Longerons are stronger and heavier than stringers, and hold the
bulkheads and formers, which, in turn hold the stringers. All these
joined together make a rigid fuselage framework.
Nacelle. The streamlined structures (nacelles) on
multiengine aircraft are used primarily to house engines. Figure 1-6
shows the construction of a nacelle in general use. Here
also, designs vary depending upon the manufacturer and the use
to be made of the nacelle. On twin-engine airplanes, nacelles
the nacelle houses a reciprocating piston or jet engine,
landing gear, or cargo, repair fundamentals are essentially the same
as for a fuselage.
The nacelle must have sufficient strength to
withstand the compression and shear loads it will be subjected to;
its weight must be kept within allowable limits; and the exterior
must be aerodynamically suited for the nacelle's location on the