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UNITED STATES PACIFIC FLEET
AIRCRAFT TACTICAL BULLETIN 3-43
REPORT OF MASTHEAD BOMBING
(Reissued by Air Information Branch
TACTICAL BULLETIN NO. 3-43.
This Bulletin is issued to Aircraft South Pacific to supplement the contents of USF-74 and USF-76. It is intended to bring before pilots details neither possible nor desired to be included in USF-74 and USF-76, but which are necessary to obtain the optimum operational efficency. The background of this Bulletin is based on practical operational experience in the South West Pacific Area.
Subject: Report of Masthead Bombing.
I. Excerpts from report by Headquarters, Fifth Bombardment Group, APO 708.
1. "One heavy bomb group in the Fifth Air Force has employed high level daylight bombing at 6500 to 7500 feet on practically all targets (land and sea) and has achieved remarkable results. Their pilots and bombardiers conduct bombing training at every opportunity and have developed an anti-aircraft fire technique, that, to date, has been successful in that no aircraft have been lost due to AA fire. However, AA fire has scored hits on their aircraft. Their method briefly is to approach the target about 2000 feet above the proposed bombing altitude. When about 10 miles from the target RPM's are boosted to about 2250, throttles closed to l5"Hg to 18"Hg and a 180 mph, 1000 ft. per min. descent started. This descent is maintained and so jockeyed that when the bombing altitude is reached (usually 600 ft.) they are ready to start their bombing run. Normally about a 70 second run is employed with a sharp diving turn when bombs are away. The undersigned was on one such mission where moderate AA fire was encountered. All of the first burst broke over and behind. By the time the AA started coming extremely close we were about out of range."
2. "Reports of the Bismark Sea Battle were studied and a number of individuals participating in the battle were contacted. From all the information that can be gathered the mission was carefully planned and coordinated. B-17's led the attack and were given pursuit protection by P-38's. The B-17's bombed from about 7500 feet, apparently causing considerable confusion among the vessels attacked, as well as scoring several direct hits starting fires on the vessels. This attack was
Subject: Report of Masthead Bombing.
followed by a strafing attack by Beaufighters. The Beaufighters followed the B-17's so close that pictures taken of vessels by them show bombs dropping directly in front of the Beaufighters. B-25C-l's then attacked, strafing and skip bombing. This is as nearly an accurate account of the initial attack as can be determined. Flights and elements within the squadrons became separated and returned to their bases individually or in pairs or threes with whatever type plane or squadron they could get together with. Planes were refueled, reloaded and returned to the attack. From then on there were no coordinated attacks, but the convoy was under continual attack until it was destroyed (about 3 days) and survivors in life rafts and boats were eliminated by strafing."
3. "It is my opinion that high level bombing, from altitudes of 6500 to 7500 feet is still very effective against land and moving targets provided the bombing team is properly trained and they continue to train; that our 120 lb. frag cluster is more effective than a "Daisy Cutter" (except on 100 lb. bombs when frag clusters are unavailable), that we now have bombs and fuses with exception of delayed action fuses, in quantity to complete any bombing mission assigned. That properly coordinated attacks with pursuit for high cover and close cover, heavy bombers leading the attack, followed by P-38's strafing the decks of war and cargo vessels alike, followed by B-25C-l's, (8 forward firing machine guns) strafing and skip bombing, can be conducted against armed convoys with extremely light losses and a great deal of success."
II. Training Bulletin by 43rd Bombardment Group.
"Skip bombing is a low-altitude attack that has been successfully used against naval targets. It consists of a string of from two
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Subject: Report of Masthead Bombing.
to four bombs dropped from such an altitude and distance from the target that a complete miss is improbable. Unless the target is of such importance that heavy losses can be accepted, this method of bombing should be attempted with large heavy aircraft only at night and under most favorable weather conditions. The attack should be delivered with the idea in mind of securing a maximum of surprise and should not be repeated against the same targets too often. Skip bombing attacks should be made with the target outlined against light of either flares or the moon, and in such a location that the pilot is able to accurately tie in his altitude with a visible beach or other well defined objects. The altitude of the attack should be from 200 to 300 feet and the bomb-release line from 350 to 200 feet from the target."
"Skip bombing attacks have proved effective under the following conditions:
(a) First light of dawn with approach made from west to east. Then just enough light exists to silhouette the vessel
(b) On clear nights with the moon below 40 degrees elevation, the attack being made into the moon.
(c) Directly out of a very low setting sun.
(d) From very low clouds or poor weather where an element of surprise is completely possible."
"The following rules have been found to apply:
(a) Start the bombing run from the darkness into the light, keeping the attacking plane against a dark background and silhouetting the target against the light.
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Subject: Report of Masthead Bombing.
(b) Deliver the attack from a fairly steep dive with throttles retarded at a speed of from 200 to 250 mph.
(c) Withdrawal (SIC) should be made in all cases directly over the target and straightaway at sea level. Any attempt to turn near the vessel presents an excellent target.
(d) Bombs should be spaced in train equal to the width of the target.
"Either the American 4 - 5 second fuze or the Australian 11 - 12 second fuze can be used. The shorter timed fuze has greater effectiveness, since in deep water the 11 - 12 second fuze occasionally sink below effective range before exploding."
5. Action of Bombs:
"Bombs dropped from this altitude will skip, hit the target direct or go underneath the water. If the attacking airplane drops its bombs from a slight dive, the bombs will usually go through the water and explode underneath the target. If bombs are dropped from level approach, they will usually skip and tumble and explode against the side of the target. In some cases, bombs have been observed to leap completely over the target. Some of the bombs of the train will probably hit directly on the target. Either of these events is effective and it is not believed important to attempt to obtain any one of three results to exclusion of others. In some instances a low order explosion has resulted from a bomb hitting the side of a vessel but in general the bomb cases hold up very well."
"Skip bombing is effective when attempted under the above stated conditions and offers the following advantages:
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(a) Very little training is required to achieve accurate results.
(b) No losses to date have been sustained by this organization from skip bombing.
(c) A surprisingly high percentage of hits is obtained by this method."
7. Precautionary Measures:
"Skip bombing with heavy bombardment aircraft must be considered an attack of opportunity. Any attempt to skip bomb a war vessel in the daylight, unsupported, would probably be particularly hazardous because of lack of speed and maneuverability and small amount of forward fire power. Successful daylight attacks have been made on unescorted merchant vessels by heavy bombers, and light bombers heavily armed forward with .50 caliber machine guns have been highly successful against war vessels. This success of light bombers was due to surprise, coordination, and heavy forward fire, none of which are likely to exist in a daylight attack on warships by heavy bombardment. Repeated skip bombing attacks in the same area would result in some form of protection designed to defeat it. It is, however, when the opportunity presents itself, an ideal sure-fire method of hitting the target."
III.Notes on Fusing.
1. The Fifth Bombardment Group states: "on all missions conducted by heavy bombardment planes it has been the pilot's choice as to whether masthead or high level bombing should be employed. To meet either situation, alternate fuses are carried, as follows:
500 lb. Bombs, Army.
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Note: The M14 variable primer detonator if (SIC) furnished in five delays; namely, .01 sec, .025 sec, 0.1 sec, 11 sec. (availability this delay doubtful) and non-delay. The non-delay is not as fast as instantaneous. The Al modification fuses have a much longer arming air travel than the A2 modification, and are not suitable for low level bombing unless prearmed properly. The A2 modification fuses arm in 450 to 575 feet of AIR TRAVEL.
The Tactical Reports of Attacks on the Bismark Sea Convoy, March 2 - 4, 1943s by Fifth Bomber Command, Office of A-2, APO 925, have been studied. The following comments are based on this report.
1. Coordination was excellent. First attacks were high level B-17's (7,000 to 8,000 feet), immediately after the B-17's came Beaufighters (strafing), then immediately after, and with them, came the A-20's, Bostons, and B-25 C-l's. The high level bombers tended to disperse the convoy and draw the majority of the AA fire. There were but few enemy VF. This drawing of the AA fire distracted the Japs on the ships (as well at the fairly effective B-17 bombing) and assisted the attacks and demoralization gained by the A/C following.
Note: It was the general opinion of all pilots and echelons of command that effectiveness of this attack was due to the planning, training, execution, and coordination of this attack.
The B-25 C-l is equipped with eight fixed forward firing .50 caliber machine guns. This was the most effective plane during the annihilation of the Japs; masthead bombing and strafing were done by the B-25 C-l's.
2. Fuses were generally of the 4 second delay type. Bombs used were generally the 500 lb, type.
3. The strafing of the Beaufighters was very effective. It was stated that strafing A/C lose much of their effectiveness unless masthead bombers come in and attack on the tails of (and with) the strafing A/C; then the ship's gunners have their heads down and demoralization is highest. Troops on the transports were firing with rifles; they were mowed down and ran when the strafing A/C attacked.
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4. The B-25 C-l's attacked singly, simultaneously. The A-20's attacked in pairs. The general I.A.S. of the attacks by the masthead bombers was 220 to 240 miles. Strafing fire was opened at 1500 yards and stopped around 400 yards in order to drop bombs from about 100 ft. level. Planes took evasive action prior to their attacks; it is believed that much of this took place too close to the water. The planes were thick in the center of the convoy. There they were relatively safe from the AA fire of the screening warships. Planes flying between ships caused them to decrease their fire to avoid mutual damage.
5. In strafing attacks against barges and ships by fighter A/C where enemy VF were believed to be in the air it is recommended to form a circle for the strafing attack. This aids the mutual protection versus enemy VF sneaking in unsighted.
6. Consideration must be given to the tendency of bombs to ricochet off of the deck and sides of the vessels attacked. In general, it seems that beam attacks are most effective. Bombs are spaced to drop no farther apart than the beam of the vessel attacked. It is believed that concentration on this type of attack may create such accuracy as to assure hitting with only one bomb dropped per pass at the target.
1. The controlled skipping of bombs dropped from a low altitude against ship targets is not possible either in theory or practice. Masthead bombing does utilize to best advantage the tendency of bombs dropped a few feet short of a ship, to ricochet forward and score a hit. The main results of masthead bombing have been achieved by aiming for and scoring direct hits on a ship's side. It is therefore believed that the application of the name "skip bombing" to the practice of MASTHEAD BOMBING is incorrect. Controlled masthead bombing will obtain HITS. Actually, bombs dropped in an effort to skip them up to the target will result, in the majority of attempts, in ricocheting the bomb over the target to no good advantage.
2 Until aircraft with the characteristics and fire power of the B-25 C-l are available in quantity, it is recommended that every effort be made to train for and perfect coordinated attacks by strafing fighters and bomber aircraft as MASTHEAD BOMBERS.
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3. Skip bombing versus land targets such as tanks, buildings, and personnel may be a most effective form of attack. No remarks contained herein should be construed as being directed against the skipping of bombs versus land targets. Operating units are requested to consider the advantages and possibilities of this form of attack using 4 and 11 second delay fuses,
VI. Excerpts from Statement by Maj. Gen. Whitehead, Deputy 5th Air Force Commander and Advanced Echelon Report.
1. "We used medium level bombing to divert the AA fire and fighters and attack bombers to make the kills. Except on destroyers and light cruisers several hits by 500 lb. bombs were required for immediate results. The 8 gun, B-25 C-l has only half enough fire power. From 15 to 20 .50 caliber guns firing forward would give a suitable covering fire for attack bomber aircraft operations against warships. One thousand bombs will, in the future, be used in attack bomber operations against shipping when their use is feasible."
2. "In the masthead attacks attempt was made to drop the bomb from 100 to 200 feet so that it would strike the side of the target at the same instant it struck the water, rather than to skip the bomb in the water into the target."
3. Excerpts from Tactical Notes Section.
(a) "Except against individual merchant ships, etc., heavy bombers only under cover of darkness should be used as masthead bombers unless the circumstances warrant a high casualty, rate. (N.B.- use of radar for search and attack at night should be stressed by heavy bombers)."
(b) "Target should be silhouetted, and a beach or other reference point should be visible. Make beam attack."
(c) "Training in this technique must be done tho(ugh) - SIC even a limited amount of training will give excellent results."
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(d) "The pilot should remember that .50 caliber fire will drop about 100 ft. in 1,000 yards when the plane is indicating 240 miles at sea level."
(e) "When within range fire is of a covering nature and directed at gun positionsj no attempt being made to cause explosions which might endanger the airplanes. Destruction is left to the bombs."
(f) "Attempts to "skip" the bombs leads to shorts and possible misses, (ricochets over the target). The bomb is aimed at the water line or a few feet short."
(g) "The accuracy of masthead bombing permits using one bomb per ship; this gives greater damage per bomb load carried. (Especially true on the attacks made by the first striking wave)."
(h) "The division and diversion of enemy fire is achieved by simultaneous attacks of as many airplanes as possible."
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South Pacific Distribution List
All Units Operating Under Commander Aircraft, South Pacific Force
National Archives & Records Administration, Seattle Branch
Record Group 181, 13 Naval District, Commandant's Office, Central Subject Files, 1942-43
Transcribed by RESEARCHER @ LARGE. Formatting & Comments Copyright R@L.
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