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Author Topic: Push rod configuration for two rudders  (Read 2607 times)

Hande

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Push rod configuration for two rudders
« on: February 12, 2016, 12:04:59 PM »

Can someone, please, explain why configuration #2 seems to have won popularity over #1.
I would think #1 is more efficient and more balanced use of the power of the servo.


One problem that I can think of in #1, is the situation where the push rods are of not exactly the same length.
How accurately would they need to be of same length?



Sorry I accidentally uploaded the diagram twice and cannot remove the extra copy...
They are identical.

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essex2visuvesi

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Re: Push rod configuration for two rudders
« Reply #1 on: February 12, 2016, 12:56:10 PM »

Im using option 1 in my CC constellation


My thoughts were it gives a more balanced loading on the servo, you do need to get the rod lengths the same length tho, or a close as possible
I used adjustable rods like these:-
http://www.rcworld.co.uk/acatalog/Carbon-Pushrod-Set-M2--F_IRVCPR2.html#SID=59


The reason being is that I had them from another project. They are a little excessive for a rudder setup but they do have mm perfect adjustability
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inertia

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Re: Push rod configuration for two rudders
« Reply #2 on: February 12, 2016, 01:45:23 PM »

Here's my take - call it Config #3. The servo arm is made from scrap 1/16" GRP circuit board and the distance between the axis and pushrod holes is identical for both tillers and the servo arm. The servo is a Hitec low profile BB job.
DM
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Fastfaz

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Re: Push rod configuration for two rudders
« Reply #3 on: February 12, 2016, 05:07:30 PM »

Hi,
   Is this going to be on a Tug that will be used for towing? if it is I would suggest two arms from the servo this balances everything out. One arm to the side of a twin screw boat and, unless it is very short in length, it will flex. Two arms seem to solve the problem of excessive flex. I can only speak from personal experience of trying out both methods. I hope this helps.
     Cheers,
           Faz. :-)) :-)) :-)) :-)) :-)) :-)) :-))
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Hande

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Re: Push rod configuration for two rudders
« Reply #4 on: February 12, 2016, 06:40:49 PM »

Very helpful, indeed!
Yes, it's a tug (- although I doubt if I ever tow anything)
I cannot place the servo between the rudders like Dave.
Adjustable rod is a very good idea!
I'm going to go for #1, because it makes more sense to me, and I hear no words of caution.



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Stan

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Re: Push rod configuration for two rudders
« Reply #5 on: February 12, 2016, 08:36:44 PM »

Hi Ande check out my Elco plastic conversation under warships and military. Close up shots using one servo and 3 rudders.


Stan
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Hande

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Re: Push rod configuration for two rudders
« Reply #6 on: February 12, 2016, 10:39:38 PM »

thank you, Stan. I will!
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Fastfaz

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Re: Push rod configuration for two rudders
« Reply #7 on: February 13, 2016, 11:51:23 AM »

Hi again,
     If you PM me your email address I will take some photos of the layout in my boats and send them to you along with a couple of ideas. I can never post photos on the forum successfully so it needs to be by email. Hope this helps.
      Cheers,
           Faz. :-)) :-)) :-)) :-)) :-)) :-)) :-))
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John W E

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Re: Push rod configuration for two rudders
« Reply #8 on: February 13, 2016, 01:30:57 PM »

hi ya

here are a couple of examples of the system I use for connecting the Servo to twin rudders and also there is a triple rudder example and, if you look closely, you will see there is a connection between the two rudders which is a threaded bar.  The threaded bar enables you to adjust the rudders to ensure that they are parallel to one another.   Also, one of the connecting rods between the servo and the rudder is also threaded which enables you to adjust to compensate for different lengths of rod.

The reason I use this system was that I was taught many years ago is that using this system balances the torque on the servo.  Imagine riding a pushbike and trying to steer just using one arm - how difficult that would be - now put 2 hands on the handlebars and how much easier is that to turn the corner?
http://www.modelboatmayhem.co.uk/forum/index.php?action=dlattach;topic=15073.0;attach=61263

john
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Hande

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Re: Push rod configuration for two rudders
« Reply #9 on: February 13, 2016, 02:49:49 PM »

Thank you, John!

An interesting system, indeed! I will study it carefully.

My point exactly. Riding bike with only one arm requires forces sideways and starts hurting in the neck.



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Peter Fitness

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Re: Push rod configuration for two rudders
« Reply #10 on: February 13, 2016, 08:53:09 PM »

I have used option 1 in three of my boats, and they all work well. I used the adjustable type clevises as shown in the RC World catalogue, they were left overs from my RC flying days, and allow precise adjustment of the length of each push rod.


Peter.
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Hande

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Re: Push rod configuration for two rudders
« Reply #11 on: February 14, 2016, 07:43:30 AM »

I buy the idea with adjustable length rods. I'll make sure to get some.
Thank you Peter and others that suggested adjustability - essential, now that I think about it.
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