[Graham Boak]

A few points. The DeH wooden technology came from internal experience, and the Mosquito does not, as far as I know, use resin-impregnated birch. It used a spruce and balsa sandwich. Therefore it has no relation to the Soviet use, other than the general worldwide knowledge of how to make wood work as a structural material for aircraft. Physics, biology and carpentry are the same for all nations, therefore engineering solutions will tend to be similar. I think it would - generally - be a mistake to see that any development as evidence of direct espionage/hand-over.

One point worth making is that once it was known that one company was making propellors from resin-impregnated wood, then every propellor company would study the idea, at first so see if it was any good, and then with the aim of finding a way around the patents. Did Rotol pay patents to Lockheed for their wartime propellors?

Wooden aircraft will always tend to be heavier than metal aircraft because wood is not as strong, and although less dense is also less consistent and reliable, so must be worked with greater safety margins. On the other hand, wooden aircraft tend to will have smoother external surfaces and hence less excresence drag. Fighters are better with metal construction than with wood, yes, but not necessarily faster.

As the Mosquito showed in British industry, that doesn't mean that it is not possible to produce a competitive aircraft using wood. As the Albemarle showed on the other hand, it rather depended upon just what you were making! The reason for doing so was not to achieve a performance benefit, but to be able to produce an aircraft at all given a shortage of aluminium. This was the position the Soviet industry was in: it would have preferred to use metal but adequate supplies were not available. Also, aluminium was used in the T-34 engine, which could reasonably have had a higher priority on whatever stocks were available. Also, being able to use the trained woodworking personnel without major training programmes, and distribute the manufacture, were seen as major benefits in the UK. No doubt this was also true in the USSR.

Problems with production quality fall into two main categories: firstly those where the process is new, and not all lessons have been learned. The LaGG does seem to have suffered from this. Then there are failures due to lack of production control. Note that the Mosquito suffered from wing failures that, although blamed on substitute glues,were caused by a reduction in production quality. The Japanese also suffered from production problems when attempting to change to non-strategic materials late in the war. In the conditions under which the Soviet industry suffered in the early years of their war, quality problems were inevitable. Any production line would have seen a reduction in quality if abused in this manner.