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Old Jul 30, 2013, 04:07 AM
CPA# 39
EscapeFlyer's Avatar
United States, MN, Brooklyn Center
Joined May 2009
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Discussion
TE/sub TE and sub LE sanding technique.

I thought I would post a thread asking anyone to please contribute.

Dealing with that pesky square balsa TE that needs to be sanded to the airfoil because it must be sheeted over with TE sheeting!!!

How do you get that perfectly straight alignment for that perfect gluing surface, yet not alter the rear airfoil on a built up wing?

I would imagine there are more ideas out there than just use tape.

Brian
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Old Jul 30, 2013, 07:17 AM
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Tulsa Jones, Oklahoma, United States
Joined May 2002
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I have always put them on after sheeting. It's difficult to plane and sand them to the foam. The main thing is to use a plane to get them close. You have to take your time and not rush using the plane. Then use the sanding block to finish.

Jeff
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Old Jul 30, 2013, 09:23 AM
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United States, VA, Suffolk
Joined Nov 2007
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I like to add it after the wing is sheeted as well. When I have to do it before, I run a strip of 2" wide masking tape along the top of the ribs or foam along the trailing edge. I plane then sand using the tape to protect the ribs or foam. I also switch to a finer grit when I get really close so that a mistake doesn't remove so much material with an errant swipe of the sanding block.
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Old Jul 30, 2013, 10:32 AM
CPA 30, SPA 523
Timthetoolman's Avatar
United States, TX, Fort Worth
Joined Nov 2009
454 Posts
I use the tape too. The set that I'm working on is the first one that has them put on after the wing is sheeted.

I haven't tried to plane them first, I'll have to look into that.

Tim
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Old Jul 30, 2013, 10:39 AM
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Quote:
Originally Posted by EscapeFlyer View Post
I thought I would post a thread asking anyone to please contribute.

Dealing with that pesky square balsa TE that needs to be sanded to the airfoil because it must be sheeted over with TE sheeting!!!

How do you get that perfectly straight alignment for that perfect gluing surface, yet not alter the rear airfoil on a built up wing?

I would imagine there are more ideas out there than just use tape.

Brian
My solution is don't do it and do it like this http://static.rcgroups.net/forums/at...3-DSC05384.JPG and http://static.rcgroups.net/forums/at...-DSC05420b.jpg

Mike
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Old Jul 30, 2013, 01:16 PM
CPA# 39
EscapeFlyer's Avatar
United States, MN, Brooklyn Center
Joined May 2009
746 Posts
Mike-

These are the very photos that have been inspiring me to use an alternate method for my Bridi UFO and Escape. I like the consistent contour/profile it creates.

Thanks!

These replies have been great! Thanks everyone!

Brian
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Old Aug 04, 2013, 11:59 PM
Kevin S. Gribben
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Joined Mar 2011
363 Posts
Great post... i have been kicking around this idea for a while.
I was at Tabi balsa about 10 years ago and got to see how they make TE stock.

Why we have settles on one angle of Te for so long is beyond me.
The solution I have seen done (in Texas) is to build a JIG that clamps to a table saw, by changing the blade angle, height of material, and cord of stock one can get any shape.

I too do it with skeleton ribs, but on some projects its just not practical.
I had to rebuild a set of warped elevators on an already sheeted Atlanta tail, here I did it with skeleton ribs.

I am with you Brian, I refuse to destroy the airfoil in the 1 1/2".
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Old Aug 05, 2013, 12:10 AM
Kevin S. Gribben
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here is the chip wing
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Old Aug 05, 2013, 01:50 AM
CPA# 39
EscapeFlyer's Avatar
United States, MN, Brooklyn Center
Joined May 2009
746 Posts
Thank you Kevin.

It's funny, sometimes the answer is starring you right in the face. but you need someone else to actually verbalize it for it to become clear!

Thanks again Kevin.

-Very nice cores btw! Wow!
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Old Aug 05, 2013, 11:55 AM
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Montreal, Canada
Joined Mar 2008
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Quote:
Originally Posted by EscapeFlyer View Post

-Very nice cores btw! Wow!
Brian,

Until you've had the pleasure of seeing and working with Kevin's cores, you won't appreciate the level of precision that can be had on a wing (stab or fin). Definitely raises the quality bar a few notches!

I can't recall if you already have Escape cores but if you don't and Kevin has the time, I highly recommend you contact him. As discussed in other recent threads (Tim's Vertigo II thread and others), they're being designed and cut for 1/32" skins and CF. Kevin has been doing the carbon atop the skins which is a more logical construction approach material and core wise. I've been thinking about how to capture the carbon under the skins during the skinning process. One approach would be to "pre-laminate" the skins with carbon along the relevant span locations and once cured, then skin the cores. This avoids you from having to deal with multiple materials, albeit very thin, on the wing surfaces in finish prep. I'm sure it's not an issue for Kevin as he dopes and then glasses but I'm thinking along the lines of water borne finishes all the way to the clear coat (which would be catalyzed urethane).

If you plan to build the UFO next, it would also be an opportunity to build two wings for it. You could do one in foam and the other from the kit. Your foam version will likely be more uniform and symmetric. However, if one starts with bad cores, the rest of the wing will just compound the errors and frame up with good ribs is preferable. I guess we all know this..,

Just some food for thought.

David
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Old Aug 05, 2013, 12:01 PM
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Montreal, Canada
Joined Mar 2008
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Kevin,

Are you simply brushing nitrate dope on to the two sides of the sanded 1/32 skins before skinning the cores? How many coats and are you sanding again afterward? What grit(s)?

On the Deception did you do one skin at a time in the shuck and bag or top and bottom simultaneously? This, after the LE is done of course.

Thanks, David
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