with the aircraft's internal weapons bays it takes up a great deal of internal space, reducing fuel and avionics load and requiring a bulkier and wider fuselage cross-section (which passes on to the A and C versions, even though they don't have a fan or V/STOL capability). It has, however, in pre-operational testing proven the ability to take off vertically and go supersonic in level flight in the same mission, a first for a combat aircraft. See also Lift fan VTOL Jet engines VTOL aircraft