The F-35 programme has overcome a number of hurdles during 2006, but production is finally in full flow

As Lockheed Martin's first F-35 Light­ning II accelerated down the Fort Worth, Texas runway on another taxi test before its first flight, the UK's defence procurement minister was in Washington DC signing for the next phase of the Joint Strike Fighter (JSF) programme. The past few weeks have been busy for the JSF team, but productive.

After a difficult summer, during which the programme struggled to secure funding for the transition from development to production, the last weeks of the year have seen a number of milestones.

© Lockheed Martin   
Aircraft AA-1 is not structurally representative of the production-standard JSF, but will "trailblaze" for the later test fleet

In mid-November, the Netherlands became the first of the eight international partners to sign the memorandum of understanding (MoU) for the JSF production, sustainment and follow-on development (PSFD) phase.

Last week, Australia, Canada and the UK signed up, with Denmark, Italy and Turkey to follow and only Norway expected to hold out into 2007.

The flurry of signings is the culmination of three years of tough negotiations on technology transfer and industrial participation that proceeded in parallel with the international design and manufacturing effort on the JSF.

The Lockheed JSF chief test pil­ot John Beesley took control of aircraft AA-1, the first F-35, Northrop Grumman prepared to deliver the centre fuselage for BF-1, the first short take-off and vertical landing (STOVL) version, and begin assembly of the centre fuselage for CF-1, the first carrier variant (CV).

By year-end, 10 F-35s will be "in flow", with production to start on 11 aircraft next year and 12 in 2008. This is a slower ramp-up than desired, but better than the delay to production that was threatened during the summer as US Congress debated funding for the programme. Now reports suggest the US services have been directed to fully fund planned JSF procurement in their fiscal year 2008 budget requests.

Meanwhile, the customers have begun to make their preparations for the JSF, with the US Marine Corps, the UK and Italy forming an informal users group to develop common operating procedures for the STOVL F-35B. A similar group is to be formed for users of the conventional take-off and landing (CTOL) F-35A, expected to be the most numerous variant of the JSF.

The busy end to 2006 comes five years after the Lockheed-led team won the JSF competition and was awarded the system development and demonstration contract.

At first glance, the first F-35 looks little different from the X-35 concept demonstrator that first flew in October 2000, but a major redesign in 2003-4 to reduce weight means AA-1 is no longer structurally representative of the production aircraft and is instead a "pathfinder" for design, manufacture and test.

The first "optimised airframe" F-35 - BF-1, the first STOVL aircraft and the next JSF to fly - is now scheduled to become airborne in the second quarter of 2008, having been delayed by the redesign and by difficulties manufacturing a new through-deck bulkhead introduced in the redesign.

The 150kg (300lb) bulkhead is machined from a 2,300kg ingot. "They thought they could machine it in one go, but had to throw the first three away when they warped," says Brig Gen David Heinz, deputy programme executive officer. "Now they flip it over six times."

Northrop was scheduled to complete assembly of the centre fuselage for BF-1 on 18 December, the same day that was to load the jig to start assembly of the centre fuselage of CF-1, the first CV F-35C. The centre fuselage for BF-1 will be shipped to Fort Worth in early January to begin final assembly. There it will be mated to the forward fuselage, centre wing and outer wing boxes produced by Lockheed, and the aft fuselage and vertical and horizontal stabilisers produced by BAE Systems in the UK.

BF-1 will be first of 14 production-representative flight-test aircraft - five CTOL, four STOVL and four CV - that are planned to fly by mid-2009. AA-1 is expected to act as a trailblazer for the test fleet, visiting the US Air Force test centre at Edwards AFB in California, and the US Navy test centre at NAS Patuxent River in Maryland.

The fleet will also include the Co-operative Avionics Test Bed, or CATBird - a Boeing 737-300 modified to test the mission system hardware and software before it flies in the F-35.

The CATBird is scheduled to fly this week at Mojave in California, where it has been modified by BAE's Flight Systems unit to mimic the F-35 by mounting sensors and apertures in almost exact alignment, using the same cable lengths and power systems.

Externally, the 737 has been modified with the F-35's forebody on the nose, stub wings on the fuselage sides and spine and canoe fairings to accommodate avionics boxes. Inside, the aircraft has 20 engineering workstations and an F-35 cockpit.

Originally planned to fly in July, but delayed because the modifications were underestimated, the CATBird will complete 10-20 flights of aerodynamic and structural testing before being flown to Fort Worth for installation of the F-35 mission avionics, including the Northrop Grumman APG-81 active electronically scanned array radar and other electronic and electro-optical sensors. The sequential blocks of mission-system software will then be flight-tested first in the CATBird.

By the end of September, some 65% of the first mission-system software load, Block 0.5, was complete and the integrated core processor and all sensors were running in the laboratory. "We are not far off putting Block 0.5 in the aircraft," JSF programme executive officer Brig Gen Charles Davis said at the time. Block 0.5 will fly in the CATBird first, well ahead of the first mission-system aircraft - AF-3, a CTOL F-35A - which is scheduled to fly late in 2008.

Even as flight testing gets under way, preparations for production are starting. Lockheed has delivered its proposal for the first low-rate initial production (LRIP) batch of two CTOL F-35s.

The Department of Defense had planned to buy five aircraft in LRIP 1 and 15 in LRIP 2, but Congress cut this to two and 12. As a result, production will increase from 10 aircraft this year to 12 in 2008. "That's a more gradual increase, so we will not come down the [cost] curve as fast," said Davis, adding. "Two is better than nothing."

The second LRIP batch will now comprise six CTOL F-35As and the first six STOVL F-35Bs. Production was planned to ramp up to 50 in LRIP 3, but the cuts in fiscal year 2007 and 2008 procurement have put this goal out of reach.

A new schedule has not been released, but Davis said: "We can at least double production every year." This would allow US procurement of 12 CTOL and 12 STOVL aircraft in FY09, plus the first six CV F-35Cs.

The earliest international purchases could come in LRIP 3 or 4, with the Netherlands, the UK and also Australia and Italy interested in buying aircraft for use by the integrated development and operational test team.

The slowing of production will push up the price of these early aircraft, but is not expected to have much of an impact on the average unit cost of the 2,000-plus F-35s planned, said Davis.

The JSF is scheduled to achieve initial operational capability (IOC) with the US Marine Corps (F-35B) in 2012, US Air Force (F-35A) and US Navy (F-35C) in 2013, and with the UK Royal Air Force and Royal Navy (F-35B) in 2014. Deliveries to the international partners are planned to begin in 2012, with the aircraft expected to become available to non-partners beginning in 2014.

Israel is likely to be the first non-partner, or foreign military sales (FMS) customer, with a requirement for 100 aircraft, but Spain is expected to sign a small FMS deal to get data on the F-35B for use in designing its new STOVL aircraft carrier, says John Schreiber, director, JSF international programmes. FMS briefings have been given to "seven or eight" countries, he says, including Greece, Japan, Poland and South Korea.

Plans call for initial pilot and maintainer training for all partner nations and FMS customers to be conducted at the integrated training centre (ITC) to be established at Eglin AFB in Florida.

Two additional US ITCs are planned beyond 2014 as the fleet grows, "and we anticipate one UK training centre and possible additional foreign training centres", says JoAnne Pugliese, JSF training system integrated product team lead. Several nations want to perform maintenance training in-country, she says.

Lockheed is leading development of the training system, which will use common courseware and equipment at all centres. Two main devices will be used for pilot training: a dome-equipped full mission simulator in the schoolhouse and at the squadrons and a deployable mission-readiness trainer comprising two cockpits side-by-side in an air-transportable container.

At the ITC, Pugliese says, the plan is to be able to switch each device, from one training session to the next, between any of the 13 aircraft configurations being developed for the nine JSF partner services.

A suite of maintenance training devices, including avionic systems, ejection seat and weapons loading trainers, is being designed to be reconfigurable between the different variants using kits.

Lockheed has so far selected Evans & Sutherland to supply the image generator, SEOS the displays, SGI the host computer and Boeing the digital radar landmass simulator to the JSF pilot training devices.

Contracts have been awarded to build the first set of devices for delivery to Edwards AFB, where they will be used for development and operational test pilot training. The Eglin ITC, meanwhile, is on schedule to begin pilot training in October 2009, says Pugliese.

The services are also beginning to step up their planning. A STOVL summit was held in October, involving the US, UK and Italian customers for the F-35B. "It is important to involve users, to mature operational concepts. We will do the same with CTOL and CV," says Heinz.

"The UK has a tremendous concept of how to use the F-35, which is close to how we see it," says Lt Gen John Castellaw, USMC deputy commandant for aviation. "They use the ship to get to the fight, operate from the ship as long as required, then phase ashore."

He says the USA is supporting UK work to increase the F-35B's bring-back capability - the weight of fuel and weapons which the aircraft can return to base - by performing a rolling, rather than vertical landing, at 30kt (55km/h).

It was a shortfall in vertical landing bring-back capability that sparked the extensive redesign by the STOVL weight attack team (SWAT) in 2003-4. Since then, the weight of the F-35 air vehicle has grown by about 3%, says the programme office.

Vertical landing bring-back still meets the requirement at the projected IOC empty weight, but is in the yellow "tripwire" band. "Bringback is yellow, but not outside the growth bounds where we think we have a problem," said Davis.

Other issues the team has had to deal with include clearing the helmet-mounted display (HMD) for flight, and a late change to the technology used for the projected cockpit display (PCD).

Although it is the primary flight display, the HMD will not be on aircraft AA-1 for its initial flights, but is planned to be installed during a scheduled break in flying early next year. The new touchscreen PCD is planned for delivery in time for installation on the early mission-system test aircraft.

Pratt & Whitney is working to reduce temperatures in its F-135 engine for the JSF and recover a 5% shortfall in rotor inlet temperature margin before initial service release engines are built.

The General Electric/Rolls-Royce team developing the F136 alternate engine is trying to stay on schedule for its first test despite a cut in funding in the budget.

These problems aside, the JSF is ending a challenging year, having gained valuable momentum that could serve the programme well as the US defence budget comes under increasing pressure.

© Lockheed Martin   
JSF chief test pilot John Beesley gets ready for the first flight

Source: Flight International