US AAC/AAF Doctrine: FM 1-10, Air Attack, 1940 - 2. Bombardment Aviation

CHAPTER 2: BOMBARDMENT AVIATION

SECTION I GENERAL

14. ORGANIZATION.-The basic element of organization in bombardment aviation is the individual airplane and its combat crew. The flight is a tactical grouping or unit consisting, according to type, of three or more airplanes. The squadron consists of two or more flights; the group of two or more squadrons; and a wing of two or more groups.

15. BASIC TACTICAL UNIT.-The squadron is the basic administrative and tactical unit. The group is the largest unit which can function as a single combat command under the direct control of an individual and is the normal unit of tactical employment of an air force. The group contains all of the elements essential for operation, maneuver, and combat. Squadron tactics fit into the group scheme of employment and also permit each squadron to function as a separate combat command under circumstances suited to such employment. When a mission requires that two or more groups operate in conjunction, each group functions as a separate combat command, one group conforming to the action of the other throughout the operation.

16. CLASSIFICATION.-Bombardment aviation utilizes air-craft of different sizes and capabilities which include different offensive armament load and operating radius. Bombardment squadrons are classified, according to the kind of aircraft with which they are equipped, as heavy, medium, and light.

17. EMPLOYMENT OF HEAVY AND MEDIUM BOMBARDMENT.-The striking forces of GHQ aviation consist of units of heavy and medium bombardment aviation. Such units are capable of destroying the most massive bombardment objectives. Heavy and medium bombardment aircraft can carry the heaviest types of bombardment munitions to great distances. Heavy bombers are long range aircraft. Medium bombers have intermediate ranges. Neither of these types is fully suited to the performance of minimum altitude attacks since neither is equipped to deliver all types of fire appropriate to such attacks.

18. EMPLOYMENT OF LIGHT BOMBARDMENT.-In general, light bombardment aircraft are smaller, more maneuverable, and have a shorter operating radius than heavy and medium bombers. The striking units of support forces usually consist of light bombardment aviation. The aircraft of light bombardment units are designed and equipped to enable them to perform minimum altitude missions when required. They usually are not capable of carrying the largest size bombs.

SECTION II: OFFENSIVE ARMAMENT

19. CLASSES.-The offensive armament of bombardment aviation is divided into the following classes:

a. Demolition bombs.

b. Fragmentation bombs.

c. Incendiary bombs.

d. Chemical bombs.

e. Chemicals for spraying.

f. Machine guns, and other larger caliber guns.

g. Torpedoes.

20. DEMOLITION BOMBS.-The demolition bomb, designed for the destruction of material objectives, is the principal destructive agent of bombardment aviation. These bombs are made in a variety of sizes suitable for the destruction of various kinds of objectives. The standard sizes of demolition bombs at the present time are as follows:

DEMOLITION BOMBS

* Limited standard.

21. BOMB FUZES.-Standard demolition bombs are fuzed with both nose and tail fuzes. Bomb fuzes are of two general types, instantaneous and delayed action. The instantaneous type explodes the bomb immediately upon impact. The delay fuze permits penetration of the objective by the bomb prior to detonation. The arming mechanism of the bomb rack permits the dropping of bombs either armed or "safe." Demolition bombs can be dropped "safe" in an emergency from altitudes below 4,000 feet without detonation upon impact even upon hard surfaces. Bombs dropped "safe" from very high altitudes will detonate upon impact on a solid surface.

22. FRAGMENTATION BOMBS.-Fragmentation bombs are designed to break into fragments, each of which is effective against personnel or light materiel. This type of bomb has some demolition action in the immediate vicinity at the instant of explosion, but its effectiveness arises principally from the fragmentation action. Fragmentation bombs are of small size, weighing up to 30 pounds complete, depending upon the model of the bomb. Standard fragmentation bombs used by bombardment aviation are fitted with nose fuzes of the instantaneous type.

23. TYPES or FRAGMENTATION BOMBS.-There are two general types of fragmentation bombs, fin stabilized and parachute bombs. The fin stabilized type is similar to the demolition bomb in general conformation. Fin stabilized fragmentation bombs, in order to avoid damage to the airplane from which they are dropped and to minimize the loss in fragmentation effect occasioned by the angularity of the bomb axis at the instant of explosion, should be dropped from an altitude of 800 feet or more, depending upon the ground speed of the airplane. The parachute type bomb is fitted with a parachute in a light weight case in lieu of the fin assembly. The parachute quickly changes the attitude of the bomb so that its axis is substantially vertical as it approaches and strikes the ground. The parachute slows down both the forward motion and the descent of the bomb. These bombs may be released at a minimum altitude of 65 feet.

24. INCENDIARY BOMBS.-Incendiary bombs are employed to set fire to buildings, grain fields, tented areas, dry wooded areas, and similar combustible materiel.

25. CHEMICAL BOMBS.-Chemical bombs are employed for the placement of chemical agents within a specific area of limited extent. They are designed to be carried and released in the same manner as demolition or fragmentation bombs. A 30-pound chemical bomb is now standard, and one weighing about 100 pounds is under development. The cases of chemical bombs are of light weight, and an explosive charge is utilized to effect better distribution of the chemicals than would otherwise be attained.

26. CHEMICAL SPRAY.-Chemical agents in liquid form are carried in special tanks and when released in flight form a chemical spray. When so released the liquid immediately forms a finely atomized cloud of droplets. The droplets of certain chemicals used for obscuring purposes hydrolize to form an opaque curtain or cloud of smoke. Other chemicals fall to the ground in small droplets eventually to vaporize or gasify and be dissipated in the air, or if sufficiently volatile to gasify before reaching the ground. Chemical spray provides a means of screening operations; blanketing hostile objectives; contaminating areas to deny their use to the enemy; causing enemy casualties; or of effecting delays and harassment of his forces.

27. MACHINE GUNS.-Machine guns are mounted on bombardment aircraft primarily for defensive fire but may be used for offensive fire. Machine guns may be used offensively against small naval craft, troop formations, aircraft exposed on the surface, or similar light materiel.

28. TORPEDOES.-The torpedo, normally used by the Navy, is not standard in the Army. The size and weight of torpedoes are within the capacity of heavy and medium bombers, and most models of such aircraft can be fitted to carry and launch torpedoes by means of suitable accessory equipment. The use of torpedoes is advantageous under conditions of low ceilings which prevent the effective use of large demolition bombs. Large size demolition bombs are effective in the attack of objectives against which torpedoes are used.

SECTION III: EFFECTIVENESS OF BOMBS

29. GENERAL.-The most effective utilization of bombardment aviation necessitates a reasonably correct relationship between the munitions used and the nature of the objectives to be attacked. The actual destructive effect of any one bomb is subject to so many variable factors that it is impossible to lay down inflexible rules for the utilization of the various types. The data presented in this section are based upon the best available information of the effectiveness of bombs and are intended as a guide to responsible commanders in the selection and use of bombs.

30. DEMOLITION BOMBS.-The explosive charge of demolition bombs normally is slightly more than half the total weight of the bomb. Maximum effectiveness is obtained only when the explosion of the bomb occurs either within or very close to the object to be destroyed. The radius of effectiveness of a demolition bomb dropped in water may be increased somewhat by the hydraulic ramming effect produced in the vicinity of the explosion. Accurate placement is essential to the most effective utilization of demolition bombs.

31. SELECTION OF BOMBS.-A knowledge of the power and effect of bombs is essential to the proper selection of the specific type for any particular mission. It is important that the size of bomb used for the attack of an objective be appropriate to the requirements of the mission. An objective against which large bombs should be used normally cannot be destroyed by a larger number of smaller bombs of equivalent or even greater total weight. The bomb used should be large enough to produce the desired degree of destruction. On the other hand, it is wasteful to use bombs of substantially larger size than that appropriate for the destruction of the objective. When the extent of the objective is such that it must be hit at more than one point in order to obtain the requisite degree of destruction, the desired effect is best obtained by attacking the several vulnerable points separately, using bombs of an appropriate size.

32. BOMB CRATERS.-a. The size of the crater produced by the explosion of a demolition bomb of a particular size depends upon the nature of the material upon which the bomb is dropped and also upon the depth of penetration prior to detonation. The depth of penetration is controlled by the striking velocity and the rapidity or delay in the functioning of the bomb fuze. The striking velocity depends principally upon the altitude and the velocity of the airplane from which released. The probable size of craters produced by demolition bombs dropped from 8,000 feet upon soil areas, such as rail centers or airdromes, can be judged from the results shown in table I.

TABLE I. Dimensions of demolition bomb craters in sandy loam soil

b. The craters produced in harder materials may be considerably smaller. A 2,000-pound bomb dropped experimentally on solid granite from an altitude of 15,000 feet produced a crater 6 3/4 feet deep by 31 feet in diameter at the surface and displaced approximately 80 cubic yards of material. Similar data are not available for 500- and 1,000-pound demolition bombs.

33. EFFECT ON REINFORCED CONCRETE.-Large demolition bombs are effective against massive reinforced concrete structures such as dams, piers, moles, and wharves. The blast effect of a bomb detonated in the water alongside a dam or reservoir wall is augmented by hydraulic pressure. The experimentally determined blast effect of demolition bombs exploded alongside reinforced concrete walls above the surface of the water is shown in table II. (See also table IV.)

TABLE II. Blast effect on reinforced concrete
 

34. EFFECT OF DEMOLITION BOMBS AGAINST PERSONNEL.-a. Demolition bombs are normally not as effective against personnel as an equivalent weight of fragmentation bombs. The effectiveness of individual demolition bombs decreases very rapidly with the distance from the point of explosion. The danger radius of blast effect is very limited. The energy of individual fragments decreases rapidly, and their dispersion at considerable distances renders them comparatively ineffective. The radius of casualty effect on personnel resulting from the blast of individual demolition bombs is indicated in table III.

b. The continuous detonation of large quantities of high explosive may produce a cumulative shock effect on personnel in the open with a consequent lessening of their combat efficiency, even though the individual detonations occur at such distances or under such conditions as to preclude direct injury from either the blast or the bomb fragments.

TABLE III.-Casualty effect on personnel
 

35. EFFECT OF DEMOLITION BOMBS AGAINST SPECIFIED OBJECTIVES.-Approximate results to be expected from the use of demolition bombs against various objectives have been determined experimentally. The results of those determinations are indicated in table IV to serve as a guide to bombardment commanders in the selection of demolition bombs appropriate to the attack of objectives of the nature specified in the table.

36. INCENDIARY EFFECT OF DEMOLITION BOMBS.-Demolition bombs are effective incendiary agents against objectives containing materials which are readily ignited. The incendiary effect is marked in the case of structures reinforced with steel or iron members and containing inflammable material in the immediate vicinity of the explosion. Heavy timbers do not always ignite.

37. FRAGMENTATION BOMB EFFECTS.-Fragmentation bombs are designed for maximum effect against personnel, animals, and light materiel objects, such as airplanes, small open boats, trucks, artillery tractors, and the equipment of mechanized forces. The fragments are relatively ineffective against rail-road engines and cars. Upon explosion, the present standard fragmentation bomb produces about 800 to 1,200 fragments. Maximum effectiveness is attained when the axis of the bomb is approximately vertical at the instant of explosion. The standard fragmentation bomb, exploded with axis vertical, has been demonstrated to be an effective casualty producing agency up to 165 feet from the point of explosion. The maximum danger radius from fragments is approximately 500 yards. The blast effect of a fragmentation bomb at a distance of 1 foot is approximately the same as that of a 100-pound demolition bomb at a distance of 3 feet. Direct hits will cause severe damage to tanks, trucks, airplanes, locomotives, and railway cars. Railway tank cars because of their usually inflammable contents are particularly vulnerable to direct hits. Fin stabilized and parachute type fragmentation bombs are identical as to size, number of fragments, and explosive charge. Differences in casualty effect will result from variations in the attitude of the bomb with respect to the ground at the instant of detonation.

38. CHEMICAL BOMBS.-The effectiveness of chemical bombs depends upon the kind of chemical employed, the type of fuze, and expelling charge, and may be materially affected by the existing atmospheric conditions. Chemical bombs, except incendiary types, normally are employed so as to affect enemy personnel and animals. By the use of bombs filled with liquid chemicals, a high concentration may be accurately applied to an objective. An effective means is thus provided for neutralization of enemy air bases and airdromes, antiaircraft artillery positions, and to delay the enemy by at least temporarily denying him the use of railroad yards, troop assembly points for motor, rail, or water transportation, communication and supply centers, bridges, bridge approaches, and other defiles. Depending upon the persistency of the chemical used and upon the atmospheric and terrain conditions, effective concentrations may persist for several days, and for considerably longer periods if conditions are especially favorable.

39. TEAR GAS BOMBS.-Tear gas acts immediately but its effect is of a temporary nature. The tear gas bomb produces a high concentration within a limited area. Extremely low concentrations of tear gas are effective in producing lachrymation. Tear gas is used against targets where immediate, although temporary, disability of personnel is required, and in areas which may be used by our own troops as soon as the gas has been dissipated sufficiently. When a tear gas bomb bursts, the cloud formed may be expected to drift with the wind for a distance of several hundred yards in a sufficiently strong concentration to cause lachrymation. Troops exposed will be forced to use gas masks with consequent loss of operating efficiency.

SECTION IV: DEFENSIVE ARMAMENT

40. GENERAL.-Bombardment aircraft are equipped with defensive armament for protection against the fire of hostile aircraft during flight. The defensive armament of bombardment aircraft is so placed as to cover all probable directions of approach by hostile fighter aircraft. Blind angles are eliminated from all directions which may favor approach of fighter aircraft and are reduced to a minimum in unfavorable directions of approach. High speed aircraft can be attacked most effectively from the rear. The machine gun is the standard defensive weapon of bombardment aviation.

41. MACHINE GUNS.-Standard aircraft machine guns are of .30 and .50 caliber, guns of both calibers being used on bombardment aircraft. All bombardment aircraft have flexibly mounted machine guns for defense against aircraft in flight. Bombardment aircraft intended for use in support force missions have, in addition to the flexible guns, fixed type guns for the delivery of forward fire against ground weapons during the approach to the objective in minimum altitude attacks. Flexibly mounted machine guns can be fired in any direction within a wide field of fire.

SECTION V: ACCESSORY EQUIPMENT

42. GENERAL.-a. Bombardment aviation requires accessory equipment in order to function. The expert manipulation of adequate and suitable accessory equipment is an important factor in the effectiveness of a bombardment force. Accurate placement of both offensive and defensive fire is essential to the efficient employment of the force.

b. Data pertaining to the construction, maintenance, and operation of accessory equipment are contained in pertinent technical orders and regulations.

43. BOMB SIGHTS.-The destructive power of aerial bombardment is controlled largely by the accuracy of bomb placement. A suitable sight is an essential item of bombardment accessory equipment. High altitude precision bombing requires a sight of great accuracy and capable of coping with several factors affecting the success of the mission.

44. BOMB RACKS.-Bomb racks may be either internal or external to the surface of the carrying aircraft. Bombs normally are carried internally. Bombs carried externally may seriously interfere with the performance of the aircraft, and external racks are used only when necessary. The racks provide a means of attaching bombs to the airplane in such a manner that they can be systematically released at will.

45. RELEASE MECHANISMS.-The bomb release mechanism may be operated manually or electrically. Accurate timing is essential to precision bombing from high speed aircraft. When the airplane is flying at a ground speed of 300 feet per second (approximately 204 miles per hour) a delay of 1/4 second in the release of the bomb after the proper time would cause an error of 75 feet on the ground. An arrangement is always provided whereby the bombardier may drop bombs, independently of the sight, singly, in train, and in salvo. Emergency releases are likewise provided whereby bombs may be released instantly in emergency.

46. CHEMICAL SPRAY EQUIPMENT.-The necessary equipment for spraying chemicals consists of chemical tanks and release mechanisms. Chemical tanks may be carried either internally or externally. The tanks may be specially mounted or they may be carried on the bomb racks. Chemical spraying equipment should be readily removable from the airplane when not required for use.

47. ACCESSORIES FOR DEFENSIVE ARMAMENT.-The principal accessories for the operation of defensive armament in bombardment airplanes are sights, mounts, control mechanisms, and ammunition containers. Flexible gun mounts must permit rapid traversing of the gun and easy handling under all conditions of flight. Sights, control mechanisms, and munition containers are designed for use with particular types of guns.

48. COMMUNICATION EQUIPMENT.-Bombardment aircraft are equipped with radio receiving and transmitting facilities. Long range radio equipment is provided for air to ground communication. Short range equipment is used for command communication. (See FM 1-45.)

49. FLIGHT CONTROL MECHANISMS.-Flight control mechanisms are standard accessory equipment on bombardment aircraft. These mechanisms usually rely on gyroscopes for their stabilization and directional control.

50. NAVIGATION EQUIPMENT.-The navigational equipment of bombardment aviation includes aperiodic compasses, drift indicators, and various other instruments required in dead reckoning and celestial navigation. (See FM 1-30) Radio equipment also constitutes an important navigation accessory in situations where radio aids to navigation are available.

SECTION VI: FLIGHT FORMATIONS

51. FORMATION FLYING.-The military airplane is a complete combat unit. Its capabilities are dependent upon its type and the character of its combat equipment. The offensive and defensive powers of even the largest and most powerful individual airplane are relatively limited. Hence the effective utilization of aircraft in warfare frequently requires that they be employed in suitable tactical formations rather than as single units. The organization of aviation forces into suitable tactical units facilitates the simultaneous employment of the aircraft in the accomplishment of an assigned mission.

52. PURPOSE.-a. Bombardment units resort to flight formations only when there is a reason therefor. The principal purposes of formation flight are

(1) The massing of defensive fire power for the security of the command against attack by hostile aircraft.

(2) The massing of offensive fire power to render more effective or immediate the destruction and/or demoralization of hostile installations or combat forces.

(3) To minimize losses during attacks upon strongly defended objectives, by delivering the maximum blow with a minimum exposure of the attacking force to the fire of defending weapons.

(4) To expedite movement of large units by air.

(5) To facilitate tactical control of aircraft in flight.

b. Bombardment units may be required at any time to utilize flight formations in the performance of their missions.

53. UNITS.-a. The bombardment squadron formation consists of two to four flights of three or four airplanes each. In the air the squadron commander exercises control through flight leaders.

b. Group formations comprise two to four squadrons. The group commander, through the squadron leaders, exercises general control in the air over the actions of the aircraft of the group.

54. SYSTEM OF ARRANGEMENT.-The arrangement of bombardment airplanes into a formation usually is based upon the strength, disposition, and employment of the tactical unit to which the aircraft pertain. It is preferable that all of the aircraft in any formation be comparable as to type and performance characteristics. The association of dissimilar types of aircraft in the same formation should be avoided.

55. TYPES.-The flying of bombardment aircraft in formation limits their freedom of maneuver, the degree of the restriction being dependent upon the size and character of the formation. There are no prescribed types of bombardment formations which must be rigidly followed. The formations described in this manual have been used by tactical units and may be regarded as basic types. Each formation must meet the requirements of the specific situation presented. The basic types described herein must be regarded only as guides in the development of the proper formations to meet varying situations confronting tactical commanders in actual operations.

56. SIZE.-a. The size of a bombardment formation depends upon the situation to be met and will be governed by the specific purpose for which it is formed. The number of airplanes that can be effectively controlled during flight in one compact formation by a single commander is definitely limited. When the number of airplanes required to perform a given tactical operation is greater than can be controlled in one compact formation, they are organized into two or more of visual signals.

b. In large formations the commander transmits his orders to subordinate commanders by means of radiophone and visual signals.

57. TACTICAL REQUIREMENTS.-a. In the arrangement of a bombardment formation to meet the requirements of any particular situation it is important that sound tactical principles be observed so that the formation may efficiently accomplish its assigned mission with minimum losses.

b. Bombardment formations should possess a sufficient degree of flexibility so they may be changed as necessary during flight to meet a new situation. Formations must also be so adjustable that the loss of one or more airplanes will not jeopardize the security of the command or prevent the accomplishment of the assigned mission.

c. Simplicity of arrangement, signals, maneuver, and control are essential. It should be possible for each pilot to maintain his assigned position by guiding on only one airplane.

d. Formations should have sufficient maneuverability to enable them readily to accomplish their mission under the complete control of the commander.

58. FORMATION ASSEMBLY.-The principal occasions for effecting the assembly of bombardment aircraft in flight formations are immediately after take-off preparatory to the conduct of a tactical mission; and the reassembly of the formation after the delivery of an assault by subordinate units or after the formation has been disrupted as the result of attack by hostile forces. The initial assembly usually occurs in the vicinity of home airdromes and will normally be completed before enemy fighters are encountered. Rally, after an assault, takes place in the vicinity of the objective and may have to be performed after enemy fighter aviation has engaged the bombardment in air fighting. (Rally point is the position in space at which the components of a formation reunite after an assault.) Prearranged points of group assembly in enemy territory may be necessary when unfavorable weather necessitates navigation through such weather by smaller units or even by individual aircraft.

59. ASSEMBLY FROM ONE AIRDROME.-In all cases of initial assembly a definite time of assembly is prescribed, and in all cases of assembly or of rally the formation, place, and altitude at which units are to assemble are specified in orders. When the formation is to consist of one squadron or less, and the entire unit is based on one airdrome, it may be conveniently assembled in the prescribed formation at the designated altitude above the airdrome. This method is particularly applicable at night or under conditions of adverse weather. Under favorable conditions the formation may be assembled en route, in which case the leader will fly at reduced speed until succeeding airplanes join the formation. If two or more squadrons are based on the same airdrome, assembly may similarly be over the airdrome or en route shortly after take-off.

60. ASSEMBLY FROM TWO OR MORE AIRDROMES.-When the formation is to include aircraft based on two or more airdromes, a place of assembly is designated in the order directing the mission. A place of assembly should be some easily recognized terrain feature in friendly territory approximately on the route to the objective.

61. RALLY.-a. Formations which have been disrupted for any reason will rally as rapidly as conditions permit at a point and altitude designated by the leader, and in the formation most suited to existing conditions. The rally point selected by the leader should be beyond the range of the weapons of opposing ground forces.

b. Formations which have been, separated into assault elements will be reassembled as soon as practicable en route to a rally point designated in the order for the mission. This order prescribes the formation for the rally and the altitude, which should be lower than the assault altitude of the lowest assault unit.

62. TYPES OF SQUADRON FORMATIONS-The possible types of squadron formations are many. Two different types, the javelin formation and the stagger formation, both of which have been found to possess merit as offensive and defensive formations, are illustrative of squadron formations.

63. SQUADRON JAVELIN FORMATION.--The javelin formation (fig. 1) is composed of two or more three-plane elements in close column. The second and succeeding elements may be either stepped-up or stepped-down. Certain defensive advantages accrue to each method and a change from one to the other can be quickly made. This formation affords one of the heaviest concentrations of defensive fire possible to present with the number of airplanes involved. While this formation offers a maximum degree of compactness, it is also very maneuverable and easily controlled. Any sector of approach may be covered by at least three gunners. In the stepped-down formation all rear gunners may fire in the upper rear hemisphere. The lower rear hemisphere is protected by cross fire. This formation is extremely narrow and makes a simultaneous close-in attack from the rear very difficult. The last element may be composed of four airplanes instead of three, as shown in figure 1.

64. SQUADRON STAGGER FORMATION.-The stagger formation (fig. 2) consists of three flights of three airplanes each and is designed to afford the maximum degree of maneuverability in a squadron formation. In this formation, B and C flights normally take position to the right and left of the leading flight (as shown in fig. 2), one being stepped-up and the other stepped-down in such a manner as to permit freedom of lateral movement across the flight path of the formation. The lateral freedom of all flights and of individual airplanes contributes to the maneuverability of the formation as a whole, and facilitates the presentation of a strong defensive fire against flank attacks by merely shifting the formation so as to uncover all of the top and side guns of the formation.

FIGURE 1.-Squadron javelin formation.

This type of formation is very flexible, and the positions and distances may be varied greatly from those shown in the figure. The freedom of maneuver of each flight and of each airplane within the flight on its own horizontal plane renders this formation readily adjustable to quickly changing conditions with great speed and effectiveness. These lateral movements may be used to confuse the enemy and minimize the effect of his fire.

65. TYPES OF GROUP FORMATIONS.-A group formation will consist of two or more squadron formations, and the arrangement may be varied according to the requirements of different situations. Two types of group defensive formations which have been found satisfactory are the wedge formation and the group stagger formation.

66. WEDGE FORMATION.-The wedge formation is composed of squadrons in javelin formation, arranged as diagrammed in figure 3. The second and third squadron formations are echeloned above and to the right and left of the leading squadron. A fourth squadron, if present, may take position to the rear and above the leading squadron and with its leader approximately opposite the leaders of the second flights of the flank squadrons. The position of the fourth squadron is not fixed, because it is a responsibility of the commander of that squadron to maneuver his formation so as to provide the maximum support possible for the other squadrons of the group. The wedge formation is sufficiently flexible to permit the shifting of squadrons for defense against all types of attack by hostile aircraft. This type of formation is easily controlled.

FIGURE 2. - Squadron stagger formation

FIGURE 3. - Group wedge formation

67. GROUP STAGGER FORMATION.-In the group stagger formation (fig. 4) , squadrons are arranged in a manner similar to that of the flights in a squadron stagger formation. In this type of formation the group is staggered in altitude and in depth to such an extent that the squadrons have freedom of lateral movement to the same extent as have the flights in each squadron stagger formation. The differences in altitude of the lowest and highest flights in a homogeneous group formation of thirty airplanes may be varied from 600 to 1,600 feet. This is probably the most flexible group formation yet developed, the whole group being able to secure any degree of change in direction with the maneuverability of one flight of three airplanes.

68. NEED FOR DEFENSIVE. FORMATIONS.-Defensive formations are necessary whenever bombardment units are employed during daylight within range of enemy weapons. Such protection is necessary in order to insure the completion of tactical missions in enemy territory and to minimize losses which may result from active opposition.

69. GENERAL REQUIREMENTS OF DEFENSIVE FORMATIONS.-a. Defensive formations are so constituted as to facilitate concentration of their own defensive fire, particularly against short range fire from hostile aircraft. Such formations are sufficiently flexible to permit rapid changes in position and increases or decreases in the intervals and distances between airplanes, flights, and squadrons in the formation to meet any form of hostile attack.

b. The commander of a large formation rarely pilots the leading airplane. The commander who controls a formation and supervises its navigation, defense, and method of attacking the objective should be relieved of the duties of piloting when practicable. He is responsible for the tactics employed and for the air discipline of his command, and must be in a position from which he can best observe the conduct of the mission and can most efficiently perform his command duties.

70. DEFENSE AGAINST HOSTILE AIRCRAFT.-a. Individual airplanes and elements in defensive formations must be so arranged as to facilitate the maximum concentration of defensive fire in that direction which is most favorable to approach of the enemy aircraft in launching attacks against the formation. It is desirable that such formations be capable of delivering simultaneous gun fire superior to that which can be brought to bear by the enemy at any one time. Defensive formations should have sufficient maneuverability to enable them to minimize their vulnerability to time-fuzed bombs and long-range aircraft machine gun or cannon fire.

b. The delivery of effective defensive fire from bombardment aircraft in flight requires coordination of the fires of the several defensive guns; proper location of guns and training of gunners to cover all sectors and avenues of approach of attackers; formation flexibility to permit concentration of fire of the defensive guns against the attackers on any avenue of approach; excellence of performance of the defensive guns; and a high degree of skill on the part of the gunners.

FIGURE 4.--Group stagger formation.

c. Simplicity and compactness are secured in a defensive formation when each pilot is able to maintain his assigned position by guiding on only one adjacent airplane. In such a formation, pilots may readily maintain their positions, and the degree of compactness attainable is limited only by the skill and training of the individual pilots. A simple compact formation may be readily controlled by the leader, who is assured that his commands will be quickly relayed to all airplanes in the formation. Efficient control requires also that the formation be capable of maneuver. A formation having great lateral width cannot be turned on a short radius without a lateral shift of elements because of the resultant distance differential between airplanes on the outside and on the inside of the turn. For efficient control and maneuverability, defensive formations should be as narrow laterally as is consistent with other requirements.

d. When a group formation is composed of two or more squadron formations, each squadron is charged with a definite responsibility in the conduct of organized defensive fire. Whatever the size of the defensive formation, its elements are arranged within themselves and with respect to each other to provide the best opportunity for supporting fire.

71. DEFENSE AGAINST GROUND WEAPONS.-a. When it is necessary to conduct air operations during daylight in an area defended by antiaircraft weapons, it is essential that the disposition of the aircraft and the tactics employed while in the danger zone be such as to minimize the effectiveness of the fire of the defending weapons. Localities which are strongly defended by antiaircraft artillery are likely also to be protected by defensive air units. A compact formation, well suited for defense against hostile aircraft, does not afford adequate security against antiaircraft artillery fire. Air commanders conducting attacks against objectives defended by both antiaircraft artillery and aircraft must so adjust their formations as to provide the most effective defense under the actual conditions encountered during the conduct of tactical missions.

b. Formations specifically arranged for defense against antiaircraft artillery fire must permit sufficient maneuver of airplanes in all directions so that no single airplane is forced to fly to the point in space at which the antiaircraft fire control instruments predict it will arrive at the end of a predicting interval.

c. The formation must be so arranged that no single anti-aircraft artillery battery round will disable more than one airplane.

d. Within the considerations of spacing required to prevent injury to more than one airplane by a single battery round, the formation should be as compact as possible to facilitate rapid transit of the danger area and to prevent, insofar as possible, aircraft being successively taken under fire by the same artillery units.

e. The formation must be able to take advantage of weather conditions that interfere with discovery and continuous observation from the ground.

f. The formation must be quickly convertible into formations suitable for air attack or for defense against hostile aircraft.

72. CONVERTIBILITY OF DEFENSIVE FORMATIONS.-Formations suitable for defense against hostile aircraft may, by increasing the intervals and distances between airplanes, be adjusted to the requirements for defense against anti-aircraft fire. Stagger formations, because of their great flexibility and variation in altitude between the highest and lowest flights, may be used to advantage in situations wherein a disposition suitable for defense against antiaircraft artillery fire may suddenly be required.

73. OFFENSIVE FORMATIONS.-a. The character of the objective and the manner in which the attack is to be accomplished will influence the plan of the formation. The nature and strength of the ground and air defense forces also may influence the type of the offensive formation. Some modification of the best offensive formation plan may at times be justified in the interest of security. The value of or necessity for greater security must be balanced against any loss in effectiveness which may result from a change of plan or formation to secure it.

b. All bombardment echelons must be imbued with the offensive spirit that carries through to success the mission assigned. Losses can be anticipated and even though severe should, when unavoidable, be accepted in those cases in which the blow to the enemy justifies the aircraft loss incurred. Higher authorities may require destruction of objectives at all costs, in which case the commander in the air can accept no alternate that does not offer excellent promise of accomplishment of the mission. Even here, however, cases will arise in which questions of security must be weighed to prevent enemy action from so depleting the force prior to its arrival at the bomb release line that the success of the attack is placed in jeopardy.

c. A detailed study of each specific objective is required to determine the best formation from which it may be attacked. The conformation of the objective will determine, in general, the appropriate form and dimensions of offensive formation to be employed. The nature of some areas does not permit division into a series of point targets for individual airplane attack. Some targets will require uniform coverage over their entire area, especially if chemical agents are employed.

74. FORMATION ATTACKS.-a. The javelin, wedge, and stagger formations are suited to attacks at all altitudes except those too low to permit minimum formation depth.

(1) Both point and area targets may be successfully bombed from javelin formation, either stepped-up or stepped-down, the intervals and distances between airplanes being adjusted to meet the requirements of each specific situation.

(2) The wedge formation is well suited to the attack of area objectives that require the fire power of more than one squadron to produce the desired effect.

(3) The group stagger formation, while especially well suited as a defensive formation, is highly adaptable for use in formation attacks of point targets. If the attack is conducted against an objective defended by antiaircraft artillery, all squadrons, flights, and even individual airplanes, which are at greatly increased intervals while within range of the antiaircraft guns, maneuver so as to present the poorest possible target consistent with the accomplishment of the mission. The squadrons approach the objective at different altitudes, and the airplanes of each squadron converge on their assigned targets in three plane elements, each at a different altitude.

b. Attack from stagger formation is characterized by an apparent complexity but actually is easy of accomplishment, and the formation is so flexible as to afford maximum freedom of maneuver to each airplane in it. The group stagger formation brings a mass attack against the objective in a minimum of time, keeps the group in a good defensive formation to resist attack by hostile aircraft, and presents a confusing target to both air and ground defensive forces.

75. MINIMUM ALTITUDE ATTACKS.-Air attacks may be launched from aircraft in offensive formation at either high or low altitudes depending upon the nature of the objective, the weapons used, weather conditions, and the character of antiaircraft defense employed by the enemy. Flexibility and maneuverability are of great importance at extremely low altitudes, and the most satisfactory arrangement under such conditions is to divide the formation into elements of three airplanes each. The elements fly in V-formation with intervals and distances as dictated by the requirements of the mission. Elements guide upon the leader and fly either in column or in echelon and at approximately the same altitude. When elements fly at different altitudes, the leading element flies at the lowest altitude. The intervals and distances between elements are varied to meet the needs of any particular situation. This type of formation has the requisite flexibility for minimum altitude missions and can readily be closed for defense against the fire of hostile aircraft. The size of the formation is determined by the offensive fire power required for the accomplishment of the mission.

76. MINIMUM ALTITUDE FORMATIONS.-A typical formation of nine airplanes in an arrangement suitable for minimum altitude air attack is shown in figure 5. In this arrangement of flights, all may fly at the same altitude while delivering the attack, or the second and third flights of the formation may fly slightly higher than the leading one.

77. NIGHT FORMATIONS.-The tactical principles applicable  to the conduct of bombardment missions in flight formation are basically the same, whether the operations are performed during daylight or at night. The differences in operating technique appropriate to the conduct of bombardment operations in flight formations, during daylight and at night, are essentially those necessary to compensate for the reduction in visibility occasioned by night flying conditions. This reduction in visibility renders undesirable the use of stagger and stepped-down formations. The squadron javelin, the group javelin (column of squadrons in javelin) , and the route column, all stepped-up, are particularly adaptable to night flight in formation.

FIGURE 5.-Minimum altitude formation.

78. FACTORS AFFECTING NIGHT FORMATIONS.-a. The visibility during night operations is subject to such wide variations that no precise rule can be stated for determining the degree of departure from daylight technique in the conduct of night flying formations under all conditions.

b. Decreased visibility incident to night operations renders the massing of defensive fire, against attack by hostile air-craft, of little if any practicable value.

c. Formations, even at antiaircraft intervals, are not normally used in night attacks against defended objectives.

d. The maintenance of compact formations, either defensive or offensive, for long periods of time is very fatiguing to piloting personnel. The fatigue of piloting personnel, incident to formation flying, is much greater at night than during daylight operations.

79. ROUTE FORMATIONS.-Close defensive formations are required only during attacks by hostile aircraft or when such assaults are imminent. Offensive formations are necessary only during the bombing assault. In the conduct of bombardment missions there will be long periods during both the advance and the return when there is no necessity for the maintenance of a compact defensive formation. During such periods the formation will be flown with sufficient intervals between airplanes to relieve the pilots.

80. GENERAL REQUIREMENTS.-a. Route formations are habitually used by tactical units during active operations whenever compact defensive or offensive formations are not required. Route formations are employed during the routine movement of aircraft by air in formation.

b. Route formations must be capable of quick and simple conversion either to defensive or offensive formations. Rear elements are habitually stepped-up in order to facilitate closing upon the leading airplane when necessary.

c. Route formations must not present a profitable target to antiaircraft artillery.

FIGURE 6-Group route column formation.

81. CONVERTIBILITY OF ROUTE FORMATIONS: -In general, route formations are assumed by spreading out defensive or offensive formations without materially altering their original conformation. Individual aircraft and elements take convenient intervals and distances to facilitate route travel without undue fatigue.

82. TYPES OF ROUTE FORMATIONS.-Typical route formations are shown in figures 6 and 7. The group route column is actually a column of squadrons in javelin up at increased intervals and distances. Similarly the dispersed column corresponds to the group wedge.

FIGURE 7.-Group dispersed column formation.