Fabrication of the Lockheed Vega Airplane-Fuselage 280066
THE monocoque type of fuselage construction seems to promise satisfaction of the three requisites of prime importance; namely, high strength-weight ratio, “streamlined” form, and unobstructed interior, according to the author.
The conventional method of building a fuselage consists, first, in the construction of a “form” of the required shape, upon which a layer of veneer is fastened. Other layers are applied, and thus a fuselage shell of two or three plies is completed. But the process is expensive and laborious, involving the handling and individual fitting of many small pieces.
In the process described by the author, a wooden form of the exact shape of one half of the fuselage body, divided on a vertical plane passing through the center line, is built. This form, or pattern, is next suspended in a large box in which reinforcing bars previously have been woven, and concrete is poured in. A reinforced-concrete block weighing from 10 to 30 tons and having a central depression exactly the shape of half of the finished fuselage is thus made.
To assemble a half shell, the outer layer is placed in position in the concrete mold and coated with a casein glue, and the second layer is placed inside the first layer. A coat of glue is given the second layer, the inner layer is put into place inside the other two and air pressure is applied to a rubber bag which fills the space between the plywood shell and the cover of the concrete mold.
After remaining under pressure in the mold for about 8 hr., the half-shell is removed and placed on a drying rack. It is without joints, cracks or laps, perfectly glued throughout and formed to the exact streamline desired. Two half-shells constituting the fuselage are clamped into position on a “skeleton” by special clamps, and automatically align themselves on the framework. They are glued and nailed in place, and cutouts are made for windows and other openings. Installation of seats and fittings completes the structure.