Guy Norris/LOS ANGELES
Northrop Grumman and the US Navy have agreed to allow the next generation carrier-landing system, the shipboard relative global positioning system (SRGPS), to be used on the company's self-funded Pegasus unmanned combat air vehicle (UCAV) demonstrator later this year.
The agreement is a crucial development in Northrop Grumman's efforts to demonstrate flying qualities "suitable for carrier operations," says programme manager David Mazur. The four-point effort is aimed at proving low-speed handling qualities equivalent to level one in a conventional aircraft, use of a simulated arrestor wire, demonstration of a next generation vehicle management system (VMS) and compatibility with SRGPS.
SRGPS is about to be installed on the demonstrator being built by Scaled Composites at Mojave, California (Flight International, 20-26 February), which is destined for flight trials due to begin at the China Lake Naval Air Warfare Center in the fourth quarter of this year. "Hopefully we will have most of the flight tests completed by the end of the year," adds Mazur who says 12 main sorties are planned.
SRGPS tests are meanwhile expected to culminate with carrier landings in April of a modified Boeing F/A-18A Hornet. Tests conducted at sea last year and earlier this month brought the aircraft close to touchdown on the USS Enterprise which is fitted with five GPS antennas and a SRGPS datalink antenna. The SRGPS is similar to the civilian Local Area Augmentation System, but includes software to compensate for deck motion and, for Pegasus, should provide sufficient navigation accuracy to position the vehicle within 200mm (8in).
Experience with SRGPS and VMS, which is being developed by Northrop Grumman and BAE Systems, will be fed into a larger, purpose-built Navy UCAV demonstrator to be built next year.
Northrop Grumman committed to Pegasus last July, shortly before winning one of two Defense Advanced Research Project Agency N-UCAV contracts. It is a concept demonstrator for Northrop Grumman's Naval UCAV which is likely to look similar to the kite-shaped, tailless Pegasus. Although the larger demonstrator's final design is not fixed, it is thought to have a span more than double the 8.5m of Pegasus. Mazur says the next vehicle will have a "bigger engine and folding wingtips". Pegasus is 8.5m long, largely built of composites, and powered by a single Pratt & Whitney Canada JT15D-5C turbofan. Mazur says that due to its high bypass ratio, and cooler operating temperatures, the exhaust duct is also built from composite. The leading edge has 55° sweep and the trailing edge is swept forwards by 35°.
Source: Flight International
