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British Mk I 100lb Anti-submarine bomb c1940
- Thread starter WATU
- Start date
This photograph shows a 100 lb. Anti Submarine Bomb Mk I-III with nose fuze No. 32 under the winglet of a Lysander, together with a 20lb "Cooper" bomb. Both bombs were already obsolete by the beginning of WW2. A number of photograph exist showing the similar 250lb AS bomb, a larger size version of the 100lb AS. Both teh 100lbs and teh 250lbs AS were operational failure and this led the British into a crash development of efficient depth charges
A surviving sample of the 100lbs AntiSubmarine bomb (though with uncorrect coloring - this bomb was always painted yellow-ochre as it was withdrawn before the introduction of the bronze green scheme) is on display at the Merseyside Maritime Museum in Liverpool
A surviving sample of the 100lbs AntiSubmarine bomb (though with uncorrect coloring - this bomb was always painted yellow-ochre as it was withdrawn before the introduction of the bronze green scheme) is on display at the Merseyside Maritime Museum in Liverpool
In the early phases of ww2, RCAF Squadrons 118 and 122 operated the Lysanders in the anti-submarine role till their replacement by Hudsons and Bolingbrokes.
Lysanders from the Canadian 111 (Army Co-operation) Squadron, RCAF Station Patricia Bay, British Columbia, were also used in anti-submaine role in 1940
The No. 5 Coastal Artillery Co-operation (CAC) Detachment (later a Flight) of the Royal Canadian Air Force (RCAF) stationed at RCAF Station Torbay, near St. John's, Newfoundland and the No. 2 Coast Artillery Cooperation (CAC) Detachment at RCAF Station Dartmouth, Nova Scotia, still used Lysanders for anti submarine patrols in 1942, equipped with AS bombs.
In fact the Lysander Mk. II serial 449 of No. 2 Coast Artillery Cooperation (CAC) Detachment made the first, and possibly the only, confirmed submarine attack by a Canadian-based Lysander, when, on the evening of 23 February 1942, it attacked and damaged U-96 , 20 minutes flying time south of Halifax harbour.
The use of sticks of AS bombs was generally dropped by Sunderland but these were usually 250lb AS - 4 under each retractable underwing rack, prior to teh introduction of the depth charges.
The inectiveness of the AS bombs was not so much due to their inaccuracy than to their fusing system
The fusing systems for those bombs provided for either an instantaneous detonation in the event of a dry hit on a submarine, or for detonation after some
timedelay if the bomb entered the water. For a variety of reasons, the shortest time-delay which could be provided was 1/2 second. A high proportion of U-boats attacked from the air were on the surface, and the most accurate attack was that at low level. Such an attack was not possible with the existing antisubmarine bombs, because, in the event of a dry hit, the resulting instantaneous detonation would cause damage to the aircraft dropping the bomb (At least one Anson and two Fleet Air Arm Skuas were destroyed by their own bombs in September 1939 alone), while, if the bomb entered the water, the 1/2 second delay caused it to detonate at too great a depth to inflict lethal damage on a surfaced submarine.
The whole issue of fusing of these bombs was a a headache - in trial done in 1934, the nose fuse was shown to effect the underwater trajectory of the bomb in an unpredictable fashion (The nose fuze was supressed on the MkIV, the standard 100lb AS bomb of the UK Coastal Command in 1940). Further trials evidenced a 40% failure rate of the No. 30 tail pistol, largely due to difficulty in guaranteeing detonation at a depth of 20-25 feet, that considered optimal for attacking a surfaced submarine.
The two Skuas were from 803 Squadron Fleet Air Arm, operating from Ark Royal. The boat they attacked was the U-30 of none other than Fritz-Julius Lemp which had just sunk the first ship of the war, the Athenia. Some reports say that they were shot down, but in fact their bombs skipped off the water, exploding under their aircraft, damaging both so that they were forced to ditch alongside their intended victim, which was undamaged.
he Anson was from 233 Squadron based at Leuchars. On the second day of the war this Anson attacked an 'enemy' submarine off the Scottish coast, in fcat the British submarine "HMS Seahorse", only to be damaged by splinters from its own bombs. It nearly made it home, but was forced to ditch in St Andrews Bay.
Versions:
In 1926 five 100 lb AS bombs had been dropped and four of them were rated as 'satisfactory' because they did not break up and did detonate below the surface. A sixth was detonated statically underwater and the fragmentation declared satisfactory. It was declared fit for service, in its MK I version, by 1928.
The Mk II, with a lighter nose and tail (and therefore better CWR) was tested in 1930 and deemed satisfactory, based on the 1926 criteria.
The Mk III followed with a strengthened suspension lug, allowing the aircraft carrying the bomb to be catapulted from an aircraft carrier without fear of leaving the bomb behind.
The MkIV had only a tail pistol and its filling was either 45 lb of RDX/TNT at 60/40 or 44 lb TNT dependng of availability,
Note that the 100lb AS bomb wasn't placed in production and issued until 1939 . Some accounts claim that the MK I and MK II were never put in production. It seems that the first production order placed in 1938 was for 50 bombs of each Mk with fIrst deliveries in 1939.
A decision was taken in 1939 to use only the Mk IV versions operationally and to keep the earlier suspect Marks as a war reserve against urgent contingency plans, pending a build up in numbers of the Mk IVs.
These bombs were not completely ineffective, but the failures did far outweigh the successes.
In 1939 Coastal Command aircraft spotted 57 U boats, attacked 40, but damaged only 8. Nonetheless, in the early days;
Two 100lb AS bombs, dropped from a Swordfish, sank U-64 in Herjangs Fjord (near Narvik) on 13th April 1940
U-55 and U-26 were both sunk or 'encouraged to scuttle' with the help of 250lb and 100lb AS bombs dropped by Sunderlands of Nos 228 and 10 Squadrons respectively, in January and July 1940.
U-46 was seriously damaged by four 100lb bombs whilst in Norwegian waters in November 1940.
Lysanders from the Canadian 111 (Army Co-operation) Squadron, RCAF Station Patricia Bay, British Columbia, were also used in anti-submaine role in 1940
The No. 5 Coastal Artillery Co-operation (CAC) Detachment (later a Flight) of the Royal Canadian Air Force (RCAF) stationed at RCAF Station Torbay, near St. John's, Newfoundland and the No. 2 Coast Artillery Cooperation (CAC) Detachment at RCAF Station Dartmouth, Nova Scotia, still used Lysanders for anti submarine patrols in 1942, equipped with AS bombs.
In fact the Lysander Mk. II serial 449 of No. 2 Coast Artillery Cooperation (CAC) Detachment made the first, and possibly the only, confirmed submarine attack by a Canadian-based Lysander, when, on the evening of 23 February 1942, it attacked and damaged U-96 , 20 minutes flying time south of Halifax harbour.
The use of sticks of AS bombs was generally dropped by Sunderland but these were usually 250lb AS - 4 under each retractable underwing rack, prior to teh introduction of the depth charges.
The inectiveness of the AS bombs was not so much due to their inaccuracy than to their fusing system
The fusing systems for those bombs provided for either an instantaneous detonation in the event of a dry hit on a submarine, or for detonation after some
timedelay if the bomb entered the water. For a variety of reasons, the shortest time-delay which could be provided was 1/2 second. A high proportion of U-boats attacked from the air were on the surface, and the most accurate attack was that at low level. Such an attack was not possible with the existing antisubmarine bombs, because, in the event of a dry hit, the resulting instantaneous detonation would cause damage to the aircraft dropping the bomb (At least one Anson and two Fleet Air Arm Skuas were destroyed by their own bombs in September 1939 alone), while, if the bomb entered the water, the 1/2 second delay caused it to detonate at too great a depth to inflict lethal damage on a surfaced submarine.
The whole issue of fusing of these bombs was a a headache - in trial done in 1934, the nose fuse was shown to effect the underwater trajectory of the bomb in an unpredictable fashion (The nose fuze was supressed on the MkIV, the standard 100lb AS bomb of the UK Coastal Command in 1940). Further trials evidenced a 40% failure rate of the No. 30 tail pistol, largely due to difficulty in guaranteeing detonation at a depth of 20-25 feet, that considered optimal for attacking a surfaced submarine.
The two Skuas were from 803 Squadron Fleet Air Arm, operating from Ark Royal. The boat they attacked was the U-30 of none other than Fritz-Julius Lemp which had just sunk the first ship of the war, the Athenia. Some reports say that they were shot down, but in fact their bombs skipped off the water, exploding under their aircraft, damaging both so that they were forced to ditch alongside their intended victim, which was undamaged.
he Anson was from 233 Squadron based at Leuchars. On the second day of the war this Anson attacked an 'enemy' submarine off the Scottish coast, in fcat the British submarine "HMS Seahorse", only to be damaged by splinters from its own bombs. It nearly made it home, but was forced to ditch in St Andrews Bay.
Versions:
In 1926 five 100 lb AS bombs had been dropped and four of them were rated as 'satisfactory' because they did not break up and did detonate below the surface. A sixth was detonated statically underwater and the fragmentation declared satisfactory. It was declared fit for service, in its MK I version, by 1928.
The Mk II, with a lighter nose and tail (and therefore better CWR) was tested in 1930 and deemed satisfactory, based on the 1926 criteria.
The Mk III followed with a strengthened suspension lug, allowing the aircraft carrying the bomb to be catapulted from an aircraft carrier without fear of leaving the bomb behind.
The MkIV had only a tail pistol and its filling was either 45 lb of RDX/TNT at 60/40 or 44 lb TNT dependng of availability,
Note that the 100lb AS bomb wasn't placed in production and issued until 1939 . Some accounts claim that the MK I and MK II were never put in production. It seems that the first production order placed in 1938 was for 50 bombs of each Mk with fIrst deliveries in 1939.
A decision was taken in 1939 to use only the Mk IV versions operationally and to keep the earlier suspect Marks as a war reserve against urgent contingency plans, pending a build up in numbers of the Mk IVs.
These bombs were not completely ineffective, but the failures did far outweigh the successes.
In 1939 Coastal Command aircraft spotted 57 U boats, attacked 40, but damaged only 8. Nonetheless, in the early days;
Two 100lb AS bombs, dropped from a Swordfish, sank U-64 in Herjangs Fjord (near Narvik) on 13th April 1940
U-55 and U-26 were both sunk or 'encouraged to scuttle' with the help of 250lb and 100lb AS bombs dropped by Sunderlands of Nos 228 and 10 Squadrons respectively, in January and July 1940.
U-46 was seriously damaged by four 100lb bombs whilst in Norwegian waters in November 1940.
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Very interesting. Have sent you a PM. Thanks.
AP1661B Vol. 1, Sect. 5, Chapter 3 says in § Identification colouring and marking
"The bomb body, with the exception of the tail adapter, is painted dark green. A red band, 1/2 in. wide, is painted round the bomb body, 1 in. from the nose end, and a light green band, 1 in. wide, 4 in. from the nose end. The tail and the transit base are also painted dark green."
"The bomb body, with the exception of the tail adapter, is painted dark green. A red band, 1/2 in. wide, is painted round the bomb body, 1 in. from the nose end, and a light green band, 1 in. wide, 4 in. from the nose end. The tail and the transit base are also painted dark green."
The regulation decribed in AP1661B was indeed passed in 1940 but introduced only very progressively with the newly maniufactured bombs. In fact, only from 1942 onwards with the MC bombs, were all British bombs manufactured with the dark green scheme.
Bombs already produced by 1940 were not repinted and remained in buff colour. This si true for the eary marks of the GP bombs, AS bombs etc..
As the production of 100lbs bombs seems to have been limited to the 1939-40 period, these bombs remained overall buff couloured.
Bombs already produced by 1940 were not repinted and remained in buff colour. This si true for the eary marks of the GP bombs, AS bombs etc..
As the production of 100lbs bombs seems to have been limited to the 1939-40 period, these bombs remained overall buff couloured.
Early manufacture 100 lb, 250 lb, & 500 lb AS Bombs were over-all yellow with appropriate stripes and markings, while later manufacture 100 lb Mk IV, 250 lb Mk IV, & 500 lb Mk IV were over-all dark green with appropriate stripes & markings. Not sure when the paint scheme changed, or if any early manufacture were repainted before issue.
Whoops!
I see Dreamk just posted the changeover period, and answered my question if any were repainted.
Whoops!
I see Dreamk just posted the changeover period, and answered my question if any were repainted.