Hardpoint

A hardpoint is any part of an airframe designed to carry an external load. This technical description includes mountings for engines, but most commonly the word is used to refer to the points on the wings of military aircraft where external stores - missiles, bombs, countermeasures, gun pods, and drop tanks - can be attached. Hardpoints on aircraft enhance the effectiveness of an aircraft but increase drag and radar returns.

By extension of the common usage, the word hardpoint is sometimes used to refer to a point on "any" vehicle where weapons or other accessories can be attached. Bench hardpoints serve the same basic purpose.

Hardpoints

In the context of aircraft, and usually military aircraft, the term hardpoint refers generally to places on the outside of the aircraft to attach external stores. Specifically, it refers to the reinforced structure of the wings or fuselage to attach some manner of intermediate suspension equipment.

uspension equipment

Free-fall stores are typically suspended from an ejector rack, which may be an integral part of, or mounted in, some type of pylon. The pylon is designed to position the rack and stores on it properly. This may be to keep stores away from moving flight controls, or to position them close to the aircraft's center of gravity. By having separate pylons and racks, their maintenance is simplified in the event of a part breaking or coming due for inspection.

The mechanical interface between the rack and various stores is standardized so that one type of rack can carry different stores, rather than having to change the rack for each type. With the aid of some type of branched multiple-ejector rack, aircraft may carry many weapons on one hardpoint, subject to various limitations of clearance, weight, drag, etc. The F-16 in the photo has 3 MK-82 high-drag bombs mounted on such a device, in this case a Triple Ejector Rack (TER). The TER in turn is suspended from a rack, that rack is attached to the pylon, and the pylon is installed on the hardpoint in the wing.

The rack will have some means of carrying the store. For NATO standard stores, this is lugs, spaced either 14" apart for lighter stores, or 30" apart for heavier items. These lugs are engaged by L-shaped hooks in the rack. The rack contains small explosive cartridges to open the suspension hooks and push the store clear of the aircraft in a predictable manner. This is necessary both for proper separation of the store from the aircraft, and to aid in accurate aiming of unguided gravity bombs. Some racks have an auxiliary cartridge in the event that the primary cartridges fail to fire. The rack will also have accessories such as arming solenoids to pull arming wires from fuzes, and electrical connections for data, video or electrical fuzing. To keep stores from rocking sideways as the aircraft maneuvers, swaybraces are provided to steady the stores. These may be automatically or manually adjusted.

Missiles with their own rocket engines are typically mounted on rail-type launchers and clear the aircraft under their own power, although for some aircraft this is unfeasible. The F-4, the F-18, and the Tornado ADV all carry AIM-7 missiles semi-recessed to the fuselage to reduce drag, and therefore have launchers to push the missile away from the aircraft before its motor ignites.

As an example, the Boeing F/A-18A/B/C/D family have nine weapons stations, numbered from left to right.

*Numbers 1 and 9, the wingtips, have a single rail launcher for an AIM-9 type store.

*Stations 2, 3, 7, and 8, located under the left and right wings, have mounting points for SUU-63A or SUU-63A/A pylons. The pylons in turn support a BRU-32/A ejector rack, to which various stores or launchers are attached. These stations may have a bomb loaded directly upon them, or have a multiple-ejector rack with several stores, or various rail-type launchers for air-to-air and air-to-ground missiles:

A LAU-115 rail-type launcher for an AIM-7; [http://www.ordnance.org/lau115.htm]
A LAU-115 with two LAU-7 or LAU-127 launchers, one bolted to either side, for two AIM-9 or AIM-120s; [http://www.ordnance.org/lau127.htm]
A LAU-117 for an AGM-65 Maverick; [http://www.fas.org/man/dod-101/sys/ac/equip/lau-117.htm]
A LAU-118 for an AGM-88 HARM [http://www.fas.org/man/dod-101/sys/ac/equip/lau-118.htm]

*Stations 4 and 6, which are located on the sides of the fuselage, are LAU-116 ejector-type launchers for AIM-7 and AIM-120 missiles. Station 4 can also support a Forward-Looking Infrared (FLIR) pod for detecting and marking targets.

*Station 5, which is on the centerline underneath the fuselage, mounts a smaller SUU-62/A pylon and a BRU-32 rack, and many of the same stores as the wing pylons. The obvious exception is anything rocket-powered, to avoid endangering the nose landing gear.

Stations 3, 5, and 7 are also plumbed to feed fuel to and from external fuel tanks.

wing-wing aircraft

Swing-wing aircraft present a unique challenge because in order to minimize drag and maximize stability the hardpoints must swivel to present the least drag possible such as on the General Dynamics F-111, or the hardpoints must be placed on another part of the aircraft, such as on the F-14 Tomcat and Mikoyan MiG-27. Due to the limited number of hardpoints that could swivel on the F-111, not all hardpoints could be used if the plane was going to travel with fully swept wings.

ee also

*Bomb bay