The Sentinel R Mk1 Airborne Stand-Off Radar System (ASTOR=Airborne Stand Off Radar) will provide a long-range, battlefield-intelligence, targetimaging and tracking radar for the RAF and the Army and will have surveillance applications in peacetime, wartime and in crisis operations. The prime contractor selected to provide the ASTOR system is Raytheon Systems Limited, using the Bombardier Global Express aircraft as the air platform. The system comprises three basic components, or segments.
The first segment is the air platform, a modified twin-engined Global Express business jet, called the Sentinel R Mk1 Aircraft by the RAF, equipped with a radar system capable of both Synthetic Aperture Radar (SAR) and Moving Target Indicator (MTI) functions. The SAR will enable allweather, day and night reconnaissance and surveillance to be carried out; the MTI will enable the operators to monitor the activity of mobile ground targets. The second segment is the transportable and mobile ground stations that will process, analyse and exploit the information data-linked by the air platform and present it in a variety of formats to commanders, tacticians and weapons operators on the battlefield. Finally, the support segment provides important mission-support functionality such as mission-planning and mission-data reply at the main operating base at RAF Waddington or for subsequent deployment.
A two pilot flight-deck crew will operate the aircraft, with a mission controller and two air-imagery analysts forming the rear crew. The aircraft, currently in production as an ultra-long range business jet, will be modified to include a radome under the forward fuselage to house the radar and datalink antennas, and a radome on the upper fuselage to house the SATCOM antenna. The aircraft can operate at up to 50,000ft, with a ferry range in excess of 5000nmls and with a mission endurance of over 14 hours. The engines used by the ASTOR aircraft are the Rolls-Royce Deutschland (RRD) BR710 engines, which are the same as those used on the Nimrod MRA4 maritime patrol aircraft. Defensive aids will include a radar warning receiver, a missile warning system, a towed radar decoy and chaff and flare dispensers.
The radar is an upgraded version of the Raytheon ASARS-2 radar used on the U-2 aircraft and will be capable of providing high resolution images of the battlefield at ranges of several hundred kilometres and from altitudes as high as 47,000ft. The SAR aspect of the radar will provide high-quality images of the area surveyed, while the MTI aspect will simultaneously track moving vehicles operating in the area. The SAR can be operated in spot mode to identify and track the direction and speed of specific targets, or can be switched to swath mode to provide a large number of picture strips which join together to form a detailed image of the surveyed area. These images can be exploited by the airborne mission crew or transmitted in real time via secure data-links, satellite communications or ground networks to mobile or transportable ground-based processing stations, which display them as visual images for inclusion in reports transmitted to land force and/or air commanders.
Airborne Stand Off Radar (ASTOR) is due to enter RAF service in 2005 when it will become the most advanced long-range, airborne-surveillance system of its kind in the world. Five Sentinel R Mk1 Aircraft will be purchased and operated by No 5(AC) Squadron, based at RAF Waddington, where they will form one arm of the UK surveillance triad of Sentinel R1, E-3D Sentry and Nimrod R1.
Sentinel R Mk1 Specifications
Powerplant: Two RRD BR710 turbofans
Wingspan: 28.65m (94ft 3ins)
Length: 30.3m (99ft 5ins)
Height: 7.57m (24ft 10ins)
Max T/O weight: 42,500kg (93,500lbs)
Max endurance: 15hrs (internal fuel)
Max speed: Mach 0.88
Max altitude: 51,000ft
• Long-range, battlefield-intelligence airborne radar aircraft for the RAF and the Army.
• Full day or night capability with a radar able to penetrate cloud, rain or smoke.
• Stand-off capability of several hundred kilometres, at altitudes up to 50,000ft.
• Provides high quality, radar ground images and tracks mobile targets.
• Near-real-time, secure data-link transmissions to mobile ground stations.
• Forms one arm of the ISTAR triad of Sentinel R1, E-3D Sentry and Nimrod R1.