The E38 system can best be described as the grandfather of all weather radar systems and was originally known as CCWR (Cloud and Collision Warning Radar). It was introduced into service as early as 1947.
While the genesis of the system is unknown in absolute terms, the origin almost certainly dates back to 1943 and the advances in 'Magnetron' design, where both 'C' band (5cms) and 'X' band (3cms) magnetrons were developed alongside the 'S' band (9cms), which was used for H2S and AI Marks VII, VIII and X.
While 'S' band was not able to se cloud formations, on both 'C' band and 'X' band indicator screens Cumulo Nimbus cloud formations would have showed up, which at that time was an undesirable feature.
The first 'X' band set used in real numbers was "ASH" or "AN/APS-4", which was rushed into service with the Royal Navy who used it with the Fairey Firefly two-seat naval fighter, some naval versions of the Mosquito, and other aircraft. It also saw service with the RAF as the 'AI Mark XV'.
The Cumulo Nimbus cloud formations showing up on the radar screen ultimately led to an examination after the war by Messer's Llewellyn and Hooper in the TRE Physics Department (probably working under FE Jones?) who were looking for a radar, which could give Cloud and Collision Warning (CCWR) due to the high number of aircraft lost during the war to bad weather, principally in the tropics and flying 'the hump', which was the route between India and China over the Himalayas (where the Americans alone lost some 200 aircraft due to bad weather).
Llewellyn and Hooper at TRE designed and built a radar set specially to look at weather so that they could understand weather phenomena and with this set, along with meteorologists undertook a series of trials using this set in a Shorts Sunderland Flying Boat flying many of the 'Empire Routes' all of which involved tropical flights – with Singapore being one of the primary bases and they proved the feasibility of cloud detection and avoidance although Collision avoidance eluded them.
In late 1946 Bill Penley at TRE invited EKCO to join the work on 'Cloud and Collision Warning' radars due to the excellent working relationship TRE had developed with them during the war and which they were keen to maintain for new work.
The result of this was that in early 1947, WDU was re-formed at Malmesbury, initially in the high street but quickly moving to Cowbridge. Here the set - based on the TRE design quickly evolved into a production system known as the EKCO type E38, which consisted of seven modules, namely
The Scanner Unit - E31, The Transmitter/Receiver Unit - E32, The Synchroniser Unit - E33, The Indicator Unit - E34, The Control Unit - E35, The Servo Amplifier - E36 and the Monitoring Unit - E37.
Since much of the basic design and development work had already been done, EKCO were quickly able to get a E38 set built, which by the end of 1947 was fitted to a B.O.A.C. 'Hythe' flying boat (a Shorts Sunderland MkIII modified for civilian use) and used extensively for 'route trials', which not only confirmed the earlier results of the TRE team, but also set the operating parameters for the airline and crews in avoiding areas of severe turbulence and how to navigate a safe passage through such conditions.
An added bonus for the airline was the 'ground mapping' facility offered to them by the system, this proved particularly useful in inclement weather (such as flying in 7/8th Strato-cu-Cloud) and the approach to (and departure from) harbours such as Southampton and Hong Kong when visual pinpointing of ground features was impaired.
