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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › What does a flybar do
05-27-2007 09:03 PM  13 years ago
Autoeject

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Using various paddles and/or weights allows the user to tune the gyroscopic stabilization response of their particular heli. As in Colin's article, the power steering effect is minimal. I did not use any different servos for my flybarless conversion and it is plenty responsive.Mark Webber
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05-27-2007 09:39 PM  13 years ago
AirWolfRC

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I beg to differ with some of the interpretations of Colin's statements.

Consider the typical (about 50/50) mixing of Bell/Hiller controls. The flybar clearly provides a fair amount of input to the main blade pitch.

Total servo torque requirements say little to nothing about this question.

Furious Predator,
You don't need to vent your temper tantrum in a PM to me.
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05-27-2007 10:03 PM  13 years ago
Autoeject

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The reason behind the mixing arm is to allow further tuning of the gyroscopic effect. As we know, the hiller design results in sluggish cyclic response while the bell design ends up too pitchy. Mixer arms allow the best of both for a flybar equipped heli.Mark Webber
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05-27-2007 10:25 PM  13 years ago
AirWolfRC

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Ok, but that does not clarify the previous point.
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05-28-2007 12:04 AM  13 years ago
swheli

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cornwall uk

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fly bar
The fly bar is specificaly there to join the paddles together..if it was not there they would fall off when the head started to turn !!
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05-28-2007 12:25 AM  13 years ago
SSN Pru

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AirwolfRC

Thanks for gaying up another thread...

you like to disagree with everyone.

i bet you sit at home at night, alone, and argue with yourself...
Stupidity can be cured. Ignorance is for life!
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05-28-2007 12:31 AM  13 years ago
AirWolfRC

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You're quite welcome.

Someone has to keep things accurate.

So, you're a Google engineer ? That would explain your comments.
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05-28-2007 01:00 AM  13 years ago
KCT

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Ontario, Canada

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Here we go again, another AirwolfRC p!ss!ng constest.

So where is that ignore button again...

Mark R. can we have an AirwolfRC default ignore, please ?

Thanks

Kay

That's not flying, that's crashing with style...

TeamBob00, WildCat, Helitron,
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05-28-2007 01:07 AM  13 years ago
AirWolfRC

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KCT, tell me, is that the only reason you posted ? ?

Is that your contribution to accuracy and keeping the static down ? ?
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05-28-2007 01:19 AM  13 years ago
GyroFreak

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gtxkid
Hmmm, great discussion, I wonder if gtxkid (the original post) got his answer out of all this ?? I sure did !!
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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05-28-2007 01:35 AM  13 years ago
arceye

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What a lot of reading and googling you people must do to quote the factual answers and then prove the facts integrity for the sake of being correct.
The original question was answered by BarracudaHockey accurately enough within 3 replies to original post and yet its now on a second page with people making every effort to keep face and be the ultimate answer machine.

I prefer to fly my heli than sit on the net reading about how every switch, nut, screw , shaft and cog works or trying to prove my knowledge is greater than the armchair pilots.

But at the end of the day its all entertaining and what makes runryder what it is, amusing reading.

Kasama Head :(
The Blingiest DOWNGRADE a Raptor can have
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05-28-2007 03:43 AM  13 years ago
CK_

rrApprentice - Redondo Beach, CA MyPosts All  Forum  Topic

The fly bar is specificaly there to join the paddles together..if it was not there they would fall off when the head started to turn !!
Good one

Thank you umdpru. I've been saying that for years. I think this power steering myth originated with Hiller mixing, for which the paddles actually do provide a power steering effect, and it just gets passed down to successive generations of newbies. Kind of like eCCPM, but that's a whole other topic.

gtxkid, I hope this explanation helps you out.

Stabilizer Bar (full size Huey, Bell 47)
A stabilizer bar is just like a flybar but it does not have paddles. Unlike a flybar, however, a stabilizer bar has hydraulic dampers to damp the teetering motion. The dampers allow the stabilizer bar disk to follow the mast when it tilts. Without these dampers, the stabilizer bar disk would act like a gyroscope and keep its plane of rotation (parallel with the ground) and would crash the helicopter if you tried to maneuver. A stabilizer bar acts as a rate damper on pitch and roll. In other words, it would be like putting rate gyros on your aileron and elevator servos. This is a common practice with flybarless heads on scale models. Stabilizer bars are almost never used on models because of the mechanical damping required and the slow response time.

Flybar with Hiller Mixing (full size Hiller Raven, fixed pitch model helis)
A flybar does not need the mechanical damping that a stabilizer bar needs. A flybar gets its damping aerodynamically by flapping up and down as it rotates. With Hiller mixing, only the paddles are controlled by cyclic pitch inputs. The tilting of the flybar disk then controls the cyclic pitch of the blades. This system does provide a power steering effect but the drawback is slow reaction time. The flybar disk takes time to tilt before cyclic pitch is applied to the blades.

Flybar with Bell/Hiller Mixing (none full size, most model helis)
Similar to Hiller mixing but also includes a direct cyclic input from the swashplate to the blades. The direct (Bell) input gets added with the indirect (Hiller) input from the tilt of the flybar. With Bell/Hiller mixing, there is no power steering effect. Response time is much quicker because the Bell input is felt at the blades immediately.

If you still believe in the Bell/Hiller power steering myth, take a look at this example:

Two workers are hoisting up a weight (W). Their load is split equally by a bar so that each worker only has to pull W/2 on the rope. If one of the two workers goes on break and ties off his rope, what happens to the force that the remaining worker has to pull? It stays the same of course. The guy that went on break is Mr. Hiller and the guy left holding the rope is Mr. Bell. Can you see where I'm going with this? The red beam is the mixing arm. When they were both holding the rope, that was a Bell/Hiller system and the force in the servo was Mr. Bell's force of W/2. The mechanical ratio or mechanical advantage of Mr. Bell was 2 to 1. When Mr. Hiller went on break he turned the system into a flybarless system. Mr. Bell's mechanical advantage is still 2 to 1 so his force is still half of the weight. So what is different between these two systems? Displacement. If Mr. Bell and Mr. Hiller both pull the rope up 1 foot then the weight rises one foot. When Mr Hiller goes on break, Mr Hiller must pull the rope 2 feet to get the weight to rise one foot. So there is no power steering effect for force with Bell/Hiller mixing. The force will only depend on the mechanical ratio between the servo and the blade grip. What you loose is displacement or the additional cyclic input angle provided by the flybar tilt. And you can't call this additional displacement a power steering effect either. The additional Hiller displacement can be positive or negative so it could increase or decrease the total cyclic so it doesn't always amplify the input. Consider if Mr. Hiller lowered his rope 1 foot when Mr. Bell raised his rope one foot. The weight would go nowhere. I hope this explanation has converted at least one person.

Chris
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05-28-2007 03:51 AM  13 years ago
AirWolfRC

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Your depiction is spot on, but it does not answer the question of "power steering". You pick up with the output force from the flybar. You do not show the input force vs output force of the flybar which is what the question of "power steering" is about.

You make a flat statement "With Bell/Hiller mixing, there is no power steering effect." but don't support it.

What you're missing can be loosely shown with a comparison to an airplane. The flybar is the elevator and the input torque to the rotor head is the motor. The position of the elevator changes the wing's pitch and as a result, the plane gains or looses altitude which the servo controling the elevator does not have the power to do by itself. That's "power steering". The torque of the main rotor is "modulated" by the flybar and used to help change the pitch of the main blades per the example you showed.

Why is that so hard to see ?
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05-28-2007 05:33 AM  13 years ago
Gardner

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I don't get it, can someone please explain this again?
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05-28-2007 06:17 AM  13 years ago
Helikrasher

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USA

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AirwolfRC

Thanks for gaying up another thread...
That's too funny .....
I don't get it, can someone please explain this again?
It's all alot easy to understand if you just 'IGNORE' the airtroll, I do ..... if not just google "heli" with the [I'm feeling lucky] button and it will be clear as day, that's how some of us do it
HK ... In a world of compromise, some don't.
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05-28-2007 02:05 PM  13 years ago
kangarooster

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Don't confuse me with facts. My mind is already made up.
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05-28-2007 02:47 PM  13 years ago
SSN Pru

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Taxachusetts

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I think this topic should be closed.

AirwolfRC is starting to call everyone else a liar.

AirwolfRC, I am a mechanical engineer. You can interpret my signature as you will but im sure the people who get it arent laughing at me but someone else here on these boards. Your constant trolling about and arguing with people is ruinning these boards. I can come into RR on any given day and find a thread with your arguing and bickering on the first friggin page.

Someone here needs to give you the door and put you out of your misery.

Go away TROLL!!!

Stupidity can be cured. Ignorance is for life!
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05-28-2007 03:26 PM  13 years ago
Helikrasher

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LMAO!!! No wonder he's so grumpy HK ... In a world of compromise, some don't.
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05-28-2007 04:28 PM  13 years ago
AirWolfRC

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AirwolfRC is starting to call everyone else a liar.
If that's your answer to my giving more detail, then you're not much of an engineer. (maybe a Google engineer) Sounds more like you're prone to exaggerate whatever suits your purpose.

Clearly, you are having difficulty telling the difference between requiring evidence or proof and calling someone a liar.

That sounds more like an emotional reaction than an engineering approach.
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05-28-2007 04:45 PM  13 years ago
AirWolfRC

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For the silent majority that actually are interested in the details,
- - - - and not just barking to see who will submit - - -

Consider this, take a wing and fly it around in a circle while holding one wing tip. Notice that a slight change in pitch will make the wing fly up or down per the change in pitch. Notice how little force it took to change the pitch, Notice how much up/down force resulted.

Now connect a linkage near the inner end of the wing and connect it to a force gage and consider how much force will be exerted with just a small force used to change the pitch of the wing.

This is how a flybar is working and the linkage is going to the mixing arm for the main blade.

Small force in - - large force out - - "power steering"
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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › What does a flybar do
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