Birch.
One finds very few instances of the use of this wood for aeroplane details, although it is used fairly extensively in America for air-screw construction, for which it is only moderately suited. It possesses a high value of compressive strength across the grain, but is much affected by climatic changes, and does not take glue well. It is useful for bent work, and might conceivably be used instead of ash for small bent work details. Its weight is about 44 lbs. per cubic foot.