American Projectiles and Explosives
2,500-pound GB-4 Air-to-Surface Missile
Overall length: 12 feet 2 inches
Wing span: 12 feet
Overall height: 6 feet 2 inches
Body diameter: 24 inches
Total weight: 2,536 poundsWarhead: 2,000-lb G.P. Bomb AN-M66
General: GB-4 is a glide bomb which is launched from an aircraft and guided by remote radio control to its surface target by employing television intelligence picked up by a television camera on the missile and radioed to a receiver in the launching plane. It has a special plywood airframe built around a 2,000-pound bomb, with rudders and elevators but no ailerons. The airframe is fastened to a magnesium casting threaded to the tail of the bomb.
The missile is effective against well defined point targets, easily distinguishable from the surroundings on a television screen, and has an average circular error of 200 feet. At present, the weapon can be used only under good visual bombing conditions, but it has been proposed to incorporate radar tracking of the missile by the parent aircraft to alleviate the handicap.
It is launched outside the normal anti-aircraft range from either a B-17 or B-25 at 175 mph at a preferred distance of 17 miles from the target at an altitude below 15,000 feet. With a glide ratio of 6 to 1, the time of flight, at average rates of 250 to 300 mph, is four minutes.
Control: The television camera mounted under the bomb is set to point along the bomb's flight path, the standard setting being 3 degrees below the axis of the bomb. The field of view is 14 degrees wide and 18 degrees high. The camera scans the area and modulates a transmitter with the picture which is broadcast to the parent aircraft. The radio control signals are transmitted by a "liaison" transmitter in the parent aircraft and are received by a standard or command set receiver installed in the glide bomb. A modulator installed int he airplane will put out any one of the five audio tones to modulate the transmitter. The relays in the control unit switch current to the elevator servo motor and the rudder capstan motor to move the control surfaces in the desired directions. In addition, two more relays are actuated to shift temporarily the gyro pick-offs either to the right or to the left when those signals are given. The missile is stabilized by a directional gyro to give roll and azimuth control.
Suspension: The missile is carried outside the plane on a Shackle D7. Electrical cables, connected to it, pull out on release.
Destructor: The Destructor T9 is placed in the control box and is actuated, on impact, by the Fuze T62.
2,500-pound GB-8 Air-to-Surface Missile
Overall length: 11 feet 7 inches
Wing span: 12 feet
Tail: 4 feet 8 inches
Total weight: 2,555 poundsWarhead: 2,000-lb G.P. Bomb AN-M66
General: This is a radio-controlled glide bomb, with flare observation, designed for use on large installations. The wing is covered with plywood and is bolted to the boom assembly. The two spar booms are of solid poplar and have hinged bands attached to their front ends which secure the bomb to the frame. The elevator is covered with metal to prevent damage by the flares.
The GB-8 should be launched with the parent plane on a bomb run when the target is at bombardier's angle of 75 degrees - which is still outside normal A.A. range at altitudes from 10,000 to 15,000 feet. It will glide at speeds varying about 6 to 1 depending on the elevator setting.
Control: The guiding system consists of a radio control link from the plane to the missile, servo connections to the control surfaces, gyro stabilization, and a flare panel of five Flares T3 and T4 (white and red) for observation.
Control surfaces are the ailerons on the wings, the elevator surface, and a single rudder on the left vertical stabilizer.
Suspension: The missile is carried outside the plane on a Shackle D7. A warm-up electrical cable pulls out on release.
Destructor: The Destructor M8 mounted under and tot he starboard of the control compartment is actuated, on impact, by the Fuze M121.
JB-2 (A.A.F.) or "Loon" (BuAer) - A Modification of the German V-1
Span: 17 feet 8.1 inches
Total weight: 5,025 pounds
Weight: 2,100 pounds
Filling: 1,875 pound of Tritonal
General: The JB-2 and "Loon" are copies of the German V-1, with modifications. As far as the ordnance components are concerned, the Army and Navy modifications are the same.
Warhead: The warhead is an aluminum-encased charge of Tritonal. The case is 3/8-inch thick and is bolted to the fuselage abaft the nose piece by four lugs.
Destructor (T15): At the appropriate distance from the target, as determined by the Veeder Root Counter, an electrical contact is closed, which sets off the electric blasting caps int he Destructor T15, igniting the small charge and blasting apart the two junctions in the wing spar. The spar breaks; the wings come off; and the missile is forced into the dive toward its target.
Previously, the missile was put into its dive by the action of the Spoiler Actuators T1. These were small steel bullet-like cups filled with black powder and an electric squib. When activated by the Veeder Root Counter, they were fired down two vertical tubes in the tail section, releasing a spring-loaded knife arm which cut the rubber hoses from the servo motors to the controls; and, at the same time, the spring pulled the elevators down, putting the bomb into its dive.
Remarks: This missile uses liquid oxygen as fuel, this oxygen being highly explosive.
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