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Old Oct 18, 2009, 05:15 AM
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Walkera 4#3B: Increasing Flybar Pitch transmission for more stability (plus an idea)

Her ye ol bell hiller modders out there, here is one way of increasing the flybar pitch transmission the the blade grip / bell hiller mixing arms without affecting the bell hiller mixing ratio, or for bell head mods for increase in stability;

The idea in simple mechanical sense is to extend the lower ball links on the flybar outwards. This increases the pitch angle on the grips on a per flybar pitch angle. This as a result increases the amount of stabilization correction from the flybar to the blades.



UPDATE: (October 19,2009)

It is also possible to make the flybar to blade grip pitch transmission data variable by simply usinga a "governor style" weighted balls sliding across the flybar. As the rotor head rotates during a hover, the weighted balls would slide outwards, stretching the links and increasing the angle of pitch transmission (thus more stable) and once cyclic is applied, the balls would slide inwards to "accomodate" the cyclic pitch data. The balls would not need to move back and forth to accomodate the cylic data but would find a neutral zone on the flybar rod to relieve the stress on the links. And once the cyclic input is removed (hover), balls would again move outwards increasing the flybar stabilization data to the grip.


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Old Oct 18, 2009, 05:18 AM
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How is this done on the 4#3/4#3B ? Simple. Just get an old flybar control ring and trim the link balls off ...



The simply slide them to the flybar shaft with the ball side touching the original flybar link ball;



Here is the final config, take note of the flybar link angle;

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Old Oct 18, 2009, 05:20 AM
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and see how stable she is even with a 1 inch flybar. And the cyclics ratio is not affected.

Walkera 4#3B: Increase flybar to blade grip stability transmission - Hover (2 min 2 sec)


Here is another video with some blade tracking tests and showing that the links are still "bind free";


Walkera 4#3B: Increase flybar to blade grip stability transmission - Tracking (1 min 22 sec)



* Just make sure when the links are extended no binding will occur and the head and flybar is still free to teeter/swing.
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Old Oct 18, 2009, 05:56 AM
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U r giving the fly bar more leverage. It works like adding weight to the flybar for added stability but in your case, u accomplished that without adding weight which imo is more efficient.
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Old Oct 18, 2009, 02:15 PM
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Quote:
Originally Posted by altronpower
U r giving the fly bar more leverage. It works like adding weight to the flybar for added stability but in your case, u accomplished that without adding weight which imo is more efficient.

Yes. Actually the flybar had weights and they were removed.
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Old Oct 18, 2009, 04:07 PM
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Quote:
Originally Posted by altronpower
U r giving the fly bar more leverage. It works like adding weight to the flybar for added stability but in your case, u accomplished that without adding weight which imo is more efficient.
Does that mean that the cylic response will be reduced? I thought it would be the same since the beller hiller ratio did not change.
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Old Oct 18, 2009, 06:02 PM
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Quote:
Originally Posted by lazer155
Does that mean that the cylic response will be reduced? I thought it would be the same since the beller hiller ratio did not change.
Cyclic response is not reduced as the ratios are not changed. Only flybar pitch to blade grip pitch transmission is increased. This works best during hover. And as a cyclic input is applied, the flybar natural stabilization is 'disturbed' by the paddles which in effect follows the disk rotation angle of the main blade grips. Thus more stabilization data during hover and retained (and less lag) cyclic data during roll/fore/aft.

I mentioned "less lag" from the above statement - remember the flybar disk angle has to follow the main blade disk during a cyclic input and this is done through the paddles. Here is the thing, because the paddles are also pitching the flybar, that paddle-flybar pitching data to the blade grip pitch transmission is also increased by the abov mod thereby minimizing any phase shift (or phase lag) between grip and flybar. Thus resulting to a more crisp cyclic control.
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Old Oct 18, 2009, 06:20 PM
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Quote:
Originally Posted by EQMOD
Cyclic response is not reduced as the ratios are not changed. Only flybar pitch to blade grip pitch transmission is increased. This works best during hover. And as a cyclic input is applied, the flybar natural stabilization is 'disturbed' by the paddles which in effect follows the disk rotation angle of the main blade grips. Thus more stabilization data during hover and retained (and less lag) cyclic data during roll/fore/aft.

I mentioned "less lag" from the above statement - remember the flybar disk angle has to follow the main blade disk during a cyclic input and this is done through the paddles. Here is the thing, because the paddles are also pitching the flybar, that paddle-flybar pitching data to the blade grip pitch transmission is also increased by the abov mod thereby minimizing any phase shift (or phase lag) between grip and flybar. Thus resulting to a more crisp cyclic control.

Cool so instead of having fast cylic response with only the beller hiller mod instead with this mod plus the beller hiller mod we get lightening fast cylic response.
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Old Oct 18, 2009, 08:17 PM
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Using CB100 Mixing Arms

Here is the best config i found so far ..

This is by using the CB100 Mixing arms provided by Cameron (Ampdraw). Thanks AMP!!

The advantages:

- Ratio Adjustable
- I could use the stock flybar links that came with the 4#3 / 4#3B without having to extend them as the ball link for the flybar is angled and follows the circular pivot of the flybar ball link;






Such config actually allows me to move the flybar balls outward some more. There is no binding as the balls can slide;




view from below;




view from top;



and the links in action;

Walkera 4#3B: Increase flybar to blade grip stability transmission - CB100 Links (0 min 25 sec)
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Last edited by EQMOD; Oct 18, 2009 at 09:52 PM.
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Old Oct 18, 2009, 09:05 PM
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Well I tried it but I am having problems. Every time I take off it trys to tip over and pitch into the ground to the right. It never used to do that. It also trys to drift backward and either to the left or right. I had a really bad crash right after I put the extender ball links on and the whole heli without warning shot backward at full speed, almost hitting me and hit a wall. Im not sure what I did wrong. What do you think I did?
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Old Oct 18, 2009, 09:22 PM
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Quote:
Originally Posted by lazer155
Well I tried it but I am having problems. Every time I take off it trys to tip over and pitch into the ground to the right. It never used to do that. It also trys to drift backward and either to the left or right. I had a really bad crash right after I put the extender ball links on and the whole heli without warning shot backward at full speed, almost hitting me and hit a wall. Im not sure what I did wrong. What do you think I did?
Make sure there is no binding and head teeters freely by hand. please post picture.
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Old Oct 18, 2009, 09:42 PM
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Ok, Outdoor videos with the CB100 Links and the ball extender mod in place;

Slightly windy and i had a minor glitch at the end of the video. I made a very hard right roll punch at time 0:54 - 0:55 which caused the right aileron servo arm to pop off (no screws as heli is lightened). Lucky no damage as the heli is flying close to ground.

Walkera 4#3B: Increase flybar to blade grip stability transmission - CB100 Link punch 1 (1 min 0 sec)


Take two:

Walkera 4#3B: Increase flybar to blade grip stability transmission - CB100 Link punch 2 (2 min 16 sec)
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Old Oct 18, 2009, 10:15 PM
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Here is what my 4#3b head looks like:
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Old Oct 18, 2009, 10:29 PM
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Quote:
Originally Posted by lazer155
Here is what my 4#3b head looks like:

Walkera 4#3B: Increase flybar to blade grip stability transmission - CB100 Links (0 min 25 sec)


At time 0:0 to 0:7, i tested the flybar to be swinging freely by hand. Make sure your flybar also swings freely. It has the tendency to tighten up if the links are extended outwards. If this is the case, try adjusting the swash to mixing arm linkages. Check also for tracking.
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Old Oct 18, 2009, 10:32 PM
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Ok I see compared to your video mine looks stiff. Should I tighten the linkages? Or loosen them?
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