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HomeAircraftHelicopterMain Discussion › Why do model helis need a flybar?
11-06-2004 05:32 PM  13 years agoPost 1
Todd74

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PA, USA

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A flybar and paddles seem fundamental in the operation of our model helis, but as far as I can tell, full scale helis don't have them. Why is this? Can a real expert out there give a detailed explanation?

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11-06-2004 05:51 PM  13 years agoPost 2
Drunk Monk

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Preston, UK

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There's some info here http://www.runryder.com/t113457p1/?...=flybar+physics


Stephen

I only open my mouth to change feet.....

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11-06-2004 06:02 PM  13 years agoPost 3
zagidave

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uk.(north london)

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flybar
before we go any further im far from an expert on this subject!

fly bars are used on model helis to damp the inputs from the swash to the blades, without a fly bar they would be so sensitive it would make them almost impossible to fly. The gyroscopic effect of the flybar damps the control imputs (in very basic terms) there are some designs that use a flybarless head but are not usually for novices.

hope this helps a bit.

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11-06-2004 06:15 PM  13 years agoPost 4
DrDan

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Potosi, Missouri

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From what I understand, to help stabilize the heli, you need to have a swashplate on top and bottom of the main blades. The flybar acts as the top swashplate. What this helps is instead of the bottom swash either pulling or pushing the blades, the flybar also help pulling and pushing. So, on each blade, you have a push/pull system at every possible angle and point of rotation. This helps stabilize the mains and helps to prevent ware on the servos. The reason the big boys don't need it is because of the length of the blades.

This may not make any since to anyone, but it is what I got from the Flybar Theory sections of few MHT magazines.


Dr. Dan

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11-06-2004 06:24 PM  13 years agoPost 5
AirWolfRC

rrProfessor

42½ N, 83½ W

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The fly bar on our helis does two things.

1) It acts as a free running gyroscope and serves as a spatial reference for controling the main blade pitch. If the heli gets off position by itself, it will adjust the main blade pitch to bring the rotor disk back into position. This helps greatly when going into forward flight. Without the fly bar, the heli will pitch up in the direction of flight. The advancing blade will create more lift and, due to gyroscopic precession, the main rotor disk will pitch up in the direction of flight. This pitch up needs to be controled. This is the BELL portion of the Bell/Hiller type of flybar we use.

2) It acts as a mechanical amplifier of the swash plate inputs to help control the main blade pitch by using the aerodynamics of the paddels. The swash input sets the paddel pitch and the motor energy is converted to additional mechanical energy applied to the main blade push rods. This is the HILLER portion of the Bell/Hiller type of flybar we use.

Full size helis have more inertia in their rotor systems and are not as responsive as our models and, as such, don't need this type of fly bar setup.

Wolfgang

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11-06-2004 06:34 PM  13 years agoPost 6
ZIGZAG

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CTRL FL

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Hi
They dont
Example the GMP legend mustang was a flybarless heli
I had one for 3 years
It was a great helli & fun to fly
wish they were still in business
ZIGZAG

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11-06-2004 08:23 PM  13 years agoPost 7
IYKIST

rrKey Veteran

London united kingdom

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Model Helicopters dont necessarily need a flybar to be stable it only helps check the latest MHW and you see a 3D helicopter wiyhout a flybar

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11-06-2004 09:07 PM  13 years agoPost 8
AirWolfRC

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42½ N, 83½ W

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Once you fly one without a fly bar, you get a much better idea of what it's all about.

Been there, done that. http://www.AirWolfRC.com

Wolfgang

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11-06-2004 09:14 PM  13 years agoPost 9
heligoole

rrKey Veteran

yorkshire,uk

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for cyclic control,turn your main blades/paddles around slowly with transmitter on.put right cyclic fully in on stick,watch flybar paddles move as you spin,as the paddle gets to the right position it returns to its neutral position,but when its at the front of heli it tilts fully right,if you watch closely a fast spinning models rotor the paddle(disc)moves and tilts proportionally with cyclic,different paddles help 3d maneouvres to be more crisp by response being faster,hope this helps

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11-06-2004 11:28 PM  13 years agoPost 10
cczarnik

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Music City, USA!

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Don't some full scale have a flybar too? Here's a link to a Bell 47 rotor:

http://www.kiwiaircraftimages.com/pages/aodbsx5.html

That bar doesn't have paddles, but must provide some kind of gyroscopic stability for main rotor like our flybars.. FWIW, Chuck

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