashplate connection and the pitch horn connection. If it is then this will have an effect on the phase angle. If it is straight up and down like on the R-22 then the offset angle is greater than on the R-22, which has an 18-degree offset. I may have this backwards but if it is straight up and down as opposed to angled then the control geometry is different between the two helicopters.
[ 20 November 2001: Message edited by: Lu Zuckerman ]
[ 20 November 2001: Message edited by: Lu Zuckerman ]
[ 20 November 2001: Message edited by: Lu Zuckerman ]