Rotorcraft Dynamics: - Rotorhead - There is a future.
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Rotorcraft Dynamics: - Rotorhead - There is a future.
In response to the overwhelming demand to develop a better rotorcraft, the following is modestly forced on you.
` . ` . ` . Constant Velocity Rotor
Russian web page . Please note that this rotor has more than two blades, yet " No blade-flapping hinges, drag hinges or hinge dampers are required.'
For those with a technical curiosity, here are the sketches of this rotor's design.
For those who are still 'hanging in', now add a hub spring and Voilą;- Tomorrow's hub for light rotorcraft.
Any comments? Any arguments?? Anyone still here???
` . ` . ` .
` . ` . ` . Constant Velocity Rotor
Russian web page . Please note that this rotor has more than two blades, yet " No blade-flapping hinges, drag hinges or hinge dampers are required.'
For those with a technical curiosity, here are the sketches of this rotor's design.
For those who are still 'hanging in', now add a hub spring and Voilą;- Tomorrow's hub for light rotorcraft.
Any comments? Any arguments?? Anyone still here???
` . ` . ` .
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hi Dave,
you know that i've been around a rotor design.
I went to the conclusion, after some tries, that the double joint or cvj is an interesting design , i plan to investigate a little more on that seriously.
I have tried flexible parts and finally went to a CVJ naturally, you were right, it has a lot of advantages.
do you mind if a have a look at your sketches ? or are they protected ?
I thinh that the advantage of this design is not to avoid flap hinges but, precisely to have flap hinges perfectly aligned with the disk normal and lead lag hinges aligned with the blades path, avoiding the scissors effect and allowing the disk CoG to be always aligned correctly and stable ( no vibes).
I thinbk also that your design has a big interest with 4 blades , the rotor could be considered as a 2 bladed teetering rotor with a stabilizator (the other 2 blades).
Thanks
you know that i've been around a rotor design.
I went to the conclusion, after some tries, that the double joint or cvj is an interesting design , i plan to investigate a little more on that seriously.
I have tried flexible parts and finally went to a CVJ naturally, you were right, it has a lot of advantages.
do you mind if a have a look at your sketches ? or are they protected ?
I thinh that the advantage of this design is not to avoid flap hinges but, precisely to have flap hinges perfectly aligned with the disk normal and lead lag hinges aligned with the blades path, avoiding the scissors effect and allowing the disk CoG to be always aligned correctly and stable ( no vibes).
I thinbk also that your design has a big interest with 4 blades , the rotor could be considered as a 2 bladed teetering rotor with a stabilizator (the other 2 blades).
Thanks
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zeeoo,
A few thoughts about this rotorhead;
A pure Constant Velocity Joint, such as the Rzeppa type, by itself, will probably not work. I do not believe that they are designed to take large axial loads. This appears to be confirmed in the Doman sketches. Here the CVJ imparts torque to the rotor, at a constant speed. However, the other forces are handled by the stationary Universal (Cardan or Hooke's ) Joint.
The sketches and drawings are open to anyone. They are produced as a .dc files in 2D by DeltaCAD, but the program is capable of saving them in an elementary, and imperfect AutoCAD .dxf format.
Regarding your last two paragraphs:
The difficult part is to start off with a full understanding of the subject of cyclical Coriolis and the Cardan Joint Effect. The underlying premise of the Constant Velocity Rotor is that the rotor disk always thinks that it is aligned with the mast. There is no cyclical acceleration and deceleration caused by flapping or teetering because there is no flapping or teetering. The 'rigid' disk (tip path plane) mearly reorients itself in space.
Smaller considerations during forward flight, such as dissymmetry of profile drag, plus flapping within the blade (out of plane bowing) due to the hub spring moment, will result in lead/lag moments. Theoretically, a strong rotor should be able to 'force' its way through these minor 'nuisances'. In addition, the difference between the precone to normal cone angle is intended to help.
Dave
A few thoughts about this rotorhead;
A pure Constant Velocity Joint, such as the Rzeppa type, by itself, will probably not work. I do not believe that they are designed to take large axial loads. This appears to be confirmed in the Doman sketches. Here the CVJ imparts torque to the rotor, at a constant speed. However, the other forces are handled by the stationary Universal (Cardan or Hooke's ) Joint.
The sketches and drawings are open to anyone. They are produced as a .dc files in 2D by DeltaCAD, but the program is capable of saving them in an elementary, and imperfect AutoCAD .dxf format.
Regarding your last two paragraphs:
The difficult part is to start off with a full understanding of the subject of cyclical Coriolis and the Cardan Joint Effect. The underlying premise of the Constant Velocity Rotor is that the rotor disk always thinks that it is aligned with the mast. There is no cyclical acceleration and deceleration caused by flapping or teetering because there is no flapping or teetering. The 'rigid' disk (tip path plane) mearly reorients itself in space.
Smaller considerations during forward flight, such as dissymmetry of profile drag, plus flapping within the blade (out of plane bowing) due to the hub spring moment, will result in lead/lag moments. Theoretically, a strong rotor should be able to 'force' its way through these minor 'nuisances'. In addition, the difference between the precone to normal cone angle is intended to help.
Dave
