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control hinges


Basil
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I am busy on Peters Li'l Cub, progressed building wise( Not flying)trying to challenge myself. I have include flaps as I wanted to stretch myself, am learning a lot. Due to being sentenced to house arrest due to  temporarary health probs.

In the books I have read 'Tape' hinges seem to be reccomended for flaps and aelerons( Or do you suggest proper hinges?).Firstly whats the thinking about that?. Secondly what about the covering, over or under. The books say both sides on flaps?. Or anternatively used the covering as daul purpose covering and flaps in the one application.

I've made this fairly short as if I get replies it usually covers all aspect. Thanks in advance.

Bas

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Hi Bas, The great advantage of tape hinges is that they cover the gap between the surfaces, and ensure a cleaner airflow 

However they can hinder a free movement, (the surfaces should move very easily under their own weight when not connected to the servo)

Keep things simple, The easiest hinges are the furry flat ones. Cut a slot in the dead centre of the

two surfaces, slip the hinges in one side, and secure with  very thin cyano. Now add the other side, keep the two surfaces as close as you can, and cyano the second half in.

If you want to be absolutely secure, you can drill a wee hole through each side, and secure with a toothpick.

Hope this helps  

ernie

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Never done tape or film hinges myself. Always as ernie says, cut a slot with a knife and glue in a hinge. The cyano hinges are perfectly good and are about the easiest of all types out there.

 

A centre line marking tool (in a pinch you can DIY one - a knife blade poked through some tough balsa) helps no end in getting the slots to line up nicely.

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My latest build, Kryton, uses film hinges for the ailerons, really easy to apply and totally free movement. I folded the aileron back onto the top of the wing, applied the underside covering first then folded the aileron back down before applying the top covering. 

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I'm a fan of those mylar hinges for all surfaces except flaps.  Which I like top hinged.

 

Best solution for that has been the 'spike' type hinges inserted in an inverted V shape so the body goes into the wing and flap at an angle, and the apex of the inverted V is level with the top surface - leaves only a small gap but seems to work well.

 

On my latest plane, I'm using top hinges again, but this time the flat hinges slightly recessed into top surfaces so the top of the hinge is level with the top of the wing and flap.  Hopefully this will work out too.

 

I've always had issues with the film lifting on film hinges - probably user error!

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Basil

As an avid foam builder I tend to use a top tape hinge nearly all the time both for simplicity and to achieve a smooth top surface.

On foam and using a matt surface tape it becomes almost invisible when painted.

AilTop.JPG.7fb073e684d3ad46e8d21eaefa02ec26.JPG

You are hard put to see anything at all on the top surface hinge line of this 40" lightweight Cub.

There is of course a big gap on the underside but a smooth top surface is more important.

AilUnder.JPG.cc386d4033af823eefbe396f818d9189.JPG

 

Edited by Simon Chaddock
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The flat furry hinges can be used as a top or bottom hinge by cutting the slot at 45 degrees from the edge . Pre crease the hinge before s.ipping into slot . When happy wick thin cyano in. Job done. For bigger model I use pin hinges . Used to be made by Robart but lots of Chinese ones now on market. Always found film hinges shrunk too much even when trying to be very careful with shrinking covering.

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On 08/03/2022 at 17:45, Ron Gray said:

My latest build, Kryton, uses film hinges for the ailerons, really easy to apply and totally free movement. I folded the aileron back onto the top of the wing, applied the underside covering first then folded the aileron back down before applying the top covering. 

Hi Ron, I take it the hinge is applied to bare balsa!.When you say top covering are you refering to another piece of tape or the final covering. When covering the underside ( Assume heat shrink film!!!)do you take the film over the tape, is it OK with heat? . Perhaps you could expand a little.As Tape seems the best candidate for flaps, I would like to use it.

Bas

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Bas, I don’t use tape it’s just the covering film applied directly to the surface to be covered. To cover the underside I first cut out the covering film to include the wing and the aileron (plus a bit for the hinge area) then I covered the wing making sure that it was well stuck to the surface of the wing, especially at the TE. I then used masking tape to hold the aileron folded back on top of the wing and then applied the covering film to the wing TE hinge surface and the aileron LE hinge surface making sure that it was fully stuck down. Next I folded the aileron back level and finished the covering of it. The top wing surface was next but the aileron was held in the down position before apply the film to it.

 

Hope that’s clear but I’ll take a couple photos when I go back up to the workshop.

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I'am with you Ron, yes I think I understand. I take it that there is a minimal effect of shrinkage on the 'Hinge' part of the covering when the iron is applied. So it's fully ironed between steps.No hinges used at all.Still have to envisage the method in my mind a few times.Thanks

Bas

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As long as you make sure that the hinge part is ironed on then there should be no further shrinking. I know that some people introduce a bit of a hinge gap by applying masking tape to the wing before folding the aileron back (underside), this holds the aileron slightly proud of the surface and gives it more 'freedom'. Personally, whether by luck or not, I haven't had to do that.

 

On the Kyten the film hinges are working well at speeds up to 125 mph!

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I used just the technique Ron describes on my lockdown 2020 built Liddle Stik, primarily because the ailerons and elevator are from 3mm sheet which makes them a bit thin to slot for conventional hinges.  They've survived some sometimes over-enthusiastic flying so far.  I normally use pin or occasionally Mylar hinges but the film seems quite reliable.

 

1506044809_complete6.thumb.JPG.1f22b17486e6c3778cb79d7db0a9c617.JPG

 

 

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13 hours ago, Martin McIntosh said:

Forget film hinges and simply use ca ones

 

Film hinges are very easy to make and they work also they give an almost invisible hinge line as viewed from above. Which style of hinge to use can depend on the model and personal preference in my case I don't like CA hinges, it's the CA glue that I don't like. Most of my models use pinned hinges which work but are not the easiest to install. Tape hinges work and are as easy as film, if not easier, and avoid the potential  difficulties encountered while heat shrinking covering film. 

 

Steve

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17 hours ago, Ron Gray said:

As long as you make sure that the hinge part is ironed on then there should be no further shrinking. I know that some people introduce a bit of a hinge gap by applying masking tape to the wing before folding the aileron back (underside), this holds the aileron slightly proud of the surface and gives it more 'freedom'. Personally, whether by luck or not, I haven't had to do that.

 

On the Kyten the film hinges are working well at speeds up to 125 mph!

Ron, I am working on the LiL cub, so speeds are on the low side.Just needed to push myself. Not achievable without the help of persons like yourselve. Once again thank you to you all.

Bas

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On 10/03/2022 at 21:35, john stones 1 - Moderator said:

 

Agreed, and they cost next to nothing, are very neat and maintainence free, they wont go brittle with age nor the glue deteriorate, and they don't need pinning.

Please can someone enlighten me as to what is meant by a "film" hinge. A film is just a thin layer. But what are the recommended materials (type of plastic?) and thicknesses? Surely these are crucial factors as to how well these work as hinges and how long they might last?

Edited by John Stainforth
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@John Stainforththe hinge is formed by extending the covering film over the hinge surfaces, i.e. one continuous piece of covering film for the underside of the wing and ailerons, ditto the top surface. The hinge is not formed from a separate piece of film.

 

Regarding how long they last, I can’t answer that as none of mine have yet to fail! How strong are they, well I’ve had a mishap with one of my models in which the wing was torn off, the aileron covering film hinge remained intact. Try pulling a piece of covering film apart with your fingers, it’s quite strong!

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7 hours ago, Ron Gray said:

@John Stainforththe hinge is formed by extending the covering film over the hinge surfaces, i.e. one continuous piece of covering film for the underside of the wing and ailerons, ditto the top surface. The hinge is not formed from a separate piece of film.

 

Regarding how long they last, I can’t answer that as none of mine have yet to fail! How strong are they, well I’ve had a mishap with one of my models in which the wing was torn off, the aileron covering film hinge remained intact. Try pulling a piece of covering film apart with your fingers, it’s quite strong!

Thanks for the explanation. Most plastics are great in tension, but not so good when bent back and forth repetitively. That's the way I destroy my old bank cards. Even mylar hinges eventually crack up as a result of this bending. I imagine the film method is only really OK for small models, but I could well be wrong.

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