The story of the unfortunate Capital Ship Bomb and the squadron that delivered it

Youngest and most famous of the RAF’s operational frontline squadrons, No. 617 ‘Dambusters’ recently ended their last operational mission with the Panavia Tornado when they returned home from Afghanistan last week. The story of the Dambusters is well known, how the squadron was set up with hand-picked crews to perform a special mission with a weapon tailor-made for the purpose. What is less well known is the history of their immediate predecessor, No. 106 Squadron, and especially its C Flight.

No. 106 Squadron first appeared in 1917 as a reconnaissance squadron, serving in Ireland during the troubles until it was disbanded.  In 1938 it was reformed, and by the time it traded its Manchesters for Lancasters in 1942 its C Flight was regarded as the most accurate unit in the whole No. 5 Group. Guy Gibbson served as the Squadron Commander.

This is where the special missions came into the picture. The problem of how to put the heavy German surface units out of action occupied quite a lot of time and resources from both the RN and the RAF during the war. While Coastal Command had noticed that harbor raids with torpedoes could potentially damage or sink even the heaviest capital ships, they were extremely hazardous. Bomber Command, on the other hand, operated from a safer altitude, but the bombs did little damage to the heavy armored decks of the battleships and heavy cruisers. The Capital Ship Bomb promised to solve the issue. It was designed to, when dropped from a high enough altitude, penetrate the armored decking, after which it would detonate and send a heavy carbon-steel plate through the bottom of the ship.

Photograph taken from one of the RAF bombers taking part in a raid on Brest in 1941. Gneisenau and Scharnhorst are seen in the drydocks in the middle part of the picture, with Prinz Eugen in the lower part. Source: Wikimedia Commons/IWM

The Capital Ship Bomb had been in development for two years, before it was felt that it was ready for use. For its day, it was very large, and originally it was intended that the Manchester would carry it, as it was the only British bomber in service with a uninterrupted bomb-bay large enough. However, as the Manchester proved to be plagued by engine problems, a modified Lancaster seemed the obvious choice. Thus the so called Lancaster ‘Provisioning’ with bulged bomb-bay doors was born, and the best unit available was chosen to carry out the first raid on Gdynia and the half-finished carrier Graf Zeppelin. The battleship Gneisenau was also present, but was apparently only a secondary target.

On the night of 27th/28th of August 1942 four of C Flight’s Lancasters took off with a single CSB each. Guy Gibbson flew the lead plane himself, but it was to no avail. The bombs, with the large round disc in the front, proved to be almost impossible to aim accurately, and all missed their target. Instead of embarking upon a radical redesign of the shape to make it more streamlined, the whole project was more or less abandoned. The first raid also proved to be the last for the weapon.

There was however no shadow cast upon the squadron. A new special mission followed, with No. 106 being responsible for the introduction of the 8 000 lbs (3 600 kg) HC-bomb (or ‘Super Cookie’, as it was called) into service. The weapon was the heaviest bomb produced at that point, but the squadron proved that it could even be brought over the Alps, when in late 1942 they struck targets in northern Italy with it.

Loading a ‘Super Cookie’ into the bomb-bay of a Lancaster. Source: Wikimedia Commons/IWM

By this time, the famous bouncing bombs were starting to mature, and it was decided to split C Flight from its parent unit to better be able to proceed with preparations for the dambusting raid in total secrecy. C Flight became No. 617 Squadron, and, as they say, the rest is history.

No. 106 Squadron continued to serve with some distinction as a ‘regular’ bomber squadron until the end of the war, when it was disbanded a second time in 1946. In 1959 it was reactivated yet again, this time as a RAF Strategic Missile squadron, equipped with the PGM-17 Thor IRBM. In 1963, with the removal of Thor from the British arsenal, No. 106(SM) Squadron was disbanded for the third and final time.

PGM-17 Thor in RAF service. Source: Wikimedia Commons/RAF

3 thoughts on “The story of the unfortunate Capital Ship Bomb and the squadron that delivered it

  1. Gordon Wyatt

    You appear to have misunderstood the method of operation of the Capital Ship Bomb (possibly because the truth was kept secret for many years). It was actually a hollow-charge warhead (as used in most modern anti-tank rockets; but on a vastly larger scale). As such, it was designed to detonate on impact and to penetrate the target ship’s armour by a high-velocity jet of super-heated plasma and molten metal. The nose disc was purely to cover the cavity at the front of the explosive. As you say, the flat nose made it hopelessly unstable in flight: however redesign was never really an option – the diameter couldn’t be reduced without greatly reducing the warhead effectiveness (penetration by a hollow-charge warhead is a function of diameter); whilst the addition of a streamlined nose cap would probably have led to premature ‘stand-off’ detonation and dissipation of the plasma jet before reaching the ship’s armour (as with the ‘schurtzen’ used to protect WW2 German tanks from bazooka rounds). I hope that this explanation is of interest.

  2. Gordon Wyatt

    Apologies – having done some more checking, I now think that you may well be correct regarding the bombs actually used in action at Gdynia. The early trials did use a hollow-charge warhead (in 2 sizes of 45 inches and 38 inches diameters) which were statically tested against a dummy ‘Tirpitz’ deck target at Shoeburyness ranges on the Thames Estuary. However, at some point, they appear to have also tested a 38 inch diameter warhead of the type you describe, and it would appear that this subsequently became the preferred type for further development. Therefore it is likely that this was the type used at Gdynia. Next time, I will try to triple-check my facts BEFORE posting a comment!

Comments are closed.