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Techniques => How to... => Topic started by: stephen.shannon on April 24, 2014, 00:24:31 AM

Title: Compound curves
Post by: stephen.shannon on April 24, 2014, 00:24:31 AM

All,

I'm struggling to get a decent finish on wing tips with compound curves when using oracover.

I've looked up videos on line and read lots but just can't seem to master it.. The technique I'm using is to use a heat gun to stretch the cover over the curve. The challenge is that I continually get creases in the finish and if I go too long with heat gun it crisps up as it's too hot.... The iron approach isn't much better..... Any of you experienced flyers have any advice??

Thanks

Title: Compound curves
Post by: andrew wallace on April 24, 2014, 08:49:24 AM

stephen could you take a picture of the curve
normally i use the heat iron and stretch the film, some times i'll run the iron up the middle first and then work out the ways
is there much of a stretch with oracover i've never used it before

Title: Compound curves
Post by: Fred on April 24, 2014, 09:16:21 AM

Same as Andrew.
But sometimes, the curve is too "steep" for the material to stretch properly...
Scissors, and a few cuts every 5mm will sort you out, and with Oracover, will be pretty much invisible :)

Title: Compound curves
Post by: stephen.shannon on April 25, 2014, 09:41:35 AM

Thanks for the response on this lads. The photo's enclosed show the curve. Its very extreme really I'd imagine its just my technique.

Let me know your thoughts.

(http://www.gliderireland.net/forum/images/uploads/stephen.shannon/IMG_2345.jpg)

The wing is from a WOT4

(http://www.gliderireland.net/forum/images/uploads/stephen.shannon/IMG_2346.jpg)[/img]

Title: Compound curves
Post by: Fred on April 25, 2014, 10:11:50 AM

Put a nav light. Problem solved  :P  :P

Not a big compounded curve. Go slow, heat the corner of the wood first in following the curve and that should do it fine :)

Not easy to explain/describe  :(

But le Internet to the rescue! :)

https://www.youtube.com/watch?v=mIYKktleZi0

Title: Compound curves
Post by: andrew wallace on April 25, 2014, 18:58:28 PM

good man stephen the photo really helps  :D
i would tend to do those bits first and use a separate piece of covering  and it's very hard to get perfect
i'm sitting here trying to put into words the way i'd do it  
i'd cut the piece of covering over size and tack the covering to the edge of the wing and then with the heat iron on the covering pull down over the tip now if you start to get a wrinkle take the covering  back off the wing and pull it back again with the heat on the film and what ever small wrinkles thats left take out with the heat iron and then trim the excess film off  
does that make since lol i could probably show you better than i can explain it  :D

Title: Compound curves
Post by: johnfireball on April 26, 2014, 01:03:17 AM

Hi Stephen,
              You need a thick glove so you don't burn your fingers and perhaps someone to hold the wing down for you. I coat the tip edge with balsaloc  first to get a good bond and then starting at the leading edge stretch the covering backwards and down holding tension after removing heat to give it time to cool and stick. The amount of tension you can apply depends on the strength of the wingtip (you dont want to break it). I found oracover the best covering material for this job and it will stretch loads although it pales in colour.
John.