The JSF program came under increased scrutiny this year, with cost overruns and flight test setbacks regularly making the news and attracting the attention of deficit hawks looking to make deep cuts in the defense budget. An aggressive restructuring of the program, with a revised development schedule slipping up to a year, occurred early in 2010, and another review is approaching. Against the background of the impending Technical Baseline Review of the JSF program by the Program Office, due to be delivered to the Defense Acquisition Board today, there have been a number of milestones achieved in the program.
First CV Variant Arrives at Patuxent River
While the U.S. Navy begins its celebration of the centennial of naval aviation, the shape of naval aviation’s future looks to have arrived in the form of this third variant of the Joint Strike Fighter. F-35C airframe CF-1 touched down at Naval Air Station Patuxent River, Md., on Saturday, Nov. 6, 2010 to begin its program of flight testing, arriving just a few days short of a century from the date aviator Eugene Ely first flew from the deck of the USS Birmingham.
The F-35C, planned to provide the Navy a first-day-of-war stealthy strike capability it has been seeking since the bad old days of the A-12 Avenger, has acquired new importance since the announcement by the United Kingdom that it would be acquiring the F-35C rather than the F-35B STOVL variant to serve aboard the Royal Navy’s Queen Elizabeth-class aircraft carriers.
While the F-35A and F-35B can be mistaken for each other in some flight modes due to their identical wingspan and flight surfaces, the F-35C shows some clear differences. The wing area is 35 percent larger, at 668 square feet, against 460 square feet for the F-35A and B. Likewise wingspan is 43 feet for the F-35C, in comparison with 35 feet for the other two variants. The bigger wing of the F-35C employs inboard flaps and outboard ailerons, beginning at the wing fold, for better control and slower approach speeds in the carrier landing environment, the other two variants using full span flaperons. Likewise, the horizontal and vertical tail surfaces are noticeably larger. One result of the increased wing area is an overlap (when seen from above) between the mainplane and the horizontal tail not seen in the other variants, to the extent that the inboard flaps on the F-35C have a cutout near the fuselage at the same angle as the trailing edge of the tail surfaces, presumably to preserve edge alignment.
Beefier landing gear to stand the shock of carrier landings, including a twin-wheel nose gear with catapult bar, and a more robust tailhook assembly are also noticeable, although a heavier internal structure is largely hidden by the skin.
The larger wing area carries a bonus of increased fuel tankage (around 19,750 pounds) and therefore longer range than the other two variants. How much the increased wing area will affect transonic performance remains to be seen, but it has to be said that the F-35C looks right.
Block 1 Software Airborne
The F-35’s “Block 1” avionics software has entered flight testing on an F-35B.
The foundation and first of three principal software-development blocks for the F-35’s mission systems first flew from NAS Patuxent River Nov. 5, 2010 in F-35B airframe BF-4. According to a Lockheed Martin news release, “all planned test points were accomplished” during the 1.5-hour flight.
“Getting this software up and flying in an F-35 is a big step in the process of validating our avionics system and ensuring that it operates in a way that gives our warfighters a clear advantage over any adversary,” said Larry Lawson, Lockheed Martin F-35 program general manager. “The flight went as planned, and we look forward to expanded mission systems testing in the coming months.”
The Block 1 software enables “most of the primary sensors on the F-35,” as well as “information fusion from the F-35’s radar, electronic warfare system, distributed aperture system, electro-optical targeting system and other sensors, and provides initial weapons-release capability,” according to the release.
The Block 1 software has been flying since May on Lockheed Martin’s modified 737 airliner, the Cooperative Avionics Test Bed, or CATBird, which incorporates an entire integrated F-35 mission systems suite, including an F-35 cockpit, to conduct initial in-flight software block validation before they are introduced into actual F-35s.
Flight Test Update
The F-35 Lightning II flight test program “continues to track ahead of plan on both the conventional takeoff and landing (CTOL) variant and the carrier variant (CV), while the short takeoff and vertical landing (STOVL) variant flight completions remain behind schedule,” according to a Nov. 4 Lockheed Martin news release, with “321 flights completed this year, 28 flights ahead of plan through October.”
“The F-35 flight test team completed 52 flights against a plan of 50 in October. The CTOL aircraft logged 22 flights against a plan of 17; STOVL jets flew 27 times against a plan of 28; and the CV jet flew three times against a plan of five. Additionally, the STOVL jet flew supersonically, and at Mach 1.3 has flown faster than any other variant to date, and achieved 7 gs, the highest load condition to date and maximum design gs for the STOVL” the release stated.
According to Lockheed Martin, the F-35A is 66 flights ahead of plan and the F-35C is three flights ahead of plan; the F-35B, however, is 41 flights behind plan for the year. The F-35B STOVL aircraft have been experiencing component reliability problems, specifically auxiliary inlet door hinges that have shown unexpected wear. The auxiliary inlet hinge problems caused a suspension of STOVL flight modes in September, and STOVL flight testing restarted only on Nov. 3. “F-35 program officials are pursuing a multi-faceted approach to improve tempo, including working to obtain higher levels of spare parts from suppliers to keep the aircraft in a flight-ready condition, while completing the analysis and corrective action planning to address the root cause of any issues,” according to the release. 51 flights are planned for November, with a planned total of 394 flights for 2010. On Nov. 18, the program logged its 500th flight, with STOVL variant BF-4 carrying out a 3-hour sortie to test the Block 1 software. It was the 366th flight of the year.