My Next Assembly ( The Trilogy ) Phoenix 60 EP

[Ron Gray]

There is another approach to your problem. You are trying to avoid having the inner part of the snake unsupported thus preventing it flexing with the subsequent lack of control ‘finesse’. So what you could do is to have a longer piece of wire fixed to the inner snake so that, in effect, most of what you see from the fuse exit to control horn is wire, not plastic snake. I have this on a couple of models and it works!

[Denis Watkins]

Looking good Toto. Just a note now on setting up. We now have amazing computer radio for small increments of movement. But start off with all movement Trims at Zero. 

Set the travel now mechanically to have equal throw, left and right rudder, up and down elevator, and ailerons with equal deflection.

Lots of trial and error picking optimum holes in horns and servo arms.

Only then compute the finer requirements.

Edited November 28, 2023 by Denis Watkins

[Outrunner]

Even with pushrods it's good practice to cross them over to give the straightest possible run to the control surface.

[leccyflyer]

I don't have a picture, because it was more than 30 years ago, but on the kit-supplied snakes with my Uno-Wot the issue with support for the control linkage  outwith the fuselage was dealt with by having a length of threaded rod about three inches long at the termination of the snake, which was then rigid, threaded into the snake inner with only just over an inch of protruding snake to permit the smooth movement of the controls. I haven't seen that before or since.

[Ron Gray]

39 minutes ago, leccyflyer said:

I haven't seen that before or since.

See my post above 😜

[Eric Robson]

I used bike spokes for that reason, 

[toto]

Thanks again chaps.

 

Good information given in time to act. I will be looking at these exit holes as I am aware that the tubes bend when lining up inside the fuselage at the exit points.

 

I want to eradicate that and in doing so shall also probably solve at least part of the issue in getting the exit points closer to the horns.

 

Many thanks.

 

Toto

[leccyflyer]

6 hours ago, Eric Robson said:

I used bike spokes for that reason, 

 

6 hours ago, Ron Gray said:

See my post above 😜

 

 

I thought it was a tidy way to deal with a potential problem and it never gave any issues over the long life of the model, then, towards the end, the clear plastic snake fractured at the end of the threaded rod section - it must have effectively acted as a stress riser/ I've since run a thin piano wire down the full length of a nylon snake in another model, to stiffen up the snake, which I felt was a bit too flexible. I'm happy to make snakes work and use whatever control run the model best suits, but in a lot of models my favourite remains good old fashioned dowels with threaded wire pushrod ends, bound and glued, then with a neat finish of heatshrink over the top.

[toto]

Yes ..... many ways to skin a cat and they all work ..... it's just favourites ....

 

I'm going to give this snake thing a bash. It may turn out to be my #1 choice going forward, however, I may rue the day I tried them 

 

The dowel and wire method should be rigid. I may experiment with that on another model going forward. 

 

Cheers

 

 

Toto

[Simon Chaddock]

toto

The thing to remember about snakes is they work best in a straight line so there is little rubbing between the inner and outer, Any curve means the inner and outer must rub together. The tighter the radius the worse it gets. Then throw in the fact the snake is pulling and pushing against a control surface load and the rubbing forces rise rapidly. The plastic used in snakes may be 'slippery' with a low coefficient of friction but any friction in a control run is not a good thing.

 

Supporting the outer along its length is good provided it keeps any change of direction to a minimum. What is mechanically essential for a snake to avoid "give" is that each end of the outer must be absolutely secure in the fuselage or wing structure.

 

Now if you can arrange for the servo to be close to the control surface.............. 😉

 

[toto]

All makes sense .....

 

As you come across these things, it gives you betterment and improvement in each build. When you first start off ...... like myself .... you dont realise how little you know and how much learning there is ..... a bit at a time .... you get there.

 

Cheers

 

Toto

[GrumpyGnome]

You'll soon discover your favourite. Or maybe not - I just use whatever I think will work best.......

 

My SE5 uses solid carbon pushrods - lots of space, straight runs (crossing one above the other)

My P47 uses snakes - pretty congested with 2 x ele, rudder, and tailwheel

My Tiggy uses closed loop - light and looks good

My Wot4 has short metal pushrods as it has servos at the tail end

 

(I take a similar approach to ic throttles - I.e. no real favourite)

 

Typically, my starting point is what the kit recommends tbh.

Edited November 28, 2023 by GrumpyGnome

[Geoff S]

4 minutes ago, GrumpyGnome said:

You'll soon discover your favourite. Or maybe not - I just use whatever I think will work best.......

 

My SE5 uses solid carbon pushrods - lots of space, straight runs (crossing one above the other)

My P47 uses snakes - pretty congested with 2 x ele, rudder, and tailwheel

My Tiggy uses closed loop - light and looks good

 

Typically, my starting point is what the kit recommends tbh.

 

Both my Tiger and Gipsy Moth use closed loop (more or less scale) but I feed the cable for the elevators down snake outers so that repair/replacement is easy.  The rudder cables are outside the fuselage anyway.

 

I'm just doing the control runs for my Fokker DVIII and I'm using my favourite 3mm carbon tube with threaded 2mm rode epoxied in at each end with a ball joint at the servos end and clevis at the control surface. Very stiff with almost zero slop.  Just noticed this pm that Modelfixings is now supplying lots of RC fittings as well as fastenings. Amongst the fitting is suitable carbon tube for push rods - he supplies the 2mm (and 3mm) threaded rod to suit.

[Nigel R]

13 hours ago, Simon Chaddock said:

The thing to remember about snakes is they work best in a straight line

 

I'd contend that just about any control pushrod type works best in a straight line (although, snakes benefit from a gentle curve to allow for expansion/contraction).

[leccyflyer]

IIRC the instructions for Sullivan Gold 'n Rods used to advise fitting them with a slight curve, securing them properly at both ands and somewhere in the middle. However I can't see any reference to that now. For a single central aileron servo operated by snakes or Bowden cable the 90 degree curved bend seems to work fine with the appropriate snakes, provided the servo is thoroughly secured and the snakes are well fixed in the wing. I consider that snakes are the most workable solution where it isn't possible to have a straight control run from servo to control horn.  The advice to have the control rods cross over, given earlier in the thread, to provide a better exit angle at the rear fuselage is good advice.

[Christopher Wolfe]

On 28/11/2023 at 18:56, Denis Watkins said:

Looking good Toto. Just a note now on setting up. We now have amazing computer radio for small increments of movement. But start off with all movement Trims at Zero. 

Set the travel now mechanically to have equal throw, left and right rudder, up and down elevator, and ailerons with equal deflection.

Lots of trial and error picking optimum holes in horns and servo arms.

Only then compute the finer requirements.

A very good friend of mine has just published a simple instrument that he designed for checking control surface throws on Outerzone Deflectometer .

 

* Chris *

[toto]

Thanks chaps.

 

I've been nowhere near the shed or the field this last couple of weeks so things have hit the skids for now. Loads of things have stole the limelight between domestics and new work commitments.

 

I am of to Breda in the Netherlands for another full week as of tomorrow. So .... tonight ... packing a case and printing of boarding passes etc. Running about to buy Euro's ..... all the usual crap associated with travelling overseas. And ..... just to add to it, I believe as of the 1st January 2024 ..... I will require some kind of Visa to travel in the EU thanks to our very carefully thought out Brexit policy ....  ..... oh the Joy's. So .... the only flying I'm doing is via Easyjet. 

 

I wonder if the pilot will give me a go on his buddy box .... Mmmmmm

 

Toto

[aidan mcatamney]

Yes, we live in an ever changing world Toto and a lot more complicated also which is not always for the better.  I wish the simple life would return and that would give each and  everyone of us a lot more freedom and lot less stress to deal with.   On the Holland front, have a good trip on Easyjet and you never know that maybe Captain Raymond Van Barneveld will let you take over the  controls and land on Dutch soil for the first time making you the first RC Pilot from Scotland to safely fly and land a full size aeroplane.   Stranger things have happened.   Good luck also with your current job Enterprise.  I wish you well and safe journey home again.