Monday, 10 December 2018

American Guided Missiles - A.A.F. Missiles (Part 2)

American Projectiles and Explosives


A.A.F. Missiles

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 pounds
Warhead: 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 pounds
Warhead: 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.

Similar Project

JB-2 (A.A.F.) or "Loon" (BuAer) - A Modification of the German V-1

Overall length: 21 feet 1.1 inches
Span: 17 feet 8.1 inches
Total weight: 5,025 pounds

Warhead (T9):
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.

Next Time: ???

Monday, 3 December 2018

American Guided Missiles - A.A.F. Missiles (Part 1)

American Projectiles and Explosives


A.A.F. Missiles

1,000-pound VB-1 "Azon" Air-to-Surface Missile

Body diameter: 18.8 inches
Warhead: 1,000-pound G.P. Bomb AN-M44, M65, or M65A1

Construction: The VB-1 is a guided bomb employing a 1,000-pound G.P. body to which a special tail unit has been attached, replacing the standard tail assembly.  The VB stands for "Vertical Bomb" and indicates that the bomb is normally released from high altitude by use of a conventional bombsight and that the guided action for the bomb is relatively small, so that direction of the trajectory at the time of impact is essentially vertical.

Tail unit: More popularly known as the "Azon" bomb, since it can be controlled only in azimuth 2,000 to 3,000 feet to either side of the normal point of impact, the VB-1 has its controls in a radio receiver housed in the tail unit.  A radio transmitter, operated by the bombardier in the parent aircraft, sends signals to the receiver, which, in turn, activates a servo motor controlling the movement of the rudders in the tail fins.  Also incorporated in the tail is a gyro and solenoid system which prevents the bomb from spinning by changing the pitch of the small ailerons in the fins.

Guide flares attached to the after end of the tail unit assist the bombardier in following the flight of the VB-1.  Three flares, the T6E1 (white), T7E1 (red), and T8E1 (green) with an intensity of 1,000,000 candlepower each, are electrically armed and ignited three to four seconds after release, and burn from one to two minutes.  Three mechanically armed and ignited flares, T21, T22, and T23 are under development.

Suspension: Suspension lugs are welded to the case in a manner similar to the G.P. bombs.

1,000-pound VB-3 "Razon" Air-to-Surface Missile

Body diameter: 18.8 inches
Warhead: 1,000-pound G.P. Bomb AN-M44, M65, or M65A1

Construction: The VB-3 is a guided bomb similar to the VB-1, with the major difference that its flight may be controlled in range as well as in azimuth, and is known generally as the "Razon" bomb.  Like the VB-1, it has a special tail unit fitted to a 1,000-pound G.P. body, and is normally released from high altitude by use of a conventional bombsight, the guided action being relatively small, so that the trajectory at the time of impact is essentially vertical.

Tail unit: The controls for the VB-3 are contained in the cylindrical section of the tail unit and consist of a radio receiver, a gyro, and a servo motor.  Surrounding this unit are two shrouds; the forward shroud merely stabilizes the bomb in flight, while the after contains the stabilizing ailerons and range/azimuth control ailerons.

On each of the four struts supporting the after shroud is an aileron controlled by the gyro.  These four ailerons steady the bomb and prevent it from rotating while in flight.  They are set 90 degrees apart and operate in pairs; ie, those ailerons placed opposite to each other move together in unison.

Four move ailerons are located on the outer surface of the after shroud.  These are ailerons which control the trajectory of the bomb and adjust its flight in azimuth and range.  They also work in pairs, and are operated by connecting rods which pass through the control unit and are activated by the servo motor.  At present, two bombardiers are required with the VB-3 bomb; one controls range and the other azimuth.  They work independently of each other and, by use of a special bombsight, they are always able to see the bomb in flight, superimposed on the target.  As the bombardiers manipulate their control switches, radio waves are sent to the receiving unit in the tail.  This unit activates the servo motor, which, in turn, moves the ailerons on the shroud, altering the flight of the bomb.

As in the VB-1, flares are employed to assist the bombardier in the visual control of the flight of the bomb.  Currently used flares are the T6E1 (white), T7E1 (red), and T8E1 (green).  They are of 1,000,000 candlepower each, electrically ignited three to four seconds after release, and with one to two minutes of burning time.  Three mechanically activated flares, T21, T22, and T23 are under development.

Suspension: Suspension lugs are welded to the case in a manner similar to the G.P. bombs.

1,200-pound VB-6 "Felix" Air-to-Surface Missile

Overall length: 91.2 inches
Overall diameter: 18.6 inches
Total weight: 1,202 pounds
Warhead: 1,000-lb G.P. Bomb AN-M65

General: The VB-6 is a heat-homing, high-angle bomb for attack against targets which give higher heat radiation than the surrounding areas.  An added nose (84 pounds) and special tail assembly (143 pounds) carried on a standard 1,000-pound G.P. Bomb AN-M65 contain the heat-seeking equipment and the mechanism which operates the airfoil controls.  Requisites for proper performance are clear weather and a target which has necessary heat-radiation quality.  The bomb is sighted and released by standard Norden procedure.

Control: The tail assembly, which resembles that of VB-3, has range and azimuth control surfaces on an octagonal shroud, and gyro-stabilizes ailerons to keep the missile from spinning.  When a target passes into view, the increased heat radiations stimulate the nose unit to apply the necessary corrections to the shroud surfaces.

Suspension: Standard lugs.

Remarks: The Nose Fuze T85 has a special plate attached to it, on which the nose assembly is bolted.

12,000-pound  VB-13 "Tarzon" Air-to-Surface Missile

No picture available

Overall length: 21 feet
Warhead: 12,000-pound G.P. Bomb T10

General: This missile consists of a modified Bomb T10 with a circular, 54-inch shroud about its body for lift, an octagonal tail surface for control, and the radio control mechanisms for guidance in range and azimuth.  It is well suited for use against targets requiring direct hits, deep penetration, and heavy explosive loads.  Good visual bombing conditions are necessary, and, when several bombs are to be used on the same target, all must be dropped together, since the first explosion will visually obscure the target area.  Another tactical requirement is for the dropping aircraft to remain on its bomb run until the missile strikes.

Control: The control mechanism and procedure are fundamentally similar to those of the VB-3.

Suspension: Depending on the aircraft employed; generally similar to that of the Bomb T10.

Next Time: A.A.F Missiles (Part 2) and the "Loon"

Monday, 19 November 2018

American Guided Missiles - Bureau of Aeronautics Missiles

American Projectiles and Explosives


Bureau of Aeronautics Missiles

"Little Joe" 650-pound Surface-to-Air Missile

Overall length: 8 feet 6 inches
Span: 4 feet 9 inches

Total weight (4 rockets): 591 pounds
Total weight (6 rockets): 651 pounds

Warhead: 100-pound G.P. Bomb AN-M30

General: "Little Joe" is a short-range (10,000 foot) radio-controlled, flare-sighted anti-aircraft missile with a 100-pound G.P. warhead, launched from a shipboard catapult with the aid of standard rockets.  A Canard-type airframe with cruciform wing and bow plane, it was designed to intercept Baka-type bombs and suicide planes.  The missile is powered by a JATO unit.

The missile would be launched from a catapult 20 feet long mounted in a 40mm gun position.  It would attain a velocity of 300 to 400 mph after two seconds.

Control: By observing the flare track, the launcher guides the missile to its target with radio signals sent to the receiver in "Little Joe".  The AN/ARW-17 receiver actuates signals which, in turn, operate the servo mechanisms to position the control surfaces.  A gyro system provides the stability.

Propulsion: An 8AS1000 E JATO unit serves as the main propulsive motor.  This unit weighs 139 pounds and contains about 75 pounds of Galcit propellant.  It delivers 1,000 pounds of thrust for eight seconds.

Four or six 3.25-inch Aircraft Rocket Motors Mk 7 are used to assist in launching.

Warhead: The 100-pound bomb has only the V.T. fuze.

1,400-pound "Lark" Ship-to-Air Missile

Overall length: 12 feet 6 inches
Wing span: 6 feet 2 inches
Tail span: 4 feet
Total weight: 1,361 pounds

Warhead: Undetermined; probably a specially designed fragmentation head.

General: The "Lark" is launched from a shipboard catapult for attacking high-altitude bombers.  It has cruciform wings and tail surfaces, the tail surfaces being offset 45 degrees from the wings, and is powered by two liquid-fuel rocket motors, one continuous and one intermittent.  It is radio-controlled in the first part of its flight, its position determined by the launching ship's radar.  When it comes within radar homing range of the target, the homing mechanism takes control.

It is launched at 150mph from a multiple-charge shipboard catapult by means of two 12AS1000 F JATO units which are jettisoned after exhaustion.  With a range of 80,000 yards, an optimum ceiling of 30,000 feet, and a rate of climb of 8,200 feet per minute, it may develop a maximum speed of 650 mph.  Designed strength permits a maximum lateral acceleration of 4g.  Slant range is estimated to be 45 miles, with time of flight of about five minutes.

Control: By use of the ship radar intelligence, radio control will maintain the missile in the center of the tracking radar beam during the initial phase of flight.  When the range of the automatic homing radar is reached, it will take over and navigate a collision course with the target.  Both remote radio control and radar homing devices are connected to control surfaces by servo mechanisms.  It is gyro-stabilized for roll, with a yaw angle-of-attack indicator.

Propulsion: Two acid-aniline liquid rocket motors furnish the propulsion.  One 200-pound thrust continuous rocket is augmented by a 400-pound thrust intermittent motor.  The latter is governed by a Mach Number meter so that a more or less constant speed is maintained.  Both rockets total about 75 pounds in weight and have a supply of 490 pounds of fuel.  The two 12AS1000 F JATO units are used to assist launching and are jettisoned after exhaustion.

Warhead: The proposed warhead is a fragmentation type of explosive activated by a fuse to be fired electrically or on impact.

1,700-pound "Gorgon IIC" Ship-to-Surface Missile

Overall length: 18 feet
Wing span: 11 feet
Total weight: 1,688 pounds

-1,000-lb G.P. Bomb AN-M65
-500-lb G.P. Bomb AN-M64

General: The "Gorgon IIC" is a radar-radio controlled, resojet-powered, Canard-type airframe carrying a 500- or 1,000-pound G.P. bomb.  Launched from a catapult, it has a range of 90 miles and a ceiling of 8,000 to 10,000 feet.  It is designed mainly for ship-to-shore round-the-clock area bombardment with an expected dispersion of one mile at maximum range.  It is radio-controlled and radar-tracked.  Launched from a 150-foot, multiple-charge type, level catapult, giving the missile an initial velocity of 240 mph, the "Gorgon IIC" has a rate of climb of 600 feet per minute, and reaches an impact speed of 450 mph.  Its radius of turn is 10,000 feet.

Control: Intelligence on the target area is provided by AN/APN-33 A1 radar, range 70 miles.  Radio control of the missile is accomplished by the receiver AN/ARW-17 (for combat the AN/ARW-37 is proposed) which has a range of 70 to 100 miles.  Radio signals from this receiver actuate servo controls which maneuver the missile.  A gyro system applies stability.

Propulsion: A resojet, of 14-inch by 10-inch diameter and 9 feet long, provides 200 pounds of thrust for 10 to 20 minutes on 174 pounds of gasoline.  Specific impulse is 1,030 pound-seconds per pound.

Warhead: The bomb is held in its cradle by two bands.  Installation of the Fuzes Mk 235 and Mk 236 is standard.

1,600-pound  LBD-1 "Gargoyle" Air-to-Surface Missile

Overall length: 10 feet
Wing span: 8 and 1/2 feet
Total weight: 1,646 pounds

-1,000-lb S.A.P. Bomb AN-M59 or
-1,000-lb G.P. Bomb AN-M65

General: The "Gargoyle" is a JATO-powered glide bomb with radio control and flare observation.  It is designed for launching from carrier aircraft against maneuvering targets on the surface, visibility permitting.  Launching should be at a speed of 200 mph to avoid stalling the missile.  It has a range of 26,000 feet in a 30 degree dive if launched from the optimum altitude of 15,000 feet.  Speed of the parent aircraft is reduced 10 mph and the take-off distance is increased 15 to 80 feet, but maneuverability is not greatly affected.  The missile has a turning radius of 2,550 feet, and is designed for a lateral acceleration of 4g's.  Top speed: 600 mph.

Control: On the V-tail, control is pitch is accomplished by "rudavators" working together; control to left and right is accomplished by the rudavators working individually.  These control surfaces are positioned by servo motors which take their signal from the radio receiver.  The receiver, AN/ARW-17 (the AN/ARW-37 is proposed for combat) weighs 20 pounds and has an estimated range of about 28 miles, depending on the antenna employed.  Weight of servo system: 125.6 pounds.

Power: A standard 8AS1000 JATO unit, weighing 150 pounds, provides a propulsive thrust of 1,000 pounds for eight seconds.  The fuel is 80 pounds of solid Galcit 63C propellant contained in a 9 and 1/2 by 28 and 7/8 inch casing.

Suspension: Exact specifications are not now available; but in test drops D-6 shackle and sway braces were employed.  When the G.P. bomb is used, two steel straps 1/16 inch by 1/2 inch through the suspension lugs on the bomb hold it to the cradle.  If the S.A.P. bomb is loaded, a strap through the single British suspension lug is used; also, an adapter block is placed in the cradle to provide a snug fit for the smaller diameter of the S.A.P. bomb.

Warhead: The proposed warhead is a fragmentation type of explosive activated by a fuse to be fired electrically or on impact.

Next Time: A.A.F Missiles

Monday, 5 November 2018

American Guided Missiles - Introduction & Bureau of Ordnance Missiles

American Projectiles and Explosives




One of the newest trends [c.1947] in American ordnance development, guided missiles became service items in the last months of World War II.  Guidance was applied to modified bombs, winged glide bombs, and standard aircraft, and in jet- and rocket-propelled airframes.

Guided missiles have great range, high payload capacity, and extreme accuracy; and their progress in designed has proceeded so rapidly that on only a few items has the design become standardized or "frozen".  All the missiles included here were at least in the testing stage and were being pursued as active projects at the time of writing.  Furthermore, only those missiles designed for combat or military purposes - none of the basic research items - are included; and, of these, only their ordnance components can be described in detail.


American missiles are usually guided by remote radio control, the receiver in the missile acting through servo units to position the air foils.


The person controlling the flight of the missile will guide its path on the basis of information obtained visually, through a television receiver, or by ordinary radar tracking.  Some missiles have automatic guidance features, of such a nature that, once the target has been "shown" to the missile's intelligence unit, it will automatically "home on" to its destination unassisted.


Depending on the particular item, a missile may be powered by gravity, aircraft, engines, JATO units, rocket motors, or jet motors.


Thus far, guided missiles have adapted standard bombs as their explosive payloads.  Fuzing of these bombs differs from the standard fuzes in that the fuzes must be made in an elbow shape, in order to fit in the fuze pockets and, at the same time, permit vane arming.


For the Navy, the Bureau of Ordnance and the Bureau of Aeronautics are developing guided missiles; for the Army, the Air Forces are in charge of the program.

Bureau of Ordnance Missiles

1,200-pound "Dove" Bomb Mk 64 (Air-to-Surface Missile)

Overall length: 84.5 inches
Overall diameter: 18.75 inches

Weight of intelligence units and special tail: 183 pounds
Warhead (1,000-pound G.P. Bomb AN-M65): 975 pounds

Total weight: 1,160 pounds

General: The Bomb Mk 64 is an experimental heat-homing bomb, consisting of a detecting, computing, and guiding mechanism housed in a nose attachment fitted on the 1,000-pound G.P. Bomb AN-M65.  It is designed for attack on maneuvering targets and is effectively employed in both high-angle and dive-bombing runs against objects which have sufficient thermal contrast to their background.

"Dove" is designed to fit the normal plane stowage, but carrying capacity is sometimes reduced because of the missile's increased length.  The special Bomb Fin Mk 1 is a box-kite shape and eight inches longer than the standard tail for this bomb.

Control: Aerodynamic control is effected in range and azimuth by means of four movable nose deflectors independently controlled, which thus form quadrants of a cylindrical surface whose axis is parallel to that of the bomb.  The deflectors may be extended a maximum distance of 4 and 1/2 inches.  The movement of the deflectors is determined by the intelligence unit, which consists of the heat-detecting eye, gyro system, auxiliary electronic relays, servo motors, and battery.

1,600-pound "Bat" S.W.O.D. Mk 9 (Air-to-Surface Missile)

Overall length: 11.9 inches
Wing span: 10 feet
Total weight: 1,600 pounds
Warhead: 1,000-pound G.P. Bomb AN-M65

General: S.W.O.D. (Special Weapons Ordnance Device) Mk 9, or "Bat", is a glide bomb equipped with a radar homing set mounted in the nose.  It is designed primarily for attacking marine targets, and is effective for night or day attacks upon shipping in any weather in which the parent plane can fly.  The launching planes need not stay in the vicinity of the target, and may release as many as four of these missiles in salvo.

The airframe consists of plywood sections which are fitted around the Bomb AN-M65.  Control surfaces consists of an elevon on each wing which can be moved to control pitch or bank.  There are no control surfaces on the tail.

To ensure destruction of the intelligence system, the Demolition System Mk 122 is used.

Installation of the Fuzes Mk 235 and Mk 236, with their outside windmills and flexible arming stems, is standard.

Control: This missile has its own radar transmitter and receiver.  When the target is located on the scope of the monitor unit in the plane, it is put into the range step of the missile's scope and is automatically kept there.  At the correct instant, determined by a glide ratio scale, the missile is released and is guided to its target by the radar signal in its own scope.  The guiding radar supplies corrections to the servo system, which is also controlled by a gyro pilot, the device which maintains flight attitude.

Suspension: Standard bomb lugs are employed on the airframe.  Also, there is the multi-conductor cable connecting the missile's radar with the monitor set in the plane, known as the umbilical cord.

Demolition System: This destructor assembly consists of the S-122-11G switch, Junction Box Mk 1 Mod 0, primacord connectors, and ten Demolition Charges Mk 4.  The S-122-11G switch incorporates an inertia weight, held by a spring tension of 11G, which will topple if that force is exceeded in an impact.  When this inertia weight topples (it is mounted on a universal pivot) the contact bar, which has been transmitting the spring tension to the inertia weight, rotates because of the spring load and completes the electrical circuit across the contacts.  This switch has an arming stem, connected to windmill vanes mounted on the outside of the missile fuselage, which unscrews to arm the switch.  These vanes have an arming wire to prevent rotation before release from the parent aircraft.  On one side of the switch is a clear plastic inspection port.  Tension on the spring is pre-set at 11g when the switch is assembled at the factory.

When the switch completes the circuit, current from the battery sets off the electric blasting cap in the junction box, which fires the primacord connectors and then the TNT blocks, placed around the intelligence unit.

Remarks: The S.W.O.D. Mk 9 is commonly known as "the 1,000-pound Bat".  The S.W.O.D. Mk 10, built around a 2,000-pound bomb is not being actively developed, because it is felt that the 1,000-pound size is large enough for currently projected use.

Next Time: Bureau of Aeronautics Missiles

Monday, 29 October 2018

American Projectiles and Explosives - Army Practice Bombs

American Projectiles and Explosives

Practice Bombs

Army Practice Bombs

3-pound AN-Mk 5 Mod 1

See Navy Practice Bombs

20-pound M48

This is a dummy of the 20-pound Fragmentation Bomb AN-M41.  It has a two-ounce black-powder charge and uses the Fuze M110 or AN-M110A1 in the nose.  It is 21.8-inches long; weighs 19.7 pounds.  It is issued in practice bomb clusters M2 and M2A1.

23-pound M71 and M71A1

These are parachute-type practice fragmentation bombs for clustering.  They do not have a fuze or spotting charge, because of the presence of the parachute.  The parachute assembly is the M3, modified from the M4 by removal of the suspension assembly, hand assembly, and pull wire container.  M71 is 26.9 inches long; weighs 21 pounds.  M71A1 differs by the addition of the shoulder to the bomb nose.

100-pound M38A2

Overall length: 47.5 inches
Diameter: 8.13 inches
Weight (empty): 15.7 pounds
Weight (sand-loaded and spotting charge): 100 pounds

This bomb simulates a G.P. bomb of the same size.  The spotting charge is assembled in a sleeve at the base of the bomb, within the fin box.  Authorized spotting charges are M1A1, M3, and M4.

100-pound M75

Length: 47 inches
Diameter: 8 inches
Filler (hematite): 72 pounds
Total Weight: 101.3 pounds

This bomb is designed to provide a target reference for practice bombing over snow-covered ranges.  Resembling the chemical bomb of the same size, it consists of a light, sheet-metal case; a charge of red iron ore (hematite); a Burster M4; and a Fuze M108 in the nose.

100-pound M85

This model is a reinforced concrete design ordered to relieve a temporary shortage of the Practice Bomb M38A2 during the war.

Spotting Charge (Army)


Overall length: 11.18 inches
Diameter: 3.43 inches
Weight: 4.25 pounds
Black-powder charge: 3 pounds
Bomb used in: M38A2

This type of spotting charge fits in the after end of the 100-pound Practice Bomb M38A2.  It produces a flash of flame and white smoke for observation of bombing accuracy.  When assembled in the bomb, the can of the charge protrudes two to three inches out of the bomb body.

The fuze is an integral part of the spotting charge assembly.  When the arming wire is pulled, the spring-loaded arming pin jumps out, leaving the inertia weight supported only by the combination firing pin and creep spring.  On impact, the inertia weight drives this firing pin into the shotgun-type primer, which, in turn, ignites the black powder.

M3: The Spotting charge M3 has a 2 and 1/3-pound dark smoke filling and a black-powder igniter.  It is 5/8 inches longer than the Spotting Charge M1A1, but otherwise is like it.  The M3, with its dark smoke filler, is well adapted for bombing practice over snow-covered terrain.  The black-powder igniter charge contains approximately 425 grains.  It is used in the Practice Bomb M38A2.

Overall length: 7.37 inches
Diameter: 2.95 inches
Material: Glass
FS filler: 14.4 fluid ounces

The Spotting Charge M5 consists of a glass bottle filled with FS smoke mixture.  An ordinary bottle cap seals the mixture.  The bottle is held to the Practice Bomb M38A2 by a wire twisted around the neck of the bottle and attached to the tail vanes.  The charge assembly weighs 2.54 pounds.

Next Time: Guided Missiles - Introduction & Bureau of Ordnance Missiles

Monday, 22 October 2018

American Projectiles and Explosives - Navy Practice Bombs

American Projectiles and Explosives

Practice Bombs

Navy Practice Bombs

Miniature 3-pound Mk 3, Mk 4, AN-Mk 5, AN-Mk 23; and 4.5-pound AN-Mk 43

Overall length: 8.25 inches
Diameter: 8.1 inches

Color: Unpainted

These small, cast-alloy bombs have a tube along their longitudinal axis which houses the Signal Cartridge AN-Mk 4 or Mk 5, a pyrotechnic charge for spotting purposes.  The differences between these bombs are matters of size.  The Miniature Practice Bomb AN-Mk 43 weighs 4.5 pounds; the others of this series weigh 3 pounds.

Miniature 13-pound Mk 19 or Mk 19 Mod 1

This bomb is like the other miniatures, except that it is larger.  Its length is 13 inches, while its weight is 13 pounds.

"Old" Series Practice Bombs (Obsolete or being replaced)

No fuzes are used in these bombs, and they contain no spotting charge, being filled either with water or with wet sand.  The filling is usually stenciled on the body of the bomb.  To prevent freezing and splitting of cases at high altitudes, anti-freeze is added.  To improve spotting of hits, a spotting dye is also used.

"New" Series Practice Bombs

Mk 15 Mod 3 uses Spotting Signal Mk 7; the others use Mk 6 Mod 0.

This series bomb is a welded sheet-steel light-case design having identical dimensions to AN standard G.P. bombs, and uses AN standard G.P. bomb tails.  The bomb has, welded to its body, two suspension lugs spaced 14 inches apart.  Seven threaded recesses, located on the periphery at the approximate center of gravity, are for various hoisting conditions.  At 90 degrees, on each side of the suspension lugs and slightly before the hoisting recesses, are threaded opening to receive trunnions.

By means of a strap, the appropriate practice bomb signal, Mk 6 or Mk 7, may be attached to the tail assembly with the forward end of the signal seated in a recess in the after end of the bomb body.

A flat-nose attachment has been designed for use with the Practice Bomb Mk 15 Mod 3 for anti-submarine bombing practice.  The flat nose is installed by removing the nose-filling cap, slipping the attachment over the nose of the bomb, and then screwing the filling cap down tightly by hand to hold the attachment in place.  The flat nose will prevent ricochet at entrance angles as low as 9 degrees.

The 2,000-pound size container was designed for an incendiary or practice filler but, thus far, it is approved by the Bureau of Ordnance for practice filling, sand, only.  As designed for incendiary loads, it would take a nose fuze, the Burster Mk 1, and the Igniter Mk 40; however this is subject to change before Bureau approval of the bomb as an incendiary.  The Mk 67 has standard suspension lugs and provision for trunnions.

Practice Bomb Signals (Navy)

AN-Mk 4 and AN-Mk 5: For the miniature practice bombs, these signals allow observers to spot the impact of salvos.  The Practice Signal Cartridge AN-Mk 4 is an extra long 10-gauge shotgun shell which is inserted in the nose of the bomb.  On impact, the cartridge is fired, expelling a large puff of black smoke from the tail of the bomb.  The firing device consists of two shallow cups separated by a spacer, the firing pin extending through the bottom of one cup.  The Signal Cartridge Mk 5 is the same size but filled with fluorescein, which stains the water, giving a spot of longer duration than the AN-Mk 4.

Mk 6 Mod and Mk 7 Mod 0: These signals are essentially cans of black powder fitted with the Fuze Mk 247.  The Mk 6 is used in the Practice Bombs Mk 65 and Mk 66; the Mk 7 in the Bomb Mk 15 Mod 3.  They are attached to the rear of teh bomb by brackets or a strap arrangement.  The Signal Mk 7 is 13.08 inches long and 2 inches in diameter.  It has a total weight of 2.5 pounds.  It has a filling of one pound of black powder.  The Mk 6 is generally the same, except that the fuze is mounted off-center and the black-powder filling weighs two pounds.

The Fuze Mk 247 consists of an inertia weight held by a jump-out pin and a creep spring.  The detonator is a blank caliber .38 cartridge.  When the signal is placed in the bomb, the firing pin assembly is unscrewed and a blank caliber .38 cartridge inserted in the cartridge chamber.  The firing assembly is then re-inserted and secured by means of a lock nut.  At the time of loading the bomb into the plane, the arming wire is inserted through the jump-out pin, and the safety pin is then removed.  Upon release from the plane, the arming wire is withdrawn, allowing the jump-out pin to be thrown free, arming the signal.  Upon impact, weighted firing pin overcomes the creep spring and impinges upon the primer of the caliber .38 blank cartridge, which, in turn, ignites the main black-powder charge.

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