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Author Topic: Covering P30 undercambered wings  (Read 639 times)
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PantherM100
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« on: November 23, 2020, 07:38:54 PM »

Hi Guys:
I know I’m jumping ahead of myself, but
I’d like to know of a simple relatively easy way
To cover under cambered wings with either
Esaki tissue or Mylar.  I will be using non taughtening
Dope for the Esaki, so I don’t want it pulling
Off the ribs while spraying with dope.  The Mylar
Will require adhesive applied to the undercambered
Ribs, then gone over with a Monokote trim iron
For adhesive activation.  What’s the lightest
And best adhesive to use so that the under camber covering
Doesn’t pull away while lightly shrinking the Mylar.
I’ve seen everything from thinned down Weldwood contact
Cement with acetone to “Modge Podge” crafting glue which
Can be heat activated.  Also of course Balsa Loc and or
Balsa Rite.
Thanks in advance for you help.
Jon B. Shereshaw
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danberry
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« Reply #1 on: November 23, 2020, 08:48:18 PM »

Velcro Cement. That's an actual brand name. Cut with MEK.
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flydean1
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« Reply #2 on: November 23, 2020, 09:57:58 PM »

Avoid acetone.  Evaporates too quickly.  Adhesive gets too thick.  MEK much better with Weldwood contact cement or Velcro cement.  The former at any Lowes, Home Depot or hardware, the latter at any fabric store..
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PantherM100
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« Reply #3 on: November 24, 2020, 12:06:59 AM »

Thanks Guys:
Is the Velcro or Weldwood adhesive heat activated?
Do I have this process right?...
I thin the adhesive with MEK, like maybe 50/50 or
Perhaps a little thicker.  Apply with brush, to
to undercambered ribs, spars, leading and trailing edges. 
Let adhesive Dry. 
Lay Mylar or Esaki on the undercambered panel.
Go over the ribs and spars with low heat Monokote
Trim iron. Seal leading and trailing edges.  Lightly
Shrink with low heat for Mylar, or mist alcohol on Esaki
Tissue.  Pin to bench to minimize warping. Let dry, lightly
Mist with non taughtening dope. Let Dry over night or a couple
Of days.  Please let me know if I have the process correct.  Please,
Please Let me know.  And thanks in advance.
Sincerely, 
Jon B. Shereshaw
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DerekMc
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« Reply #4 on: November 24, 2020, 02:25:33 PM »

Fascinating how we get nice results with different materials.  I thin Velcro cement with acetone and it's worked fine.  MEK might work better because it doesn't evaporate as fast.  Currently I use Deluxe Materials Cover Grip to apply Mylar. It works fine as well and it's water based which I like.  
Whatever you decide to use I suggest you try it out on a practice piece of some sort.  Try different ratios of glue to thinner and see what works for you.  There are differences in Mylar shrink rates so figuring out the process for the Mylar you have is important.

I put together a Mylar and tissue tutorial many years ago.  What I did worked for some and didn't didn't work for others. Several people tried my technique and told me it didn't work. There must be something wrong.  Interesting because I have the parts right there covered with the technique I used. It worked for me.
Fascinating.


Here is a link to that old tutorial if you want to check it out. The Velcro glue part begins on page 5.
https://www.hippocketaeronautics.com/downloads/Mylar_and_Tissue_over_Mylar_Tutorial.pdf

A wing covered in mylar ready for tissue. I used Cover Grip as the adhesive.

Covering P30 undercambered wings
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Derek
PantherM100
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« Reply #5 on: November 24, 2020, 04:55:53 PM »

Derek:
Thank you very much for the tutorial!  I’m
That I will re-read it many times as I go along!
Sincerely,
Jon B. Shereshaw
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USch
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« Reply #6 on: November 24, 2020, 05:26:31 PM »

I think any Neoprene-mastic based glue will work for attaching the mylar. As I found out, by trying and recovering more than once, the trick is how much you apply. That's especially true for deep undercamber. You need a less diluted glue respect to the top of the wing where a very small amount suffices.

During the years I have used any thinner near the workbench. Lately I use a special thinner made exclusively for neoprene adhesive and found at my nearby hardware shop. It cost less than acetone. On the label is written:
Toluene-Acetone-Methyl acetate
It does evaporate less fast than acetone, but I anyway brush it on and leave it 5-10min before attaching the mylar.

A picture to show a real deep undercamber.

Urs
Attached files Thumbnail(s):
Re: Covering P30 undercambered wings
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NormF
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« Reply #7 on: November 24, 2020, 09:36:44 PM »

Here's another related thread: https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=25293.msg260902#msg260902

Norm
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PantherM100
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« Reply #8 on: November 28, 2020, 10:46:55 AM »

Hi Guys:
Can I use Randolphs brand, Nitrate - Or - Butyrate
Dope Thinner, for thinning the Velcro cement? Please let
Me know which would be preferable.  Or I can
Get regular Acetone at Home Depot.  I’d prefer
Not you use MEK, it’s nasty!
Thanks Again!
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flydean1
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« Reply #9 on: November 28, 2020, 05:16:36 PM »

Just came from ACE Hardware.  They now have a MEK substitute.  Said to have the same properties of MEK but less dangerous.  I got some to try as cement thinner.
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PantherM100
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« Reply #10 on: November 28, 2020, 10:00:39 PM »

Dereck:
I did the same thing today!  Went to Home
Depot, bought a can of Acetone and this stuff
Called “MEK” substitute.  They didn’t have any
Velcro Cement, so I’ll have to get some online.
Sincerely,
Jon B. Shereshaw
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DerekMc
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« Reply #11 on: November 28, 2020, 10:32:15 PM »

That was Dean, not me.  Please share how the MEK substitute works.
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Derek
flydean1
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« Reply #12 on: November 28, 2020, 10:34:35 PM »

A good sewing ship like Jo-Anne's has Velcro(tm) cement.
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PantherM100
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« Reply #13 on: November 28, 2020, 10:36:21 PM »

Dean: Sorry for mistake, I will post
As soon as receive the Velcro Cement..
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NormF
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« Reply #14 on: November 28, 2020, 10:58:42 PM »

I tried a can of "KleanStrip MEK Substitute" and it did NOT work. Turned Weldwood contact cement into jelly. If you do use the substitute, do a small sample test first. I did find that Famowood putty thinner worked but I see it is no longer available. MEK is also listed at Aircraft Spruce.

Norm




That was Dean, not me.  Please share how the MEK substitute works.
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