London's Daily Telegraph reports this morning that the UK is preparing to switch from the short take-off, vertical landing (STOVL) version of the F-35 Joint Strike Fighter to the F-35C carrier (CV) model, because it costs less and has a greater weapon load and range.
According to the paper, its sources say that the decision is not final, and that a choice one way or the other will be announced this fall. It quotes procurement minister Quentin Davies as saying: “We have to take an immensely important decision. We have to take a decision as to which version of aircraft we shall be agreeing and we shall be focusing on this situation in the coming months.”
The BBC later quoted Davies as saying the reports that a decision had been taken were "utter drivel" but confirming that the decision would be taken in the next few months.
The Telegraph said that the UK MoD is estimating an average acquisition cost of GBP90 million ($151 million) for each F-35C and GBP105 million ($177 million) for the F-35Bs. Moreover, MoD sources apparently told the paper that fewer F-35Cs than F-35Bs would be needed because of their greater performance, saving more money.
The UK's two new carriers have been designed from the keel up so that they can accommodate catapults and arrester systems. This was both a hedge against problems with STOVL or a US cancellation of F-35, and provision for a CV-type F-35 follow-on in the longer term. Delays in funding and building the carriers have, so far, postponed the date after which switching the first-of-class Queen Elizabeth from STOVL to CV becomes impossible without changing the schedule. The gas-turbine/electric ships would be fitted with separate steam generators to power the cats.
The UK's baseline plan for the JSF involves buying 138 F-35Bs that would form a joint RAF/Navy force similar to today's Joint Force Harrier, capable of sustaining two deployed shipboard air wings and a land-based force. That flexibility, however, may depend on the use of the F-35B, because its virtually automatic vertical landing mode will require less recurrent training than CV operations do today.
However, the UK's buy profile is unusual. Most of its jets are expected to be delivered between 2016 and 2021, matching the working-up of the two carriers. There is then a four-year hiatus before some 50 aircraft arrive in 2026-29, filling out the land-based force. It's quite possible that when the MoD talks about fewer aircraft, they're talking about these later orders.
One factor that could come into play: the UK has so far timed the drop-dead date for the CV-versus-STOVL decision so that it would not take place until the F-35 had demonstrated successful STOVL operations. Following the redesign and restructure of the program in 2004-05, those tests were scheduled to happen in the fall of 2008, a few months after the first flight of STOVL prototype BF-1 - right now, they won't be any earlier than September, and that date looks increasingly unlikely.
The UK government has also described the jet's STOVL performance as "at risk" (page 52 of the NAO Project Summary sheets, available here). The UK has adopted a more stringent hot-day requirement than the US, in the light of Harrier experience, and has funded a shipboard rolling vertical landing (SRVL) demonstration as a way to boost the bring-back load. Also, in a recent interview, Pratt & Whitney executives said that there is effectively no growth margin in the vertical-lift system: increasing VL thrust would mean redesigning the entire lift fan, including more advanced materials.
What that means: If the UK government decides to go STOVL this fall, before STOVL tests are complete, it's doing so in the knowledge that the controversial SRVL technique (which will have a lot of knock-on effects on deck operations) could be a permanent feature, not a stop-gap until a propulsion upgrade is available.
Update: Check the discussions at RumRation and Pprune, It's suggested that no decision will be taken before the looming UK election (although shipbuilding factors might force one), that the RAF might prefer the longer-range F-35C, and that the decision could give the money-counters and some RAF elements the chance to retire the Harrier.