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Surveillance Aircraft “SRA–1”

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Figure 1: Golfstream III fitted with the “SRA–1”

Surveillance Aircraft “SRA–1”

In 1984 Grumman introduced the “SRA–1”, a modified Gulfstream III intended to advertise the type's adaptability to more warlike roles. The “SRA–1” featured a mockup of a Motorola “Side-Looking Airborne Modulated Multimode Radar (SLAMMR)” system in a pod under the fuselage; three dummy stores pylons under each wing, for a total of six; and small dummy pods on the wingtips for an “electronic support measures (ESM, or emitter targeting)” or other EW system. The “SRA–1” also featured a new, large cargo door, apparently not only to support getting large pieces of electronics gear in and out, but to give the aircraft a secondary cargolifter role.

SLAMMR is a long-range surveillance radar intended for use in maritime patrol, border surveillance and mapping. The aircraft installation consists of seven main subassemblies: antennas, antenna switching unit, receiver/transmitter, display processor, display, control unit and signal processor. The antenna consists of two yaw stabilised, horizontally or vertically polarised, slotted waveguide arrays. These can be mounted back-to-back within a single pod, or individually mounted on either side of the aircraft to provide an unobstructed view.

The remaining units are either pallet- or rack-mounted inside the aircraft for easy removal. The display processor provides radar timing and control functions and, based on inputs from the aircraft inertial navigation system, creates latitude and longitude references for display with the radar imagery. The receiver/transmitter contains the magnetron transmitter and the low noise receiver. The antenna switching unit directs the radiated power and received signal to either the left or right antenna.

The data can also be recorded for future use as well as transmitted to ground stations, in real time, via a radio link. The signal processor is a moving target indicator option that is available for the detection of moving targets at long range for border surveillance. By the use of this processor, surveillance can be carried out at ranges up to 148 km. A high-quality fixed target map is also available for radar mapping and geological exploration.

“SRA–1” was the start for a development of a wide programm of reconnaissance aircrafts based on bizjets. General Dynamics has developed their own concepts for a Gulfstream V EW variant, designated the “EC-37 Special Missions Aircraft (SMA)” and clearly a descendant of the “SRA–1”.