Aircraft pylon

A hardpoint (more formally known as a station or weapon station) is a location on an airframe designed to carry an external or internal load. This includes a station on the wing or fuselage of a civilian aircraft or military aircraft where external jet engine, ordnance, countermeasures, gun pods, targeting pods or drop tanks can be mounted.

In aeronautics, the term station is used to refer to a point of carriage on the frame of an aircraft. A station is usually rated to carry a certain amount of payload. It is a design number which already has taken the rated g-forces of the frame into account. Therefore, point loads on the structure from externally or internally mounted stores, engines, equipment, passengers, and payload are simply the weight of the item and any pylons, seats, mounting brackets, etc. multiplied by the maximum load factor which the aircraft will sustain when these items are carried.

In civilian aviation a station is usually used to carry an external engine or a fuel tank. As engines are usually a fixed installation, operators usually refer to them with the designation of the engine. Therefore, the term is mostly being used for load points meant for non-fixed installation.

In the military, a station can also be called weapons station. Unlike civilian aircraft, NATO aircraft frame strength is required to remain without detrimental deformations at 115 percent of the limit or specified loads, and without structural failure at ultimate loads. Most stations on a military aircraft serve to carry pods or weapons. A minor number of stations can also serve to carry external fuel tanks. These stations are called wet, a general aeronautic term referring to usage of fuel like wet thrust. The term wet is also carried over to the adapters, such as a pylon.

Wing stations require pylons to carry objects. Stations on the fuselage may not necessarily require a pylon, such as the fuselage stations on the McDonnell Douglas F-15 Eagle, while other aircraft need pylons for certain stations in order to provide clearance for the landing gear retraction sequence (like in F-14 Tomcat) or to provide necessary item space (like in Mikoyan MiG-27). Swing-wing aircraft that mount pylons on the moving portion of the wing (such as the General Dynamics F-111 and the Panavia Tornado) must include a mechanism for swiveling the pylon as the wing sweeps fore or aft, in order to keep the pylon and store facing directly forwards at all times. The F-111's outermost pair of hardpoints do not swivel, and can only be used while the wing is fully extended. This restricts the aircraft to subsonic flight only while these pylons are fitted, usually fitted with fuel tanks during ferry flights. The pylons are automatically jettisoned if the wing sweep moves past 26 degrees, which would mean that the aircraft is accelerating towards transonic speeds.

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Wikipedia