Rotor Rooter
Dave Jackson
To my understanding, Birdy's questions in post #149 are ;
The subject is a difficult one for even for the experts. Referring to the note in post #155.
This sketch shows the Yaw control for different configurations.
For ‘conventional’ coaxial and intermeshing helicopters it is by differential torque between rotors. These ‘conventional’ helicopters cannot vary the rotation speed between their 2 rotors because they must maintain constant blade crossing azimuths; both coaxial and intermeshing. But, the blades on these helicopters can change their pitch; by swashplate, etc.
Rotors that do not have the ability to change the pitch of their blades must; vary their RPMs differentially, or put drag tabs on the blades, or place a rudder in the rotors downwash, or have separate small propellers etc.
Chuck mentions in his latest post that “Bensen's yaw control was via a small engine/propeller blowing on a conventional rudder.” In other words, the yaw control on Bensen’s coaxial helicopter has nothing to do with the rotor system. This is basically the same as the two small propellers in Pegg’s PAM-110B, which is linked to in post #157.
It is interesting (for me at least) to see that Pegg's newer 1/5-scale helicopter does not appear to have these small propellers.
For the ‘conventional’ coaxial and intermeshing helicopters, autorotation, is a meaningful concern since they do not use the so-called ‘band-aid’ type of solutions.
Dave
1/ "The system of yaw control in a differential collective coaxial machine”, and
2/ “yaw control is reversed dureing an auto”
2/ “yaw control is reversed dureing an auto”
The subject is a difficult one for even for the experts. Referring to the note in post #155.
~ Kamov is, arguably, the most knowledgeable company on coaxial helicopters.
~ Gareth Padfield is the head of Helicopter Aerodynamics Section at Defense Research Agency in England. His book Helicopter Flight Dynamics: The theory and Application of Flying Qualities and Simulation Modeling is over 500 pages and extremely complex.
~ Gareth Padfield is the head of Helicopter Aerodynamics Section at Defense Research Agency in England. His book Helicopter Flight Dynamics: The theory and Application of Flying Qualities and Simulation Modeling is over 500 pages and extremely complex.
This sketch shows the Yaw control for different configurations.
For ‘conventional’ coaxial and intermeshing helicopters it is by differential torque between rotors. These ‘conventional’ helicopters cannot vary the rotation speed between their 2 rotors because they must maintain constant blade crossing azimuths; both coaxial and intermeshing. But, the blades on these helicopters can change their pitch; by swashplate, etc.
Rotors that do not have the ability to change the pitch of their blades must; vary their RPMs differentially, or put drag tabs on the blades, or place a rudder in the rotors downwash, or have separate small propellers etc.
Chuck mentions in his latest post that “Bensen's yaw control was via a small engine/propeller blowing on a conventional rudder.” In other words, the yaw control on Bensen’s coaxial helicopter has nothing to do with the rotor system. This is basically the same as the two small propellers in Pegg’s PAM-110B, which is linked to in post #157.
It is interesting (for me at least) to see that Pegg's newer 1/5-scale helicopter does not appear to have these small propellers.
For the ‘conventional’ coaxial and intermeshing helicopters, autorotation, is a meaningful concern since they do not use the so-called ‘band-aid’ type of solutions.
Dave
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