An interplane strut is an aircraft airframe

Airframe

The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...

 component designed to transmit lift

Lift (force)

A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...

 and landing

Landing

thumb|A [[Mute Swan]] alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the [[Stall |stall]]ing speed...

 loads between wing (mainplane) panels on biplane

Biplane

A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...

s and other aircraft with multi-wing designs. They also maintain the correct angle of incidence

Angle of incidence

Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...

 for the connected wing panels and are often braced with wires

Flying wires

The flying wires of an aircraft work in conjunction with other wing components such as spars and interplane struts to transmit flight loads. Most commonly used on biplane aircraft they are also used on monoplanes and triplanes.-Purpose:...

. Very early aircraft used interplane struts made from bamboo

Bamboo

Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....

, while later designs employed streamlined struts made either from spruce

Spruce

A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...

 or ash; woods chosen for their strength and light weight. More modern or higher performance aerobatic

Aerobatics

Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in normal flight. Aerobatics are performed in airplanes and gliders for training, recreation, entertainment and sport...

 biplanes often feature metal interplane struts.

Configuration

The most common configuration is for two struts to be placed in parallel, one behind the other. These struts will usually be braced by "incidence wires" running diagonally between them, and more than one of these strut pairs may be placed along the span of the wing, creating multiple "bays" (see below). Other common arrangements include N-struts, where the diagonal bracing wires are replaced by an extra wooden or metal member running diagonally from the top of one strut to the bottom of the other in a pair; V-struts, where the struts from the upper wing converge to a single point on the lower wing (commonly used when the lower wing has a considerably smaller chord

Chord (aircraft)

In aeronautics, chord refers to the imaginary straight line joining the trailing edge and the center of curvature of the leading edge of the cross-section of an airfoil...

 than the upper wing); and the I-strut, where the pair of struts is replaced by a single, thicker strut. Some biplane wings are braced with struts forming a Warren truss

Girder

A girder is a support beam used in construction. Girders often have an I-beam cross section for strength, but may also have a box shape, Z shape or other forms. Girder is the term used to denote the main horizontal support of a structure which supports smaller beams...

.

Bays

The compartments created by adding interplane struts are known as "bays"; this relates to only one side of the aircraft's wing panels. For example, the de Havilland Tiger Moth

De Havilland Tiger Moth

The de Havilland DH 82 Tiger Moth is a 1930s biplane designed by Geoffrey de Havilland and was operated by the Royal Air Force and others as a primary trainer. The Tiger Moth remained in service with the RAF until replaced by the de Havilland Chipmunk in 1952, when many of the surplus aircraft...

 is a single-bay biplane where the Bristol F.2 Fighter

Bristol F.2 Fighter

The Bristol F.2 Fighter was a British two-seat biplane fighter and reconnaissance aircraft of the First World War flown by the Royal Flying Corps. It is often simply called the Bristol Fighter or popularly the "Brisfit" or "Biff". Despite being a two-seater, the F.2B proved to be an agile aircraft...

is a two-bay biplane.