Wednesday, July 27, 2011

Aeromodeller 1957-11


The outstanding characteristic of Balsa is, of course, its light weight; but no wood has such a variation in weight. Balsa commonly occurs in weights of from 6 lb. to 16 lb. per cubic foot. The top weight is still light-weight compared with other woods but much too heavy for the man who wants 6 lb. Balsa for some particular purpose. It wouldn't be so bad if any one piece of Balsa was consistent in weight, but Balsa planks are commonly much heavier on one side than the other and I have seen an 8-ft. long plank where the wood at one end weighed more than twice the weight of the wood at the other end. The mills' biggest worry is to find a market for their low grade Balsa wood, just as it is our biggest worry here! Balsa is so full of defects thai I think it is the most variable raw material in the world. There seems to me to be three ways of dealing with Balsa wood. Firstly, there are two big American companies who have their own mills in Ecuador who do as good a job of grading for quality at their mills as is possible. They sell wood in bulk to individual purchasers in the grade that they require for their particular job. The proportion of really top grade, absolutely clear stock resulting from these mill operations is low and, therefore, relatively expensive. Even with the best of Balsa faults are found which don't show on the surface and it isn't possible to buy the exact size you want for your particular job. Therefore, it is impossible not to have some waste in manufacture.