How to Do Curves - Smooth Air

Let's cover something flat with curves. In this case, it's the rudder for my Hurricane. It's mostly flat and is all curves! Here's all the stuff together.

Here's my ultra-precision cut out from the covering:

Tack down the entire border of the side you're covering and turn the rudder over. Trim the edges per this picture, with slight (about 1/8") overhang and cut out the corners as shown. Where you see little pen-drawn "tick" marks is where I'll make cuts in the covering with my knife. This allows a smoother finish around the end and opposite side. I also cut a slit at a 45 degree angle into the corner between the rudder and counterbalance.

I work my way around from one side of the curve to the other. At each spot, I make sure to hold the next section away from the iron as shown in the pic below. This pic shows three sections - the first is at the right side of the surface as shown, and has been rolled around to the backside. The second is still overhanging, but is directly facing the camera. The third is where you see my finger, as I'm holding it away from where the iron will be. Use your iron in a rolling motion from the covered side to the backside. You can increase the heat a little bit for this to ease getting out the micro wrinkles.

Once you've laid all of the overhanging edges down on the backside, shrink the open areas with your preferred method and you're ready to do the backside. Lather, rinse, repeat. Do the back side precisely the same. The overhang amount on both sides can depend on what color of covering you're using. For example, I'd decrease that overhang for white, as you can partially see through it. However, for this olive green, it's totally opaque, so the overhang I left at about 1/8"

Once you get practiced a bit, you can eventually cover simple surfaces like this fin all with one piece.

Tack down and trim one side as instructed above....

In this example, I've cut the covering flush with the bottom of the fin to allow for gluing the fin to the stab. Do this AFTER shrinking the covering in the open areas or you'll watch that nice clean cut line creep up your wood and leave an ugly bare patch.

Use your iron to fold the covering around the backside and repeat the process. With practice, this can be done with no wrinkles aside from the small ones typical of the open areas before shrinking. Ta da!