Something I do is to ca a small piece of spruce ,1/16th or 3/32nds square,to the back of the surface and then file it down with a combination rasp, using the flat side. It gave me a hard surface that kept it from tapering too much, and created a dent-resistant surface when I was through.

Your 1/2X 1 1/4 aileron stock seems to be an odd size. I can find 1/2X 1 1/2 at Balsa USA, but that is as close as I can come. If you need this size, you are pretty much stuck with doing it yourslef or haveing someone cut it special for you. It's no big deal doing it yourself, but it will take a little while if this is the first time you have done anything like this. Most people that are into plan or sctatch building do a lot of that themselves and don't think twice about it. There are more then likely as many ways to do it as there are people doing it. Pick one and have at it. It's no big deal really. Once you have done it you won't think twice about doign it again yourself, unless you mess it up big time the first time through. That happens too. Ihave done it with saw and sander and either way is pretty easy. Just depends on what you have your hands on at the time. Take care and have fun.

Ed

i have a large belt sander that does the trick! i use my micromatic eye to keep the taper right