Drawing: Cobra Drawing: Cobra

The Life and Times of the Tow Missile

Extensible Probe Encapsulated Electronic Unit Warhead Wings Batteries Batteries Attitude Gyro Flight Motor Actuator Subsystems Infrared (IR) Light Source Infrared (IR) Light Source Actuator Subsystems Launch Motor Wire Dispensers Drawing: TOW missile image hotmap

TOW2 Hotspot Image Map

Actuator Subsystems Attitude Gyro Batteries
Encapsulated Electronic Unit Extensible Probe Flight Motor
Infrared (IR) Light Source Launch Motor Warhead
Wings Wire Dispensers

The life span of the TOW missile is extremely short in our normal time span (approximately 24 seconds), but it is an eternity when you are sitting in the front cockpit guiding the TOW to its target while in the heat of battle. The following information should give you a better understanding of how a TOW missile comes to life.

Gingerly the pilot unmasks the helicopter. The gunner has spotted the target and now switches from two power magnification on the TSU to 13 power. With slight pressure application on the joystick the gunner brings the TSU crosshairs unto the target. The pilot brings the aircraft to prelaunch constraint. The attack flag in the TSU pops on. The gunner squeeze the trigger on the left handgrip. Now the missile is born.

Throughout this sequence of events T equals missile launch time, not when the trigger is pulled.

T -1.52 seconds When the trigger is pulled, three batteries are activated that provide power to the electronics, the Xenon or thermal beacon and the actuator subsystem. The attitude control gyro spins up to 42,000 rpm. Electronic signals are balance between the Missile Command Amplifier and the missile.
T = 0.0 seconds The launch motor ignites producing 15,000 lbs. of thrust for 0.35 to 0.50 seconds. This causes the missile to accelerate to 250 ft/sec.  The launch motor is completely expended before the missile exits the tube. The wings on the missile extend as it exits the tube and completes the circuit to activate the flight motor, which occurs about 7 meters from the launcher
T + 0.5 TOW missile launcher stows
30 - 65 meters Warhead arms by acceleration G forces
Upon capture, the TOW missile becomes a closed-loop system. The Xenon beacon and thermal beacon ( TOW 2,  TOW2A ) are installed in the rear of the missiles and are detected by the Xenon detector or thermal tracker in the TSU. Two wire dispensers are mounted on the rear of the missile at 90 and 270 degree positions. These dispensers contain 3,750 meters of single strand wire. Control surface flippers respond to signals from this wire command link. Helium powers the control actuators. The attitude gyro, which limits yaw and roll, is driven by nitrogen
T + 1.35 sec./ approximately 230 meters The IR sensors in the TSU switches from wide field of view (FOV) (+ 6 degrees) to medium FOV (+ 1.5 degrees).
T + 1.6sec./ approximately 350 meters The flight motor burns out. Missile velocity is approximately 1,080 ft / sec. (639 knots or 735 mph).
T + 1.85 seconds Automatic wire-cut occurs if no IR source.
T + 2.0 sec./ 500 meters Minimum effective range
T + 2.34 sec./ approximately 520 meters TSU IR sensors medium FOV (+1.5 degrees) end; narrow FOV (+0.25 degrees) begins. Narrow FOV IR sensor is contained in 13 power lens.
T + 3.9 sec./ approximately 1000 meters Missile velocity is approximately 840 ft / sec (497 kts or 571.4 mph
T + 4.325 seconds Control surfaces (flippers move at 12.5 cps instead of 25 cps to conserve helium gas in the high pressure bottle.
T + 8.6 sec./ approximately 2000 meters Missile velocity is approximately 620 ft / second (367 kts or 422 mph).
T + 14.8 sec./ 3000 meters Missile velocity is approximately 450 ft / second (266 kts or 306 mph).
T + 20.5 sec./3750 meters Missile velocity is approximately 375 ft / second (222 kts or 255 mph). Missile is at maximum range of the wire. Automatic wire-cut happens at the tube when the wire breaks.
T + 23.04 seconds Automatic wire-cut occurs if no wire-cut signal has been previously received.
T + 23.12 seconds Trigger reset for the next missile.

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Updated: 12 January 2008
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Born on 05 February 1999