<P> Structural composites in the F - 35 are 35% of the airframe weight (up from 25% in the F - 22). The majority of these are bismaleimide (BMI) and composite epoxy material . The F - 35 will be the first mass - produced aircraft to include structural nanocomposites, namely carbon nanotube - reinforced epoxy . Experience of the F - 22's problems with corrosion led to the F - 35 using a gap filler that causes less galvanic corrosion to the airframe's skin, designed with fewer gaps requiring filler and implementing better drainage . The relatively short 35 - foot wingspan of the A and B variants is set by the F - 35B's requirement to fit inside the Navy's current amphibious assault ship parking area and elevators; the F - 35C's longer wing is considered to be more fuel efficient . </P> <P> A United States Navy study found that the F - 35 will cost 30 to 40 percent more to maintain than current jet fighters, not accounting for inflation over the F - 35's operational lifetime . A Pentagon study concluded a $1 trillion maintenance cost for the entire fleet over its lifespan, not accounting for inflation . The F - 35 program office found that as of January 2014, costs for the F - 35 fleet over a 53 - year life cycle was $857 billion . Costs for the fighter have been dropping and accounted for the 22 percent life cycle drop since 2010 . Lockheed stated that by 2019, pricing for the fifth - generation aircraft will be less than fourth - generation fighters . An F - 35A in 2019 is expected to cost $85 million per unit complete with engines and full mission systems, inflation adjusted from $75 million in December 2013 . </P> <P> The Pratt & Whitney F135 powers the F - 35 . An alternative engine, the General Electric / Rolls - Royce F136, was being developed until it was cancelled by its manufacturers in December 2011 for lack of funding from the Pentagon . The F135 and F136 engines are not designed to supercruise . However, the F - 35 can briefly fly at Mach 1.2 for 150 miles without the use of an afterburner . The F135 is the second (radar) stealthy afterburning jet engine . Like the Pratt & Whitney F119 from which it was derived, the F135 has suffered afterburner pressure pulsations, or' screech' at low altitude and high speed . The F - 35 has a maximum speed of over Mach 1.6 . With a maximum takeoff weight of 60,000 lb (27,000 kg), the Lightning II is considerably heavier than the lightweight fighters it replaces . </P> <P> The STOVL F - 35B is outfitted with the Rolls - Royce LiftSystem, designed by Lockheed Martin and developed by Rolls - Royce . This system more resembles the German VJ 101D / E than the preceding STOVL Harrier Jump Jet and the Rolls - Royce Pegasus engine . The Lift System is composed of a lift fan, drive shaft, two roll posts and a "Three Bearing Swivel Module" (3BSM). The 3BSM is a thrust vectoring nozzle which allows the main engine exhaust to be deflected downward at the tail of the aircraft . The lift fan is near the front of the aircraft and provides a counterbalancing thrust using two counter-rotating blisks . It is powered by the engine's low - pressure (LP) turbine via a drive shaft and gearbox . Roll control during slow flight is achieved by diverting unheated engine bypass air through wing - mounted thrust nozzles called Roll Posts . </P>

What is the top speed of the f-35