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Advice for tail linkages

Advice on hooking up elevator and rudder on an an Adagio

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Graeme Evans19/10/2020 19:59:47
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43 forum posts
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I've just started building a Ken Binks Adagio from plan + cloud models partial kit. Mostly because I like the look of it, I'm not that great a flier so I'm not really thinking precision aerobatics - but hopefully it'll be a nice model.

Its a large model by my standards, a good 50% bigger than most of my other models builds at 72" span and about 60" long.

The plan doesn't indicate anything for control rods / linkages for the elevator/rudder (and tail wheel). The elevaror halves are separate, though could be linked, maybe. I'm unsure whether to go for push rods, plastic snakes or put servo's at the back - or any other arrangment someone may suggest. I'd rather not do pull pull cables unless its really nescessary.

I'm going to be fitting an electric motor, inplace of the origional 60-90 glow so expect to be slightly tail heavy already, which makes wary of 2 or 3 rear servos.

There is a build blog for this model (Ken Binks' Adagio Build Blog) but its not quite the same kit.

 

Edited By Graeme Evans on 19/10/2020 20:00:14

Edited By Graeme Evans on 19/10/2020 20:00:34

Edited By Graeme Evans on 19/10/2020 20:01:15

Denis Watkins19/10/2020 20:36:16
4655 forum posts
132 photos

dsc02120.jpgdsc02119.jpgTail wheel bracket fitted inverted, to accommodate long tiller bar

This halves the Tail wheel movement relative to the rudder input

Making ground control much easier

Edited By Denis Watkins on 19/10/2020 20:38:53

Graeme Evans19/10/2020 21:57:19
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43 forum posts
16 photos

Interesting method to reduce tail wheel movement, never seen that before.

I'm more interested though to get an opinion about pushrods vs snakes or wires and what the best way to handle a split elevator would be. My previous builds, smaller like the one you have pictured, have not needd this. On this model the snakes would be almost 1m long each and I'm not sure how effective they would be or if my fears are misplaced.

I could use 2 elevator snakes and fashon a 'Y' adapter for them at the servo end, or possibly use one and have some sort of Y or T piece at the tail end.

Alternatitavely I'm thinking something like this may be a good option, though I'd probably make one from hardwood and FR-4 so i can paint it in colour scheme:

Edited By Graeme Evans on 19/10/2020 22:02:35

Edited By Graeme Evans on 19/10/2020 22:07:53

Nigel R19/10/2020 23:38:31
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4271 forum posts
711 photos

I would use two blue sullivan snakes.

A dowel pushrod with a Y rear end would be second choice.

Carbon is another option but I'm not familiar with it.

Simon Chaddock19/10/2020 23:52:14
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5807 forum posts
3069 photos

Are you sure the motor plus battery is lighter than the glow equivalent?

The battery does not have to go on the CofG and by the same token the electric motor does not have to use stand offs.

It pays to make use of the attribute of an electric motor. Smooth running.

Just saying.

Graeme Evans20/10/2020 07:45:33
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43 forum posts
16 photos

Simon, your right, the total weight of a 60 size motor plus full tank will be amost 1kg which is similar to my motor and battery I have planned, so thats kind of a lie - but the majority of the weight will be on the nose with the engine whereas in the electric setup the majority of the weight is in the battery which is inevitabley further aft. So its the tail I need to be lighter or at least as light as possible.

My approximation is that the glow setup would have a moment about the CG of 0.353N whereas the electric would be 0.323N. Assuming (=massive guess) the centre of mass of the rear fus and tail at about 800mm aft I need to save 40g at the rear to achieve the origional CG location.

FlyinBrian20/10/2020 07:53:39
677 forum posts
4 photos

Why not just use a wire joiner for the elevators as per most sport models. Depending on the elevator thickness say 14 or 12 gauge piano wire.

I'd use a pushrod for elevator control and pull pull arrangement for the rudder

Andy Stephenson20/10/2020 09:48:12
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281 forum posts
43 photos

With a conventional installation having servos in the radio compartment and with separate elevator halves my preferred solution is to use two push rods joined near the servo or even at the servo with two ball joints to link to the servo arm. This makes it much easier to thread the pushrods at the tail end and prevents any off-centre effects making one elevator half move relative to the other.

Graeme Evans20/10/2020 11:08:15
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43 forum posts
16 photos

Andy I'd be curious how what you mean by two ball joints on one servo arm, any pics?

perttime21/10/2020 05:34:36
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211 forum posts
11 photos

A pushrod idea from Norway:

"make a square tube of balsa-sheets
...
The main problem with the pushrod shown below, is that it's very low-tech: no carbon-fiber, no ball bearings, no pink aluminum parts.
"

**LINK**

There's other things for building there, too.

Graeme Evans21/10/2020 09:24:32
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43 forum posts
16 photos

I did offer up some square balsa/spruce to use a simple pushrod but it felt too flexible for the length, I'll definatly make up a box section like show even if its only for my own curiosity.

Edited By Graeme Evans on 21/10/2020 09:24:58

Paul C.21/10/2020 10:51:44
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697 forum posts
165 photos

20201021_101836.jpg20201021_101700.jpgHi Graeme the attached photo is my loaded dice 30e, the set up is as per Terry's plan. I gave used this type of set up on other models as well and has worked fine for me. I am building an Adagio as well and have decided to go closed loop for the rudder and a servo at the back of the fuselage for elevator, I realise that will probably make it tail heavy so I will use a larger heavier battery in the nose plenty of room there. It's just my personal preference as I just can't get on with snakes or push rods , tried a carbon rod set up and gave up on it. One thing I did was to connect the elevators, added a lite ply plate into the elevator that the wire joiner went through as it's only foam there.

20201021_101549.jpg

Paul C.21/10/2020 10:52:49
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697 forum posts
165 photos

Sorry but I got the photos out of order.

Paul.

Graeme Evans21/10/2020 11:28:54
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43 forum posts
16 photos

Thats some nice neat work Paul. I can't help feeling the same about snakes and long pushrods just don't sit well with me.

Paul C.21/10/2020 12:04:19
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697 forum posts
165 photos

I purchased the wing and ply parts from Cloud Models as was very happy with the quality of all the parts, will definatly use them again. Same as you I just like the look of the model I am going for fixed uc my landings are not up to using retracts, the way things are going we should have plenty of building time ahead of us.

Paul.

Nigel R21/10/2020 12:14:09
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4271 forum posts
711 photos

If you're happy with closed loop, then use two runs, one to each half of the elevator. Light, positive, simple.

kc21/10/2020 12:27:40
6769 forum posts
174 photos

I would use a forked pushrod- a 6mm or 8mm birch dowel with two steel quick link rods bound to it at the elevator end. It may be necessary to insert this at the building stage. Easier than fitting an elevator joiner.

I wouldn't trust that built up balsa pushrod in anything except very light models.

Edited By kc on 21/10/2020 12:30:10

Graeme Evans21/10/2020 12:38:46
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43 forum posts
16 photos

I'm happy with closed loop as far as implementing it, and it ticks the boxes. I would just have to get over having my planes bits on show! I rather like having them tucked away - purely for the asthetic blush

 

I'm going to make up a pushrod and see how it sits, fuselage is still open enough to build anything in which is why I'm thinking about it now. Infact its even more open than it was yesterday as my son smashed about 25cm off the back end yesterday getting is bike in to the garage angry. I think he rather sh*t himself - should have seen the look on his face when he case to fess up!

 

Paul C. - Yes I like the cloud models stuff, I've used them a few times. I'm planning to put fixed UC on but on the fusealage instead of the wings as I too 'need the extra resiliance'.

Edited By Graeme Evans on 21/10/2020 13:01:25

Paul C.21/10/2020 13:25:07
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697 forum posts
165 photos

20201021_125515.jpg

This was my attempt at a forked pushrod , all was going well until I tried to thread it down the fuselage and get the exit bends in the right place. Fortunately I had not put the bottom sheet on at this point so I could get in and thread everything through, at this point I decided it would be a real pain to do this after i added the sheeting. Its a long fus on this model so i decided opt for the servo, nothing wrong with the carbon pushrod method but I could not get it to work for me.

perttime21/10/2020 13:48:15
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211 forum posts
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Posted by kc on 21/10/2020 12:27:40:

...

I wouldn't trust that built up balsa pushrod in anything except very light models.

Edited By kc on 21/10/2020 12:30:10

I haven't tried it myself, but it did go into a sub 5kg 2x2 meter F3A competition model - by one of the top Scandinavian competitors. The balsa box does have some sections of solid 8x8mm balsa in it.

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