Newsnight understands that the first 14 aircraft will be bought for £58m ($96m) apiece*. However, once spares, maintenance and initial support are included, the price will be much higher
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There is concern in the MoD that observers will simply divide the approximate £2.5bn cost of this stage of the project by the 14 planes being ordered, whereas this price tag includes certain support costs for the entire, eventual UK fleet
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People in the MoD say they are confident the aircraft will be "combat capable", with a basic range of bombs and missiles, by 2018, although they concede that getting some of the RAF's more advanced missiles to work with the F-35 will not happen before 2022.
However, others in the industry have suggested that 2025 might be a more realistic date for full combat capability, and that funding to "integrate" some of these weapons with the F-35 could come under threat at some future point.