Military planners have raised fears ministers may order inferior jets for the Royal Navy's new aircraft carrier to save money.
Labour had originally intended to buy the jump jet version of the Joint Strike Fighter, but the coalition decided to go for the catapult-launched carrier version.
Since then the cost of fitting catapults have spiralled, leading to speculation that the government is set to revert to the original plan.
Ministry of Defence papers seen by the Daily Telegraph compare the two planes in a range of military scenarios, ranging from the Falklands to striking terrorist camps in Chad and a stabilising operation in Saudi Arabia.
The document apparently finds the carrier version proves more effective in most cases.
An MoD spokesman said: "We are currently finalising the 2012-13 budget and balancing the Equipment Plan.
"As part of this process we are reviewing all programmes, including elements of the carrier strike programme, to validate costs and ensure risks are properly managed.
"Unsurprisingly the facts and technical details have matured significantly since any previous assessments of the JSF types.
"As you would expect, the MOD works up a wide range of hypothetical scenarios, many of which are highly unlikely, to scope contingency work as fully as possible."