The Pentagon last month relaxed the performance requirements for the Joint Strike Fighter, allowing the Air Force F-35A variant to exceed its previous combat radius -- a benchmark it previously missed -- and granting the Marine Corps F-35B nearly 10 percent additional runway length for short take-offs, according to Defense Department sources.
On Feb. 14, the Joint Requirements Oversight Council -- in a previously unreported development -- agreed to loosen select key performance parameters (KPPs) for the JSF during a review of the program convened in advance of a high-level Feb. 21 Defense Acquisition Board meeting last month, at which the Pentagon aimed to reset many dimensions of the program, including cost and schedule.
Pentagon sources said a memorandum codifying the JROC decisions has not yet been signed by Adm. James Winnefeld, the vice chairman of the Joint Chiefs of Staff and the JROC chair.
Sources familiar with the changes, however, said the JROC -- which also includes the service vice chiefs of staff -- agreed to adjust the "ground rules and assumptions" underlying the F-35A's 590-nautical-mile, combat-radius KPP.
Last April, the Pentagon reported to Congress in a selected acquisition report that "based on updated estimate of engine bleed," the F-35A would have a combat radius of 584 nautical miles, below its threshold -- set in 2002 -- of 590 nautical miles.
To extend the F-35A's combat radius, the JROC agreed to a less-demanding flight profile that assumes near-ideal cruise altitude and airspeed, factors that permit more efficient fuel consumption. This would allow the estimate to be extended to 613 nautical miles, according to sources familiar with the revised requirement.
The estimated combat radius of the short-take-off variant, which is being developed for the Marine Corps, is 15 percent lower than the original JSF program goal even though the aircraft is slated to carry fewer weapons than originally intended, according to the April report.
The short-take-off-and-landing KPP before the JROC review last month was 550 feet. In April 2011, the Pentagon estimated that the STOVL variant could execute a short take-off in 544 feet while carrying two Joint Direct Attack Munitions and two AIM-120 missiles internally, as well as enough fuel to fly 450 nautical miles. By last month, that take-off distance estimate grew to 568 feet, according to DOD sources.
The JROC, accordingly, agreed to extend the required take-off distance to 600 feet, according to DOD officials.
The JROC review of the F-35 program last month was held in accordance with a policy adopted by the council in June 2010, which requires a reassessment of requirements for all programs with cost growth exceeding 25 percent of the original program baseline. One goal of the policy is to determine whether a decision to relax requirements should be made to improve acquisition cost and schedule estimates. -- Jason Sherman