MTK

Hi Claude,

No that isn't the technique, BUT what you show in the photos will work. Many many years ago, Hal DeBolt described this same method in his "Solution" build plans. I built the Solution (a 60 sized pattern model) using Hal's wing crutch method (that your photos show) around 1977 or 1978.

Bob Hunt's Lost Foam technique is different and it doesn't use foam ribs; balsa ribs that are hollowed out are just as light but stronger, stiffer. Both techniques can build an accurate surface

Having built the individual crutches under each rib back then, I remember it was a lot of work. It seems to me the Lost Foam method has been easier. There are several good sources for cutting foam cores using CNC cutters. In my opinion you will get a better, more accurate product if the LE was cut at the correct radius by the CNC cutter. Also, you will have to sacrifice one panel when using the Lost Foam technique, because you need to make the tooling needed. One shouldn't get emotional about cutting up a foam core and losing 30$. Done right and from denser foam, the tooling will last several stab or wing builds so the lost money is miniscule in the long run......

The end result will be lighter that a foam-balsa composite but will be strong enough for the job.

BTW- Bob showed me his latest Stunt model and I wish I had taken a photo to show all of you. Made from molded balsa, an outstanding build. It is a large model for Stunt at around 60 inches of span, with two electric motors driving. The completed model fully covered in carbon veil and ready for primer,(with no equipment), weighed in at about 26 ounces. That is extremely light and with the carbon skin, strong enough for Stunt!