P-site, liquid propellant test stands and ancillary structures at SP7099717449, designed in 1948 with later alterations and additions.
Reason for Listing
P site, a liquid propellant test site of late 1940s date at the former Westcott Royal Ordnance Establishment, is listed at Grade II for the following principal reasons:
* Rarity: with the Westcott test-stands at A-B and C-D sites, the only surviving 1940s test-stands nationally from the pioneering phase of rocketry research and development;
* Fabric: two complimentary stands with P1 surviving in its original late 1940s form whereas P2 has been modified for later important research programmes. They are the largest liquid propellant test-stands on the Westcott site. The survival of ancillary buildings for P-site aids understanding of its function;
* Intactness: P1, although backfilled, survives as originally built;
* Technological interest: P2 stand is associated with two of Britain's major missile programmes - the development of Blue Streak, Britain's only Intermediate Range Ballistic Missile which was later adopted for Europa 1 (space rocket), and the top-secret Chevaline (the improved Polaris missile) development programme;
* Machinery: P2 retains much of its control room equipment from its highly significant Chevaline test era;
* Group value: with A-B and C-D sites at Westcott, representing the primary 1940s test-stands at the site. Also group value with later test stands, including those for solid propellants. Westcott is the most significant site nationally for rocket propulsion research and development and the test stands collectively express through their form the technological advances in this field in the second half of the C20.
Westcott has been synonymous with rocket research and development since the mid 1940s. The Second World War saw this work take on a new urgency given Germany’s success in developing the devastating V1 and V2 missiles. After the cessation of hostilities, the importance of German rocket research was fully realised and incorporated into British programmes. The Guided Projectile Establishment opened at Westcott in 1946 and, until 1948, German scientists, classed as special internees, were relocated there to continue their research into liquid propellants alongside their British counterparts. Early research concentrated on liquid bipropellants for rocket engines (using liquid oxygen, hydrogen peroxide and nitric acid oxidisers) with solid propellant research beginning in 1949 (using solid fuels such as extruded cordite and plastic propellants).
In the early post-war years and renamed the Rocket Propulsion Department of the Royal Aircraft Establishment (RAE), Westcott continued research into liquid propellants alongside the Waltham Abbey experimental station. In the early 1950s all work connected with this programme was transferred to Westcott as the large remote site with its specialised and purpose-built facilities allowed rockets to be tested and fired, although not launched.
In the late 1950s the liquid propellant motor for the Blue Streak missile (the RZ2) was developed at Westcott and went on to be used in the Europa 1 space rocket launch vehicle. Naming most of their rocket motors after birds the scientists at Westcott developed many successful engines which were used variously in upper atmosphere research programmes (the Raven) and for the Black Knight research rocket testing re-entry into the earth’s atmosphere (the Cuckoo). Smaller missile programmes were designed and built in Westcott between the 1960s and 1980s including Blowpipe and Seawolf. Large missile programmes, such as Polaris in the 1960s and Chevaline in the early 1970s, were also developed there and are perhaps more widely known. In 1977 Westcott and the Waltham Abbey research station were merged to form the Propellants, Explosives and Rocket Motor Establishment.
Westcott remains at the forefront of liquid propellant rocket motor research and development with, for example, its LEROS liquid engine used in the Mars missions of the late 1990s.
The P site test stands, the largest liquid propellant firing points on the Westcott site, were originally built in the late 1940s for testing liquid fuel rocket motors, initially the Research Test Vehicle 1 (RTV1). The stands were designed by J C Clavering, Ministry of Works, in 1948 and were significantly different in layout and form from their predecessors, responding to the fatal accident at D stand in November 1947. Principally the design improved the safety of the test stand for its scientists with the firing bays observed through periscopes rather than directly through observation windows, and the control room facilities separated from the stands in the form of semi-sunken blockhouses. Traverses, or earth bunds, separated the various components providing additional protection.
Aerial photographic evidence indicates that construction was underway at P site in July 1949 although not finished. Subsequent aerial photographs of 1952 show the site to be complete. One stand, P1, remained unmodified and survives in its late 1940s form. It was built for the research test vehicle RTV2 and the full missile, which would have been lifted up the ramp by crane, was fired here (pictures survive which illustrate such tests). Whereas the engines only could be tested at A, B, C or D stands, P site was a good location for this full missile test-firing given its remote location, as the fuel made this a highly dangerous operation.
P2 was the subject of two main phases of modification, the first being in 1955 to enable the vertical testing of the Rolls Royce RZ1 engine which was test fired approximately 500 times at Westcott. Maxwell (1993, 287) suggests that it was then subject to minor modifications to enable the development of the modified version RZ2 engine designed to power the British Blue Streak intermediate ballistic missile. (This burnt a mixture of liquid oxygen and kerosene and produced a thrust of 150,000 lbs.) However, there is some dispute as to how much of the RZ2 tests took place at Westcott, Maxwell (op cit) indicating that testing began here in May 1958 and that the RZ2 was test-fired in excess of 500 times by April 1960, whereas a former employee asserts that all RZ2 test firings took place either at Anstey (Coventry) or RAF Spadeadam (Cumbria). Either way, by April 1960 the Blue Streak programme had been cancelled (although Blue Streak was later adopted for the first stage launch vehicle for the European Launcher Development Organisation's (ELDO) Europa 1 rocket and the test-firing for this later incarnation was certainly accommodated in purpose-built facilities at Spadeadam).
A drawing of the modified P2 test-stand at P-site can be found in Cocroft (2000, 258) and in Hill (2001, 27). In its latest modification, from the mid-late 1970s to 1980s, it was used as a drop-test facility for the Chevaline missile programme (the more mobile and sophisticated successor to the Polaris missile) to ensure the safety of various components. At this time the flume channel was partly filled in and the upper stage of the 'tower' added. The tower was partly functional and partly to hide the top-secret Chevaline research taking place here.
ANCILLARY BUILDINGS: to the north-west of the stands is Building 304, a bi-partite building providing site security (an extension built at some time between 1961 and 1994) and an instrument store (built pre-1952 and therefore presumed to be original). Between the two stands is Building 302 (not of special interest) which is presumed to have functioned as the site support workshop.
At the base of P2 are currently (2013) stored fragments of a 1/6th scale missile silo for Blue Streak. While of undoubted historic interest these items are not fixed to P2 and are not therefore included in its listing.
MATERIALS: Reinforced concrete, sheet metal, steel girders, earth bunds, brick.
DESCRIPTION: P site is located close to the northern edge of the test area and comprises two test stands, P1 and P2 with P1 to the north-east and P2 to the south-west.
P1 remains in its late 1940s form, an open-roofed firing bay shored by sheet piles with steel girder edging. It was backfilled in the mid 1990s thus preserving its form. The firing bay is protected by a large earth traverse which incorporates discreet fuel bays (to keep the oxidant and fuel separate) and a semi-detached observation bay allowing viewing of the test by periscope. There is a channel for collecting spent fuel and a further channel for directing the test flume. Also surviving is the ramp allowing access to the top of the test-stand (and via which the test vehicle or missile would have been lifted into the stand by a crane). The control room (Building 301) is south-east of the stand. It is still accessible and takes the form of a sunken rectangular reinforced concrete building with a flat roof, protected by concrete retaining walls and the earth traverse. This design, with greater separation between the firing bay and the observation and control areas, was in direct response to the fatal explosion at D stand in November 1947.
P2 was originally of identical form to P1 - an open-roofed firing bay protected by a substantial earth traverse - but unlike P1 it has experienced later modification and its three phases of build are visible externally. It was originally heightened in the late 1950s to allow testing of the rocket motor for Blue Streak. The upper stage and roof, clad in corrugated sheet, is from its drop-test incarnation of the 1970s and 80s for Chevaline. Probably because it has remained in use until more recently, and has avoided the infill of its pair, it is a more immediately legible structure with, for example, the ramp to direct the test flume visible as well as channels allowing run-off to nearby settling ponds. As at P1, the loading ramp allowing access to the top of the stand also survives. Internally are partial floors and connecting ladders. The semi-detached and semi-buried control room (Building 303) is to the north-west of the stand. It is the same form as 301 and retains some machinery although this is not of 1950s date but is from its drop-test incarnation. The holes for the original observation periscopes survive. The 1950s and later modifications add interest to the structure, given the significance of the programmes for which it was modified.
A drawing of the P2 test stand (see both Cocroft 2000 and Hill 2001) shows the main test chamber, the deflector bucket below the chamber (to deflect the flume on firing) as well as ancillary equipment for the storage and transfer of high pressure gas and fuel. Photographs in the site archive show the P2 stand under various test firings from the mid to late 1950s and therefore chart the modified super-structure.
ANCILLARY BUILDING: to the north-west of the stands is Building 304, a bi-partite flat-roofed structure of red brick to the north-east (formerly site security - this part of the building is not of special interest) and of reinforced concrete to the south-west (former instrument store). This was not internally inspected.
Listed building text is © Crown Copyright. Reproduced under licence.