Atomic Weapons Research Establishment. Orford ... - English Heritage

sealing fuel tanks. During the war a small number of buildings were also added to The
Street. On the mainland a 10cm rotating radar was positioned on top of one of Orford
Castle’s towers, traces of its foundations may still be seen. In summer 1944, to counter
the threat from V1 flying bombs seven temporary ‘Diver’ batteries of 3.7-inch guns were
installed around Orford. Four batteries and associated accommodation huts were
located close to Raydon Hall, another one to the west of the town on Chantry Marshes
and two at the western end of the former Orford Ness airfield.
Post-war bomb ballistics
The association of Orford Ness with the British atomic bomb project began some
years before the arrival of the Atomic Weapons Research Establishment in 1955. To
produce an operational weapons system required a warhead, bomb casing and a suitable
aircraft. The latter two were the responsibility of the Royal Aircraft Establishment
(RAE), Farnborough, working in association with private industry. The size of the bomb
casing, and hence the aircraft that were to carry it, was dictated by the dimensions of the
nuclear device, or physics package, at its centre. The first British device was modelled
on the wartime implosion device Fat Man that had been dropped on Nagasaki in
August 1945. This was relatively large and measured about 5ft (1.5m) in diameter, and
was originally encased in relatively crude egg shaped casing. Personnel from the ARL
(variously referred to as the ‘Airfield Radio Laboratory’ or ‘Airfield Research Laboratory’)
section of the RAE Farnborough took the lead in designing the casing (Cocroft and
Thomas 2003, 238-9). Working with Vickers Armstrong they developed a casing with
far better aerodynamic performance than the wartime Fat Man bomb. During the early
1950s flight trials at Orford Ness problems were experienced dropping bombs from high
speed aircraft, as it was found that the bomb gained lift and returned back to the bomb
bay, this was solved by fitting strakes to the underside of the aircraft to disrupt the air
flow (Allen 2005). In flight, once it had left the aircraft a Blue Danube might travel on a
ballistic flight path for 19-24km.
The casing comprised three sections; a nose cone that contained a series of radars to
trigger the bomb at a given height above the ground, and to guard against jamming
these were backed up by barometric, impact and graze fuzes (TNA: PRO AIR 2/13689).
Other electrical components included batteries and turbo-generators to power the
bomb’s electrical systems. The central section housed the nuclear device, while the tail
contained additional electronics and fins which were designed spring out to their full
extent once the bomb had left the bomb bay. Most of the bomb’s electronic circuits
were designed by the High Explosives Research team at Fort Halstead, Kent, and it was
here too that some of the assembly work for the test rounds probably took place (Wynn
1994, 94). At 24ft (7.3m) in length the Blue Danube casing was far too large for the
RAF’s only jet bomber Canberra, introduced in 1949, and for the early trials a modified
Lincoln aircraft with Python turbo-prop engines was used. The trials were designed to
understand many aspects of the bomb’s performance; each series of trials was prefixed
by letter to denote its main purpose, B ballistics, E end point, F fuzes, R release, and T
temperature. Most of the casings were fitted with small explosive charges to destroy the
telemetry equipment before they hit the water, and in the later trials it is known that the
casings were not recovered (Wynn 1994, 96). During these trials numerous of aircraft
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