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Rebecca/Eureka transponding radar
The Rebecca/Eureka transponding radar was a short-range radio navigation system used for the dropping of airborne forces and their supplies. It consisted of two parts, the Rebecca airborne transceiver and antenna system, and the Eureka ground-based transponder. Rebecca calculated the range to the Eureka based on the timing of the return signals, and its relative position using a highly directional antenna. The 'Rebecca' name comes from the phrase "Recognition of beacons". The 'Eureka' name comes from the Greek word meaning "I have found it!".
The system was developed in the UK at the Telecommunications Research Establishment by Robert Hanbury Brown and John William Sutton Pringle. Rebecca was essentially an ASV radar fit to a new broadcaster unit, while the Eureka system was all-new. Initial production began in 1943, and the system was used for dropping supplies to resistance fighters in occupied Europe, after delivery of the portable Eureka unit. The US Army Air Force started production in the US as well, and both examples could be used interchangeably. Over time, the Rebecca/Eureka found a number of other uses, including blind-bombing, airfield approach, and as a blind-landing aid in the BABS (Beam Approach Beacon Signal) form.
As many of the war-era systems used similar display units, the Lucero system was introduced to send the proper signals to interrogate any of these systems, allowing a single display unit of any type to be used for H2S, ASV, AI, Rebecca and BABS.
Rebecca/Eureka owes its existence largely to the efforts of Robert Hanbury Brown, an astronomer and physicist who worked with the Air Ministry's AMES group on the development of radar. During 1940, Brown had led development of a new version of the AI Mk. IV radar that included a pilot's indicator, better known today as a C-scope. This display directly represented the relative position between the fighter and its target, as if the pilot were looking through a gunsight. It was hoped that this would greatly ease the problems that the radar operators had trying to relay instructions from their instruments to the pilot, especially at closer range.
Prototype sets became available in late 1940, with the first production examples arriving in January 1941. During a test flight in February, the aircraft was flying at 20,000 feet (6.1 km) when Hanbury Brown's oxygen supply failed and he passed out. The test pilot, Peter Chamberlain, realized what had happened and quickly landed the plane. Brown awoke in an ambulance. This accident, along with the many previous flights at high altitude, aggravated an ear injury he had received at RAF Martlesham Heath in 1939, and during the spring he was hospitalized for a mastoidectomy operation in Brighton. The operation was successful, but a post-operation infection caused him to go deaf in both ears and several follow-up visits were required.
By the time he returned to the AMES research center, now in Worth Matravers and renamed the Telecommunications Research Establishment (TRE), major research on the early AI sets had ended in favour of new systems working at microwave frequencies using the recently invented cavity magnetron. Brown had missed most of the development of this system, and he was no longer allowed to fly at high altitudes, so his work on AI ended. He was instead placed in a new group led by John Pringle, a zoologist from Cambridge University, and the two began to study new applications for radar technologies.
In June 1941, Brown visited the Army headquarters at Old Sarum Airfield to see if the RAF Army Co-operation Command's School of Army Co-operation might put radar to good use. The Army Co-operation squadrons carried out a variety of missions including artillery spotting, general reconnaissance, and ground attack. He found the group was only mildly interested in radar, thinking it might make a useful device for warning of the approach of enemy fighters, but were perfectly happy using flags and smoke signals for navigation and communications. Brown then visited a military exercise involving ground attacks in close coordination with the Army, and was convinced that radar systems could be used to improve these results. However, he also came to realize that almost all such missions would be carried out by aircraft of other forces, notably the RAF, so any system they proposed would have to be mounted in those aircraft.
Pringle then arranged for Brown and himself to meet with the Commander in Chief (C-in-C) for Army Co-operation, Sir Arthur Barratt. In a long conversation, the two outlined the possibilities of radar for bombing, navigation and return-to-base roles, all of which proved to be interesting to Barratt. Barratt then stated that any system they did adopt would have to fit in single seat aircraft like the Tomahawk, which eliminated most of these possibilities. Both Pringle and Brown then focused on the use of a transponder system combined with existing radars to allow accurate bombing or delivery of supplies or troops by parachute, a role that would almost always be carried out by twin-engine aircraft or larger. If this broadcast on the 200 MHz frequency then being used by many British radars, any aircraft with aircraft interception (AI) or air-to-surface-vessel (ASV) radar could pick it up.
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Rebecca/Eureka transponding radar
The Rebecca/Eureka transponding radar was a short-range radio navigation system used for the dropping of airborne forces and their supplies. It consisted of two parts, the Rebecca airborne transceiver and antenna system, and the Eureka ground-based transponder. Rebecca calculated the range to the Eureka based on the timing of the return signals, and its relative position using a highly directional antenna. The 'Rebecca' name comes from the phrase "Recognition of beacons". The 'Eureka' name comes from the Greek word meaning "I have found it!".
The system was developed in the UK at the Telecommunications Research Establishment by Robert Hanbury Brown and John William Sutton Pringle. Rebecca was essentially an ASV radar fit to a new broadcaster unit, while the Eureka system was all-new. Initial production began in 1943, and the system was used for dropping supplies to resistance fighters in occupied Europe, after delivery of the portable Eureka unit. The US Army Air Force started production in the US as well, and both examples could be used interchangeably. Over time, the Rebecca/Eureka found a number of other uses, including blind-bombing, airfield approach, and as a blind-landing aid in the BABS (Beam Approach Beacon Signal) form.
As many of the war-era systems used similar display units, the Lucero system was introduced to send the proper signals to interrogate any of these systems, allowing a single display unit of any type to be used for H2S, ASV, AI, Rebecca and BABS.
Rebecca/Eureka owes its existence largely to the efforts of Robert Hanbury Brown, an astronomer and physicist who worked with the Air Ministry's AMES group on the development of radar. During 1940, Brown had led development of a new version of the AI Mk. IV radar that included a pilot's indicator, better known today as a C-scope. This display directly represented the relative position between the fighter and its target, as if the pilot were looking through a gunsight. It was hoped that this would greatly ease the problems that the radar operators had trying to relay instructions from their instruments to the pilot, especially at closer range.
Prototype sets became available in late 1940, with the first production examples arriving in January 1941. During a test flight in February, the aircraft was flying at 20,000 feet (6.1 km) when Hanbury Brown's oxygen supply failed and he passed out. The test pilot, Peter Chamberlain, realized what had happened and quickly landed the plane. Brown awoke in an ambulance. This accident, along with the many previous flights at high altitude, aggravated an ear injury he had received at RAF Martlesham Heath in 1939, and during the spring he was hospitalized for a mastoidectomy operation in Brighton. The operation was successful, but a post-operation infection caused him to go deaf in both ears and several follow-up visits were required.
By the time he returned to the AMES research center, now in Worth Matravers and renamed the Telecommunications Research Establishment (TRE), major research on the early AI sets had ended in favour of new systems working at microwave frequencies using the recently invented cavity magnetron. Brown had missed most of the development of this system, and he was no longer allowed to fly at high altitudes, so his work on AI ended. He was instead placed in a new group led by John Pringle, a zoologist from Cambridge University, and the two began to study new applications for radar technologies.
In June 1941, Brown visited the Army headquarters at Old Sarum Airfield to see if the RAF Army Co-operation Command's School of Army Co-operation might put radar to good use. The Army Co-operation squadrons carried out a variety of missions including artillery spotting, general reconnaissance, and ground attack. He found the group was only mildly interested in radar, thinking it might make a useful device for warning of the approach of enemy fighters, but were perfectly happy using flags and smoke signals for navigation and communications. Brown then visited a military exercise involving ground attacks in close coordination with the Army, and was convinced that radar systems could be used to improve these results. However, he also came to realize that almost all such missions would be carried out by aircraft of other forces, notably the RAF, so any system they proposed would have to be mounted in those aircraft.
Pringle then arranged for Brown and himself to meet with the Commander in Chief (C-in-C) for Army Co-operation, Sir Arthur Barratt. In a long conversation, the two outlined the possibilities of radar for bombing, navigation and return-to-base roles, all of which proved to be interesting to Barratt. Barratt then stated that any system they did adopt would have to fit in single seat aircraft like the Tomahawk, which eliminated most of these possibilities. Both Pringle and Brown then focused on the use of a transponder system combined with existing radars to allow accurate bombing or delivery of supplies or troops by parachute, a role that would almost always be carried out by twin-engine aircraft or larger. If this broadcast on the 200 MHz frequency then being used by many British radars, any aircraft with aircraft interception (AI) or air-to-surface-vessel (ASV) radar could pick it up.