[Bomb Reconnaissance] [From the U.S. Government Publishing Office, www.gpo.gov] BOMB RECONNAISSANCE UNITED STATES OFFICE OF CIVILIAN DEFENSE Washington, D. C. Prepared under the direction of The Chief of Ordnance, U. S. Army with suggestions of the National Technological Civil Protection Committee BOMB RECONNAISSANCE Prepared by the WAR DEPARTMENT With the Assistance and Advice of Other Federal Agencies AUGUST 1942 UNITED STATES OFFICE OF CIVILIAN DEFENSE Washington, D. C, FOREWORD The War Department has assumed the chief responsibility for the disposal of unexploded or delayed-action bombs within the continental limits of the United States and the training of military and civilian personnel for that purpose. Although this is fundamentally a military problem, the Office of Civilian Defense working through State and local Defense Councils, has the very important responsibility of verifying the presence of such bombs and the application of safety precautions at the site of the unexploded bombs. From past experience it may be expected that our enemies will use delayed-action (time) bombs. Such bombs are designed to detonate hours and even days after the raid has taken place. The object of dropping these time bombs is to attack civilian morale and prevent use of areas and facilities. They are intended to frighten people away from activities essential to the war effort and to impair normal operations by disrupting public services. Varying proportions of bombs which are dropped may not explode because of mechanical failures. The use of a few time bombs gives the same potential danger and the same effect as though every bomb which failed to explode was a genuine time bomb. It is necessary to classify all unexploded bombs as time bombs until technical examination proves them otherwise. Slowness or failure to report the presence of unexploded bombs may result in loss of life, injury, avoidable damage, and delay in the war effort. If, through excessive caution or lack of knowledge, false reports of the presence of unexploded bombs are furnished, the result is delay in dealing with genuine time bombs. Thus it can be readily understood that the training of military and civilian personnel who are responsible for the reporting of and rendering harmless unexploded or delayed-action bombs must be painstakingly thorough. Prompt action, accuracy, skill, and cooperation are essential. BOMB RECONNAISSANCE II TABLE OF CONTENTS Part One Chapter I.—GENERAL Paragraph Purpose...................................................... 1 Definitions................................................ 2 Responsibilities............................................. 3 Control.................................................... 4 Training of Civilian Personnel............................... 5 Incendiary Bombs............................................. 6 Chapter II.—REPORTING General.................................................... 7 Discovery.................................................... 8 The Air-Raid Warden......................................... 9 The Control Center...........................r.............. 10 The Bomb-Disposal Officer. . . ............................. 11 Chapter III.—RECONNAISSANCE DATA Ground Signs................................................ 12 Penetration and Path of Bomb................................ 13 Indications of Explosions.................................. 14 Detection of Camouflet...................................... 15 Bombs Falling on Hard Surfaces.............................. 16 Bombs in Buildings . ...................................... 17 Chapter IV.—EFFECT OF BOMB EXPLOSIONS British Experience.......................................... 18 Unburied Bombs.............................................. 19 Buried Bombs................................................ 20 Underground Effects......................................... 21 Craters .................................................... 22 Camouflets.................................................. 23 Chapter V.—SAFETY PRECAUTIONS Danger Period.............................................. 24 Priority Designation.................................. . 25 Police Responsibilities..................................... 26 Evacuation Rules............................................ 27 Unexploded Parachute Mines................................. 28 Safety Precautions for Railroad Traffic..................... 29 Chapter VI.—PROTECTIVE WORKS General..................................................... 30 Protective Trenches.................*....................... 31 Sandbag Abutments........................................... 32 Sandbag Walls.............................................. 33 Sandbag Mounds............................................. 34 Vents............................................... . 35 BOMB RECONNAISSANCE III TABLE OF CONTENTS—Continued Part Two Chapter I.—OBJECTS WHICH MAY BE DROPPED FROM THE AIR Paragraph Introduction__i_____________________________________________ 1 Unexploded High-Explosive Bombs__________________________ 2 Unexploded Parachute Mines__;_______________________________ 3 Incendiary Bombs__________________________________________ 4 Flares___________________________________________________ ' 5 Airplane Cannon Shells_____________________________________ 6 Antiaircraft Shells_______________________________________ 7 Miscellaneous Objects_______________________________________ 8 Chapter II.—GERMAN BOMBS Chapter HI.—JAPANESE BOMBS Chapter IV.—ITALIAN BOMBS Chapter V.—AMERICAN AIRPLANE CANNON SHELLS Chapter VI.—AMERICAN ANTIAIRCRAFT SHELLS Chapter VII.—MISCELLANEOUS OBJECTS NOTE.—The weights of all enemy bombs are given in KILOGRAMS (Kg.). 1 kilogram is approximately 2.2 pounds. IV BOMB RECONNAISSANCE Chapter I. General Part One 1. Purpose.—This pamphlet is furnished as a common basis for instructions to aid civilian defense organizations in the proper and efficient discharge of their responsibilities in connection with the disposal of unexploded and delayed action (time) bombs and to explain how their cooperation with military personnel for that purpose is most essential. 2. Definitions.— a. Service commands.—The continental area of the United States is divided into nine service commands for purposes of administration, each commanded by a United States general officer who is the Service Command Commander. b. Defense command.—The continental area of the United States is divided into the Eastern, Western, Southern, and Central Defense Commands for defense purposes, each commanded by a United States Army general officer, who is the Defense Commander. Defense Commanders are authorized to assign duties to Service Command Commanders. c. Regional area.—The Office of Civilian Defense has decentralized its activities by creating regional areas which are coterminous with the Army’s service command. d. Regional director.—The civilian official in charge of a region. e. Service command ordnance officer.— Special officer in charge of ordnance activities and under the service command commander is responsible for bomb disposal within the command boundaries. f. Bomb disposal unit.—Military organization made up of Ordnance Department personnel, who are highly disciplined, trained, and skilled experts capable of disarming or unfuzing a bomb without exploding it. BOMB RECONNAISSANCE g. Bomb disposal officer.—Commissioned officer in the Ordnance Department, United States Army, who is also an expert on bomb disposal. h. *United States Citizens Defense Corps.—An organization of enrolled civilian volunteers in each community to minimize the effects of enemy air raids by Civilian Protection measures. i. Control center.—The Command Post and Headquarters of the Commander of the Citizens Defense Corps. Its functions and general characteristics are analagous to those of a military headquarters in a stabilized situation in the field. As in a military Command Post it has a message center equipped with all available means of communications to keep the commander informed as to enemy air attacks, present or probable, or other hostile threats, and as to air raid incidents; and to enable him to direct and coordinate the operations of the forces at his command in order to protect the people and facilities in his area. He has his staff, an operations map, and other normal aids to the efficient operation of a Command Post. j. Controller.—The civilian official, on the staff of the Commander of the Citizens Defense Corps, similar to a military Chief of Staff or an Executive Officer, in direct charge of operations at the Control Center (Command Post) to relieve the Commander for general supervision and important decisions. k. Incident officer.—Civilian Staff officer of the Commander of the Citizens Defense Corps, available to be sent from the Control Center as a liaison officer to the *See Office of Civilian Defense Pamphlets: “The Control System of the Citizens’ Defense Corps,” “Staff Manual, United States Citizens Defense Corps,” and “The United States Citizens Defense Corps.” 1 scene of an incident to keep the Commander informed and if the emergency so demands it, and the Commander so directs, to take charge. A number of incident officers should be available at any large Command Post. 1. Bomb reconnaissance agent.—Civilian staff official who has received special training in reconnaissance, reporting and safety measures. At incidents involving unexploded bombs, he is, in effect, the Incident Officer. m. Aerial bomb.—One designed to be dropped from the air, consisting of the following parts: (1) Body. (3) Filling. (2) Tail. (4) Fuze and its as- sociated exploder system. n. Delayed-action (or time) bomb-One whose exploder system functions at a predetermined time after fall. o. Unexploded bomb.—A bomb which does not explode because of mechanical failure or delayed action. p. Parachute mine.—Mine with light steel casing filled with high explosive. It is dropped by parachute to prevent penetration and to insure maximum blast effect. q. Unburied bomb.—Although the majority of unexploded bombs penetrate the ground, a few may be found on the surface. For the purposes of this pamphlet an “unburied” bomb is one which is on the surface or buried not more than 2 feet in the case of a 50-kg. bomb; 4 feet in case of 250-kg. bomb; 6 feet for a 500-kg. bomb. Depths refer to body of bomb and not to tail fins. T. Buried bomb.—One which penetrates the ground for distances greater than in q above. s. Tail fin.—Tail attached to bomb to steady it in flight. t. “Kopfring.steel ring, triangular in section, around the nose of a large German bomb. If fragments of this “Kopfring” are found in or near a small crater, they may indicate the presence of an unexploded bomb of 1,000-kg. or larger. u. Crater.—Excavation made in ground by the explosion of a bomb. v. False Crater.—Excavation made in ground by shock of impact, not due to explosion. w. Camouflet.—Underground cavity or pocket caused by the explosion of a bomb buried so deeply that the ground surface is little or not at all disturbed. x. Kilogram.—Metric measure of weight equivalent to 2.2 pounds; abbreviation— kg., thus a 50-kg. bomb weighs 110 pounds. 250-kg. bomb weighs 550 pounds. 500-kg. bomb weighs 1,100 pounds. 1,000-kg. bomb weighs 2,250 pounds. y. “UXB”.—British abbreviation for “unexploded bomb.” The British film for training civilians is titled “UXB.” 3. Responsibilities.— a. The Ordnance Department of the United States Army is responsible for: (1) The disposal of all unexploded and delayed action bombs. (2) Organizing suitable bomb disposal units within the department. (3) Schooling and training of military and civilian key personnel in bomb disposal. (4) Preparation of instructional material. (5) Assistance to and cooperation with the Office of Civilian Defense as indicated in c below. b. The Chemical Warfare Service is reponsi-ble for cooperation with the Ordnance Department in the training of military and civilian personnel in the identification and handling of chemical bombs. c. The Office of Civilian Defense, working through local and State Defense Councils, is responsible for the following measures in the continental United States, exclu 2 BOMB RECONNAISSANCE sive of military and naval reservations and theaters of operations: (1) The disposal of incendiary bombs. (2) Extinguishing of fires. (3) Bomb recognition, to include only the ability to distinguish between different types of bomb craters, parachute flares, or mines, etc. (4) Locating and reporting unexploded bombs for disposal by military personnel. (5) Application of safety precautions at the site of the unexploded bomb. (6) Selection of key personnel to cooperate with military personnel in discharge of responsibilities. d. The disposition, training, and operation of bomb disposal units and the training of civilian bomb reconnaissance agents are the responsibility of the appropriate military commanders. 4. Control»—Because of the extreme hazards connected with the disposal of unexploded bombs requiring the services of highly skilled and disciplined personnel and of the element of secrecy so essential to the safety and morale of this personnel, control of this function must remain exclusively with the military. This control extends also to the schooling and training of key civilian personnel, selected by the Office of Civilian Defense, in their duties as bomb reconnaissance agents. 5. Training of Civilian Personnel.— The training of key civilian personnel is the responsibility of defense commanders or of corps area commanders when the latter are assigned this duty, who will conduct such training courses as are necessary within the geographical limits of their respective commands. Necessary arrangements will be made with regional directors for selection of personnel to attend these courses and the schedules for these courses. Training will be conducted by bomb disposal officers, who will employ such means of instruction available to them, as this pamphlet, the training film “UXB” to be shown only when a bomb disposal officer is present, and film strips. It should be emphasized that the key civilian personnel include particularly bomb reconnaissance agents, who do not become members of the Army of the United States, and who do not participate in actual bomb removal. 6. Incendiary Bombs.—Instruction in the handling of small incendiary bombs is given at War Department Civilian Protection Schools conducted by the Chemical Warfare Service. The subject of incendiaries is covered in the Office of Civilian Defense pamphlet “Fire Protection in Civilian Defense” and will not be discussed in this pamphlet. Chapter II. Reporting 7. General.—There is a military interest in all objects dropped from the sky because they may provide valuable intelligence data. These include fallen planes, both enemy and friendly, unexploded shells, unexploded bombs, parachute mines and bombs. These objects should be reported by the public to air raid wardens who initiate reports to the proper authorities. For the purposes of this pamphlet, however, reporting only unexploded bombs will be considered in detail. BOMB RECONNAISSANCE 8. Discovery.—It is common practice with the enemy to include delayed action bombs among those dropped. A thud with no explosion may indicate the presence of a delayed action bomb. Considerable damage may be done by a bomb which strikes a building and does not explode. Roof tiles or shingles may be knocked off, walls or partitions cracked, glass broken and even floors brought down, but the characteristic effects of blast are absent. A hole in the ground, roughly circular in shape, and six or more inches in 3 466125°—42---2 Damage to brick-built garage due to the impact of a 1,000 kg. (2,200 lbs.) UXB. diameter, may also indicate an unexploded bomb. Other means of detecting their presence are covered in the training film “UXB.” Radio talks, local conferences and newspaper articles will assist in making the public “bomb conscious” and aware of the danger of unexploded or delayed action bombs. When any individual discovers an object which is suspected of being lethal or a hole which may have been made by an unexploded bomb he should report his discovery to the nearest air raid warden. Damage caused by 250 kg. (550 lbs.) UXB as it fell through a dwelling house. Damage caused by an unexploded 250 kg. (550 lbs.) bomb falling through a brick building. No shaft of entry is visible. 9, The Air Raid Warden •—The air raid warden whose duties keep him in contact with the general public, is the logical person to be responsible for the initial report of unexploded bombs. After receiving the report of an unexploded bomb from any source, he will proceed immediately to the site to make a personal reconnaissance. He completes the warden’s report and telephones the information on it or sends it by messenger to the control center. He also posts warning signs and takes other preliminary precautionary measures prior to the arrival of the police. IO. The Control Center,—a. When the warden’s report is received at the control center, the “In” message form is completed and given to the controller or the staff official in charge. A bomb reconnaissance agent is sent at once to the scene of the incident where he makes a personal reconnaissance. If he confirms that an unexploded bomb is present, he will then report to the controller or the official in charge of the control center, giving the location, main characteristics of the incident and the time it was first discovered. The controller will enter its location and time of fall on his list of unexploded bombs, giving a serial number. He will then contact the bomb disposal officer responsible for disposition of bombs in that locality, giving all available details, and arrange to guide him to the scene of the incident. He will also arrange for representatives of any public utilities affected by the operations to be present. b. After report to the control center, the bomb reconnaissance agent will then insure that proper precautionary measures are taken. He will decide whether it is necessary to have the police assigned to the incident, evacuate residents and workers from an area and to divert traffic. It may 4 BOMB RECONNAISSANCE REPORTING THE UXB BOMB RECONNAISSANCE 5 be necessary to close roads in or near the affected area. Roads or streets, which have been closed, may still have to be used by military and other vehicles engaged in work made necessary by the incident. Common sense should be exercised in applying evacuation rules. If houses have to be evacuated, particularly at night, the inhabitants should be allowed to take an adequate supply of clothing and other personal effects. He should remain at the scene of the incident to be available to and render assistance to the bomb disposal officer. c. Precautionary measures mentioned above are not necessary where anti-aircraft shells have fallen. These shells are dangerous but can be left undisturbed until an opportunity occurs for their removal by the bomb disposal unit. Unignited small incendiary bombs and small aircraft gun shells should be removed with extreme care to a place of safety to await disposition by the bomb disposal unit. 11. The Bomb Disposal Officer.— a. The bomb disposal officer will investigate the report of an unexploded bomb at the earliest opportunity and confirm or deny the report. He will inform the control center when a bomb has been found to be harmless, when he is about to deal with a bomb and when he has disposed of it. In order that information may be conveyed in a form which leaves no doubt of its authenticity, he furnishes certificates to the control center that a bomb is harmless or that it has been destroyed. He is the authority for classifying bombs in the order of their priority for disposal. He advises and assists the bomb reconnaissance agent to insure that proper precautionary measures are taken. b. The aforegoing reporting and reconnaissance procedure can be modified to meet local conditions. Chapter III: Reconnaissance Data 12. Ground Signs.—a. Bomb holes.— The size of hole made when a bomb enters the ground usually gives a good indication of the size of the Very small crater formed by the explosion of a 50 kg. (110 lbs.) bomb on the surface of a concrete road. bomb. The hole is normally roughly circular in shape, and some 2 inches or more larger than the bomb making it. For information on size and appearance of unexploded bombs, see “Unexploded Bombs, Part Two, Objects which may be dropped from the Air.” Holes under 6 inches in diameter are not usually made by bombs; if they are regular in shape, it can be assumed that they have been made by antiaircraft shells. In England it has been found that in case of German bombs : Holes between 8 inches and 12 inches indicate a 50-kg. bomb. Holes between 14 inches and 18 inches indicate a 250-kg. bomb. Holes between 18 inches and 26 inches indicate a 500-kg. bomb. Holes over 26 inches indicate a bomb of 1,000 kg. or more. 6 BOMB RECONNAISSANCE b. Craters.—Unexploded bombs of 1,000 kg. or larger may form a crater as big as 10 feet in diameter and 5 feet deep when they enter the ground. This is not due to explosion, but to the shock of impact. (See pl. No. 1.) Similar, but smaller, craters may be formed when bombs of smaller diameter wobble in flight or are deflected by hitting a building. In such cases the true size of the bomb can often be ascertained by scraping away the earth at the bottom of the crater to disclose the true hole of entry. Unless a bomb shaft is examined within 24 hours of the bomb falling, it will frequently be found that it has crumbled or broken away at the surface and has partially filled up. In built-up areas, debris from any buildings, etc., hit by the bomb in its fall, will often fill up the hole, making it impossible to determine the size of the bomb until the debris has been cleared away. c. Tail fins.—A reliable guide to the size of bomb is provided by the tail fin whenever it can be recovered in a reasonably unmutilated condition. (For sizes of tail see “Part Two, Objects which may be dropped from the air.”) Shaft of entry 250 kg. bomb through floor of building, after debris shown above had been cleared away. Hole of entry of 500 kg. (1,100 lbs.). German unexploded bomb, through hard earth. The bomb is 18 inches in diameter, and the hole is about 24 inches in width. “False Crater” caused by a 1,000 kg. (2,200 lbs.) unexploded bomb. BOMB RECONNAISSANCE 7 Pieces of the “Kopfring” from a large unexploded bomb found near the small crater made by the bomb as it hit the ground. Signs of explosion near a small bomb—breakage of windows, displacement of roof tiles, and splinter-marks on the wall of the house. 13. Penetration and Path of Bomb in Ground.—a. The depth to which bombs penetrate depends on: (1) The height from which dropped (up to about 17,000 feet, after which there is no added penetration). (2) To some extent on the weight of the bomb. (Heavier bombs go deeper.) (3) What the bomb hits before reaching the ground (i. e., ricochet off building). (4) The nature of the ground surface (concrete, etc., or soft ground). (5) The nature of the soil. (6) Shape of bomb. (7) Angle of impact. b. In the case of low-altitude and dive-bombing attack, bombs may not penetrate the ground at all, but may be found lying on the surface; or they may go into the ground, travel more or less horizontally, and either come to rest near the surface some distance away from the entry hole, or even come to the surface again. c. From high-altitude attack, penetration will usually be in ascending order in rock, gravel, compact sand, chalk, dry clay, wet sand, and wet clay. Typical penetrations are: In hard compact sand, 8 feet. In dry clay or chalk, 15 to 20 feet. In wet clay 25 feet or more. 8 The greatest depth so far recorded is 63 feet, which was reached by a 1,800-kg. bomb in clay. d. Statistics indicate that: 40 percent of unexploded bombs penetrate less than 15 feet. 40 percent of unexploded bombs penetrate between 14 and 20 feet. 15 percent of unexploded bombs penetrate between 20 and 25 feet. TYPICAL SHAFT OF ENTRY OF AN UNEYPLODED BOMB Signs of explosion—breaking of windows and debris thrown on the windowsill, roof, etc., of nearby buildings. 4 percent of unexploded bombs penetrate between 25 and 30 feet. 1 percent of unexploded bombs penetrate over 30 feet. e. The path of a buried bomb generally starts slanting slightly away from the vertical, and continues straight for some 6 to 12 feet. It then may swerve forward or sideways up to 10 feet or even more from a vertical line through the hole of entry, though the average is about 4 feet. A common case is shown in plate No. 2. f. The tail fins of the bomb are generally wrenched off during its passage through the earth. A probing rod, pushed down the hole will probably be stopped by the tail fins, and cannot, therefore, be relied on to give the depth of the bomb. 14. Indications of explosion.—In all cases the following are signs that a bomb has exploded: a. Formation of a definite crater. b. Presence of steel splinters in or around the place where the bomb falls. Large German bombs have a steel ring, triangular in section, around the nose. If fragments of this “Kopfring” are found in or near a small crater, they indicate the possible presence of an unexploded bomb of 1,000-kg. or larger. c. Extensive breakage of windows and other damage due to blast. d. Blackening of earth in bomb hole or crater. e. Characteristic smell of explosives. Effect of explosion—note broken windows, broken tiles on the roof, and outward bulging of the wall of the house. f. Smoke by day; a flash by night. If a bomb explodes after falling in a stream, the presence of dead fish points to explosion. 15. Detection of Camouflet.—a. A bomb which buries itself deeply in the ground before exploding may form an underground cavity or pocket called a camouflet when it explodes, but may leave few or no signs of surface disturbance, and little or no blackening of the hole. See Plate No. 3. If any of the following signs are noticed, however, they form an indication that the bomb has exploded and indicate the probable presence of a camouflet: (1) The formation of a mound near the hole of entry. (See pl. No. 3, fig. 1 and 2.) (2) Cracking or displacement of neighboring buildings, walls and trench linings. Persons in such buildings feel a violent shock. b. A small mound near or around the hole may be simply a displacement of surface earth caused when the bomb hit the ground. This is particularly true in soft or marshy areas and care should be taken to distinguish these from a true camouflet. c. Occasionally a bomb explodes so deeply in the ground that there is no indication whatever, on the surface, that an explosion has taken place. Such incidents will, of course, be diagnosed in the first place as unexploded bombs, and will be reported as such. Subsequent investigation by a Bomb Disposal Office will disclose a camouflet. BOMB RECONNAISSANCE 9 NOTE SL/GHT MOUND 1 SHALLOW CAMOUFLET /VOTE ABSENCE OF MOUND SI DEEPER CAMOUFLETS CAMOUFLETS f UNDERGROUND CAV/T! ES FOAMED BY EXPLODED BOMBS. THE CAV/T/ES ARE F/LLED WITH POISONOUS GASSES ) 3 DEEPEST TYPE PLATE No. 3 View, from below, of hole made through a concrete roof by a 50 kg. (110 lbs.) unexploded bomb. (Note the flaking-away of concrete on the under surface, and the girder sheared through by the bomb). Hole made by 250 kg. (550 lbs.) unexploded bomb through a concrete road. The hole is about 18 inches in diameter. IO BOMB RECONNAISSANCE 13. Bombs Falling on Hard Surface»—Bombs may penetrate concrete surfaces and reach a considerable depth before exploding. The concrete will be very slightly raised around the edges of the hole and cracked. An unexploded bomb hitting a concrete road may make a fairly clean hole with local cracking of the concrete. On the other hand a bomb exploding on contact with a concrete surface may produce a small crater (2 to 3 feet across) which may be mistaken for the entry hole of a larger unexploded bomb. This case can be distinguished by the presence of splinters in the crater and splinter and blast effects in surrounding buildings. 17» Bombs in Buildings»—Considerable damage may be done by a bomb which strikes a building and yet does not explode. A considerable number of roof tiles or shingles may be knocked off; walls and partitions cracked; glass broken and even floors brought down. In these cases, however, the characteristic effects of blast, and splinters are absent. Bombs which explode inside a building have the effect of bulging the walls outwards near the point of explosion, shattering internal partitions and glass and marking walls, etc., with splinters. In one or two storied houses, sheds and factories, a bomb may penetrate deeply into the ground under the building before exploding. In this case the visible effect may be as in the case of a camouflet, but explosion will be easily detected by the cracking of walls combined with the blackening of walls and ceilings. Chapter IV. Effect of Bomb Explosions 1S» British Experience»—All bombs of a given size, regardless of nationality, have a similar explosive effect. While the information contained in this chapter is based on British experience tables showing the results of German bombs, it would apply to the explosive effects of the same size bombs of any nationality. In applying this information for use in this country, some allowance should be made for the differences in American and British building construction. 19. Unburied Bombs»—The majority of unexploded bombs penetrate the ground, but a few may be found on or near the surface, which for the purposes of this pamphlet are called “unburied” bombs. When unburied bombs explode, the damage they may cause is largely due to blast and flying splinters which may be thrown several hundred yards. For all practical purposes the safety distance in the open can be put at 300 yards, but this distance can be much reduced when the bomb is screened, as in built-up areas. The following BOMB RECONNAISSANCE 466125°—42----<8 table shows the effect of explosion of unburied bombs on houses with 9 inch brick walls. Table I Bomb (kg) Completely demolished Houses damaged beyond repair Damaged but capable of repair Houses inhabitable but minor repairs needed Feet Feet Feet Feet 50 10 20 40 200 250 30 60 120 600 500 45 95 190 950 1,000 70 140 280 1,400 20» Buried Bombs»—When buried bombs explode, the splinter and blast effects vary with the depth below the surface, type of soil, and the size of the bomb. As the splinter and blast effects diminish, the underground shock effect tends to increase. Clods of earth, stones, pieces of concrete road, etc., may be flung into the air and thrown a considerable distance whenever any buried bomb explodes. Under normal conditions of firm, solid ground, nc serious splinters or blast effects may 11 be expected when bombs explode at the following depths: 50-kg. bomb buried more than 10 feet deep. 250-kg. bomb buried more than 15 feet deep. 500-kg. bomb buried more than 20 feet deep. In these cases the debris is likely to be thrown mainly upwards without spreading over a wide area. But where the ground contains boulders, or where bombs have penetrated below concrete roads, etc., large pieces of debris may be thrown out with a dangerous effect. The following table shows the effect of the explosion of buried bombs on houses with 9-inch brick walls. Table II , Houses com-Bomb (kg.) I pletely demolished Houses damaged beyond repair Houses damaged but capable of being repaired Feet Feet Feet 50 12 23 50 250 22 44 70 500 35 70 100 l,000___, 60 120 200 21. Underground Effects»—Earth shock, due to the explosion of a buried bomb, may cause damage to the foundations of buildings and to buried pipelines, cables and other utilities installed underground. Distances within which damage may be expected to occur are shown in Table III. 22. Craters»—The size of craters formed when buried bomb explodes varies with the depth of penetration and the nature of the soil. Average figures are: For a 50-kg. bomb—10 to 15 feet diameter. For a 250-kg. bomb—18 to 25 feet diameter. For a 500-kg. bomb— 25 to 30 feet diameter. Table III [Distances in feet beyond which damage will not be done] Bomb (kg.) Cast-iron main, concrete pipes Brick sewers, earthenware drains Electric cables, steel pipes 1 Foùndations and buildings Feet Feet Feet Feet 50 20 30 15 50 250 30 50 24 70 500 35 60 27 100 1,000 45 70 34 200 1 These data are believed to be for cable buried in earth. Under American draw-in practice the distances probably would be increased materially. b ^13^e"—F°r ground the above figures should be multiplied 23» Camouflets»—Camouflets constitute a danger as the ground above them may subside. Also, they are filled with poisonous gases (the most important of which is carbon monoxide) against which the service gas mask affords no protection. Cases have occurred where men digging for a supposed unexploded bomb have fallen into the camouflet and have been gassed. For this reason men probing or working over a suspected camouflet should always wear a life line and stand on a plank or ladder. In case a man falls into a camouflet and is gassed, immediate action must be taken. Only immediate resuscitation will save a life. When a camouflet is suspected or has been verified by a bomb disposal officer, it should be clearly marked and roped off until it can be filled in or made safe under bomb disposal unit supervision. Chapter V. Safety Precautions 24. Danger Period»—Most buried unexploded bombs may be left alone until bomb disposal experts consider them to be safe. The time bomb fuzes now in use may function at any time after the bomb falls until the danger period has passed. All buried unexploded bombs must be regarded as potential time bombs until the contrary has been proved. To avoid unnecessary risk to bomb dis posal personnel, disposal of a buried, bomb does not start until the danger period is past, unless its prior explosion at the site would produce disastrous results. Unburied bombs are given a higher priority than buried bombs as they constitute a more dangerous condition. Their disposal is undertaken as soon as possible after their discovery. 12 BOMB RECONNAISSANCE Effect of explosion of 250 kg, (550 lbs.) bomb in a row of houses—two houses have been completely destroyed, debris being flung outwards, whilst the adjoining houses are almost collapsing. 25. Priority Designation of Bombs.— a. It is essential that unexploded bombs be classified in the order for their removal, for reasons of safety and because bomb disposal personnel are not sufficient to dispose of large numbers of unexploded bombs at the same time. It is necessary to insure that risk to personnel treating a bomb within the danger period be incurred only under urgent circumstances. b. Categories will be assigned on the following basis: A—Those bombs, whose immediate removal is essential to the war effort. They are in or near important munitions plants and utilities and require immediate disposition to prevent possible explosion. B—Those bombs whose removal is urgent but less important than A. They are in densely populated residential districts and should be disposed of as soon as possible after the danger period to permit resumption of normal habits. C—Those bombs falling in fields or open spaces, where they may be disposed of at the convenience of the Bomb Disposal Unit or left indefinitely in the roped off area. c. The controller will designate the priority , for order in which removal is desired, of bombs in categories B and C. In the event that any interested agency feels that a particular bomb should Signs of explosion—note (a) crater in left foreground, (b) house partially demolished in center, (c) breakage and lifting of roof tiles and broken windows in house at right background. have a higher classification than category B, the bomb disposal officer should be so informed through the control center. The bomb disposal officer has full authority as to the removal of bombs in category A. 26. Police Responsibilities.—The police normally control the general public and are therefore responsible for public safety and the enforcement of safety precautions. As soon as the report of an unexploded bomb reaches the control center, the police official on duty there assigns policemen for duty at the site of the bomb. In addition to the preliminary precautions taken by the air raid warden, they will set up the necessary barriers to close streets and roads to ordinary traffic and pedestrians. They also handle the evacuation of persons living or at work in the danger zone. The extent of areas to be evacuated varies under different circumstances, which are described in following paragraphs. All evacuation distances should be increased by 50 percent where wooden buildings are involved. Common sense should prevail in the application of evacuation rules. 27. Evacuation Rules.—a. To insure the public safety against the effect of unexploded bombs with long delayed fuses, a system of evacuation for danger areas must be set up and enforced. The severe effects of safety precautions upon the normal life of the community require that extreme care be exercised in setting up and enforcing safety regulations. It is for this same reason that BOMB RECONNAISSANCE 13 the importance of preventing false reports is stressed. The training of the bomb reconnaissance agent must enable him to determine the extent of evacuation necessary to provide the maximum of public safety with a minimum public inconvenience. Size of bomb, location of bomb, types of building construction involved, and any incidental conditions influence the decision. The bomb disposal officer may recommend reduction of safety precautions upon the complete investigation of the accident. He may, however, recommend increased safety precautions when further investigation indicates they will be necessary. b. Where the bomb is unburied, the splinter and blast effects are more marked than in the case of buried bombs, and comparatively large clearance areas have to be evacuated when they are found. For this reason, a higher priority for , their disposal is given unburied bombs. However, unburied unexploded bombs are seldom found except as a result of low-altitude or dive-bombing attacks. The following precautions should be observed: (1) All buildings within 100 yards of the bomb should be cleared entirely, except for the indispensable personnel and noninterruptible activities such as public utilities. (2) In buildings between 100 and 200 yards from the bomb, all rooms facing the bomb should be cleared. (3) Traffic should not be allowed within 150 yards of the bomb. 29. Unexploded Parachute Mines.— Unexploded parachute mines are extremely sensitive to vibration. Their blast effect may break windows up to a distance of 2,000 yards. Experience in England has shown the following evacuation distances to be effective. a. All buildings, including industrial premises within 400 yards of the mine must be evacuated except where the parachute mine is screened by strong steel-framed concrete buildings the distance may be reduced to 300 yards, and except for the indispensable personnel and noninterruptible activities such as public utilities. b. All traffic, including pedestrians, bicycles and horse-drawn vehicles must be stopped by 14 Hole of entry of a large unexploded antiaircraft shell. Approximately 8 inches in diameter. physical barrier at not less than 400 yards from the mine. If the mine is screened- as indicated in a above, this distance may also be reduced to 300 yards. This rule applies also to rail traffic and to military vehicles. c. All doors and windows within 800 yards should be kept wide open with proper blackout provisions in evacuated buildings. d. All the above restrictions should remain in force until the mine has been made safe. 29. Safety Precautions for Railroad Traffic Near Unexploded Bombs.—a. It is vitally important that railroad traffic be hindered as little as possible. . All unexploded bombs within 100 yards of a railroad (including subways) will be reported by railroad officials direct to the Control Center or by wardens through the usual channels. The following information should be given wherever possible: (1) Exact location, including distance from track. (2) Diameter of hole of entry. (3) Any other particulars, i. e., type of attack (high or low altitude), nature of soil, whether on embankment or cut, or near bridges. A bomb disposal officer will reconnoiter all bombs affecting railroads as soon as possible, and will then advise as to the precautions to be taken. b. Pending the arrival of the bomb disposal officer, the following restrictions on rail traffic will be applied. It must be remembered that in built-up areas, although the risk to the railroad BOMB RECONNAISSANCE Hole of entry of 250 kg. (550 lbs.) German unexploded bomb. The bomb is 14)^ inches in diameter, and the hole is approximately 18 inches across. may be small, the risk to important buildings or houses near the railroad may be great. Railroad officials should consult the control center on the application of safety precautions. (1) 50-kg. bombs.—Where the diameter of the hole of entry is less than 1 foot, it can be assumed that it has been caused by a 50-kg. bomb or an antiaircraft shell. All traffic may proceed normally unless the hole of entry is on the track. In this case traffic should proceed at reduced speed until the track has been examined by a railroad official, as there is the possibility that an underground cavity has been formed. (2) 250-kg. or larger bombs. (a) If the bomb is not visible and the hole of entry is 1 foot or more in diameter, all traffic may pass at 5 miles per hour at distances between 30 and 70 yards from the bomb; at more than 70 yards from the bomb, no speed restrictions are necessary. (b) If any part of the bomb is visible, passenger traffic may not pass within 200 yards of the bomb unless it is screened. If the bomb is .screened, passenger traffic may pass at 5 miles per hour at not less than 50 yards from the bomb. Commercial traffic may pass at 5 miles per hour at distances between 30 and 70 yards from the bomb whether it is screened or not; beyond 70 yards from the bomb, no speed restrictions are necessary. c. Where there is important traffic to be taken along the line and the Bomb Disposal Officer cannot make his reconnaissance for some hours, railroad authorities may authorize traffic to run nearer to the bomb than laid down in paragraph b, subject to the following precautions: (1) Trains must run at not to exceed 5 miles per hour. (2) An attempt should be made to screen the bomb by placing cars on the track nearest to the bomb or by some other method, but this should only be done where the cars or other screening material can be placed not less than 10 yards from the hole of entry. Where-ever possible, the running track next to that on which the screening cars are placed should not be used. (3) Traffic should not be allowed to run in these circumstances until the bomb disposal officer has been notified. It must be remembered that there is a definite risk of severe damage to a train if it is run within 10 yards of a buried unexploded bomb larger than 50 kg. d. There may be cases requiring special handling which differ from the general rules indicated above. For instance: (1) If the bomb is within 15 yards of the pier or abutment of a bridge, a tunnel, or retaining wall, or it endangers the slope of a deep cut, no train must run within 30 yards of any part of such structure or cut without the authority of a railroad official and then only at a speed not exceeding 5 miles per hour. (2) When a reconnaissance has been made by a bomb disposal officer, the foregoing instructions may be modified after consultation with railroad officials and other authorities concerned. It may be necessary to impose special restrictions when disposal of the bomb is in progress. (3) No railroad traffic should be run within 400 yards of an unexploded parachute mine except where the mine is screened by a strong steel framed concrete building, in which case the distance may be reduced to 300 yards. BOMB RECONNAISSANCE 15 Chapter VI. Protective Works to Reduce Bomb Damage 30. General.—a. PROTECTIVE WORKS TO REDUCE BOMB DAMAGE SHOULD BE UNDERTAKEN ONLY BY TRAINED PERSONNEL AND IN VIEW OF THE POSSIBILITY OF THE BOMB EXPLODING WHILE WORK IS IN PROGRESS, ONLY PROTECTIVE WORK SHOULD BE UNDERTAKEN. IT IS MOST IMPORTANT THAT ANY WORK CARRIED OUT BY PERSONNEL OTHER THAN BOMB DISPOSAL UNITS SHOULD NOT HINDER THE ULTIMATE DISPOSAL OF THE BOMB. (1) IN CASE OF “CATEGORY A” BOMBS. (2) WHEN THERE IS NO REGULAR BOMB DISPOSAL UNIT IMMEDIATELY AVAILABLE. (3) WHEN THE WORK IS NECESSARY TO PROTECT SOME SPECIFIC AND VITAL OBJECT. b. Unexploded bombs may fall where their explosion would cause great damage to military installations, munitions plants, important utilities, or other vital installations. Such bombs cannot always be dealt with at once by bomb disposal units, but certain prompt precautionary measures can be taken by trained civilian personnel immediately after the bomb falls, to minimize the damage should explosion take place. These measures consist of : (1) Protective trenching to minimize damage from earth shock to structures and utilities. (2) Packing basements with sandbags to resist earth shock and prevent collapse. (Note.—Protective sandbagging requires large numbers of sandbags. It is wasteful to keep many sand bags ready filled owing to their tendency to rot, but about 3,000 per control center might well be kept ready under cover and others filled as required.) (3) Sandbagging walls to protect against blast and splinters. c. Estimating the depth of the bomb should be done only by trained and experienced personnel as soon as possible after the bomb is discovered and before the hole of entry has caved in. If the hole has caved in, it should be possible to determine whether the depth is over or under 10 feet by probing with flexible rods. 31. Protective trenches,—Table No. Ill shows the distances within which sewers, pipe lines, cables, building foundations and walls are liable to damage from explosion of a buried bomb. If a buried bomb is within these distances from an important vulnerable object, damage caused by possible explosion can be minimized by digging a trench between it and the bomb about 2 feet wide and 2 feet deeper than the object to be protected 16 BOMB RECONNAISSANCE Protection of foundations of a building against explosion by packing sandbags against the nearest weight-sup-porting wall of the building. Protection of building against blast from a buried bomb by building a sandbag wall just outside the crater which will result if the bomb explodes. and as close to it as possible without danger of undermining the protected object due to earth disturbances if and when explosion takes place. Thus a pipe buried 4 feet below the surface of the ground and 30 feet from a 250-kg. bomb buried to a depth of 15 feet, would be protected by a trench 6 feet deep dug close to the pipe between it and the bomb. Such trenches need only be of the minimum width required for excavation. Owing to the size of the crater made by explosion of the bomb, no protection could be given by a trench within 10 feet of a 50-kg. bomb; 20 feet of a 250-kg. bomb, and 30 feet of a 500-kg. bomb. 32. Sandbag Abutments.—Basements and cellars may be packed with sandbags to avoid damage to foundations and walls in cases where the bomb is so near the buildings or the foundations are so deep that the depth of a protective trench would be prohibitive. The method consists of packing sandbags into the internal space against the outer wall to support it against the force of the explosion. It is not possible to lay down the depth to which the sandbags behind the wall should extend, but generally speaking, the tighter they are packed, and the deeper the pile, the more effective the support will be. In practice a depth of 10 \ METHOD OF PROTECTING UNDERGROUND PIPES BY MEANS OFA TRENCH BOMB RECONNAISSANCE 17 feet will probably be effective, but the sandbags should not extend as far as an internal weightcarrying wall as the latter might be damaged by thrust due to explosion. The method of minimizing damage to foundations as given in paragraph 31, “Protective trenches,” can be combined with the sandbag abutment treatment to good advantage, where conditions permit. 33. Sandbag Walls.—a. Sandbag walls may be built to minimize damage from splinters, debris and blasts where a bomb, buried or unburied, is close to a building. Sandbag walls also may be used to isolate the effects of a bomb inside a building, The basic principle is that the sandbag wall must be built just outside the crater which will be formed if the buried bomb explodes. For practical purposes suitable radii from the hole of entry are shown in table IV: Table IV 10 feet from a 50-kg. bomb 1 These figures make an allowance for the 20 feet from a 250-kg. bomb!- fact that the path of a bomb in earth is 20 feet from a 500-kg. bomb) not usually straight. b. The circumstances in which it is desirable to build a sandbag wall are as follows: 18 (1) Bombs falling in open ground usually penetrate at least to the depth shown in table V. In such cases there are no serious splinter effects, and there should be no danger due to falling debris outside the area given in table V. The local effect of blast may still be very serious, and the blast can be deflected upward by a sandbag wall built outside the crater area (table V): Table V Size of bomb (kg.) Depth or penetration Area to which dangerous debris confined Feet 50 10 Circle 30-foot radius from bomb. 250 15 Circle 50-foot radius from bomb. 500 20 Circle 7S-foot radius from bomb. (2) At distances greater than those shown for foundations in table III, little or no structural damage to buildings is to be expected from a buried bomb. In the case of an unburied bomb, damage can be limited to windows and roof if a sandbag wall is provided. BOMB RECONNAISSANCE c. The following points should be noted in the construction of sandbag walls: (1) Wall should invariably be 2 feet 6 inches thick at the top and preferably 10 feet high. Open faces should be sloped at % requiring a base wider than the top, say 4 feet 2 inches. (2) Walls must not be built nearer to the bomb than the distances shown in table V. 34. Sandbag Mounds.—a. General.—If bombs bury themselves deep enough an explosion may form an underground cavity or camouflet but no crater. In the case of bombs buried less deeply which would otherwise form a. crater on exploding, the addition of a mound of sand or earth over the crater area will produce the same camouflet effect. The “sandbag mounds” method aims at driving the explosion underground. It has the effect of increasing possible damage to utilities, foundations, and walls, but in situations where the added earth shock can be accepted, this method may prove useful. This method is applicable both to neutralize the above ground effect of buried bombs and to mask splinters from “unburied” bombs. b. Buried bombs.—The weight of sand or number of filled sandbags required to neutralize entirely a bomb buried 10 feet is shown in table VI. Table VI Bomb (kg.) Soil Weight Number of sandbags Arranged in cones 50 Clay 1 40 tons 1,600 20 feet diameter. 6 feet high. 50 Sand 60 tons 2,400 24 feet diameter. 6 feet high. 250 Clay. - - _ _ 125 tons 5,000 40 feet diameter. 6 feet high. 500 . 270 tons 1 - _ 10,800 1 Prohibitive. Smaller amounts than the above will reduce the damage but less than two-thirds of the amounts shown in the table are not worth the labor entailed. It can be assumed that if the bomb falls in open ground or through a hard floor not exceeding 6 inches thick, the bomb will be at least 10 feet deep and possibly more. If the bomb is deeper than 10 feet, the weight of covering required to eliminate dangerous splinters is shown in table VII. Table VII Bomb (kg.) Soil Weight Number of sandbags Arranged in cones 50 Clay Tons 40 1,600 (20 feet diameter 50 Sand 40 1,600 / 6 feet high. 250 Clay 90 3,600 140 feet diameter 250 Sand 90 3,600 / up to 6 feet high. 35. Vents.—Recent experiments shows that when a shaft is excavated to gain access to a bomb, and the bomb explodes at the bottom of the shaft, there is appreciably less earth movement than if the same bomb had exploded before the excavation was made. Furthermore, a smaller crater would result. On the other hand, damage by blast will probably be greater where a shaft has been excavated. In cases where it is vitally important to diminish earth shock and movement, (i. e., railway lines, bridges, dams, lock-gates, important gas and water mains and foundations) and where the effect of blast would not be serious, it is advantageous to excavate an 8 foot by 4 foot shaft down to the bomb at once. In some cases it may also be an advantage to direct the force of explosion away from the structure it is desired to protect. This can be done by excavating a trench, above the bomb, about 12 feet by 4 feet, as shown in Figure 2, Plate VI. If the bomb then explodes before it can be dealt with by a bomb disposal unit, the minimum damage will be done to the structure. In deciding to use the methods described in this paragraph, the damage likely to be done by blast, chiefly to windows and roofs, must be balanced against that likely to be done to foundations and walls. BOMB RECONNAISSANCE 1» Chapter 1. Objects Which May Be Dropped From the Air Part Two 1, Introduction. a. Unfamiliar objects.—Many unfamiliar objects will be found after an air raid. Some are perfectly harmless and can be removed at once. On the other hand some of the objects will be highly dangerous and must on no account be moved by any untrained personnel but must be left for disposal by army bomb disposal units. Moreover, certain objects may not only be dangerous to move, but may explode even though they are not interfered with in any way as, in the case of time bombs where it will be necessary to evacuate people from the danger area around the missile and to take other safety precautions to prevent casualties should an explosion occur. b. Harmless objects.—Some harmless objects bear a superficial resemblance to dangerous missiles. c. Purpose of training.—It is therefore essential that every Bomb Reconnaissance Agent be able to distinguish between harmless objects and those missiles which are dangerous so that necessary evacuation and safety measures may be initiated at once if necessary or that unnecessary interference with the public may be avoided if the object is harmless. d. Buried UXB.—Most unexploded high-explosive bombs will bury themsleves in the ground when they fall and will not be visible. However, they will make a hole in the ground which will show their location and give an indication of their size. e. Bombs on hard surfaces.—Unexploded bombs which strike a building or a very hard surface, or are dropped from a low altitude, may be found lying on the surface or partly buried by debris. These bombs may be recognized from the dimensions and descriptions given later in this handbook. f. Bomb fittings.—Even when the bomb is buried and not visible, pieces of the tail or other fittings from the bomb may be found lying on or near the surface nearby, or in the shaft which the bomb made in the ground, and these may give a clue to the size and type of the bomb. g. Time bombs.—Many unexploded bombs will probably be those which failed to function mechanically but a proportion will be time bombs. All are extremely dangerous to handle or move and can only be dealt, with by trained army bomb disposal personnel with special equipment. It therefore follows that ALL unexploded high-explosive bombs must be regarded as time bombs whether they are visible or are buried, regardless of their size or appearance. h. Notes.—The following notes will assist the Bomb Reconnaissance Agent to distinguish between various objects which may be found; DANGEROUS MISSILES FOR WHICH EVACUATION AND SAFETY MEASURES ARE NECESSARY 2. Unexploded High-explosive Bombs. a. General.—The bomb consists essentially of a body, made normally of steel, holding the explosive charge. Inserted in the body are one or more fuze pockets in which the fuze or fuzes are located. The fuze pockets may be in the side of the bomb, as in the German high-explosive bomb, or in either or both the nose or tail of bombs of other nationalities. The nose of the bomb is normally much thicker than the rest of the body to prevent the bomb, breaking up when it penetrates its target. In some part of the bomb a screwed filling plug is provided, usually found in the tail end of the bomb. The bomb is held in the airplane by a suspension 20 BOMB RECONNAISSANCE lug or eyebolt which may be fitted in the nose of the bomb, when vertical suspension is used, or in the side of the bomb, at the center of gravity, when held horizontally. Some bombs are fitted with both nose and side suspension lugs or eye bolts; others may be fitted with two suspension lugs or eyebolts on the side. Attached to the rear end of the bomb is a tail, which usually consists of a cone to which four fins are fixed. The tail ensures the true flight of the bomb through the air. It is usually made of sheet steel, and almost always the tail tears off when the bomb strikes its target. Certain German bombs have a tail made of cast magnesium alloy. When a bomb tail is found, it will usually be badly crumpled and distorted, or may be broken into pieces.’ The larger German general-purpose bombs have an unusual steel ring, “Kopfring,” welded to the nose to reduce penetration of the bomb. Pieces of the “Kopfring” are frequently found lying near the place where a large German unexploded bomb entered the ground, and, of course, give a valuable clue to the size of the bomb. The “Kopfring” is triangular in section. There are three types of high-explosive bombs: b. General-purpose bombs.—These have relatively thin walls, and a large explosive charge. Time-bomb fuzes are most likely to be found in this type of bomb. The bomb may break up if it strikes a building or hard surface. The tail or other fitting of the bomb may be found nearby, giving an indication of the size of bomb, if the bomb itself is not visible. The German designation for general-purpose bombs is S. C., and is usually found painted on the body. In German, S. C. means “Spreng Cylindrisch,” or freely translated means steel, thin-walled, high-explosive bomb. Details of general-purpose bombs are given in Chapters II, III, and IV of this publication. c. Armor-piercing bombs.—These have thick walls and are of a more substantial construction than the general-purpose bombs. Even though the bomb hits a building or hard target it will not break up. If the bomb is not visible, the tail may be found nearby or in the hole which the bomb made. On the body of German armor-piercing bombs, the two letters S. D. will usually be found. S. D. in German is “Spreng Dickenwand,” or freely translated means steel,-thick-walled, high-explosive bomb. Full details of bombs of this type are given in Chapters II, III, and IV of this publication. d. Antipersonnel bombs.—They are usually smaller than other types of high-explosive bombs, and may be of curious shape. They are usually dropped in large numbers, and although not normally fitted with a time-bomb fuze, unexploded antipersonnel bombs are usually very sensitive and liable to explode if disturbed. Full details of enemy antipersonnel bombs are given in Chapters II, III, and IV of this publication. Although there is no need to evacuate an area around unexploded antipersonnel bombs, the bomb must be roped off or protected in some way until it can be dealt with by army bomb-disposal personnel. On no account must the bomb be moved or interfered with in any way. 3. Unexploded Parachute Mines. Unexploded mines are potentially dangerous because they are sensitive to vibration and cause great destruction if they explode. The mine will usually be found lying on or near the surface, and can be recognized at once by its parachute attachment. On no account must unexploded mines be approached or vibrated, but evacuation measures must be at once initiated. A German parachute mine is shown in Chapter II of this publication. MISSILES FOR WHICH EVACUATION AND SAFETY MEASURES ARE NOT NECESSARY 4. Incendiary Bombs» Many types of incendiary bombs are at present in use by the enemy, varying from small incendiary leaves to large oil bombs containing many gallons of inflammable liquid. The type most commonly used consists of a small magnesium bomb filled with a priming composition. These combustible-case bombs are used in large numbers, and burn with great fierceness. BOMB RECONNAISSANCE 21 Incendiary bombs may be found after an air raid, either unburned or partly burned. Full details of the appearance of these bombs are given in Chapters II, III, and IV of this publication. Although no evacuation is required for unburned incendiary bombs, it should be remembered that the bomb may have a small explosive charge, or may be coated with phosphorus, which will cause serious burns if touched. The bombs should be carried carefully to some safe place where they can remain until collected by an army bomb disposal unit. 5, Flares, Partly burned or unburned parachute flares may be found after a night raid. They should be handed over to the army bomb disposal unit for destruction. Although not dangerous to handle, care should be taken not to pull any cords or wires which may be attached to the flare as certain types have a pull-match igniter system. Details of flares are given in Chapters II and III of this publication. It is important that the warden should be able to distinguish between the parachute mine, which is dangerous and for which evacuation must be carried out, and the parachute flare which can be removed at once without any clearance of a danger area. 6, Airplane Cannon Shells, After any aerial engagement, numerous unexploded airplane cannon shells may be found. These contain a small but powerful explosive charge and a fuze which may be in a sensitive condition, When they are collected, they should be kept in a horizontal position in a box packed with sawdust or cotton wool (not more than 3 in a box) and handed over to a bomb disposal unit for destruction. The unexploded airplane cannon shell must always be handled with the greatest care. For details of airplane cannon shells see Chapter V of this publication. 7, Antiaircraft Shells, Unexploded antiaircraft shells may be found lying on the surface; dr small holes, less than 6 inches in diameter, may be found in the ground where a shell penetrated. A shell can always be distinguished from a bomb by the driving band which shows the marks made by the rifling of the barrel of the gun. No evacuation or other precautions are necessary, but the shell must not be interfered with until it is collected by the army bomb disposal unit. (See Chapter VI of this publication for details of American antiaircraft shells.) S. Miscellaneous Objects, After every air raid a number of completely harmless objects are likely to be found. These will include: Incendiary bomb containers. Auxiliary gasoline tanks. Airplane parts. Parachute mine caps. Flare cases. All the above objects, described in section 6, should be collected and handed over to the army bomb disposal unit for inspection and disposal. 22 BOMB RECONNAISSANCE Chapter II. German Bombs I. 2 Kg. Antipersonnel “Butterfly” Bomb. II. 1 Kg. Incendiary Bomb. II—A. 1 Kg. Incendiary Bomb Nose. III. 4 Candle Parachute Flare. IV. Flash Bomb. V. 110 Kg. “C 250 Flam” Incendiary Bomb. VI. Type “D” and “C” Parachute Mine. VII. 50 Kg. General-purpose High-explosive Bomb. VIII. 250 Kg. General-purpose High-explosive Bomb. IX. 500 Kg. General-purpose High-explosive Bomb. X. 1000 Kg. General-purpose High-explosive Bomb. XI. 1800 Kg. General-purpose High-explosive Bomb. XII. 50 Kg. Semi-armor-piercing High-explosive Bomb. XIII. 250 Kg. Semi-armor-piercing High-explosive Bomb. XIV. 500 Kg. Semi-armor-piercing High-explosive Bomb. XV. 1000 Kg. Semi-armor-piercing High-explosive Bomb. XVI. 1400 Kg. Semi-armor-piercing High-explosive Bomb. HA / O \ / 36 ; o V A PROPORTION OF THE GERMAN 1 KILOGRAM INCENDIARY BCMBS CONTAIN A SMALL EXPLOSIVE CHARGE LOCATED UNDER THE TAIL AT THE REAR END OF THE BOMB (shown in the sketch as dotted line). BOMBS ■WITH THIS EXPLODER CHARGE MAY HAVE A RED LETTER "A" ON THE NOSE OF THE BOMB AS SHOWN IN THE ABOVE DRAWING. 2 KG- ANTI-PERSONNEL 1 KG. INCENDIARY ••BUTTERFLY" BOMB BOMB BOMB RECONNAISSANCE 23 24 BOMB RECONNAISSANCE BOMB RECONNAISSANCE 25 26 BOMB RECONNAISSANCE Chapter III. Japanese Bombs I. 15 Kg. Antipersonnel Bomb. II. 50 Kg. Incendiary Bomb. III. 50 Kg. Gas Bomb. IV. 33 Kg. Parachute Illuminating Flare. V. 50 Kg. General-purpose High-explosive Bomb. VI. 60 Kg. General-purpose High-explosive Bomb. VII. 100 Kg. General-purpose High-explosive Bomb. VIII. 250 Kg. General-purpose High-explosive Bomb. IX. 250 Kg. Semi-armor-piercing High-explosive Bomb. X. 800 Kg. Armor-piercing High-explosive Bomb. WEIGHT OVERALL LENGTH LENGTH OF BODY DIAMETER OF BODY POSITION OF FUZE 15 Kg 25.2” 14.3" 4 " Nose 50 Kg. 50 Kg. 33 Kg. 40" 45 " 27 " 22" 26.4" — 7" 7.5" 6.1* Nose Nose Nose BOMB RECONNAISSANCE T7 28 BOMB RECONNAISSANCE Chapter IV. Italian Bombs I. 800 Kg. General-purpose High-explosive Bomb. II. 500 Kg. General-purpose High-explosive Bomb. III. 500 Kg. Delayed-action High-explosive Bomb. IV. 250 Kg. General-purpose High-explosive Bomb. V. 160 Kg. Antisubmarine High-explosive Bomb. VI. 104 Kg. General-purpose High-explosive Bomb. VII. 100 Kg. Semi-armor-piercing High-explosive Bomb. VIII. 100 Kg. General-purpose High-explosive Bomb. IX. 100 Kg. Practice Bomb. X. 70 Kg. Incendiary Piercing Bomb. XI. 70 Kg. Spherical High-explosive Bomb. XII. 50 Kg. General-purpose High-explosive Bomb. XIII. 40 Kg. General-purpose High-explosive Bomb. XIV. 31 Kg. Semi-armor-piercing High-explosive Bomb. XV. 24 Kg. General-purpose High-explosive Bomb. XVI. 20 Kg. Incendiary Bomb. XVII. 20 Kg. Antipersonnel High-explosive Bomb. XVIII. 15 • Kg. Semi-armor-piercing High-explosive Bomb. XIX. 12 ! Kg. Bomb. Antipersonnel High-explosive XX. 12 ! Kg. Bomb. Antipersonnel High-explosive XXI. 3 Kg. Bomb. Antipersonnel High-explosive XXII. 3 Kg. Bomb. Antipersonnel High-explosive XXIII. 2 Kg. Bomb. Antipersonnel High-explosive XXIV. 1 Kg. Incendiary Bomb. BOMB RECONNAISSANCE 29 ITALIAN BOMBS^ 30 BOMB RECONNAISSANCE F/gÆ. ITALIAN BOMBS. BOMB RECONNAISSANCE 31 Chapter V. American Airplane-Cannon Shells I. 40 MM. II. 37 MM. III. 20 MM. IV. 50 Caliber. V. 30 Caliber. NOTE.—These are American airplane-cannon shells which will be found after an aerial battle along with enemy shells similar in design. The fuzes found in these shells are clearly shown in the 40 MM., 37 MM., and 20 MM. shells. 40 MM. 37MM. 20MM. 50 30 T tt CALIBER i he _ HE Jt. 32 BOMB RECONNAISSANCE Chapter VI. Anti-aircraft Shells I. 105 MM. II. 90 MM. III. 3 Inch. IV. 40 MM. V. 37 MM. VI. 20 MM. NOTE.—These are American anti-aircraft shells fired by our own antiaircraft batteries and will be found after air raids. The driving or rotating bands are clearly shown at the base of the shells. The sensitive fuze may be seen in the nose of each of the shells. 105 MM. 90MM. 3 INCH 40 37 20 I X nr n BOMB RECONNAISSANCE 33 Chapter VII. Miscellaneous Objects As described in paragraph 8 of the introduction to Part II, certain miscellaneous objects will be dropped. To guide the Bomb Reconnaissance Warden in his reconnaissance, the following specific items are listed. These are German objects but the other axis powers can be expected to drop similar objects, and the Germans themselves will develop and use new models from time to time. Figure No. 1.—Incendiary Bomb Container.— A vertical rod, 43 inches long, with a lug at the top end; it carried three trays with felt pads, on which the incendiary bombs are stacked vertically around the rod. FIGURE NO. 2 Figure No. 2.—Incendiary Bomb Container.— It is composed of three side pieces, which, together, form the cylinder illustrated. A clockwork release mechanism is carried on the side near one end of the case. Figure No. 3.—Incendiary Bomb Container.— A cylinder of two side pieces, with the bottom plate hinged in the middle. Figure No. 4.—Incendiary Bomb Container.— This is a rectangular metal canister with the vertical edges rounded, about 12 by 10 by 6 inches to carry 15 of the 1 Kg. Incendiary Bombs stacked on end as indicated by the circular marks in figure No. 4A. Figure No. 5.—Auxiliary Gasoline Tank.— An auxiliary plywood gasoline tank sometimes jettisoned by enemy aircraft is shown in figure No. 5. Figure No. 6.—Parachute Flares.—Parachute FIGURE NO. 3 FIGURE NO. 4 FIGURE NO. 4A 34 BOMB RECONNAISSANCE flares are of two main types: One has a single candle; the other has four candles. The complete unit usually consists of a cylindrical aluminum casing which contains the parachute, detonator, and the candle or candles. When found, some or all of the candles are likely to be burned down to a short stump, and will be attached to the housing of the detonator unit (an aluminum pressing resembling a saucepan (see fig. No. 6A)). AUXILIARY GASOLINE TANK • Estimated capacity 200 gallons Built up of plywood and glued Fitted to release gear for jettisoning B Vent C&E Circular cross member D Heavy circular cross member and baffle plate F Four steadying rods with ball joint heads G Attachment lug for release H Stay Not to scale- FIGURE NO. 5 U. S. GOVERNMENT PRINTING OFFICE: 1942 BOMB RECONNAISSANCE 35