Radar, Air-to-Surface Vessel, Mark II, or ASV Mk. II for short, was an airborne sea-surface search radar developed by the UK's Air Ministry immediately prior to the start of World War II. It was the first aircraft mounted radar of any sort to be used operationally. It was widely used by aircraft of the RAF Coastal Command, Fleet Air Arm and similar groups in the United States and Canada. A version was also developed for small ships, the Royal Navy's Type 286.
Early units worked on such long wavelengths that the only available aircraft that was large enough to carry the antennas was this Heyford.
Avro Anson K8758, as seen from K6260. The experimental radar on K6260 made the fateful detection of Courageous and Southampton that led to the ASV efforts.
The EF50 made airborne radars practical due to their relatively small size, good frequency response, and good power handling.
The Mk. I units used an antenna arrangement similar to the Mk. II unit seen on this RCAF Douglas Digby at CFB Rockcliffe. This particular aircraft also carried an experimental high-gain antenna under the wings, which cannot be seen here.
Air-to-Surface Vessel radar
Radar, Air-to-Surface Vessel, or ASV radar for short, is a classification used by the Royal Air Force (RAF) to refer to a series of aircraft-mounted radar systems used to scan the surface of the ocean to locate ships and surfaced submarines. The first examples were developed just before the opening of World War II and they have remained a major instrument on patrol aircraft since that time. It is part of the wider surface search radar classification, which includes similar radars in ground and ship mountings.
Avro Anson K8758 demonstrated ASV in commanding fashion in September 1937.
The antenna array of the Mark II was quite large and produced considerable drag.
With the radome of the Mark III well streamlined, the Leigh light installation was also cleaned up by placing it in a retractable "dustbin".
The Swordfish mounted the ASV Mark XI radome between its landing gear.
