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Wipers, replace/repair question

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Scram

How do you repair or replace completely missing flap wiper?

Wiper is completely missing from one of my Vampire flaps.  I'm looking for methods to sort this.

IMG_3608s.thumb.jpg.e60d260cfe5cd34102df

To replace it, I thought to use a piece of suitable tube.  The flap depth is about 10mm so a tube of about 20mm dia would do it and this is provided by plastic overflow pipe which is 3/4" or 19mm dia.  I cut a sample piece and routered a rebate, then sent it down a band saw to cut it to width.

2 or 3 problems.  The rebate angle is wrong and the wiper would not sit tangential to (or below) the upper surface of the flap and when cut from the tube, it bends  :huh:

IMG_3606s.thumb.jpg.d58d51a70bb10c1d09c3

If I managed to get the rebate angle right, the remaining problem would be - how on earth do I get it to sit in the opening correctly so's it can be stuck to the top, inside of the flap.

Do I really need to go to all this trouble?   :unsure:   Would a piece of sticky clear plastic stuck on and hanging over the wing back edge be sufficient if it just covers the opening under normal flying flap up/down deflection.  I guess that when the flaps are lowered for landing, a big gap does not matter much.

 

 

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Woodstock

The solution in your last paragraph is the easiest and most efficient aerodynamically IMO   I use Diamond tape back-to-back. Just make sure the covers are long enough that they don't get caught under the lip of the flaps as they return to neutral..

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Scram

You can see on the floor, I have a load of stickers left over from my Easyglider build (years ago, I keep all sorts of rubbish).  Some stips of this can do the job with a little more stiffness than magic tape I recon.

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isoaritfirst

Originals are often moulded from epoxy and microballoons. 

I have repaired a few areas but never a whole one.

Fix tape onto wing to form seal and run epoxy mix onto back and leave inverted and hope....

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Andy_B

I was going to suggest the same as Mike . I have done wipers like this before , or Jerry you can just use the tape   but fix it to the flap and not off the back of the wing /sub spar

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Scram
2 hours ago, Andy_B said:

I was going to suggest the same as Mike . I have done wipers like this before , or Jerry you can just use the tape   but fix it to the flap and not off the back of the wing /sub spar

Why the flap?

There was some on there, fixed to the flap but it was squidged up and out of any useful shape I recon  :huh:

I have used a piece of EG sticker, clear, stuck on wing surface.  Not very stiff but should seal the gap unless it lifts due to airflow ??  Should not do that unless the wing is stalled, surely.

2 hours ago, isoaritfirst said:

Fix tape onto wing to form seal and run epoxy mix onto back and leave inverted and hope....

..... hope it does not stick the flap to the wing??  ........  :rolleyes:

I guess there's a way to do that and then sand it to profile.  Maybe a balsa quarter circle (90°) section strip would go in.

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mtreble

There is a Video here:

From 15 mins in he does the wipers.

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Scram

Thank you Mark.

That is truly brilliant  :thumbsup:

Be interesting to know what tape he is using and can we get it.  Clearly not the rubbish masking tape that is now normally sold here in UK.

Also, I presume he's probably using laminating epoxy mixed with micro balloons.  Lam epoxy for long pot time.

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martynk

The tape looks like an automotive quality masking tape. Halfords or eBay. I have also used frog tape (B&Q) with quite a lot of success. As you say, the brown rubbish that is used by decorators is not appropriate. I only use it for holding newspaper together when masking

 

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mtreble
oipigface

Looks to me as if a big bushy beard is needed as well!

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Scram

I think I will have to try some decent 3M auto masking tape.

Halfords don't have any.  They have Harris auto masking tape which has a blue tinge to it ???

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satinet

Definitely worth doing properly on a model of that caliber.

Have you got a broken plane to practice on?

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Scram

Is this broken enough for you?

IMG_221.thumb.JPG.c735fdb796792fd9238e0b

IMG_219.thumb.JPG.de2aaab596d732f5711b5a

......... the only "broken" wing I have but most of the wipers are OK

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chiloschista

Jerry, more than microballons, which benefit is weight reduction of the resin, I would use thixotropic agent to force the resin stays where it should and some cotton flocks to have some structure with micro balloons as well, but not mandatory.

Ric

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Scram
5 hours ago, mtreble said:

Doesn't seem to be available in Britain, but you can get it on eBay from the US if you really want the same stuff, and don't mind paying for it:

You can get it from Amazon  :thumbsup:

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Woodstock
On 11/9/2015, 3:00:51, Andy_B said:

I was going to suggest the same as Mike . I have done wipers like this before , or Jerry you can just use the tape   but fix it to the flap and not off the back of the wing /sub spar

Isn't the tape just going to blow back in the airstream?

 

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satinet
Jerry, more than microballons, which benefit is weight reduction of the resin, I would use thixotropic agent to force the resin stays where it should and some cotton flocks to have some structure with micro balloons as well, but not mandatory.

Ric

Agree.

Micro balloons don't thicken mixes well. Even with a lot in it would be runnier than in the video imho.

I didn't catch what he called it but i assumed it was like cabosil or some such.

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Scram
12 minutes ago, chiloschista said:

Jerry, more than microballons, which benefit is weight reduction of the resin, I would use thixotropic agent to force the resin stays where it should and some cotton flocks to have some structure with micro balloons as well, but not mandatory.

Ric

Thanks Ric.  For making stronger joints with epoxy, I do use microfibers which I find are also described as cotton flocks and I have a large tub of colloidal silica which research shows me is your thixotropic agent.

So now I just need the tape.

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