As most of you know I produce, among other things, sheeted foam wings through my Robin's View Productions company. I strive to get the very best materials possible, and it is always a struggle to obtain large quantities of contest grade 4 to 6 pound/cubic foot density wood. I just spoke with my supplier and told them that I was not getting the requisite amount of such wood with my recent orders to fill my wing orders. I was told that contest grade balsa will very soon become a thing of the past. There are industries that are using huge amounts of balsa to make their products (mostly to make those huge props used on "wind farms.”) Those industries have been buying up all the wood that is available - including the light stuff... - and leaving only the dregs for those who service the modeling industry.
The situation is not as dire as you might think, if you are willing to change your thinking about how we use balsa. Back in the 1970s I produced wings under the company name Control Specialties (and before that Control Line Specialties...). We had a similar problem getting consistently light wood back then. In those days the industry that was using all the available balsa was ship building. Specifically freighters that required holds that were refrigerated. Balsa was the ideal (at that time) insulating material, and we had a bear of a time getting good light wood for many years. When they found other, better, insulating materials, the balsa supply eased up a bit and we could once again get some decent density wood. During that period I started using .045 (3/64-inch) thick balsa for sheeting, and virtually all of the wings that I produced throughout the 1970s were covered with that thickness wood. Because the wood was thinner, but of a heavier density, the actual finished weights of the wing panels were no different than they had been when using the lower density 1/16 wood. But, the denser wood did not soak up as much finish, and, because of that, the models built around those wings actually came out lighter overall. I even covered several foam core wings with very dense 1/32-inch balsa, and those models came out very light when finished. An added bonus is that the denser wood is also stronger than very soft but thicker wood.
I order wood in lots of several hundred sheets at a time, and then grade the wood when it arrives. I use wood that is 8 to 9.5 grams per sheet for the inboard panels, and wood that is 10 to 10.5 grams per sheet for the outboard panels. This is done to reduce the amount of tip weight that is required, and to make use of the wood more efficiently. The wood that grades out heavier than 10.5 grams per sheet is sold locally to modelers for rib stock for built up wings, or to the local RC guys. Even so, I have stockpiled a lot of slightly heavier density wood; more than I can use or sell.
In talking with a good friend of mine abut this problem and explaining how we used to use denser but thinner wood, he revealed to me that he had a micro sander that could be used to make .045 sheets out of my stock of unusable .062 (1/16-inch) wood. Long story short, I delivered to him about 500 sheets of that wood, and he has so far sanded about 100 sheets to .045. And, it is beautiful! A sheet of 1/16 x 3 x 36 that weighed around 11 grams came out to weigh about 8.5 grams at .045. Woo Hoo!
We have all been used to getting wood from hobby shops and/or suppliers that was cut to the popular thicknesses that have been the paradigm for years. Remember, balsa does not grow in 1/16, 3/32, 1/8, 1/4, 3/8 -inch thicknesses. We can get it cut and sanded to whatever thickness we desire.
I have been using denser 1/16 wood for top and bottom shells for a long time. The denser wood takes a bit longer soaking to be moldable easily, but when fully soaked, it bends around the bucks jut as easily as the softer 3/32 that is most often used to make shells for our models. An added benefit is that the denser, stiffer wood will not cave in between the formers and give that “starved horse” look. I have also been using stiff 1/16-inch balsa for fuselage sides instead of 1/8 or 3/32-inch balsa, and have had great results.
All I am saying is that we will most likely have to adjust our paradigms to the reality of what will be available to us in balsa densities in the very near future. If we do, we can continue to produce light and strong models for years to come.
Later - Bob Hunt