F-35 WEIGHT LOSS AND BLOCK DEVELOPMENT

here is a passage from AFA dealing with weight issues and block development and capability.

The STOVL Diet

The Joint Strike Fighter program office and prime contractor Lockheed Martin had to slash roughly 3,000 pounds from the short takeoff and vertical landing (STOVL) F-35 last year to meet performance requirements. The changes also benefited the conventional and carrier F-35 variants, as they, too, had gotten fat.

Some of the major changes included propulsion system improvements for more thrust, a new assembly joint that weighs 160 pounds less, and a series of electrical system changes netting 222 pounds of weight savings.

Perhaps most significantly, the weapons bay was redesigned. The F-35B STOVL weapons bay has a “long and sordid story,” said Rear Adm. Steven L. Enewold, program director. The operational requirements document dictates that the carrier and conventional takeoff and landing variants have internal bays large enough for two 2,000-pound weapons; STOVL would only have to carry a pair of 1,000 pounders.

“About a year into the program, we said it would really improve our commonality and reduce our flight testing … if we could get that same weapon bay into STOVL,” said Enewold. So it was made to fit. But “when we got into the weight discussion,” officials determined the larger weapons bay had to go, so the 1,000-pound bay is back.

Opening up that internal space “allowed us to do a great many things,” Enewold said, and was “the linchpin of getting the STOVL design weight down.” The aircraft can still carry 2,000-pound weapons on wing hardpoints, and there is even an external 5,000-pound station. In an era of increasing concern about collateral damage, smaller weapons are in vogue, and this was deemed an acceptable trade. “It made STOVL viable around the ship,” Enewold said.

There are still about 300 pounds of additional weight-saving “ideas” the program office is looking into. They may not be worth implementing.

“We’re struggling a little bit,” Enewold said, because if it costs the government $50 million to cut 300 pounds, “I’m just not sure if that’s a great trade or not. The operational guys would say, ‘Great trade.’ The money people may not.”

Brig Gen. (sel.) Charles R. Davis, JSF deputy director, added that the remaining possible weight savings make for tough decisions. “Lots of items weigh five, seven, [or] 12 pounds,” he said—all the big cuts have been made.

blocks

To effectively meet immediate combat requirements with minimum risk, the F-35 will be fielded through a spiral, “block” approach. The first operational aircraft, Block 1, will have modest capabilities. It will be followed in rapid succession by two more-powerful blocks.

For the initial warfighting capability, “you need to have a radar, you need to have missile warning,” an electronic warfare system, and be able to drop bombs and shoot missiles, said Enewold. Block 1 will offer stealth, air-to-air missiles, a data link, and Joint Direct Attack Munitions, he said, describing it as “pretty rudimentary warfighting.”

Block 2 will add “some close air support,” counterair, and interdiction missions, as well as an expanded weapons portfolio. The program office is trying to define exactly which Block 2 weapons “have the biggest bang for the warfighter,” Enewold said. The specifics should be locked in this October, with Block 2 operational testing complete in 2012.

Block 3 will be the full-up F-35 with solid capabilities across the entire mission spectrum, including offensive and defensive air superiority missions, suppression and destruction of enemy air defenses, and CAS. This is “the whole gamut of strike warfare,” Enewold said. Plans call for Block 3 capabilities to be frozen in 2006 with testing completed in 2013.

The program also continues to refine the mission profiles. Weight is not a key performance parameter, but range is (measured as combat radius). The STOVL is required to have a combat radius of 518 miles, the CTOL variant 678 miles, and the carrier version 690 miles. All three variants are expected to meet these standards, but the program office would like to eliminate any uncertainty.