- Joined
- Oct 30, 2003
- Messages
- 18,373
- Location
- Santa Maria, California
- Aircraft
- Givens Predator
- Total Flight Time
- 2600+ in rotorcraft
My opinion of how a hub bar works.
My opinion of how a hub bar works.
If you have a question please ask.
Fundamentally I am challenging your assertion that the pictured hub is inherently superior and that most hub bars are unsafe on a gyroplane that weighs over 500 pounds.
”Vance, as I've done this exercise it's frightened me. I hope I am wrong about it. A 3" by 1 1/8" hub bar might work for a 250 pound Bensen loaded to 500 pounds, but how many out there are well over that weight? And even if they are under 500 pounds, they are at the deformity rating of the best materials at two Gs.”
In my opinion when I don’t know what questions to ask it is difficult for me to calculate forces and quantify the superiority of a particular design.
I am also challenging your assertion that:
“There is no such thing as centripetal or centrifugal force.”
I have already explained this in post #29.
In my opinion one of the wonderful things about a gyroplane rotor is it is self regulating.
In my experience, when you load it more it speeds up and the coning angle is very close to the same.
I feel that the coning angle is only a convenient way to describe what is actually a gentle curve as the centrifugal force balances the lift of the rotor blades.
I feel that the centrifugal force does not suddenly end where the blade joins the hub bar. It appears to be lifting the machine through the teeter bolt so it is likely that although the load path is somewhat convoluted the centrifugal force meets in the middle.
In my opinion the hub bar acts as a spring to keep the blades from breaking at the root.
In my opinion the primary force acting on the hub bar is the centrifugal force trying to pull it apart. I feel that the hub bar is bent and twisted in many directions from many different perturbations.
I have seen many rotorcraft fly with hinges at the root of the blade and some even had a second set of hinges quite a ways from the hub.
There you have my opinion about how a Bensen style hub bar works and why it may not be inferior to the hub in your picture. I hope this answers your unasked questions.
Thank you, Vance
My opinion of how a hub bar works.
If you have a question please ask.
Fundamentally I am challenging your assertion that the pictured hub is inherently superior and that most hub bars are unsafe on a gyroplane that weighs over 500 pounds.
”Vance, as I've done this exercise it's frightened me. I hope I am wrong about it. A 3" by 1 1/8" hub bar might work for a 250 pound Bensen loaded to 500 pounds, but how many out there are well over that weight? And even if they are under 500 pounds, they are at the deformity rating of the best materials at two Gs.”
In my opinion when I don’t know what questions to ask it is difficult for me to calculate forces and quantify the superiority of a particular design.
I am also challenging your assertion that:
“There is no such thing as centripetal or centrifugal force.”
I have already explained this in post #29.
In my opinion one of the wonderful things about a gyroplane rotor is it is self regulating.
In my experience, when you load it more it speeds up and the coning angle is very close to the same.
I feel that the coning angle is only a convenient way to describe what is actually a gentle curve as the centrifugal force balances the lift of the rotor blades.
I feel that the centrifugal force does not suddenly end where the blade joins the hub bar. It appears to be lifting the machine through the teeter bolt so it is likely that although the load path is somewhat convoluted the centrifugal force meets in the middle.
In my opinion the hub bar acts as a spring to keep the blades from breaking at the root.
In my opinion the primary force acting on the hub bar is the centrifugal force trying to pull it apart. I feel that the hub bar is bent and twisted in many directions from many different perturbations.
I have seen many rotorcraft fly with hinges at the root of the blade and some even had a second set of hinges quite a ways from the hub.
There you have my opinion about how a Bensen style hub bar works and why it may not be inferior to the hub in your picture. I hope this answers your unasked questions.
Thank you, Vance