British Aerospace is proposing an aircraft wingtip-mounted synthetic-aperture radar to meet the Royal Navy's Future Organic Airborne-Early-Warning (FOAEW) requirement, while GKNWestland is looking at a compound-lift variant of the Westland/Agusta EH101 Merlin as an AEW platform for the RN's proposed future carrier.

BAe has carried out windtunnel tests of its Sidetrack radar on a BAe Sea Harrier to meet the requirement.

Malcolm Bird, of the strategic-marketing carriers/warship prime-contracts office in BAe's naval-systems division, unveiled Side- track details at a UK conference on future naval aviation at Lancaster University's Centre for Defence and International Security Studies.

Each wingtip pod contains a variant of the MESAR radar, developed by Siemens Plessey for use on the PAMS frigate programme. Under the concept detailed by Bird, the Sidetrack aircraft would fly in orbit at 35,000-40,000ft (10,700-12,200m), detecting air and surface threats.

The antenna would have a 120¹ azimuth average, but the radar footprint can be expanded by altering the aircraft's orbit. Raw radar data would be datalinked to the carrier in near- real-time for analysis.

Although a Sea Harrier was used for the windtunnel tests, the concept could be applied to whichever aircraft the RN operates - including the Joint Strike Fighter.

Rear Adm Richard Phillips, Assistant Chief of Defence Staff for Operational Requirements (Sea), says that the RN is considering options for its FOAEW needs to meet the increased use of stealth on hostile aircraft and missiles. These choices include conventional helicopters, the Bell Boeing V-22 Osprey tilt-rotor aircraft and unmanned air vehicles.

He says that a compound helicopter approach, which involves the addition of a stub wing, coupled with improved engine performance, offers the possibility of a step increase in speed, range, endurance, agility and altitude capability to the Merlin (Flight International 1-7 January).

Initial studies suggest cruising speeds and maximum altitudes similar to those of a tilt-rotor aircraft, says Phillips. "Compounding has potential for all future helicopters and, next year, I will be sponsoring a technology-demonstrator programme to advance the concept," he adds.

Westland says that if the demonstrator goes ahead it will use a Lynx helicopter powered by a Rolls-Royce Turboméca RTM322 engine, rather than the R-R Gem.

Source: Flight International