Searchlight Control radar
Searchlight Control, SLC for short but nicknamed "Elsie", was a British Army VHF-band radar system that provided aiming guidance to an attached searchlight. By combining a searchlight with a radar, the radar did not have to be particularly accurate, it only had to be good enough to get the searchlight beam on the target. Once the target was lit, normal optical instruments could be used to guide the associated anti-aircraft artillery. This allowed the radar to be much smaller, simpler and less expensive than a system with enough accuracy to directly aim the guns, like the large and complex GL Mk. II radar. In 1943 the system was officially designated Radar, AA, No. 2, although this name is rarely used.
SLC Mark VI on a 150 cm searchlight being demonstrated for visiting MPs
The GL Mk. II required huge antennas to provide the desired accuracy while working at the relatively long 5 m wavelength.
This Australian Mark VI is an earlier example and lacks the IFF antenna. For transport, the antennas are stowed and moved on the same carriage. Unlimbering took the crew only a few minutes.
For contrast, the US SCR-268 radar dwarfs the searchlight it directs and required a major logistics effort to emplace.
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.
