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Hinging elevators - I'm struggling!


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Having got Lazy Bee #3 airborne yesterday, I'm now planning the (hopefully) much-improved #4, and I really do need to sort out the elevator hinging.

I'm OK for the rudder because I can use those small plastic pinned hinges, but I struggle with the elevators - mainly because the tailplane is 1/8 balsa sheet, and the l/e of the elevator is laminated 1/8" square sticks.

I tried a couple of different types of flexy plastic hinges on some scrap wood before I built my first Bee, but went off the idea fast on the grounds of (a) difficulty cutting accurate slits central in and parallel to the sections, and (b) cyano tending to stick the t/e and l/e to each other.

So, with each Bee I've built so far, I've chickened out and used stitched hinges, which work perfectly fine. But I'm beginning to go off the look of them, and besides, I'm a big boy now so I should really get to grips with hinging.

What do you guys suggest I use, bearing in mind that we're talking 1/8" thick tailplane and elevator? I'm tempted to try Slec's "Flocked cyano Mylar hinge SL163-R", but how stiff are they?

And what's the secret to cutting accurate slits for them to go in?

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I have no idea what sort of model the Lazy Bee is but on elevators and ailerons it is quite easy to use the film covering itself or special hinge tapes. You have to keep the gap small to avoid slack but there is no air leakage so they are efficient.

There are plenty of examples in books and magazines. As John says. It comes with practice and there are plenty of people who really like hinging - it seems.

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Posted by john stones 1 on 20/06/2014 15:29:14:

Flocked hinges are good Spikey, will be plenty stiff enough they soak up cyano

I'm actually more concerned about 6 of them being too stiff but maybe they won't

When you say they soak up the cyano, doesn't that tend to stiffen 'em a bit?

(I know I can just order some from Slec and meddle with them, but have you seen their minimum p&p??!! And besides, I still have to cut the slits)

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check on E.bay there are modeling suppliers that will do ca hinges with free postage. you can use a simple tool to find the elevator centre line then gently and carefully widen the slot along the line use do the same for the tailplane edge. assemble after covering (well I do ) use suitable spacers to keep the surfaces an equal distance apart drill a 1mm hole about 3-4mm back from surface edges use CA that comes in a little bottle 10ml I think a pound for 5 from poundland and inject a small amount of CA into drilled hole that should stop the CA wicking to the centre of hinge. leave for a while then for added security push a length of cocktail stick in to drilled hole cut and sand flush. disguise stick end with a bit of spare covering film or paint. I should add only drill hole down to just through hinge not all the way through . Practice the slits on some offcut of same thickness You'll soon get the hang of it

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Gosh, there's a thing!

I'll have a bit of a practice with the clothes horse idea. If I manage to screw it up on the real thing, I can always fall back on cyano hinges and say that the patches of film are covering flak damage ...

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Posted by Spikey on 20/06/2014 19:32:53:

Gosh, there's a thing!

I'll have a bit of a practice with the clothes horse idea. If I manage to screw it up on the real thing, I can always fall back on cyano hinges and say that the patches of film are covering flak damage ...

The clothes horse hinge, I found, is a difficult one to get right and can end up tight or very loose in places. The CA hinge will be perfectly fine. It is dead easy.

Look here for info on how to do it and how strong the hinged joint is. Note this is without any form of pinning!

Edited By John F on 21/06/2014 07:21:13

Edited By John F on 21/06/2014 07:25:57

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The clothes horse hinge, I found, is a difficult one to get right and can end up tight or very loose in places. The CA hinge will be perfectly fine. It is dead easy.

When done with Solarfilm as described you would have try really hard and make a total dog's dinner of it to get them tight. In fact due to the way they work you can't get them tight.

But then, I have used them on and off for years usimng film and of course back in the control line days using tape.

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Spikey

It does depend on the speed and weight of the plane but I am a firm believer in full length top tape hinges on lighter planes.

The aileron top surface of my 40" Super Cub hinged with 'Invisible' tape. It has a matt finish so can be painted.

Aileron top side

Very free moving (the aileron drops down under its own weight) and darn near invisible. You would be hard put to create a smoother surface! wink 2

Yes, there has to be a 'slot' on the under side to allow for the aileron 'down' movement but in terms of aerodynamics the top surface is the more critical.

On EDFs I still use top tape hinges but with 'duct' tape instead.

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