LOCKHEED Martin is expected to brief the UK Ministry of Defence in July on a proposed derivative of the F-117B, now under study for the US Air Force. The aircraft is being pushed as a deep-strike stealthy replacement for the Panavia Tornado GR4.

Industry sources say, that the proposed discussions, have been cleared by, the US Department of Defense, executive committee. The aircraft is aimed at the Royal Air Force's Staff Target (Air) 425 deep-strike requirement, for which the cancelled A-12 Avenger II was the most likely candidate. It was the UK's initial interest in the McDonnell Douglas and former General Dynamics aircraft which allowed "early conversations" to begin, say sources.

Senior RAF officials, however, are sceptical that the F-117 would be capable of meeting ST(A)425.

The variant to be proposed to the RAF will have a high UK content, including a predominantly GEC-Marconi-supplied avionics system, Eurojet EJ200 engines with full after burning, and possible fuselage structural content from British Aerospace. Sources say, "...we made some changes, like adding the afterburner, to give it fighter capability. It will have a performance comparable to that of the Northrop Grumman F-14D plus."

The F-117B itself will build on a F-117X technology demonstrator being "actively" proposed to the US Navy. Lockheed Martin has pushed the F-117X Sea Hawk, once designated the F-117N, without success since 1993 but now appears to be making some headway.

"At this point the programme is sold, but unfunded," says an industry source. The company stresses that the aircraft complements the McDonnell Douglas F-18E/F as a "high-end strike fighter."

The technology demonstrator proposal covers "...taking an F-117A test aircraft and developing it to do low-speed flying and simulated carrier landings, plus showing maintainability and supportability". Although the demonstrator will retain the original F-117A engines and systems, it will be heavily modified aerodynamically.

Key changes to all the proposed derivatives will be a new folding wing with a reduced sweep angle of 42¡, compared to 67¡ 30' on the present aircraft. Span will be increased from 13.2m to 19.8m, giving an approach speed of 135kt (250km/h), almost 20kt slower than at present. A horizontal tail will be added either side of the V-shaped "ruddervators", which are less raked than the current design.

The navalised F-117 would have a maximum gross take-off weight (MGTOW) of 31,200kg compared with almost 24,000kg for the F-117A. It would be powered by the same General Electric F414 turbofans being developed for the F-18E/F, but with a low observable afterburner.

Lockheed Martin's bid to the US Navy is believed to specify unit cost at $70 million, based on a production run of 255. This would be further amortised if the proposed F-117B were developed for the USAF and, possibly, the RAF.

The F-117B would have a higher MGTOW of 33,230kg and a mission radius of 1,850km (1,000nm) with a load of four 900kg weapons compared with 1,100km with 2,270kg of weapons for the present version.

Lockheed Martin's priority is the F-117X. "You will see a test aircraft on the deck of a carrier within two years. We're talking about an EMD [engineering, manufacturing and development] programme starting in 1997/8," says the source. o

Source: Flight International