Ramon Lopez/WASHINGTON DC Graham Warwick/SEAL BEACH

The US Navy successfully tested the Shipboard Relative Global Positioning System (SRGPS) late last month using a modified Boeing F/A-18A Hornet strike aircraft flying from the USS Theodore Roosevelt (CVN71).

The navalised Raytheon Joint Precision Approach and Landing System (JPALS) sea trial follows a dress rehearsal on CVN71 in January and land-based flight trials at NAS Patuxent River last year. They also come after a UK Royal Navy SRGPS evaluation a year ago involving a Type 23 frigate and an EH Industries Merlin, which considered how JPALS could assist high sea-state helicopter recovery.

A pending US-UK memorandum of understanding calls for JPALS trials with a Royal Navy BAE Systems Sea Harrier in 2002-3. The UK is acquiring the automatic landing system along with the Joint Strike Fighter.

In the latest SRGPS flight trials, 10 fully automatic approaches were conducted, showing a vertical accuracy of 0.3m (1ft). Development of the joint autoland system is being led by the USAF, which is responsible for the fixed- base, tactical and special mission variants. The USN is responsible for the shipboard version, incorporating a two-way UHF datalink.

The ship measures its GPS position, adds its roll, pitch, yaw and forward motion and transmits this to the aircraft, which passes its GPS position back to the ship. The system will be used for air traffic control, replacing TACAN navigation beacons and the USN's present radar-based shipboard precision approach system on aircraft-capable USN warships by 2008.

In 2002-03, additional flight trials are planned using a Sikorsky SH-60 and naval unmanned combat air vehicle (UCAV-N) demonstrators built by Northrop Grumman and Boeing for the US Defense Advanced Research Projects Agency's (DARPA) UCAV-N programme.

The company says its UCAV-N demonstrator will be a scaled-up variant of the diamond-planform Pegasus. The larger, which must carry a weapons load internally, will require a 5,000-7,000lb-thrust (22.3-31.2kN) powerplant. Pratt & Whitney and Rolls-Royce turbofans are UCAV-N candidates.

Boeing has taken the wraps off its UCAV-N design, which resembles a "mini" Northrop Grumman B-2. Boeing's UCAV-N demonstrator will be larger and longer range than the DARPA-USAF-Boeing X-45 as the navy's requirement is for a platform for surveillance missions as well as strike and defence suppression.

DARPA plans to award Phase 2 contracts to Boeing and Northrop Grumman in December to build and fly test demonstrators.

Source: Flight International