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Vast and Rotor

Page history last edited by Alan Hartley-Smith 2 months, 1 week ago




This is an extract from a paper by E-R on the Marconi background and involvement in the specification and realisation of these projects:


When, in 1948, the Government realised that there was an urgent need to re-establish the UK radar defence system of the UK, with performance improvements, it was essential for them to turn to industry as the large majority of radar-experienced people were, by then, in industrial firms (the radar experienced staff in the combination of EECo and MWT was significant).  In short, this resulted in them turning to MWT to augment the very limited resource in TRE.  A major study contract was placed with the Marconi Co. under Dr E. Eastwood, who had been transferred from English Electric to MWT. The final Study Report, issued on 29th April 1949, recommended a multi-stage programme (See Chapter II p.48/50 ‘The required new Radars’ and Appendix G of “Watching the Skies” - J. Gough -HMSO)


A copy of this report has now been found and is available here

[NOTE:- Dr Eric Eastwood (later Sir Eric Eastwood) - had returned to EECo, from advisory service to HMG and the RAF, and then transferred to MWT as Deputy Chief of Research of the Marconi Research Labs. at Great Baddow. In 1950 he became Chief of Research - later MWT Director of Research and then, after the GEC-EECo merger, Director of Research for the whole of the GEC Group.]

The Eastwood Study Report included eight particularly important recommendations which were to have a dramatic impact on the radars and business within Marconi’s.

As far as I can recall these were:-
1)  That, rather than just re-engineering the Type 7 (1.5m wavelength = 200 MHz.) equipment it was recommended that it should have a completely  revised antenna and be equipped with an entirely new transmitter of at least ten times the power of the wartime unit (less than 40kW. increased to 400kW. or more).
2)  That the static Type 13s & 14s should be re-engineered with a new turning equipment, hydrogen thyratron modulator and improved receiver and duplexing sub-system and  antennae.
3)  That larger, more flexible and more comprehensive displays with improved brilliance and persistence should be developed immediately. That a second phase should be put in hand, as soon as possible, to develop a system of fixed-coil displays capable of comprehensive inter-trace marking to permit console-to-console target indication and to permit simultaneous display of radar data from more than one radar head. The ultimate aim being simultaneous display of geographically displaced radar heads and the addition of on-screen data provision.
4)  That the re-engineering of the wartime coherent 600MHz (or 50cm band) Type 11 should be completed with a new high-power transmitter and that it should be equipped with MTI. (Moving Target Indication - the signal processing system which was intended to cancel out all radar returns which did not have the characteristics of a moving aircraft - this type of processing had been started by TRE during the war.)
5)  That the development of equipment to exploit the additional radar frequency band of 1215 to 1365 MHz (often referred to as “the 23cm band” but formally designated L-Band - later NATO designated D-Band) should be commenced.
6)  That study work should be started with the aim of finding a means of exploiting the jamming signal to accurately locate the plan position and plot the energy source.
7)  That, in view of the UK experience of the German V2 and the fact that some German rocket experts had been taken to Russia, there should be serious consideration of the defences required to deal with the ICBM. Under this heading it was proposed that the 400MHz frequency should be studied for ICBM tracking.
8)  That the development of a static Type 14 replacement with a much larger antennae and a much higher power transmitter should be put in hand as soon as resources became available.

The contract that was placed ( March or early April 1949) was for re-engineering of the mobile radars AMES Types 13, 14 and 15 (a mobile version of Type 7), complete with a new mobile display and information handling system (The system designated AMES Types 21 & 22 convoys). This to be carried out, and taken through to full production (a total of over 1000 complete radars !), on a crash time scale. This contract was code named Project VAST. The design aims set-out for the re-engineering of the radars, by the Ministry, were based on a draft of the Study Report part made available in (about) January 1949.

In the autumn of 1949 a further contact was placed on MWT to implement most of the recommendations, in part or in full, of the April Study Report under the code name ROTOR using as much of the VAST equipment as possible for the early stages of the static installations.  This to fulfill the appropriate aspects defined in the April Report (i.e. Types 13 & 14 but without the mobile aspects plus the Transmitters & Receivers of the Type 15 for static application in the improved Type 7).

[NOTE:- While Jack Gough’s “Watching the Skies” contains a very great deal of the history of the period comprehensively, unfortunately the book also contains many errors and omissions.  These include the statement that the first major implemented contract was for the static radars of ROTOR. This was not the case as HMG placed the priority on mobile radars and the first implementation contract placed on MWT was code named VAST.  However, the ROTOR contract followed months later and this, while in line with Study recommendations, was based in many respects on the adaptation of the equipment already well under development for VAST. However, the “Technical improvements to the radars”  given in Appendix G are materially correct for Types 13 and 14 - (the new Tx's were  500 KW peak at 2 microseconds. 250 or 500 prf.) and Type 7  (Tx at 450 KW peak at 5 microseconds pulse at 250 prf. - Rx nf. = 7-8dbs) {All achieved by the electronics being developed for the Type 15 system}. 


The Study Report specifications, for all the electronics of the sensors, were met in full.
Because of the considerable magnitude of the task it was necessary to break down the work to fulfill the appropriate aspects defined in the April Report. The work within MWT was divided approximately as follows:


Eastwood Report
Item 1 to Radar Development Group (RDG) - new antennae by Marconi Research (MR).
     “  2     RDG
     “  3     Phase 1 - RDG,  Phase 2 - MR
     “  4     New 400-500 Kw. Tx and Rx and MTI system - RDG, Antennae - MR
      “ 5     Initially - MR, Later transferred to RGD
     “  6     MR
     “  7     MR
     “  8     MR

RDG was a new Group set up in 1949.  After a few months it was moved to a separate, newly-purposed and refurbished, site at Broomfield on the outskirts of Chelmsford while Marconi Research was on the other side of Chelmsford at Great Baddow.

MWT was specified as the Prime Contractor for all the work involved to implement VAST and ROTOR. However, because of the very considerable resources required to implement the programme, it was proposed that the production should be shared around British Industry. Eventually over 100 firms (large and small) were involved with the final systems being brought together and proved by MWT.

By 1952 complete Type 13s and 14s were in production and full equipment was on trial with the RAF.


News clipping


Rotor 1

Rotor 2

Rotor 3

Rotor 4

List of Rotor sites

Details of typical site


Interesting note from Roy Simons

Interception aids
During the latter part of World War II, with the availability of plan position indicator  displays,  transparent overlays were provided to interception controllers to help them optimise the track of the fighter towards the hostile target and in particular to give instructions to the pilot when to make his turn.  I have given an RAF version of this aid, in its case to Sandford Mill.

With the implementation of the new displays as part of the ROTOR system and the expectation that both hostile and fighter aircraft would be flying at speeds approaching Mach 0.9 at 60,000 feet a new aid was required. The problem with such high-speed aircraft is that should the hostile manoeuvre immediately after the plot data input from the radar, which was at four per minute, simple dog-chase systems were not useful.

At Baddow we were commissioned to devise an aid which could be applied to the Consoles type 64 and which after every plot, assumed that the target had made the most significant manoeuvre away from the normal track. We were provided with the engine performance and flight performance of the P1A aeroplane and that expected of the P1B and had discussions with the test pilots at Warton (WCdr Beamont) and also on interception tactics at Central Fighter Establishment at West Raynham in Norfolk.

The P1A which had Armstrong Siddeley engines which I saw and the  P1B which was to have Rolls engines had to turn and use an energy climb approach to the target, and be at the firing position, as they did not have much manoeuvrability at this altitude. When the P!B went into service as the Lightning it was fitted with a rocket pack which gave much greater flexibility.

As a result of considerable analysis by people in the theoretical sciences laboratory at Baddow  (Norman Huttley) a family of curves was produced which could be overlaid on the display and would take account of the optimum flight path of the fighter aeroplane assuming that the hostile had made its maximum manoeuvre.

I have a set of these curves but I’m not sure that they were ever used



Experimental L-band radar at Bushy







Comments (1)

Ian Gillis said

at 10:21 pm on Feb 15, 2016

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