Non-Metallic Gantry

Introduction

Orford Ness was the location of a non-metallic gantry built for telemetry testing. The tests were designed to determine the best locations for the internal telemetry aerials for various weapons then under development.¹ This specifically designed wooden gantry, and the associated measurements building, 90m away, were located in the Orford Ness ‘airfield’ site: tests were conducted by AWRE staff.

The strength of radio signals received during tests, each having differing orientation and frequency was used to create polar diagrams and these were then analysed by telemetry specialists to determine the optimum locations for the internal aerials within the nose cone.

The wooden gantry itself was dismantled in 1966², but the remains of the brick receiving building and the nearby metal mast** remain and are still visible to visitors from across the marshes. However, the circular concrete base itself, can only be seen using online satellite views with online mapping resources such as Google Earth, as visitor access to this marsh area is normally not allowed (in order to protect breeding birds).

Weapons programmes associated with the non-metallic gantry

Evidence suggests that the gantry was designed to test weapon aerials, but initially with no specific programme in mind. A memo dated February 1958 mentions Red Beard as a probable candidate, and also lists Blue Steel and Yellow Sun as possibles.³

Blue Streak

We have some anecdotal evidence during a 2002 visit of an Orford Ness ‘Veteran’. He had been a teenaged AWRE Scientific Assistant when part of the project team in 1960, and asserted that the gantry was used for testing telemetry aerials on the Blue Streak nose cone.

Blue Streak was a British Intermediate-range ballistic missile (IRBM) with a designed range of 4400 km. The intention behind adding Blue Streak to Britain’s independent nuclear capability was to replace the V-bomber fleet which was due to become obsolete by 1965.

Blue Streak’s design was completed by 1957, built by a consortium of specialist suppliers. The main contactor was de Havilland Propellers, with many subcontractors being involved such as Rolls Royce and Raytheon, with AWRE designing and building the nuclear warhead. The missile was 18.75m tall, 3.05m in diameter and weighed 90,000 kg. Propulsion was via two Rolls Royce RZ.2 liquid oxygen/kerosene engines that had been tested at the Spadeadam Rocket Establishment in Cumbria.

It became clear during its development that Blue Streak, as a missile, was too expensive and too vulnerable to a pre-emptive strike, even though designed to be launched from underground silos. This project was thus cancelled in 1960, with US-led Skybolt the preferred replacement.

Blue Streak telemetry was divided into two parts. The missile body had its own telemetry aerials and came under the design responsibility of RAE. The nose cone and warhead, and associated telemetry, were the responsibility of AWRE.

Orford Ness Gantry

AWRE’s engineering drawings, specifically de-classified for the IRGON researchers in 2019, showed that this non-metallic gantry with its rotating table could raise, rotate and tilt a weapon secured on various clamps or tables. The gantry,19.2m high, was designed to rotate on the 10 m diameter concrete circular base.

The AWRE drawings served as general layout drawings, and IRGON research has found that the gantry was contracted to one of the companies in the Frazer Nash engineering group, Wood Street Developments Ltd., of 34 Wood Street, Kingston-upon-Thames, Surrey. The final construction differed somewhat to the AWRE layout.

The weapon under test would have been fixed to one of three platforms, each one clamping the weapon, or different sections of it, in slightly differing ways. It was then elevated, rotated and tilted so that the strength of radio signals, transmitted in all directions by the aerials could be measured at the measurements building some 90m away. This was repeated with many frequencies, orientations and locations.

To minimise interference with the radio signals the gantry was entirely made of wood. Thousands of small wooden blocks had been glued together with different grain alignments to prevent any warping or distortion of the wooden structure. This allowed the differing design ‘tables’ or ‘clamps’ holding the nose cone to move freely within the four vertical corner columns. Necessary nuts and bolts were made from “Tufnol”, a loaded phenolic resin.

Period of Operation

We know that the non-metallic gantry was completed by Wood Street Developments Ltd in May, 1959. Some other companies were involved in the construction (C.W. Glover & Partners were responsible for the conrete foundations, and Air Service Training Ltd., of Hamble, Southampton were responsible for the superstructure, carriers and operating mechanism. The turntable base was designed to accomodate a jeep, and it was installed by Sheppard and Sons Ltd., of Bridgend.) We are not yet sure of when the gantry fell out of use; as mentioned above, it was dismantled in 1966.

A Work In Progress

IRGON’s research continues to increase our wider knowledge of this largely unknown Orford Ness facility. Valuable assistance has been provided by the Frazer Nash Archives in Henley-upon-Thames.

** We know that the metal tower was a later addition, as it is not present in 1959 photos of the installation.