Mahogany.
The term “mahogany” covers an infinite variety of woods, possessing widely different characteristics, many of the species being quite unsuitable for the requirements of aircraft work. That known as Honduras mahogany possesses the best strength values, is of medium weight, about 35 lbs. per cubic foot, and is in general use for airs-crews and seaplane floats. It has been used on some German machines for such parts as rib webs, but is not really suitable for parts of comparatively small section, such as longerons, as it is inclined to brittleness. It is of particular value for seaplane floats and the hulls of the flying-boat type of machine, as it is not affected by water. A defect peculiar to Honduras mahogany is the occurrence of irregular fractures across the grain known as thunder shakes. Although other so-called mahoganies are similar in appearance to the Honduras variety, a species quite distinct in appearance is that known as Cuban or Spanish mahogany, which is of darker colour, and much heavier in weight, averaging about 50 lbs. per cubic foot, which latter factor almost precludes its use for aeroplane construction.