Weapons and systems

This page lists the links to other pages which deal with the technology of war, the weapons (apart from the aircraft) which contributed to the battle, and the systems which supported them. So far we have, in various stages of writing:

Anti-aircraft guns
Barrage balloons
Luftwaffe bombs
Radar

More will be progressively added.

Anti-aircraft guns

Known popularly as "ack-ack", guns available ranged from the pintle-mounted .303 machine-guns, through to 20mm cannon, the 40mm Bofors and the 3.7-inch QF, which was the primary heavy anti-aircraft gun, the equivalent of the German 88mm, with a slightly larger calibre of 94mm.

While the Germans allocated their heavy FlaK to Luftwaffe units, anti-aircraft guns in British service, apart from light calibre weapons for local defence, were operated by the Army personnel. Organisationally, they came under the Anti-Aircraft Command, formed in 1 April 1939 under General Sir Alan Brooke.

He passed command to Maj Gen Sir Frederick Pile (pictured) in July 1939, who remained in command until the end of the war, under the general operational direction of RAF Fighter Command. The Command HQ was based in the grounds of Bentley Priory, home of Fighter Command.

After the end of the war, Sir Hugh Dowding was to say that, in theory, the Commander-in-Chief, Fighter Command was the authority responsible for settling the dispositions of all guns allotted to the Air Defence of Great Britain.

But, he said, this was little more than a convenient fiction. The number of guns available was so inadequate for the defence of all the vulnerable targets in the country, and the interests concerned were so diverse and powerful, that it was not to be supposed that an individual member of any one Service would be left to exercise such a prerogative uninterruptedly.

A disproportionate amount of his time was taken up in discussions on gun distribution, and each decision was at once greeted with a fresh agitation, until finally he had to ask that all proposals should be discussed by a small Committee on which all interests were represented. Dowding normally accepted the recommendations during quiet periods. During active operations he consulted General Pile, and the pair acted according to our judgment.

The early days

At the start of the war, the Command consisted of seven anti-aircraft divisions. At its height, it numbered over 350,000 personnel drawn from the Royal Artillery, the Royal Engineers, the Auxiliary Territorial Service (the women's branch of the Territorial Army), the Royal Marines and the Home Guard. However, at end of July 1940, the Command had only a half of the heavy and less than a third of the light anti-aircraft guns considered essential.

It was desirable to protect aircraft factories, airfields, ports, naval bases and industrial areas, but priority had to be given to the first of these. When the Germans switched their assault onto London, many guns had to be moved immediately to its defence. Despite the problems, anti-aircraft guns claimed approximately 300 German aircraft shot down during the Battle of Britain.

One of the biggest problems faced by Pile and his command was, as Dowding indicated, the shortage of quipment. At the beginning of 1940 there were only 695 heavy Anti-Aircraft guns (many of which were becoming old and on loan from the Navy) along with only 253 light guns. Command planning had projected a requirement of 2,232 heavy and 1,200 light guns

Another problem was the lack of trained manpower. The Territorial Army operationally manned the seven divisions of Anti-Aircraft batteries but lacked the necessary training required against the modern aircraft of the Luftwaffe. Many experienced men along with guns were lost during the campaigns of Norway and France so by July 1940 Anti-Aircraft Command resources were seriously stretched. For many new recruits the field of combat would become their training ground.

By July 1940 as the Battle of Britain unfolded, there were in place around the UK 355 x 4.5-inch, 620 x 3.7-inch and 230 x 3-inch heavy guns operational along with 270 x 40-mm Bofors, 135 x low-level 3-inch, 140 x ex-navy 2-pounder and 40 x Hispano 20-mm cannon low level guns for the country's defences.

Searchlights

Also within the Command were the vitally important searchlights, for which approval had been given for 4,128 Light Batteries. At the start of 1940, though, there were only 2,700 operational. Searchlights were vitally important during night-raids as they hunted for air targets by combining the use of sound and radar location.

Searchlights were deployed in single light stations at approximately 6,000 yards spacing throughout the area, but with a closer spacing in certain instances along the coast and in "gun defended areas" where the distance between lights was approximately 3,500 yards.

These lights were deployed on a brigade basis following RAF. sectors, and each light was connected by direct telephone line and/or RT set No. 17 to Battery Headquarters via troop HQ and thence to an army telephone board at the R.A.F. Sector Operations Room.

The equipment of a Searchlight site consisted of a 90cm Projector with, in most cases, Sound Locator MkIII. In some instances sites were equipped with Sound Locators MkVIII or MkIX. During the late Summer and Autumn the number of MkVIII and MkIX Sound Locators gradually increased, and VIE. equipment and 150cm Light Projectors were introduced.

Each Searchlight site was equipped with one AA light machine gun for use against low-flying aircraft and for ground defence. Operating searchlights was hazardous, as batteries became Luftwaffe targets. Many of the Searchlight Battery locations throughout southern England, during the Battle of Britain and the Blitz, had bomb craters on and around them along with an ever-increasing list of casualties

The 3.7-inch heavy gun

Developed in the late thirties from a British Army specification for a weapon between the then current 3 and 4.7 inch calibre Anti-Aircraft guns.

Research suggested that a 3.7-inch gun firing a shell of approximately 25lb weight could fill the gap. Thus, in 1933, a specification for a 3.7" gun weighing eight tons was issued. The gun had to be capable of being put into action in 15 minutes and of being towed at 25mph.

A design by Vickers-Armstrong was accepted and the pilot model passed proof in April 1936 with production being authorised a year later. The first production guns were delivered in January 1938. It was extremely advanced and complicated, yet regarded as one of the best of its type.

The first production model could fire a 28lb 94mm shell to 30,000 feet at a rate of 20 rounds per minute. It was crewed by seven men or, from 1941 onwards, increasingly by women when deployed for Home Defence.

Production was initially slow, particularly due to its complicated carriage but modifications to the design to simply it for production helped and peak production was reached for guns in March 1942 (228) and for mountings June 1942 (195).

The guns were made in the United Kingdom until 1943 and then in Canada for the rest of the war. Unlike the Germans, who used their 88mm guns as both anti-aircraft and anti-tank, the QF 3.7 was too heavy to be used in mobile warfare and was damaged by low elevation firings. The last version, Mark VI, was only employed in static positions.

The guns were normally deployed as batteries of four, either in the open or with temporary sand-bag protection or from fixed emplacements of increasing sophistication.

The fixed emplacements were most often clustered in a horse-shoe layout see left, around a command post. The battery would often operate in unison with searchlight batteries, accoustic detectors and radar.

Searchlights, which also came under the control of the Anti-aircraft command, were more plentiful than guns, nearly 4,000 being available towards the approved total of 4,128. In daylight, their crews had the important function of reporting air activity to the gun operations rooms.


Further reading

Supplement to the London Gazette of 18 December 1947: The Anti-Aircraft Defence of the United Kingdom from 28th July 1939 to I5th April 1945.

Radar

It was a German physicist Heinrich Hertz who in 1887 began experimenting with radio waves in his laboratory. He discovered they could transmit through certain materials but was affected by others. In 1904 another German Christian Hulsmeyer gave public demonstrations of his patented Telemobiloskop which used radio echoes to detect shipping to avoid collisions at sea.

In Britain and the USA physicists continued the work, but the invention was all but ignored for 30 years in Germany until in 1934 two German scientists Hans Hollmann and Hans-Karl von Willisen built the first commercial version of radar for use by shipping. The Kriegsmarine showed enormous interest and in 1935 pulse radar was invented. Eventually the Luftwaffe became interested ordering a dozen sets of what later became known as Freya

German radar had almost nothing in common with British radar as the Germans used a wavelength one tenth that of the British home chain stations. Although having lower range the system had better resolution. The Telefunken Company developed an improved version of radar that became known as Wurzburg, mainly for home defence. Radar although of immense value to the British during the Battle of Britain, was only utilised by the Germans in a limited role for tracking shipping in the Channel.

British radar came about because of a far fetched idea at the end of 1934 at the Aeronautical Research Committee under the leadership of Robert Watson-Watt (1892-1973) a radio expert he was asked about so called rumours rife at the time about a German "death ray" a magnetic weapon that it was suggested could shut down aircraft engines.

Watson-Watt dismissed this fanciful rumour and like aircraft designers Sidney Camm and Reginald Mitchell he would make key behind the scenes technical contributions to the success of Fighter Command. Watson-Watt a descendent of the 18th Century inventor James Watt, experimented with equipment that could detect long range radio signals given off by thunderstorms and discovered that these radio waves were "bounced back" to earth not only by certain weather conditions but also by the metal fuselages of the aircraft overhead.

12th February 1935 Watson-Watt and his team produced a crucial report "The Detection and Location of Aircraft by Radio Methods" that impressed the Air ministry and of particular note Sir Hugh Dowding soon to become CO of Fighter Command. Watson-Watt demonstrated his theory by having a Handley Page Heyford bomber fly along the centre line of a 150 foot radio beam transmitted by the BBC station at Daventry, the detection equipment using a cathode ray oscilloscope showed a significant "disturbance" of the signal when it picked up the aircraft eight miles distant.

An experimental unit was set up and further funding granted so that by the end of 1935 the range had extended to 50 miles and plans were drawn up to create 20 coastal "home chain" stations. By the end of 1936 the range had extended to 100 miles. By the summer of 1940, 32 stations had been established. The one drawback was that these transmitters could not detect low flying aircraft, so to fill the gap mobile units were established using a lower frequency.

Luftwaffe bombs

Bombs dropped by Luftwaffe aircraft largely comprised either high explosive (HE) or incendiary, although there was also a range of specialist bombs. The former were designed to deliver a blast effect, shattering or demolishing buildings and structures, the latter setting fire to flammable materials.

Very often the two weapons were used together, often as composite loads in the same aircraft, the incendiaries being used to exploit the opening-up effect of the HE, exposing otherwise protected materials.

Early in the war, German HE bombs (known as Sprengbombe) were often of low weight, 50kg being the most common type. Another widely used type was the 250kg, but heavier weight bombs were also used.

The type was identified by a prefix, either SC, SD or PC, according to function. The number would specify the weight in kg, so an SC50 would be a 50kg Sprengbombe Cylindrich.

In addition to type and weight designations, HE bombs sometimes carried a suffix to indicate the type of fuze or zünder employed, i.e,. mV = mit Verzögerung (with short delay action) and LZZ = LangZeitZünder (long time delay). Thus, for example, the designation SC250 LZZ identified a general purpose, high explosive bomb, weighing 250kg and fitted with a long delay fuse.

The thin-cased general purpose was called the sprengbombe cylindrich (SC). Used for blast effect, they had a relatively high charge ratio of 55 percent. Used primarily for general demolition, something like 80 percent of German high explosive bombs dropped on the UK were of the SC type.

This picture immediately above gives the relative sizes of the bombs. From front to back are the 50k, the 250kg, the 500kg (in the wooden frame), the 1000kg (nicknamed by the Germans "Hermann") and the 1800Kg (nicknamed by the Germans "Satan"). The bomb right at the back appears to be a 50kg variant.

The picture at the top has 250kg bombs being "decorated" by Luftwaffe personnel, giving some clues at to the size. The bomb is actually 64.5 in. Its filling is either 60/40 Amatol/TNT, or TNT with a variety of additives including wax, woodmeal, aluminum powder, naphthalene and ammonium nitrate. The weight of the filling is 287lbs, making 52 percent of the total weight of 548lbs.

The picture below shows a pair of 1,000kg "Hermann" bombs, in front of a wrecked He 111. The two represent the maximum bomb load for this aircraft type.

Specialist bombs used included the thick cased semi-armour piercing type, known as the Sprengbombe dickwandig (SD). These were medium cased steel weapons and, being either anti-personnel or semi-armour piercing, had a load factor of 35 percent explosive. Because of their penetration qualities they were used primarily against ships and fortifications. These also came in a range of weights, ranging from 50, 250, 500 to 1,700kg.

There was also the armour piercing bomb, known as the panzerbombe cylindrich (PC). With a thicker, armoured steel casing, as little as 20 oercent of the total weight was explosive. It was used against shipping - and especially warships - and fortifications. The heaviest used was the 1,400kg "Fritz" version.

Another air-dropped device was the parachute flare, or licht cylindrische(LC50 ). These were approximately the same size as a conventional SC50 bomb. They were used for target illumination and marking at night.

At times the Luftwaffe also purposely dropped its standard sea mines, fitted with a suitable detonator, on land targets.

By their intended recipients, these were referred to as "Land Mines", often with some awe, reflecting the amount of damage they could do. With a high charge ratio of 60-70 percent and parachute-retarded descent,  they created considerable blast damage in built-up areas.  The 1000 kg Luft Mine B was normally employed, and as such was designated Bomben B when used against land targets (see right - an unexploded version).

Below is an indication of their destructive power, evident from the size of the crater. An air burst could often demonish a complete block of houses.

Although the available HEs possessed great destructive power, perhaps the most potent bombs remained the incendiary which, dropped in profusion in 1940/41, caused millions of pounds worth of fire damage and virtually burnt out whole districts of British cities. However, since they were so often used in combination with blast bombs, the two together could be regarded as a composite weapons system.

The type used in the Battle of Britain was the tiny B1El, a 1kg bomblet known as the brandbombe, 1kg Elektron, hence B1El. The consisted of a cylinder of Magnesium Alloy (Elektron), with an incendiary filling of Thermite. These weapons, which burnt with a heat sufficient to melt steel, were ignited by a small percussion charge in the nose which fired on impact.

In an attempt to make these weapons even more effective, and to defeat the fire-fighters efforts, the Germans introduced explosive charges into the nose or tail of some incendiary bombs.

The charge was initiated either by the heat of combustion, or by a more complicated device that incorporated a delay of about 7 minutes. The various versions of this bomb included the letter Z in their designation, indicating explosive charge. Thus the standard B1El incendiary bomb fitted with an explosive charge detonated by heat was designated B1EL ZA, and that detonated by a delay B1El ZB.

The Luftwaffe used various types of containers to carry and drop small incendiary bombs and in the early part of the war these were usually expendable, aimable types, designated AB (Abwurf Behalter) or BSK (BombenSchaltKasten), holding some 36 B1Els.

Dropping was enabled by an ESAC 250/IX cartridge. The ESAC 250 is an abreviation for (in German) Elektrische-Senkrecht-Aufhangung fur Cylinderbomben 250/IX. In English, this is "an electric activated vertical bomb rack system mark IX for cylindrical bombs up to 250kg. "An He 111 bomber was equipped with eight ESAC 250s in its internal bomb bay, giving it a carying capacity of 2,000kg.

It was possible to load into the cartridge one 250kg bomb or 4 x 50kg bombs, using an adaptor. This would permit loading four BSK-36 incendiary containers. With each containing 36 incendiary devices, theoretically, an He 111 could carry 1,152 of them. In practice, it would carry a mixed load.

The original large incendiary device, the so called Oil Bomb which was known to the Germans as the flam or flammenbombe. It contained an oil mixture and a high explosive bursting charge.

These weapons, based on the 250kg and 500kg high explosive bomb case, were thus designated Flam 250 and Flam 500. They were fitted with an impact fuse which often failed to detonate. This resulted in the case splitting open to disgorge its contents without igniting, and as a result of their reliability they were withdrawn from widespread use by January 1941.

Barrage balloons

British Balloon Command was formed in 1938 under the command of Marshall Sir E Leslie Gossage (1891-1949) to protect cities and other key targets. By the summer of 1940 there were 1,400 balloons deployed, a third of them over London. Their purpose was to deter low level bombing attacks at 5,000 ft or under. The intent was to force attackers to go higher where their bombing accuracy was reduced.

This also assisted anti-aircraft units which found it difficult to track low level faster moving aircraft. Most balloons were 29ft long and 25ft in diameter and were connected to the ground by a single or series of steel cables. The maximum height of the balloon was 4,925ft the maximum height at which the cable(s) could support their own weight. The principle was that the cable(s) would act like a cheese wire cutting through the wings of aircraft bringing them down.