You can't keep a good man down. A new design is born.
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On a counter clockwise rotor system viewed from above with the rotor system having four blades (it’s easier to explain that way).
First, thanks! Yeah I was using the "O'clocks" in a purely abstract fashion (or perhaps I was hovering sideways?).
Now then, the rigid hub works for a four blade system, as the blades are happy going through their flapping phases at 180/90 degrees opposition. But what happens with three or five or six blades?
Now on to the dreamy stuff...
The idea of a giant elastomeric bearing substituting for a rotor hub is interesting. Terrifying, but interesting! Perhaps we could combine that with a digitally controlled, pezioelectric-driven servo-flap rotor - eliminate the swash plate and all moving parts beyond the main rotor driveshaft (but don't fly too near those high-KV powerlines...).
Join Date: Apr 2003
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Lu,
" To simplify Dave’s’ design get rid of the two hooks joints and use the hub spring as the constant velocity joint.
"
Your ideas are right on the money. However, the problem is that of implementing the idea. The hub's joint must allow tipping about the two horizontal axes while rigidly transmitting torque about the vertical axis. In addition, there can be no linear motion along any of the three axes. Sikorsky has a patent that attempts to achieve the above. It is 'Elastomeric high torque, constant velocity joint' 4,714,450 and it can be viewed at; US Patent Full-Text and Full-Page Image Databases
The Sikorsky patent requires that the special elastomeric bearing compress in certain locations. Unfortunately, compression is a no-no for elastomeric bearings. I have tried to develop a CVJ elastomer bearing design that overcomes this problem, but no luck, also.
An interesting and related hub is the one that was used on the Doman LZ-1A. It consisted of a CVJ located inside a Hooke's joint. It appears that the CVJ delivered the torque and perhaps handled the horizontal loads, while the Hooke's joint handled the thrust load.
So far, it appears that only a Concentric Double Universal (Hookes) Joint can meet the requirements. The addition of the hub spring does two things. It becomes the mechanisms for locating the angle of the CDUJ's central components and it provides more control authority over the rotor disk.
delta3,
Your comments are of interest. I agree that even if the lead/lag coming from the Hooke's Joint Effect (cyclical Corollas Effect) is eliminated, by the implementation of a CVJ, there are other contributors to lead/lag. Would you elaborate a little more about your concerns?
Thanks,
Dave
" To simplify Dave’s’ design get rid of the two hooks joints and use the hub spring as the constant velocity joint.
"
Your ideas are right on the money. However, the problem is that of implementing the idea. The hub's joint must allow tipping about the two horizontal axes while rigidly transmitting torque about the vertical axis. In addition, there can be no linear motion along any of the three axes. Sikorsky has a patent that attempts to achieve the above. It is 'Elastomeric high torque, constant velocity joint' 4,714,450 and it can be viewed at; US Patent Full-Text and Full-Page Image Databases
The Sikorsky patent requires that the special elastomeric bearing compress in certain locations. Unfortunately, compression is a no-no for elastomeric bearings. I have tried to develop a CVJ elastomer bearing design that overcomes this problem, but no luck, also.
An interesting and related hub is the one that was used on the Doman LZ-1A. It consisted of a CVJ located inside a Hooke's joint. It appears that the CVJ delivered the torque and perhaps handled the horizontal loads, while the Hooke's joint handled the thrust load.
So far, it appears that only a Concentric Double Universal (Hookes) Joint can meet the requirements. The addition of the hub spring does two things. It becomes the mechanisms for locating the angle of the CDUJ's central components and it provides more control authority over the rotor disk.
delta3,
Your comments are of interest. I agree that even if the lead/lag coming from the Hooke's Joint Effect (cyclical Corollas Effect) is eliminated, by the implementation of a CVJ, there are other contributors to lead/lag. Would you elaborate a little more about your concerns?
Thanks,
Dave
Last edited by Dave_Jackson; 25th Oct 2004 at 05:59.
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Flingwing207,
The blue blade in your post has not passed its max flapped down position at 270, that was where it was at its max rate of flapping down. It still flaps down (but at a decreasing rate) until it is at the rear of the disc.
The blue blade in your post has not passed its max flapped down position at 270, that was where it was at its max rate of flapping down. It still flaps down (but at a decreasing rate) until it is at the rear of the disc.
Iconoclast
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Which way is up and for that matter which way are we going?
To: deeper & Flingwing207
If the blade flaps down at the rear of the disc you are flying backwards.
The blue blade in your post has not passed its max flapped down position at 270, that was where it was at its max rate of flapping down. It still flaps down (but at a decreasing rate) until it is at the rear of the disc.
