In a fixed-wing aircraft
, the spar
is often the main structural member of the wing, running spanwise
at right angles (or thereabouts depending on wing sweep
) to the fuselage
. The spar carries flight loads and the weight of the wings whilst on the ground. Other structural and forming members such as rib
may be attached to the spar or spars, with stressed skin
construction also sharing the loads where it is used. There may be more than one spar in a wing or none at all. However, where a single spar carries the majority of the forces on it, it is known as the main spar.
Spars are also used in other aircraft aerofoil
surfaces such as the tailplane
and serve a similar function, although the loads transmitted may be different to those of a wing spar.
The wing spar provides the majority of the weight support and dynamic load integrity of cantilever monoplanes
, often coupled with the strength of the wing 'D' box itself.<!-- Need to clarify 'D' box --> Together, these two structural components collectively provide the wing rigidity needed to enable the aircraft to fly safely. Biplanes
employing flying wires
have much of the flight loads transmitted through the wires and interplane struts
enabling smaller section and thus lighter spars to be used.
Some of the forces acting on a wing spar are:
- Upward bending loads resulting from the wing lift force that supports the......