The F-35 Gets Real

March 1, 2004

The new F-35 Joint Strike Fighter is transforming from a “paper” airplane into a “real” airplane. The shift got underway in November, when the fighter subcontractors began fabricating the first actual airframe components. This is always a tense time for a big procurement program, but F-35 officials are confident that they will keep development turbulence at a minimum.

The changeover has not been without its rough spots, however. What had been a nearly problem-free program began to experience some difficulties. The F-35 for years had seen little or no cost, schedule, or design problems, but, in recent months, it has seen some of each—for example, unanticipated weight growth.

The Air Force and prime contractor Lockheed Martin are not exactly novices at handling fighter growing pains. They have the recent experience of bringing in the F/A-22 Raptor, a highly complex aircraft. Lessons derived from the Raptor’s past difficulties with avionics and aerodynamics will be applied to the new strike fighter, enabling program officials to head off many problems before they occur.

The F-35 is also benefitting from the Raptor’s technology—primarily in the areas of avionics, propulsion, and stealth. Some 30 percent of the mission software in the strike fighter’s avionics comes from the F/A-22, said Tom Burbage, executive vice president at Lockheed Martin and JSF general manager. Reuse of that code will reduce the nominal cost of the F-35 program by roughly $400 million, said Burbage.

The F-35’s Pratt & Whitney F135 engine, which will be installed in the initial production aircraft, is derived from the F/A-22’s PW F119 power plant, and program officials say the engine has performed flawlessly so far. An alternative engine, the General Electric F136, will be introduced around the fifth production lot. Thereafter, the two engine makers will compete for annual sales. The two engines will be functionally identical to ensure either engine can be used at any time.

The strike fighter program also has benefitted from USAF and industry F-117 and F/A-22 stealth technology experience.

Ambitious Effort

The F-35 program is the largest Defense Department acquisition effort ever. It’s an ambitious undertaking to replace thousands of legacy fighter and attack aircraft with three highly common variants of a single fighter.

The Air Force, Marine Corps, and Navy each have their own variant. The three JSFs are designed with maximum commonality in mind, to simplify and streamline development, supply, and maintenance.

The Air Force’s F-35A will be a conventional takeoff and landing (CTOL) version to replace F-16s and A-10s. The Navy plans to replace F-18A/Cs and introduce stealth into its fleet with its carrier variant (CV) F-35C. The Marine Corps version, the F-35B, will be a short takeoff and vertical landing (STOVL) aircraft to succeed its elderly AV-8 Harriers and early F/A-18s.

Each F-35 is expected to be able to perform all the missions of the legacy aircraft it replaces.

For the Air Force, the role of the JSF may become more a function of training specialization or commander requirements.

“How we decide to employ that [aircraft], as a service, is going to be up to our leaders of the time,” Col. Daniel Conroy, chief of Air Combat Command’s JSF management office at Langley AFB, Va., said in an interview.

“Right now, you’ve got F-16s that do SEAD [suppression of enemy air defenses] only, you’ve got F-16s that concentrate on interdiction, you’ve got the A-10 in the CAS [close air support] role,” explained Conroy, adding, “You could design … all those capabilities in a single squadron.” Then, he said, a combatant commander “can roll [the F-35] into his warfighting effort any way he wants to.”

Alternately, Conroy said, USAF could decide to continue to organize squadrons the way it does today, developing different mission expertise in specific squadrons.

The US military needs the Joint Strike Fighter primarily in an air-to-ground role. The Air Force plans to use it to complement its new F/A-22 fighter. Likewise, the Navy wants a similar complement for its new F/A-18E/F.

The JSF will also have an aerial combat capability, due largely to another unique aspect of the program—extensive international cooperation in the development of the aircraft. To fulfill the needs of the JSF program’s international partners, the F-35 will have “a reasonable, inherent air-to-air capability,” said Air Force Maj. Gen. John L. Hudson, JSF program manager.

The program’s international partners (Australia, Britain, Canada, Denmark, Italy, the Netherlands, Norway, and Turkey) want a true multirole aircraft—for everything from close air support and suppression of enemy air defenses to aerial combat. They are contributing to the program’s development phase, in exchange for input into the design and preferential consideration for their national suppliers.

The partner nations have varying input into the program, based on the level of their financial support. The US will receive more than $4 billion from these nations to help develop the F-35.

Britain was the first international participant in the program and, as the leading partner, has significant input into the design. Britain plans to procure 150 STOVL versions for the Royal Air Force and Royal Navy to replace the GR7 and the Sea Harrier.

Britain is already making plans based on the JSF’s advanced capabilities. The strike fighter is “extremely important to us,” said Air Chief Marshal Jock Stirrup, Chief of the RAF. In an interview last fall, Stirrup said the RAF envisions the JSF will perform most of the “heavy lifting” in well-defended zones because of its stealth characteristics. Meanwhile, the RAF’s Eurofighter Typhoon fleet will operate in a standoff role in the early days of a conflict.

Britain expects the JSF “to mount offensive air operations from either afloat or ashore,” Stirrup explained. “Hence, we have formed what we call Joint Force Harrier … under a single command, RAF’s Fighter Command.” This unified force, now flying Harriers, will later migrate to the JSF. That will give Britain “a powerful, precision attack capability,” he said.

The F-35 will bring a “leap in technology” and be “one of the more flexible fighters,” said Conroy. It will also have a “range that will exceed any of our legacy fighters,” he added.

That technology leap creates a minor concern for the international consortium. Some participants have said that technology transfer has been too difficult—an issue the program office continues to work.

“Access to sensitive US technology is always a concern and needs to be treated with the utmost care,” said Jon Schreiber, JSF’s director of international programs.

Schreiber said partner nations have been assured they will receive an aircraft, at the end of the day, that meets their national requirements and that is “not only superior from a performance standpoint, but one that is more affordable from a life cycle cost perspective and [which] can be operated and maintained [abroad].”

Affordability has been a central theme from Day 1 for the JSF program, which has been billed as “the affordable solution” both from a sustainability and up-front cost perspective.

In the year since Air Force Magazine reported that the F-35 program had reached its first major development milestone with cost and schedule on track, development cost has risen. (See “The F-35 Steps Out,” April 2003, p. 46.) At that time, Hudson said, “So far, our cost performance has been excellent.”

In that same article, however, Hudson did allude to potential software difficulties and efforts to save weight. Now, those two issues, plus some design problems, are adding to a cost increase and schedule delays.

The Key Problems

“My two biggest concerns are weight—because that’s one of the drivers for performance—and software,” Hudson told Air Force Magazine in January.

Every additional pound limits performance, but contract specifications primarily are directed toward achieving certain performance requirements for each individual system, not toward maintaining a specific weight for those systems.

“The empty weight of this airplane is about 27,000 pounds—it’s a pretty good size airplane,” Hudson said. That is without weapons or gas. “When you put 18,000 pounds of gas in it, two 2,000-pound bombs, two air-to-air missiles, … you are up to about 50,000 pounds at takeoff or around the low 40s at maneuvering weight,” he added.

Hudson projects that the Air Force’s CTOL version will be “about 1,400 pounds heavy” when it becomes operational. He said that the Navy’s CV aircraft probably will also be about 1,400 pounds beyond its target weight and the Marine Corps’ STOVL version about 2,200 pounds overweight.

Those extra pounds translate into reduced capability in a key performance parameter—combat radius. The KPP requirement for the Air Force’s CTOL combat radius is 590 nautical miles. At its target weight, said Hudson, that version of the strike fighter would actually have a radius of about 660 nautical miles. However, he said, “If we’re at the 1,400 pounds heavy figure, we’re at about 640 [nautical] miles.”

Hudson emphasized, “That’s still pretty darn good,” but it’s obvious that weight is degrading range.

On the software issue, Hudson said, “We have our work cut out for us to stay ahead of the game on software.” While JSF avionics have not yet caused problems, they pose an area of potential concern.

There are about six million lines of code in the airplane and another six million in the simulator, plus about three million in associated systems. Some of that 15 million lines of code can be lifted from other programs, such as the F/A-22. However, given the F/A-22’s troubled avionics history, F-35 program officials cast a cautious eye toward software development.

“We know that software is, and will continue to be, a big challenge for us,” Hudson acknowledged, but he added that avionics design is “going pretty well.”

The avionics are critical to the aircraft. “In some ways, this is an extremely sophisticated set of avionics and sensors that needs an airplane to carry it … into combat,” Hudson said.

A slowdown in design of the Air Force’s CTOL airframe is also causing some problems. The CTOL design is “not coming as quickly as we’d like,” said Hudson, adding that it is “going to take us a little longer than we’d anticipated.”

The Air Force’s CTOL F-35 is still scheduled to undergo its critical design review next month, the last major developmental milestone before the aircraft begin flying. At the CDR, program officials expect to lock in the strike fighter’s CTOL design as much as is possible before flight testing begins in late 2005.

The CV and STOVL variants will have separate CDRs. Hudson said, “We’ve got some schedule pressure on both of those.”

All these current program challenges led the Office of the Secretary of Defense late last year to direct a slow down—beginning with the Fiscal 2005 budget—in the F-35’s development program. The delay has forced the program office to move funds from production accounts into development. That means fewer aircraft will be built in this decade than originally planned. (See “DOD Shuffles JSF Schedule, Dollars,” p. 47.)

The Pentagon still plans to produce a total of 2,443 aircraft: 1,763 for the Air Force and 680 for the Navy and Marine Corps. And the program is still slated to achieve initial operational capability for the Marines in 2010, the Air Force in 2011, and the Navy in 2012.

Program officials also noted that since the F-35 does not operate under a cost cap like the F/A-22 does, production funds (and aircraft) that are cut in the near term can be added in again later.

The Scorecard

In other ways, the JSF is on track, said Hudson. He rated the program “good” on four of six key performance parameters common across all three variants. (The progress of two KPPs is unknown at this time.) The KPPs are the core fighter capabilities that cannot be traded away in a tug of war between capabilities and affordability. The common KPPs are:

Radio frequency signature.

  • Combat radius.
  • Sortie generation.
  • Logistics footprint.
  • Mission reliability.
  • Interoperability.

Hudson said that radio frequency signature, also known as radar cross section (the very low observability feature) was in good shape, to a great extent because of previous stealth work with the F-117 and F/A-22. He said, “We learned a lot from these systems, not only about how to make it work but how to keep it supportable, so it’s not a burden to our maintainers.” That last comment also supports elements of both the logistics footprint and mission reliability.

Combat radius, as stated earlier, depends primarily on weight. Even though the CTOL version is heavier than its target weight, program officials still expect to see a better-than-required combat radius.

Hudson projected that the CTOL variant will demonstrate the needed sortie generation rates as it heads into April’s CDR.

He said the logistics footprint is defined as the number of “C-17 loads it takes to deploy a fighter squadron for a combat operation.” The footprint is on track, he said, adding that the F-35 will be significantly easier to deploy than the F-16.

Interoperability is an unknown, but Hudson said that most interoperability factors, such as the way the fighter will communicate with joint and coalition aircraft, ships, and space assets, are progressing well. Other interoperability factors, he said, are in the category of “we just don’t know if we’ll meet [them].” The reason, though, is simply that the “standards … haven’t been defined yet or they’re shifting,” said Hudson. He added, “There’s some uncertainty out there about what those standards are going to look like.”

Another unknown is mission reliability. The rate for that KPP must be at least 93 percent for USAF’s F-35A.

Despite the program’s current problems, Hudson maintains that it has been successful in the past in hitting its milestones on time. And there have been naysayers at every turn.

“I’ve been in the program almost five years,” Hudson said. In that time, “people said the concept demonstrators wouldn’t be able to fly. They did.”

He went on to say critics also questioned the ability of the CV and STOVL versions to fly in time for the 2001 downselect. There was a Congressional mandate that those variants would fly 20 hours before source selection. That requirement was met, Hudson said, and source selection occurred “on the day and the time we said.”

The delays began to emerge last spring, when the preliminary design review took longer than expected. The PDR “took an extra three months to close,” said Hudson. That was due primarily to “weapons bay issues and internal routing issues, but we got through that,” he noted.

Still, Hudson said, “We’ve got some significant challenges ahead.”

DOD Shuffles JSF Schedule, Dollars

The Defense Department in February announced that the F-35 Joint Strike Fighter program was being restructured because the cost of the system development and demonstration phase was increased by $7.5 billion. The restructure will yield a “net zero change” in the overall program, according to DOD.

The cost estimate for the development phase rose from $33 billion to $40.5 billion when officials had to extend the program schedule by one year to accommodate “additional design work, known risks, and [to provide] a higher-confidence, risk-adjusted cost estimate,” stated a DOD budget document outlining the restructure.

“Schedule delays on this very complex aircraft are prudent and necessary to mature its design and ensure its ultimate success,” noted the Pentagon in its news release on the 2005 budget.

In the near term, $5.1 billion was shifted out of procurement appropriations in Fiscal 2005-09. As a result, there will be 70 fewer aircraft built by 2009.

Additional design work is necessary because some integration activities are taking longer than planned, and all three variants are estimated to be at least 1,400 pounds overweight. Officials point out, though, that weight growth is not uncommon.

“To my knowledge, there’s not a single aircraft in the last 50 years that hasn’t had weight growth,” said DOD Comptroller Dov S. Zakheim at the Feb. 2 DOD budget press briefing. “Weight growth correlates phenomenally well with increase in cost,” he added. The department needs to address the problem “now, not later,” he said, so significant research and development funding is now going to be devoted to cutting the F-35’s weight.

Officials said production funds may be added back into the F-35’s budget in later years, because the Air Force and Navy quantity requirements have not changed. Further, the triservice F-35 does not operate under a cost cap, as the F/A-22 Raptor does. Therefore, aircraft lost from the early production lots could be bought later.

The restructure means USAF in Fiscal 2006 will buy six fewer of its conventional takeoff and landing F-35s and 35 fewer through Fiscal 2009. The Marine Corps will cut its purchase of the short takeoff and vertical landing variant by 35 through 2009.

Overall, the Pentagon will acquire 164 fewer F-35s through 2013.

The restructure also produces a one-year delay in low-rate initial production. The first aircraft for the Air Force and Marines will now be built in Fiscal 2007, not 2006. Officials said there is no schedule change on the Navy’s carrier version; production is still set to start in Fiscal 2008.

A senior Air Force budget official said that the changes are not expected to delay the first flights of the program’s developmental aircraft or postpone USAF’s initial operational capability date of 2011.

There Will Be an Air Force F-35 STOVL

The Air Force recently ended any ambiguity over whether it intended to buy the short takeoff and vertical landing F-35. The service will buy some STOVL F-35s.

Top leaders made the announcement on Feb. 12 at the Air Force Association’s annual Air Warfare Symposium in Orlando, Fla.

Gen. Ronald R. Fogleman, Air Force Chief of Staff in the period 1994-97, first broached the idea of acquiring STOVL versions to replace some A-10s. Until last month, however, service officials had not made an official commitment.

When asked about the STOVL last fall, Gen. John P. Jumper, the current Chief, did say, “It is not out of the question that the Air Force would be interested.”

Jumper said that USAF must pay “specific attention” to CAS, but he noted that USAF was developing new ways to conduct the mission. These included use of USAF bombers dropping satellite guided bombs in the CAS role.

“The course we are on right now is to make sure we can get everything we can out of the A-10,” he said, adding, “we know that in the not-too-distant future, the A-10 will be difficult to make survivable in the most difficult battlespaces.”

That means, Jumper said, “we’re going to have to have something else.”