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AIM-7 Sparrow

The AIM-7 Sparrow is a radar-guided, air-to-air missile with a high-explosive warhead. The versatile Sparrow has all-weather, all-altitude operational capability and can attack high-performance aircraft and missiles from any direction. The AIM/RIM-7 series is a semiactive, air-to-air, boost-glide missile, designed to be either rail or ejection launched. Semiactive, continuous wave, homing radar, and hydraulically-operated control surfaces direct and stabilize the missile on a proportional navigational course to the target. Propulsion for the missile is provided by a solid propellant rocket motor.

It is a widely deployed missile used by U.S. and NATO (North Atlantic Treaty Organization) forces. In the Persian Gulf war, the radar-guided AIM-7 Sparrow proved to be a potent air-to-air weapon used by Air Force fighter pilots. Twenty-two Iraqi fixed-wing aircraft and three Iraqi helicopters were downed by radar-guided AIM-7 Sparrow missiles. The Sparrow is limitated by the requirement that the aircraft it is fired from must continue to paint the target with radar, limiting that aircraft to straight and level flight.

The AIM-7M/P Sparrow Missile is employed during air-to-air combat missions by Navy F-14, Navy and Marine Corps F/A-18, and Air Force F-15 and F-16 aircraft. The AIM-7 (series) is used primarily to neutralize the threat of high performance enemy aircraft. It is a supersonic, medium-range missile with Defensive Counter Countermeasure capabilities, which includes Electronic Protection from Electronic Attack. It guides on radio frequency energy, processing radar signals received via its rear signal receiver from the launch platform's radar system and reflected target energy received directly from the target. The AIM-7M/P is controlled in flight by four movable delta platform wings. Missile stability is provided by four fixed delta fins which are located in-line with the forward wings. Missile propulsion is provided by a dual-thrust, solid propellant rocket motor. An active radio frequency fuze detonates the warhead when the missile is within lethal range of the target.

The missile has five major sections: radome, radar guidance system, warhead, flight control (autopilot plus hydraulic control system), and solid-propellant rocket motor. It has a cylindrical body with four wings at mid-body and four tail fins. Although external dimensions of the Sparrow remained relatively unchanged from model to model, the internal components of newer missiles represent major improvements with vastly increased capabilities.

Sparrow is a supersonic, medium range, aerial-intercept missile, which guides on RF energy. The missile processes radar signals received directly from the launch platform's radar via its rear signal receiver, and also processes RF energy reflected from the target received by its own internal radar receiver (front signal). Sparrow is controlled in flight by four movable delta platform wings. Missile stability is provided by four fixed delta fins which are located in line with the forward wings. Missile propulsion is provided by a dual-thrust, solid propellant rocket motor. An active RF fuze detonates the warhead when the missile is within lethal range of the target. To increase performance in either application, air-to-air or surface-to-air, Sparrow contains switching circuits that automatically program missile operation for optimum performance in the appropriate environment. The Sparrow Weapon System consists of the radar-guided missile; the support equipment consisting of test, handling, and training equipment, tools and reusable containers; and the aircraft or ship's equipment required to launch the missile.

AIM-7 Sparrow - Components

Guidance and Control Section. The GCS tracks a target, directs and stabilizes the missile on a lead-angle navigation course to the target, and starts warhead detonation by use of an active radar proximity fuze or a backup contact fuze. The guidance system uses energy reflected from the target and data received from the missile fire control system to track the target. A comparison of these signals allows the guidance section to sense changes in target position and create signals used by the control section to control movement of the wings and thus maintain course to target intercept. Missile-to-target closing speed is derived by a comparison of the signals (doppler shift) received by the front antenna and the rear reference antenna.
Guidance Section. The Guidance Section is a solid-state design. The Guidance Section is constructed modularly and includes a radome, tunnel cable to the control section, forward antenna, target and rear receivers, an embedded Missile Borne Computer (MBC), a radar fuze unit, and electric gimbaled motors.
Control Section. The control section consists of an autopilot and a hydraulic control group which provide wing control to guide the missile to the target and to stabilize the missile. An accumulator supplies the hydraulic power to move the wings in response to guidance command signals from the autopilot. In addition to circuits for processing guidance and stabilization signals, the control section also contains an AC/DC converter for adapting external power for missile requirements before launch.

Warhead Assembly. The Warhead Assembly includes a fuze booster, transfer lead (WAU-17 warhead only), Safe-Arm Device (SAD), and the main explosive charge. The warhead assembly is located between the guidance section and control section. It is connected electrically to the guidance section by a SAD cable. At launch, a thrust-activated mechanism in the SAD starts the arming cycle. When the missile receives a launch signal, voltage is applied to unlock the arming mechanism. As the missile accelerates, the arming rotor turns, aligning the explosive train and removing the shorting circuit. This completes the firing circuit. Detonation is triggered by a fuze pulse from the active RF fuzing circuit in the guidance section at the nearest point of intercept or by an impact switch located in the control section.
WAU-10/B and WAU-10A/B Warhead Assembly. The WAU-10/B Warhead Assembly includes a MK-71 Mod 0 Warhead Section with a MK-33 Mod 0 SAD and MK-33 Mod 1 fuze booster. The WAU-10A/B Warhead Assembly is similar to the WAU-10/B except it has a MK-38 Mod 2 fuze booster. Both warhead assemblies are of the insulated continuous-rod type.
WAU-17B and WAU-17A/B Warhead Assembly. The WAU-17B Warhead Assembly includes a WDU-27B Warhead Section with a MK-33 Mod 0 SAD, a MK-38 Mod 1 fuze booster, and a MK-26 Mod 0 transfer lead. The WAU-17A/B Warhead Assembly is similar to the WAU-17B except it has a MK-38 Mod 2 fuze booster. The transfer lead extends the explosive train from the SAD to the fuze booster. Both warhead assemblies are of the end-initiated blast fragmentation type.

Fuze Booster. When ignited by a SAD, the fuze booster charge ignites the main warhead charge. The MK-38 Mod 2 fuze booster is designed to melt rather than detonate when exposed to high heat. This provides an added safety feature for ordnance personnel and fire fighters.

Rocket Motor Assembly. The MK-58 Rocket Motors are dual-thrust, solid propellant propulsion units. The case bonded grain consists of separate boost and sustain propellants in a side-by-side configuration. The rocket motor assembly consists of three major subassemblies: a case with propellant grain, a safe-arm ignition assembly and a nozzle weather seal at the rear. Integral parts of the case are the attachment points which include the forward skirt, launch hooks, waveguide clips, antenna bracket, and fin dovetail slots.
MK-58 Mods 2, 3, and 5 Rocket Motor Assemblies. These rocket motor assemblies are used with the air-launched missiles (AIM-7M/P) and include a safe-arm ignition assembly with an Arm-Fire Device (AFD) relock assembly. The AFD relock T-handle, which locks in either the SAFE or ARM position, cannot be removed, and is used to arm the rocket motor manually before flight.

Wing and Fin Assemblies. Four wings and four fins provide the flight control surfaces for Sparrow. The wings attach to the hub assembly of the control section and the fins mount into dovetail quick-attach fittings on the rear of the rocket motor.

Rear Waveguide Assembly. A structural rear waveguide assembly containing the rear antenna is installed externally on the missile airframe. The rear waveguide is constructed in two parts with the forward section connecting to internal RF circuitry in the guidance section. The forward section also serves as a protective cover for the tunnel cable which electrically interconnects the GCS. The aft assembly contains the rear antenna and is joined to the forward section at the rear of the control section, and runs aft to the rear of the rocket motor.

Training Missiles. The AIM-7 Missile System uses several types of training missiles: Air-launched Training Missile (ATM)-7M/P; the Captive Air Training Missile (CATM)-7F-3; and the Dummy Air Training Missile (DATM)-7F-11. The ATM-7M/P is a live-fire missile that is an AIM-7M/P with the warhead section replaced with a telemetry section. The CATM-7F-3 and the DATM-7F-11 are used primarily for AIM-7M/P maintenance training, and are completely inert. Additionally, the CATM-7F-3 is used by F-14 aircrews for some training events/exercises. F/A-18 aircrews use a simulator plug (commonly referred to as a wafer) in the launcher umbilical that precludes the use of the CATM-7F-3, and enables the aircraft's embedded training capability via its on-board computers.

AIM-7 Sparrow - Variants

The Sparrow missile is a supersonic, medium-range, aerial-intercept missile that guides on Radio Frequency (RF) energy. Sparrow incorporates Electronic Counter-Countermeasure (ECCM) capabilities, also known as Electronic Protection (EP), to defeat countermeasures such as jamming. The Sparrow began as project Hotshot in 1946, and became operational in late 1953.

Experience during the Vietnam war demonstrated it to be virtually useless against manuvering targets. A special AIM-7E-2 dogfight version was produced to overcome these shortcomings. During extensive captive flight operations in SEA, SPARROW missile failures were caused by misture intmsion of the electronic circuitry. The problem is caused by free moisture from rain and clouds entering the missile through unsealed areas. By 1968 proposals from NAVMISCEN and Raytheon had been in review for three years. ALMC 17, requiring the squadron to tape the tunnel covers, eliminated a major portion of the failures; however, this wws an unnecessary maintenance burden to place on the operating activities.

The SPARROW wing locking mechanism was difficult to unlock for wing removal; consequently, wings were frequently damaged by the missile handling crews by using improper tools, i.e., screwdrivers, hammers, and aircraft chocks, during removal. The difficulty encountered in removing the wings from the SPARROW III missile during unloading and shipboard handling contributed to an excessive number of damaged components. This damage did not significantly affect missile flight reliability but, rather, was a logistics problem due to the requirement for new components.

Non-standardization of section screws and jaints betyeen the air launched missiles and between sections on the ssme nissile has created problem areas. The SPARROW missile is held together by special purpose screws with a NYLOC locking feature whlch deteriorates with repeated use, yet the screws must be removed fcr repeated nissile test and assembly. Deviation in production quality required investigation, and ccrrection of Fleet problems in both the SPARROW and SIDEWINDER during the two years 1966-1968. One SPARROW missile in-flight breakup was attributed to improper section screws.

Current configurations of the Sparrow missile include four air-launched variants, AIM-7M F1 Build, AIM-7M H Build, AIM-7P Block I, and AIM-7P Block II, and as many ship-launched variants, RIM-7M F1 Build, RIM-7M H Build, RIM-7P Block I, and RIM-7P Block II.

Each new version has resulted in substantial improvement in missile performance. The AIM/RIM-7E reduced minimum range restrictions and provided dogfight capabilities. The RIM-7H incorporates rapid run-up capabilities, providing improvements over previous versions. The AIM-7F incorporates solid state circuitry and modular design, an improved warhead, and a boost-sustain rocket motor. The AIM/RIM-7R is most recent configuration and adds a dual mode radio frequency/infrared (RF/IR) seeker capability.

The AIM-7F joined the Air Force inventory in 1976 as the primary medium-range, air-to-air missile for the F-15 Eagle. The AIM-7F was an almost completely new missile, gaining ability from improved avionics that allowed the warhead to be moved to the front, allowing a bigger motor to be carried that has improved range.

The AIM-7M, the only current operational version, entered service in 1982. It has improved reliability and performance over earlier models at low altitudes and in electronic countermeasures environments. It also has a significantly more lethal warhead. The latest software version of the AIM-7M is the H-Build, which has been produced since 1987 and incorporates additional improvements in guidance. AIM/RIM-7M DT and OT was successfully completed in FY82. The F-15 Eagle and F-16 Fighting Falcon fighters carry the AIM-7M Sparrow.

The RIM-7M Sparrow is employed during ship-to-air combat missions by Spruance class Destroyers outfitted with the North Atlantic Treaty Organization (NATO) Sea Sparrow Missile System (NSSMS). In ship-to-air combat evolutions, Sparrow is used primarily to neutralize the threat of high performance, anti-ship missiles. The RIM-7M guidance and control section is common with the AIM-7M. When used in the surface launched RIM configuration, folding wings, clipped fins, and a remotely armable rocket motor are used.

The AIM/RIM-7P Sparrow missile has undergone two block modifications. The AIM/RIM-7P Block I provides low altitude guidance and fuzing capability. The AIM/RIM-7P Block II provides increased memory and throughput to the MBC, enhanced production software reprogrammable capability, and mid-course uplink improvements to the rear receiver. The AIM/RIM-7P Block I retrofit included an upgrade of the MBC in the guidance section (WGU-6D/B) and incorporation of a new fuze (DSU-34/B). Approximately 600 missiles were upgraded to the Block I configuration.

The AIM/RIM-7P Block II upgrade included modification of the MBC in the Guidance Section (WGU-23D/B), incorporation of the new fuze, and a new rear receiver. The AIM/RIM-7P Block I and AIM/RIM-7P Block II have the same approximate weight, center of gravity, and general mass distribution properties as the AIM/RIM-7M Guidance Sections. The AIM/RIM-7P program began as a retrofit program to AIM/RIM-7M Guidance and Control Sections (GCS) and resulted in a new build contract for AIM/RIM-7P Block II GCS. Follow-on AIM/RIM-7P Block II procurements will upgrade existing AIM-7M inventories and provide replacement for AIM-7M missiles lost through FMS. Remaining AIM-7M Missiles will continue to be supported until phase-out or other action through the FMS Replacement-In-Kind (RIK) program. The AIM/RIM-7P Sparrow Test and Evaluation Master Plan, M159-1RIM-7P, dated 21 July 1989, was developed for the AIM/RIM-7P. Developmental and operational test and evaluation phases for the AIM/RIM-7P have been completed. Developmental Test (DT) for the AIM/RIM-7P occurred in first quarter FY90 through second quarter FY90.

Operational Test (OT) occurred in third quarter FY90 through second quarter FY91. Follow-On Test and Evaluation (FOT&E) for Block I and II AIM/RIM-7P Missiles was completed fourth quarter FY93 through second quarter FY94 using retrofit kits in Government Furnished Equipment missiles. The AIM/RIM-7P was introduced to the fleet through GCS retrofit and GCS new production contracts. The AIM/RIM-7P retrofit program began deliveries in November 1993. Because the upgrade from AIM/RIM-7M to AIM/RIM-7P did not impact Carrier Air Group (CAG) operation and maintenance procedures, a unique Fleet introduction was not required. All AIM/RIM-7P upgraded elements are contained in the guidance section to reduce technical risk. The AIM-7P modifications are incorporated in blocks.

The AIM/RIM-7R was the latest Sparrow new development, but the program was halted in the first quarter of FY97 following completion of its DT/OT program. The AIM/RIM-7R integrated a passive infrared seeker in its radome for terminal guidance. Requirements for a dual mode seeker AIM-7R were rescinded in FY96. The AIM/RIM-7P Block II was the baseline for the AIM/RIM-7R missile.

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