TOW Missile Components

Actuator subsystems:

1. The control surface ( flippers ) are spring loaded and extend upon leaving the tube.
2. Upon extension, an electrical squib valve (small explosive device) is actuated which punctures the diagram of a pressurized bottle containing 6,400 psi of helium gas to power the flippers.
3. Four solenoids ( one for each flipper ) are individually controlled by the electronics section. The solenoids allow the helium gas to extend or retract a piston which moves each flipper at 25 cycles per second (CPS) for 4.325 seconds, then reduces to 12.5 CPS for conservation of the helium gas.
4. Each piston is connected to the control surface actuator by a shaft ( push-pull tube ).

Attitude gyro:

1. It is mounted in the center section case.
2. The gyro is driven and accelerated to 42,000 rpm by a 3,000 psi nitrogen charge. This is a part of the sequence between trigger pull and launch motor ignition.
3. The nitrogen is release when an explosive piston ruptures a diagram at trigger pull.
4. Gyro is caged during spin-up. Caging device is released when nitrogen pressure is exhausted.
5. Gyro sends yaw information for only the first 0.76 seconds of flight, but sends roll information for entire flight.

Batteries:

1. There are three identical, solid electrolyte, thermal-type batteries which are activated upon trigger pull. When the trigger is pulled the electrolyte melts, generating electrical voltage.
2. Two of the batteries, connected in parallel, supply power to the electronics assembly and the IR source. The other battery also supplies power to the electronics assembly and the actuator subsystem solenoids.

Encapsulated Electronic Unit:

1. Receives corrective guidance signal from the MCA through the wire command link.
2. Receives yaw and roll error signals from the missile attitude control gyro.
3. Combine signals processed into commands which operate the four control surfaces (flipper) actuators.
4. Eight circuit boards encased in a styrofoam type material.
5. Electronic section assembly fits at rear of the warhead.

Extensible Probe:

This feature was installed in the ITOW and later models to improve the standoff detonation. This feature increases the armor capability of the missile warhead. On the TOW2A an explosive charge was added to the forward end of the telescoping probe. The explosive charge causes reactive armor to detonate prior to missile impact, enhancing the effectiveness of the shape charge when the missile impacts the actual vehicle armor.

Flight Motor:

1. Located at the center of the missile to prevent center of gravity shift during burn.
2. When the wings spring open and lock ( about 0.1 seconds after launch ) an electrical circuit is completed igniting the propellant for the flight motor.
3. The propellant provides approximately 1,500 lbs of thrust for 1.5 seconds ( time and thrust vary with temperature and humidity ) accelerating the missile to its maximum velocity of about 1,080 ft / second or 735 mph.
4. Upon reaching 15Gs acceleration, the arming sequence is initiated.
5. There are two exhaust nozzles mounted at 30 degrees from the longitudinal axis to prevent exhaust from obscuring the target and interfering with the wire command link.

Infrared (IR) light source.

1. Mounted in extreme aft end of missile.
2. IR source provides a beacon that is detected by the IR sensors in the TSU to determine the missile's position relative to the TSU's line of sight.

Launch Motor:

1. Located at aft end of missile.
2. 2.1 inches in diameter; 17 inches long.
3. Contains four tubular grains of M-7 double base propellant weighing 1.2 pounds
4. Activated 1.5 seconds after trigger pull.
5. Propellant provides 15,000 lbs of thrust for approximately 35-50 milliseconds, and is expended prior to the missile leaving the tube.
6. Accelerates missile to about 250 ft / second.

Warhead:

1. The basic TOW ( BGM - 71 A/B ) carries High Explosive hollow charge.
2. BGM - 71C carries 4 kg of HE.
3. BGM - 71D carries 6 kg of HE.

Wings:

1. Four wings are located in the center section and are spring loaded to open when the missile exits the tube.
2. Extension of the wings completes completes an electrical circuit which ignites the flight motor's propellant.
3. The wings provide lift and aid stability of the missile during flight.

Wire dispensers:

1. There are two wire dispensers mounted in the extreme aft end of the missile 180 degrees apart ( 90 degrees and 270 degrees from vertical ). Each contains 3,750 meters of wire.
2. The wire is a single strand, high strength insulated wire with a command leader wire ( 5" long with an additional five strands of wire, laminated with white plastic for shock absorption and detection ) which remains attached to the tube until wire cut.
3. The wires provide a passive line for transmission of steering commands from the aircraft to the missile.

• Missile flies beyond limit of wire.
• If the missile is not electronically "capture" within 1.85 seconds after launch or if the IR source is lost for more than 0.5 seconds after capture.
• Missile impact
• Time sequence ( T + 23.04 seconds ) is completed and no wire cut signal was previously received.
• Switch movements made during missile flight. ( i.e. armament switchology ).

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Updated: 12 January 2008

Born on 09 February 1998