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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › What does a flybar do
05-26-2007 11:55 PM  13 years ago
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gtxkid

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Gulf Breeze Florida

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What does a flybar do
What exactly does a Flybar do.
Reason for having one is what.
Futaba 14Mz / 1300mm Multi rotor / Logo 10
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05-26-2007 11:59 PM  13 years ago
BarracudaHockey

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Jacksonville FL

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Gyroscopic stability and it helps change the pitch of the main blades for cyclic inputs, power steering kinda since we use servos instead of hydraulic systems like most of the real ones but mainly stability. Remember the Hueys and Bell 47's (mash choppers) had them but instead of paddles they were just weights.Andy
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05-27-2007 12:49 AM  13 years ago
MOS15T

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KATTERBACH AAF (GERMANY)/ ST. CHARLES MO

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to see the full effects of a flybar and paddles, you could use different size paddles and weights. you will notice a more sluggish response with a heavier wight with smaller paddles, in effect it will seem more stable than a lighter larger paddle. also the longer the flybar itself the more "control" you have.
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05-27-2007 01:22 AM  13 years ago
BarracudaHockey

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Jacksonville FL

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To add to that, a heavier paddle (or weights on the flybar) will be less responsive to cyclic but more stable in forward flight and less disturbed by wind in a hover. Its all a big trade off.Andy
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05-27-2007 03:29 AM  13 years ago
ShempHoward

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San Francisco, Ca - too many beggars + bad drivers

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Yer both wrong - A Barfly is someone who hangs around a Bar all day long bumming drinks from other alcoholics.

Oh wait, I see now - Fly Bar.
See above explanation.
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05-27-2007 04:15 AM  13 years ago
3D_Pilot

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Vallejo, CALI.

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LOL. "barfly".
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05-27-2007 04:31 AM  13 years ago
karlo

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Montreal

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barfly...hahaha!!
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05-27-2007 10:12 AM  13 years ago
Andy from Sandy

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UK

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After watching a guy fly his CSM flybarless setup I can only see the flybar is for stability. We are using servos with immense power these days and with ccpm setups all three servos are acting together.
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05-27-2007 12:29 PM  13 years ago
Autoeject

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Ashtabula, OH, USA

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After watching a guy fly his CSM flybarless setup I can only see the flybar is for stability
Yep, it's a mechanical gyro. You can fly without a flybar, gyros or special blades but pitchiness is a problem. I went flybarless on my raptor but use the AP2000i and 401's to manage the cyclic pitchiness.
Mark Webber
wai-rc.com
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Outrage Helicopters
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05-27-2007 01:59 PM  13 years ago
SSN Pru

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Taxachusetts

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flybar doesnt perform any power amplification. a flybar performs two jobs.

1. It stablizes the main rotor disk again purturbances such as wind gusts.

2. It mechanically limits the cyclic rate of the rotor disk to the cycic rate of the flybar. the cyclic rate of the rotor disk is much much faster than the flybar.
Stupidity can be cured. Ignorance is for life!
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05-27-2007 02:46 PM  13 years ago
GyroFreak

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Orlando Florida ...28N 81W

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flybar doesnt perform any power amplification.
If thats true, why not just weights instead of paddles, like the 'MASH" heli's.
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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05-27-2007 03:08 PM  13 years ago
TheRickster

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Beaumont Texas

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Spin the front tire on a bicycle and then turn the handlebars. The feedback you feel is what the FlyBar imposes on the rotor disk through the mixing arms. The amount of action is dependant upon what the flybar mixing ratio is.

Rick
If in doubt lean it out . We don't do this to save money, we save money to do this
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05-27-2007 03:50 PM  13 years ago
SSN Pru

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Taxachusetts

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there are two main paths of control inputs from the swash to the blade grips. one is through the flybar and the other is directly from the swash. the hiller control passes through the flybar and to the blade grips to allow the flybar to have some control authority over the rotor disk (ie for purturbance stababilization and for rotor disk cyclic limiting). the problem with this sole control application is that it causes the controls to get really slow and mushy cause the flybar is fighting your control inputs. thats where the bell control comes in. it is a direct control input into the swash to get rid of that mushy, slow response.

initally the flybar was developed solely for stabilization, perhaps now becaus of the mixing ratios used, it could ass some power assist although its not used.

if the flybar does indeed provide power steering then why dont flybarless helis use MASSIVE servos for control? they dont, because thats not what the flybar is for.

when i was green in this hobby and thought i knew everything, i also thought the flybar was "power steering" too. ive since done a lot of reading both on the forums, and books concerned with helicopter dynamics and theory.

i would suggest that if you truly are curious as to the function of th flybar the you do a lot of reading.

start with this webpage. if you back up to the articles directory, at the bottom of the page there are 10 more articles related to helicopters that are written very well.

http://www.w3mh.co.uk/articles/html/csm9-11.htm

pru
Stupidity can be cured. Ignorance is for life!
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05-27-2007 04:32 PM  13 years ago
GyroFreak

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Orlando Florida ...28N 81W

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Yep, after sitting back and visulizing the torque that the blades cause around the feathering shafts (pitch rotation), I realized that the position of the feathershaft to blade center line (length wise) defines whether positive or negitive torque is required to change the pitch. In the right place the torque required to change pitch is near zero (excluding inertia, friction, blade dynamics from bending), so no power boost for pitch changes should be needed.

Yes, I have had Colin Mill's articals bookmarked for quite some time, very good refrence..
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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05-27-2007 06:04 PM  13 years ago
AirWolfRC

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42½ N, 83½ W

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The flybar is primarily for stabilization, secondarily, for power steering.

It acts as a gyroscope. It's position can be altered by cyclic inputs. It's position also has some control over the main blade pitch. It does this with linkages at the hub and acts as a sort of power steering. Cyclic inputs change the flybar disk position which uses aerodynamic forces to help change main blade pitch. Conceptually like the elevator on an airplane is used to change the wing pitch.

If the main rotor disk deviates from a certain position relative to the flybar disk, the linkages cause main blade pitch changes to bring the main rotor disk back. That's called Hiller mixing. Cyclic inputs also control the main blade pitch directly, that's called Bell mixing. The systems we typically use are called Bell/Hiller mixing.
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05-27-2007 06:51 PM  13 years ago
Furious Predator

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Kitchener, Ontario, Canada

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Collin Mill makes a good post explaining what a flybar system does. according to him, the power steering effect is a common misconception. its more for stabilization, without the flybar, the heli would be so pitchy it would be uncontrollable.

its a good read, it sounds like he is one of the few people who actually know what they are talking about, and not just assuming what something does.

Click Here
Shawn
Team Leisure-Tech
Team HelixRC
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05-27-2007 06:52 PM  13 years ago
Furious Predator

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Here is a quote from him from pg3
Hi Furious Vigor

Ah, perhaps I can help. I had not appreciated that people thought (quite reasonably) that the flybar was some sort of servo assistance for applying pitch to the blades. Although it may now serve that function to a degree it was not the original reason for models to adopt one. The original reason for the flybar was primarily to slow down the response of the helicopter to cyclic controls. There was a very good book that discussed all this with good numerical examples written by John Drake - well worth getting a second hand copy if you can find one. Anyway, the natural 'following rate' of the main rotor is high so that say 1 degree of cyclic pitch causes about 60 deg/s of roll or pitch - rather twitchy!. The flybar, because it is relatively heavy with smallish area paddles which because of the smaller radius than the blades move slower through the air has a much lower following rate which is more in tune with what the human pilot can cope with. In the early Hiller control arrangement used in models the flybar was controlled by the swashplate and the cyclic pitch of the blades was controlled only by the tilt of the flybar. This effectively forced the main rotor to only roll at the rate dictated by the flybar but gave a big delay between the control inputs and the response. In Bell-Hiller control some input direct from swash to main blades is mixed in to help remove that delay.

So, I guess, coming back to the real question about servo loads it is possible to keep the forces needed to control the pitch of the blades quite small. I'm in the middle of doing some numerical examples which I hope to post up here fairly soon.

Best regards

Colin
Shawn
Team Leisure-Tech
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05-27-2007 07:08 PM  13 years ago
AirWolfRC

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42½ N, 83½ W

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according to him, the power steering effect is a common misconception.
That's what you say.
. . . . people thought (quite reasonably) that the flybar was some sort of servo assistance for applying pitch to the blades. Although it may now serve that function to a degree it was not the original reason for models to adopt one.
That's what Colin says.

How is it that you use Colin's statements to contradict yourself ?
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05-27-2007 07:13 PM  13 years ago
Furious Predator

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Kitchener, Ontario, Canada

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he said "TO A DEGREE"

NOT THAT SIGNIFICANT

sorry if i didn't initially quote him exactly, i was going from momory, that thread happened a long time ago, and i'm sorry you cant bare to be even a little wrong airwolf.
Shawn
Team Leisure-Tech
Team HelixRC
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05-27-2007 07:18 PM  13 years ago
AirWolfRC

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42½ N, 83½ W

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It's very simple, you said
according to him, the power steering effect is a common misconception
The fact is he didn't say that . . . . . and you provided the evidence !

Colin did not deny or dispute the power steering function, only you called it a misconception and tried to hang it on Colin.

It's a shame you failed to see the error of your assertions.
. . . . even after you provided the proof !
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