Proper Sizes For Frame.
Allowing that the biplane form is selected the construction may be practically identical with that of the 20-foot glider described in Chapter V., except as to size and elimination of the armpieces. In size the surface planes should be about twice as large as those of the 20-foot glider, viz: 40 feet spread instead of 20, and 6 feet deep instead of 3. The horizontal beams, struts, stanchions, ribs, etc., should also be increased in size proportionately.
While care in the selection of clear, straight-grained timber is important in the glider, it is still more important in the construction of a motor-equipped flying machine as the strain on the various parts will be much greater.