Twinwall Wings - Cutting Out the Wing

How hard could it be?

OK, so cutting out a wing can't be the most difficult thing you'll ever attempt in life, but there are a number of ways you can save time and effort in the process.
The following step by step method is how I make my wings. It allows for very fast scratch building, saves building board scrawling and also makes an almost foolproof way of achieving correct flute orientation of your wings.

Wing flute orientation

I've found through building dozens of wings that the best orientation for the flutes is parallel to the airflow over the top of the wing. As far as possible, I try to adhere to this rule unless it means unnecessary material wastage.
Flutes running parallel to the airflow over the wing theoretically makes aerodynamic sense but, theory aside, in practice it makes for a very useful guide for lining up wing stripes.... well, I find it useful...

Step by step procedure

The following step by step example is based on a fairly simple double tapered wing featuring indented ailerons. Note that for ease of illustration the most efficient use of the sheet has not necessarily been made. In practice you can easily cut down on material wastage by laying out the shapes more carefully on your sheet.

1. Layout the sheet

The plan for your wing, including any cutouts for ailerons etc, should be transferred to your twinwall sheet. This can be either by measuring and drawing or tracing through a translucent sheet to the building board sketch below.
The wing as laid out (left) is going to be the right hand wing. If you find that working top down a little unnatural, you can flip the sheet round and build the other way... just be sure that you end up making a pair of wings and not two wings for the same side!


2. Score the LE and cut the wing out

Score the leading edge (red line) and work the material to achieve a sharp leading edge.
Now cut the rest of the shape out, extending the cuts to the edges of your sheet. Remove the unwanted material and you'll be left with your right hand side wing top surface.


3. Fold the wing over and cut out the mirror image

This step saves a lot of time drawing out the wing shape mirrored around the leading edge. Note how the LE is illustrated in green as we're now looking at the outside of the fold.
Hold the top surface down over the remaining sheet and carefully cut or draw round it. The purpose is to remove all the unwanted sheet, colour coded orange, however you go about it.


4. Open out the wing half

You now should have half a wing, mirrored near perfectly about the leading edge. If you like, practice folding the wing over and seeing how the flutes run in different directions top and bottom.

Now repeat steps 1-4 but with your original shape flipped horizontally on the sheet and you should end up with another wing half... this time the left wing.

They can now go together...

5. Join the wings ready for insertion of the spar

Put left and right wing halves together on your building board and rotate them so that the wing roots fit perfectly together. Make sure that the leading edges meet in the middle and then lay a single piece of tape down the join between the two wings. The wing is then ready to take a spar and then be folded over and glued.

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