The Radar Room

ASV RADAR   ( Air to Surface Vessel Radar )

Here are a brief words about the development of this radar system.

AI (Airbourne Interception) and ASV radar sets were developed on parallel paths, with advances on one side often being used to advantage on the other. Unfortunately the ASV Mk I which was installed on both Hudsons and Sunderlands and was not very reliable. Early experiments with different aerials improved things no end until ASV Mk II was introduced in 1940.

The first ASV success was recorded on 30th November 1940, when a Whitley Mk.VI equipped with ASV Mk II damaged U-71 in the Bay of Biscay. By mid-1941 the ASV radar had increased daytime attacks on U-boats by 20%, and made nightly attacks possible.

Late 1942 saw ASV Mk III which gave the operator a new PPI (plan position indicator) radar tube. By May 1943 Bay of Biscay U-boat sightings improved dramatically and shipping losses decreased accordingly.

When ASV Mk.VI was introduced, it was much more powerful than the older Mk.III. It also had an attenuator fitted to reduce the radar power level (which the enemy could detect) thus misleading them into thinking that the aircraft was flying away from them.

ASV Mk.VII system was a development of the H2S radar system to try and detect a new type of U boat that was equipped with a "Schnorkel". A device that made it unnecessary for the submarine to surface to charge it’s batteries. This was an issue that ws never really solved even with the later ASV Mk.XI

B17 with ASV radar fitted

(above) RAF Boeing B17 with ASV radar aerial circa 1943

Sunderland having ASV aerials fitted
Sunderland having ASV aerials fitted

(above and left) Fitting ASV aerials to a Short Sunderland flying boat of Coastal Command.

(below) Vickers Wellington of No. 221 Squadron seen here at the Vickers-Armstrongs Ltd. works at Brooklands, Surrey, following its "stickleback" conversion from a Mark IC aircraft by fitting ASV Mark II anti-submarine radar.

Vickers Wellington with ASV Mk II
ASV MkII with L scope display
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(left) The front panel of an ASV MkII with an ‘L’ scope screen. The ‘L’ scope title meaning  two radar ‘A’ scopes back to back. This gave the joint display the ability to view the input from the LEFT hand aerial, alongside that of the RIGHT hand aerial. Hence the display had the ability to show whether a ‘contact’ was either to Port, to Starboard, or dead ahead.

(above) A sample screenshot from our ASV Mk II radar indicator showing a single contact about 2 miles out to the starboard on the 9 mile range. Sea echoes at the very bottom of the trace.