Understanding the rotorhead.
10-22-2004, 03:25 PM
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Understanding the rotorhead.
I am just assembling my first heli, a Raptor 50 V2. It’s an amazing piece of machinery. However, when I look at the flybar with its linkage to the main rotor, I can not fully understand how it works. The flybar can even be rocked up and down when the servos are stationery, and it rotates the main rotor grips as well.
Does anyone know where I can find an understandable explanation on the principle of this kind of rotorhead?
Thx,
Helge.
Does anyone know where I can find an understandable explanation on the principle of this kind of rotorhead?
Thx,
Helge.
10-22-2004, 07:15 PM
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RE: Understanding the rotorhead.
The servos control flybar pitch, which in turn provides the leverage to move the mains. A regular heli generally doesn't have a flybar, but it does have heavy duity hydralic actuatos holding the swash.
10-31-2004, 05:41 PM
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RE: Understanding the rotorhead.
Hello,
First Thing Was your Question About A Good Reference Of Where You Can Look Information Such As This Up And I Would Have To Refer you to Ray's Authoritative Helicopter Manual, Is A 200+ Page Great Book Explaining The Theory And Setup Of Model Helicopters.. If You Get It, Make Sure To Get The Updated One With Raptors In It, This Book Retails For about $25 Dollars.
Next I Will try to Explain Why the Flybar Is Not Locked In Place in Semi-Lamens Terms. When Your Rotor Head Is Spinning, You Create A Giant Disk of Lift, If you Tilt the Disk In One Direction (Via Cyclic Control) The Helicopter Moves That Way. The Flybar is Not Locked In Place Because When The Rotor Head Is Spinning Centrifugal Force Pulls It To A Position That Is 90 Degrees To The Rotating Object (In This Case the Main Shaft), When you give A Control Input on the Cyclic The Flybar Paddles Tilt In The Direction of The Input To Move the Helicopter That Way, And The Flybar Will Follow After It Once It Has Settled In (We are talking Nano-Seconds Here) If the Flybar was locked in place the helicopter would lose almost all stability that it currently has and would be almost unflyable. If this makes no sense at all to you, Refer to Ray's Book... Justin
First Thing Was your Question About A Good Reference Of Where You Can Look Information Such As This Up And I Would Have To Refer you to Ray's Authoritative Helicopter Manual, Is A 200+ Page Great Book Explaining The Theory And Setup Of Model Helicopters.. If You Get It, Make Sure To Get The Updated One With Raptors In It, This Book Retails For about $25 Dollars.
Next I Will try to Explain Why the Flybar Is Not Locked In Place in Semi-Lamens Terms. When Your Rotor Head Is Spinning, You Create A Giant Disk of Lift, If you Tilt the Disk In One Direction (Via Cyclic Control) The Helicopter Moves That Way. The Flybar is Not Locked In Place Because When The Rotor Head Is Spinning Centrifugal Force Pulls It To A Position That Is 90 Degrees To The Rotating Object (In This Case the Main Shaft), When you give A Control Input on the Cyclic The Flybar Paddles Tilt In The Direction of The Input To Move the Helicopter That Way, And The Flybar Will Follow After It Once It Has Settled In (We are talking Nano-Seconds Here) If the Flybar was locked in place the helicopter would lose almost all stability that it currently has and would be almost unflyable. If this makes no sense at all to you, Refer to Ray's Book... Justin
11-01-2004, 07:51 PM
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RE: Understanding the rotorhead.
If this makes no sense at all to you, Refer to Ray's Book... Justin
trying to read your post with every word capitialized made reading it difficult
11-10-2004, 03:42 PM
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RE: Understanding the rotorhead.
... I Was Just Wondering About That Myself... <heh>
At least the information is good and he's being a good guy in trying to share what he knows.
p.s. Just razzin' ya little tiny bit is all
At least the information is good and he's being a good guy in trying to share what he knows.
p.s. Just razzin' ya little tiny bit is all
11-18-2004, 09:31 PM
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RE: Understanding the rotorhead.
Raptortechnique.com
If you cant find it here, you will not find it anywhere.
Michael knows more about Ratptors than Thunder Tiger does.
Lean540
If you cant find it here, you will not find it anywhere.
Michael knows more about Ratptors than Thunder Tiger does.
Lean540
11-19-2004, 09:50 AM
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RE: Understanding the rotorhead.
Without getting into a giant pissing contest here let me see if I can explain it in simple terms.
Dieter Schluter invented the modern Bell Hiller control system that has been standard in model helis back in 1972 or thereabouts. The flybar is the outcome of initially using the Hiller only system of rotor control albeit in a very simplified form on a fixed pitch rotor head. I say simplified because the original Hiller rotor utilised flybar paddles that changed pitch as well. The modern Hiller system for models does not use a pitch change system for the flybar paddles. The modern model heli rotor system is basically a Hiller system with Bell direct input superimposed onto the control system. The flybar is essentially a "servo rotor" in that the pilot flies the servo rotor which in turn flies the main rotor. The benefit to this system is the reduced load on the servos. A modified Bell system of control where the swashplate controlled the cyclic pitch changes directly requires servos of relatively high torque to maintain control over the system. A good example of this technology can be found on Varios website. Take a look at their multiblade heads and you will see direct bell input to the main blades. The original Bell system as in the Bell 47 consisted of a stabiliser bar with tip weights fitted to the bar to provide gyroscopic stability and dampen the head response. This gyro stabiliser system was difficult to reproduce on a model as it is quite complex to tune on the fullsize. The flybar also has another benefit in that it insures 90 degree gyroscopic precession of the rotor head. A flybarless system does not necessarily precess at 90 degrees, it is more like 70-90 degrees depending on the system. Gyroscopic precession is where the actual input to the main rotor is put in 90 degrees prior to the action being completed. A simple illustration of this is to spin up a toy top or gyroscope and then give it a push with your finger and you will see that it moves at about 90 degrees to the point that you tried to make the input.
In short, the thing to remember is that in the model world, the pilot controls the flybar and the flybar flies the main rotor. Various ratios of control is what makes the various models handle differently. On a typical model rotorhead running at 1500 rpm or better things can happen rather quickly, even with a flybar doing the translating.
TM
Dieter Schluter invented the modern Bell Hiller control system that has been standard in model helis back in 1972 or thereabouts. The flybar is the outcome of initially using the Hiller only system of rotor control albeit in a very simplified form on a fixed pitch rotor head. I say simplified because the original Hiller rotor utilised flybar paddles that changed pitch as well. The modern Hiller system for models does not use a pitch change system for the flybar paddles. The modern model heli rotor system is basically a Hiller system with Bell direct input superimposed onto the control system. The flybar is essentially a "servo rotor" in that the pilot flies the servo rotor which in turn flies the main rotor. The benefit to this system is the reduced load on the servos. A modified Bell system of control where the swashplate controlled the cyclic pitch changes directly requires servos of relatively high torque to maintain control over the system. A good example of this technology can be found on Varios website. Take a look at their multiblade heads and you will see direct bell input to the main blades. The original Bell system as in the Bell 47 consisted of a stabiliser bar with tip weights fitted to the bar to provide gyroscopic stability and dampen the head response. This gyro stabiliser system was difficult to reproduce on a model as it is quite complex to tune on the fullsize. The flybar also has another benefit in that it insures 90 degree gyroscopic precession of the rotor head. A flybarless system does not necessarily precess at 90 degrees, it is more like 70-90 degrees depending on the system. Gyroscopic precession is where the actual input to the main rotor is put in 90 degrees prior to the action being completed. A simple illustration of this is to spin up a toy top or gyroscope and then give it a push with your finger and you will see that it moves at about 90 degrees to the point that you tried to make the input.
In short, the thing to remember is that in the model world, the pilot controls the flybar and the flybar flies the main rotor. Various ratios of control is what makes the various models handle differently. On a typical model rotorhead running at 1500 rpm or better things can happen rather quickly, even with a flybar doing the translating.
TM
