No other fighter jet to date has garnered as much controversy as the F-35 Lightning II. While it is the most capable carrier jet ever built, the production issues and mind-melting $2 trillion price tag for the whole program are deservedly a cause for concern. We're going to take a closer look at the whirling heart of the F-35B's impressive short take-off and vertical landing capability: Its shaft-driven lift fan system mounted near the airframe's center.
Shrouded beneath a flap behind the canopy is the intake for the Rolls-Royce LiftFan, a 50-inch, two-stage counter-rotating fan. This fan can generate over 20,000 pounds of cold thrust. Yes, cold as in no combustion from this specific turbofan, just lift. An F-35's single Pratt & Whitney F135 engine delivers 29,000 horsepower to the LiftFan through a driveshaft and clutch. These are just two elements of the unique Rolls-Royce LiftSystem.
The LiftSystem also includes a 3 Bearing Swivel Module (3BSM) and a pair of Roll Posts. The 3BSM is mounted to the main engine's exhausts and twists to direct thrust downward at a 95-degree angle to produce 18,000 pounds of thrust. The Roll Posts direct bypass thrust from the engine and direct it out through both wings. While each produces an additional 1,950 pounds of thrust, the hydraulically actuated nozzles serve a more crucial purpose of providing the pilot roll control while hovering. The entire LiftSystem's over 41,000 pounds of thrust is more than capable of allowing the 32,300-pound F-35B to float, rotate, and land at a standstill.
Paul Nelhams / Wikimedia Commons
If you're wondering, British aerospace giant Rolls-Royce shares a name, a logo and a lineage with the luxury automaker, but the two have been separate entities for 54 years. Rolls-Royce Limited was forced to liquidate in 1971 after hitting financial hardship developing a new turbofan engine for the Lockheed L-1011 TriStar. The British government indirectly nationalized Rolls-Royce by purchasing all of its assets.
Rolls-Royce was nationalized because its turbine manufacturing capacity for aircraft, maritime vessels and heavy industry was deemed essential for national defense. However, keeping massive Phantoms rolling off the assembly line wasn't. The automotive manufacturing division was spun off into a separate business, which was eventually sold off in 1980. Today, Rolls-Royce is the second-largest aircraft engine manufacturer in the world and generates over $255 billion in annual revenue. Is the British public benefitting from this highly profitable venture? No, Prime Minister Margaret Thatcher privatized the aerospace side of Rolls-Royce in 1987.
Circling back to national defense, the F-35B isn't Rolls-Royce's first rodeo with a vertical landing-capable fighter jet. The aerospace company produced the Pegasus engine that powered the Harrier, starting in the late 1960s. The British-American family of jump jets used four rotating nozzles to vector its thrust downward for take-off and landing. The same nozzles produce the rearward thrust for conventional forward flight. Naturally, the F-35B has been the go-to replacement for the Harrier in most militaries as the aging jump jet is phased out of service.
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