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Scram

Wipers, replace/repair question

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Scram

I like the sound of this dymo tape method but maybe see a couple of problems.

- can I get tape wide enough so that it won't flip out when the flaps lowered?

- if it is that wide, will it jam against the rear spar, preventing the flap raising/closing, because the tape wants to be straight rather than curved?

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mark_r
7 hours ago, Scram said:

I like the sound of this dymo tape method but maybe see a couple of problems.

- can I get tape wide enough so that it won't flip out when the flaps lowered?

- if it is that wide, will it jam against the rear spar, preventing the flap raising/closing, because the tape wants to be straight rather than curved?

I guess you need to try it to find out, but this could be easily done just using a short piece of any tape as a trial. The Dymo tape is available in different widths, and would also be easily trimmed if needed. I was concerned about the fit right at the tip on my radical, but it was no problem. It is of course also dead easy to replace it for very little cost/effort. I'm not suggesting it's the best solution out there, but it does seem to work very well for me, and using clear tape with the white micro balloons method makes it look like a conventional wiper as well.

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chiloschista
On 6/12/2015 at 19:57, mark_r said:

Quick comment on wiper tape - as Mike said, the Radicals use the tape method. It's dymo tape, which very conveniently has the backing split along its length. You remove 1/2 the backing and then rub micro balloons on the sticky edge - stops it sticking and makes it white in the process. Then peel the other half of the backing pressing it in to place as you pull the backing clear. Fold the aileron back to tuck the tape inside (running the back of a scalpel along the wiper length makes this easy). Makes a very easy effective wiper.

Nice idea, thanks!

There is the Graupner tape, done for the same purpose, but it is crazy expensive. Here is a picture.

Ric

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Scram

Well I've still not got round to replacing the Vampire wiper  :no:

but on sorting the servo action on my recently acquired Crossover, I found one flap wiper with 4-5" hanging off with about 1½" missing, so determined to fix it before I lost it all.

IMG_3754.JPG

I stuck 3M blue masking tape inside the back of the flap to ensure I did not epoxy the hinge and mixed some epoxy to go inside the break to glue it back in place and then added micro-balloons to form a stiff-ish mix.

I stuck another piece along the edge of the wiper extended to the inside edge of the flap and put the epoxy mix inside reinforcing the joint and extending the wiper near to the inside edge, then using a piece of tape to form the curve.  I left this over night to harden.

IMG_3756.JPG

The first mix did not form the wiper complete to the inside edge (no picture) so I then mixed some more epoxy/balloons to form a complete wiper

IMG_3758.JPG

 

IMG_3759.JPG

I wonder that the joint of the wiper to the flap/aileron is so weak when a small amount of reinforcement inside should make a lot of difference to keeping them, with little impact on weight.  Perhaps an idea to add some on all my models though for strength, I would use micro-fibres instead of balloons.

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Phil.Taylor

nice fix there Jerry

why do they just use epoxy sploooge for wipers anyway? - the Radical I got recently has proper carbon-fibre wipers - a nice detail touch - plane is well used/abused but the wipers are fine!

Phil.

 

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oipigface
1 hour ago, Phil.Taylor said:

why do they just use epoxy sploooge for wipers anyway?

It's cheap?

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Scram

I thought about laying some carbon in the back but narrow strips of carbon are a b****er to handle without it falling apart  :ermm:

Then I remembered how I protect edges of my carbon cloth with a narrow strip of masking tape which holds the edge together and I cut bits off, through the tape.  I have then found that this can be laid with laminating epoxy and the masking tape will come off after the epoxy has cured - as long as it is not covered with overlapping carbon.

So I could cut a strip of suitable width for backing the wiper from the roll of carbon using the right width of masking tape on one side.  Load with epoxy and press it in with foam.  When it's cured, the masking tape will come off ............. bingo  :yes:

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satinet

Spray your carbon with 3m77 spray or similar (spray mount etc). This stops the problem of it unravelling from the edges. Then just wet out as normal.

HtH

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Scram
3 hours ago, satinet said:

Spray your carbon with 3m77 spray or similar (spray mount etc). This stops the problem of it unravelling from the edges. Then just wet out as normal.

HtH

I've not tried that but suspect it could stick bits to my fingers which then pull the weave apart when I extract them.  It also makes a lot of other stuff sticky  :frantics:

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oipigface

I've tried both 3M77 and masking tape, and I agree with you Gerry: the carpet glue tends to be sticky. It may of course be that I was too impatient to let it dry fully! Tape works well.

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satinet

I'm not being funny but I wouldn't say it if I hadn't done it plenty of times.  What you need is a fine mist spray (e.g 3m 77) not a carpet spray.  The point is when you try and work with cloth the weave comes apart, especially when you try and wet it out.  Anyway, that's what I learnt at the knee of the Fumeister

Part of the problem sounds like you are using a heavy grade of carbon cloth. e.g 200g is  not that great for doing repairs IMHO. Maybe you're not but it's well worth investing in a m2 of good carbon cloth, and treat it like what is it - black gold.  The other thing I would say is I would not even use carbon cloth for what you are doing. Light weight glass cloth is well cheap and easier to work with than heavy carbon. 

The problem with taping is that the excess glue has no where to go. I always use peel ply over repair layups nowadays. It's fantastic, IMHO.  Possibly not relevant for a repair like this but super cheap and makes like a lot easier AND you can soak the excess glue through to foam/paper on the other side and just peel it right off. 

In my experience you really want to extract your cloth from the wetting board out with a scalpel blade or similar, not your fingers.  Speaking in general terms, going perhaps further from the realm of wiper repairs, is that 25g cloth is very useful stuff to have - i.e to blend out repairs. Bit hard to work with though. 

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satinet

nice fix on the wiper btw

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Scram

I haven't actually done a wiper strengthen using this method.  It was just a suggestion on my part, but I take your points.

Up to now, I have only used 200g/m² for fuselage repairs etc., and I do use the peel ply n tissue method for extracting excess epoxy.

Where do you get those light grades of carbon?

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satinet

light grades of carbon are very expensive. I got a meter of a I think 93g of ebay. It's not the greatest, but it's okay. You can get cloth from places like emc vega but it's £$£$£

Like I say though carbon isn't needed for everything. Glass cloth is really cheap.

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