Wood Dominates in Aircraft Construction

Washington, D. C., Nov. 25.-TheU. S. Department of Agriculture is authority for the statement that 90 per cent of the 8,000 to 10,000 airplanes built during 1929 had wing structures of wood, and that other parts made wholly or partly of wood in,cluded propellers, control surfaces, fuselages, the pontoons and hulls of s.eaplanes and flying boats, wing beams (solid and box types), ribs, leading and trailing edges, bow embraces, reinforcing or shear blocks, light compartments, aileron ribs, braces and covering; rudder, stabilizer, and elevator parts; tank compartments ; center covers, step boards and walkways; turtle decks, engine bearers, bulkheads, instrument boards, floors, seats, cabin sides, fairings, doors, strut streamlining, keels, ribs, partitions, braces, and the coverings of su,ch pontoons and hulls of seaplanes and flying boats as are not of all-wood construction.

This marked predominance of wood in the manufacture of vehicles which serve as carriers in the most advanced method of transportation is detailed in Technical Bulletin No. 205, issued by the Department in October, 193O, and bears the title "Gluing Wood in Aircraft Manufacture, by T. R. Truax, Senior Wood Te,chnologist, Forest Products Laboratory."

The general use of wood is not confined to commercial planes. "Even in the fast combat type of military plane," says the bulletin, "wooden wing structures,are used, and in some planes the entire wing framework and covering is of glued-wood construction."

Glue is used not only in laminating and building up large and irregular wooden parts and in the making of plywood, but it also affords the principal means of fastening the various wooden parts together into the finished structure. Most uses of glues in aircraft require adhesive which retains a large proportion of their strength under rnoist conditions, even to the extent of remaining safe in service after exposure to free water. A,ccording to the Forest Products Laboratory, blood-albumin and casein glues most nearly meet these requirements.

Gluing tests have been made at the Forest Products Laboratory of about forty different species and the bulletin publishes the results obtained with 31 species of wood, using different kinds of glues.

This 60-page pamphlet contains several illustrations of wood-built aircraft, also interi,or views of woodworking departments in commer'cial aircraft factories, as well as many tables, and graphs. Copies are for sale by the Superintendent of Documents, Washington, D. C. Pri,ce, 25 cents.