Military

PART I

THE STINGER WEAPON SYSTEM

CHAPTER 1

System Description

The Stinger weapon is a man-portable, shoulder-fired, infrared radiation (IR) homing (heat-seeking), guided missile system. It requires no control from the gunner after firing. Stinger has an identification, friend or foe (IFF), subsystem which aids the gunner and team chief in identifying friendly aircraft. Operations at night or in adverse weather conditions are somewhat restricted by the gunner's ability to see and identify the target. Stinger provides short-range air defense for maneuver units and the less mobile combat support units. The Stinger system is designed to counter high-speed, low-level, ground attack aircraft. Stinger is also a lethal weapon against helicopter, observation, and transport aircraft.

READY-ROUND

The Stinger missile-round consists of a Stinger missile sealed in a disposable launch tube assembly. The Stinger weapon-round is made up of a missile-round mated to a separable gripstock assembly. When a battery/-coolant unit (BCU) is inserted into the weapon-round to provide prelaunch power to the system, it becomes a ready-round. For IFF capability, an IFF interrogator is connected to the gripstock assembly as illustrated below.

MISSILE-ROUND

Major components that make up the missile are shown in the Stinger Missile-Round illustration.

The guidance section of the missile consists of a guidance assembly, a control assembly, a missile battery, and four control surfaces. The guidance assembly processes target IR and provides guidance commands for the missile during flight. The seeker tracks the IR source automatically after the gyro is uncaged and during missile flight. The control assembly converts the guidance commands into movement of control surfaces which direct the flight of the missile. The missile battery provides the in-flight power for the Stinger guided missile.

The warhead section consists of a fuze assembly and a quantity of explosives, all within a cylindrical case. After the flight motor ignites, the fuze arms the warhead. The fuze can detonate the warhead in two ways: by means of a low impact switch or by a hard target sensor. Should target intercept not occur within 15-19 seconds after launch, a self-destruct circuit initiates warhead detonation. Safety features are included to insure that the missile is safe for shipping and handling.

The propulsion for the missile is provided by a separable launch motor and a dual thrust flight motor.

The launch (eject) motor provides initial thrust that ejects the missile from the launch tube. It allows the missile to coast a safe distance (about 9 meters/29 feet) from the gunner prior to ignition of the flight motor. The launch motor is expended and separated from the flight motor before the missile is out of the launch tube. The expended launch motor leaves the launch tube and falls a safe distance forward of the gunner. Also, at separation, a lanyard attached to the launch motor pulls the shorting plug from the flight motor ignition circuit, thus enabling the flight motor.

The flight motor provides propulsion for the missile during flight. The flight motor fires after the missile coasts for a safe distance from the gunner. Thrust for the flight motor is provided in two phases: boost and sustain. Initially, both burn simultaneously. The boost phase rapidly accelerates the missile to its top speed. The boost phase ends, but the sustain phase continues. The sustain phase maintains the missile speed for a time sufficient to complete the mission.

The tail assembly of the Stinger missile consists of four folding tailfins that provide roll and missile stability. Within the launch tube, the fins are in a folded position. As the missile leaves the launch tube, the fins are erected by spring action and by the force generated by missile spin, and then locked into place.

The launch tube is a fiberglass tube which provides the main support for all parts of the launcher. Both ends of the launch tube are sealed with breakable disks. The IR window (front disk) is transparent to IR. Both the IR window and the blowout disk (rear) break when the missile is fired. A desiccant cartridge/humidity indicator on the launch tube indicates whether moisture has entered the tube.

The aperture sight assembly is the sight which is used for aiming the weapon and visually tracking the target. Attached to the sight is a clear plastic eye shield to protect the gunner's left eye when the weapon is fired. The open sight of the Stinger weapon consists of a front sight with range ring, a sighting aperture with three open reticles, and a rear peepsight. The range ring is used by the gunner to determine if the aircraft is in range and also to visually track it. The rear-sight reticles are for insertion of superelevation and lead. Superelevation is an additional elevation angle which overcomes the effects of gravity on the missile. Lead is applied to assist the missile on its flight path to the target. Lead is applied to all targets except directly incoming or outgoing fixed wing aircraft. The peepsight is located at the rear of the sight and is used by the gunner to properly align the other elements of the sight as shown in the Sight Assembly illustration.

Two acquisition indicators are mounted under the sight assembly. One is a small speaker and the other is a small unit which vibrates against the cheekbone. These indicators provide IFF tone response and an acquisition IR tone. These indicators allow you to both hear and feel the IFF tone and the IR acquisition signal.

IFF SUBSYSTEM

Stinger is equipped with an IFF subsystem to aid in the identification of aircraft. The IFF system classifies aircraft as either friendly or unknown. It does not identify hostile aircraft (see Hostile Criteria, chapter 4). The IFF components are shown in the illustration and are described in the following paragraphs.

The gunner initiates the IFF sequence by pressing the IFF INTERROGATE switch on the gripstock assembly. Once the gunner issues a challenge, the rest of the sequence is automatic. The IFF interrogator, attached to the gunner's belt, sends a coded challenge (via an IFF antenna) to the aircraft. Aircraft with Mark X or Mark XII transponders will automatically decode if the interrogator is programmed with Modes 4 and 3. Mode 3 is built into the interrogator; however, if during programming the Mode 4 position is used, Mode 3 (Mark X) will not be challenged until the 2 or 4 days of Mode 4 coded have expired. The aircraft's transponder then prepares and sends a coded reply. The reply is received by the Stinger IFF antenna and is routed to the interrogator for decoding. The interrogator converts the reply into an audible tone which is then routed via the interconnecting cable to the gunner as a friendly tone. If the aircraft's transponder sends an incorrect reply to the IFF challenge, the reply is processed by the IFF system into an unknown tone. Additionally, aircraft not equipped with the transponders will not reply to the challenge, and this is also interpreted into an unknown tone. The gunner hears the friendly or unknown tone in his right earphone immediately after challenging the aircraft. The tones are further described in chapter 4.

The IFF challenge is coded in either a complex, crypto secure Mode 4 form or a simpler Mode 3 form. All US combat aircraft and helicopters are equipped with transponders to provide friendly Mode 4 and 3 replies. However, some aircraft operating in the combat zone, to include US commercial aircraft and some aircraft belonging to our allies, are not capable of providing friendly Mode 4 replies. They can only provide friendly Mode 3 replies. Thus, since the Mode 4 code is secure, a friendly Mode 4 reply is considered a true friend reply. A friendly Mode 3 reply is considered only as a possible friend reply.

GRIPSTOCK ASSEMBLY

The separate gripstock assembly contains all the necessary circuits and assemblies that allow the gunner to interrogate aircraft and to prepare and launch missiles. The gripstock is attached to and removed from a launch tube by means of a latch. Located on the gripstock assembly are the safety and actuator device, UNCAGING switch, firing trigger, IFF antenna assembly, IFF INTERROGATE switch, IFF interrogator connector, and BCU receptacle (see illustration below).

The antenna assembly folds into a holder on the right side of the gripstock assembly when not in use. When it is deployed and the interrogator is connected to the gripstock, it is capable of interrogating aircraft and receiving coded replies. After a missile is fired, the separable gripstock assembly is removed from the launch tube assembly for reuse. The separable gripstock assembly can be reused until failure.

The BCU is used to energize the weapon's electrical circuits and to cool the IR detector in the missile's seeker prior to launch. It contains a thermal battery and pressurized argon gas coolant. Prior to use, the BCU is inserted into the BCU receptacle and tightened one-quarter turn. It is activated when the safety and actuator device on the gripstock is pressed forward, outward, and downward (until a click is heard) and then released. Once activated, the BCU supplies electrical power and seeker coolant to the weapon for 45 seconds or until missile launch. The BCU is not reusable after it is activated. Either two or three BCUs are supplied with each weapon-round and missile-round (depending on year of issue).

IFF SUPPORT EQUIPMENT

Support equipment for the IFF system is available at section headquarters. This equipment includes a programmer/battery charger AN/GSX-1, computer KIR-1A/TSEC (with power supply model ZAC A/1), and two code changing keys KIK-18/TSEC. The computer and code changing keys (when set with classified code) are classified CONFIDENTIAL, and must be safeguarded as outlined in AR 380-40. The interrogator (specifically, the reply evaluator module within the interrogator) is also classified CONFIDENTIAL and proper security measures for it must be taken. An IFF subsystem training set is available for training purposes and is described in chapter 13.

The programmer/battery charger programs the IFF interrogator and charges the interrogator batteries. Each function may be done separately or both may be done at the same time. Section headquarters personnel normally program and recharge the interrogator and battery. A brief description of each function follows. The -10 operator's manual and the KAM225C/TSEC may be consulted for more detailed interrogator programming and battery charging procedures. Also, the code book (AKAK) contains coded key numbers and instructions for destruction of the code book. The code book is kept at custodial level. Custodians will extract and annotate the code tables with the effective dates to support the situation.

BATTERY CHARGING

The battery charger can charge up to six interrogator batteries at one time. It takes a minimum of 4 hours to fully charge the batteries. Additional charge time will not hurt the batteries. A freshly charged battery is installed in the interrogator prior to programming.

INTERROGATOR PROGRAMMING

After a charged battery is installed, the IFF interrogator is manually programmed for 4 days of operation. The code changing key is used to insert the proper Mode 4 codes into the computer (Mode 3 codes are already built into the interrogator). The programmer provides the means for extracting the Mode 4 codes from the computer and inserting them into the interrogator.

Either one of two programs is selected by operating a function switch on the programmer. For either program, a 4-day countdown period is started in the interrogator by the programmer. At the end of the 4-day period, an automatic time clock stops. The interrogator switches to Mode 3 operation and continues operating in Mode 3 until the batteries are discharged or until the interrogator is reprogrammed.

In the Mode 4/3 position (the normal setting used for programming), the interrogator is programmed to interrogate in Modes 4 and 3. Initial interrogation is made in Mode 4. If there is no Mode 4 reply by the aircraft or the reply is incorrect, the interrogator automatically switches to Mode 3 and interrogates again.

In the Mode 4 position, the interrogator is programmed to interrogate in Mode 4 only. The interrogator will not automatically interrogate in Mode 3 after an incorrect Mode 4 reply. Certain situations may require that the interrogator be programmed for Mode 4 only operation. Tactical standing operating procedures (TSOP) dictate where the interrogators will be programmed in this matter.

Programming is done every 2 or 3 days, depending upon the tactical situation. The interrogator may be programmed--