The Lockheed Martin F-35B Lightning II was the version of the Joint Srike Fighter (JSF) that was capable of vertial takeoffs and landings. It was intended for the US Marine Corps as a replacement for the AV-8B Harrier. 340 are on order. The Royal Navy and the Italian Navy are also customers for the F-35B. So far, it is the only STOVL aircraft capable of supersonic flight.
Instead of lift engines or using a direct lift engine like the Rolls-Royce Pegasus in the Harrier Jump Jet, the F-35B was powered by the Pratt and Whitney F135-PW-600 which used the new shaft-driven lift fan system. The lift fan was mounted ahead of the engine and was driven by a drive shaft connected th the engine. A portion of engine power was extracted via a turbine, and used to drive a shaft running forward via a clutch-and-bevel gearbox to a vertically mounted, contra-rotating lift fan located forward of the main engine in the center of the aircraft. There were large doors in the upper fuselage covering the fan inlet and doors in the lower fuselage covering the fan exhaust which had to open and close on every flight. The rear exhaust of the engine was fitted with a “three-bearing” vectoring nozzle, with the tail pipe incorporating two angled segments connected by rotating bearings. The nozzle that could be tilted downward to provide lift during vertical takeoffs and landings. There were doors in the rear fuselage that opened to allow access of the rear nozzle to downwrd thrust ooperation.There were exhausts underneath each wing that could divert unheaded engine bypass air which could provide roll control during vertical takeoffs and landings.
Because of the presence of the lift fan, the F-35B has a smaller internal weapons bay and less internal fuel capacity than the F-35A. It cannot carry 2000-pound “bunker buster” bomds internally, and must carry them on external underwing pylons, thus spoiling the steath capability. the underwing pylons of the F-35B cannot carry as heavy a load as those of the F-35A. But even if the F-35B took off in the conventional manner with a maximum load being carried, it cannot vertically land when it is carrying its maxium load, and would either have to expend its weapons or jettison them in order to land vertically.
Unlike the F-35A, The F-35B has no internal gun and instead can use a Terma A/S multi-mission pod (MMP) carrying a GAU-22/A cannon along with 220 rounds; the pod is mounted underneath the fuselage on the centerline of the aircraft and shaped to reduce its radar cross-section. There are two internal weapons bays, along with four external underwing attachment points to carry weapons when stealth is not a priority.
The F-35B has a probe and drogue midair redueling system, with a retractable probe in the nose.
The F-35B is equipped with AN/APG-81 Active Electronically Scanned Array (AESA) multi-functional radar set built by Northrop Grumman. It also houses an AN/AAQ-37 Distributed Aperture System (DAS), a Barracuda AN/ASQ-239 electronic warfare system, a Multifunction Advanced Data Link (MADL) communication system and missile warning system.
The first F-35B, BF-1, flew on 11 June 2008. The F-35B’s first hover was on 17 March 2010, followed by its first vertical landing the next day. At-sea testing of the F-35B was first conducted aboard USS Wasp. In October 2011, two F-35Bs conducted three weeks of initial sea trials, called Development Test I.[232] The second F-35B sea trials, Development Test II, began in August 2013, with tests including nighttime operations; two aircraft completed 19 nighttime vertical landings using DAS imagery. The Marines achieved IOC for the F-35B in 2015. The first operational testing involving six F-35Bs was done on the Wasp in May 2015. The final Development Test III on USS America involving operations in high sea states was completed in late 2016.
The Marine Corps was the first to deploy the JSF abroad, and was the first to use the plane in combat.
F-35B Specifications Powerplant: one Pratt & Whitney F135 turbofan rated at 40,000lb st (177.88kN) with afterburning and 40,500lb st (180.10kN) for vertical take-off. Length: 51ft 2¼in (15.60m) Height: 14ft 3½in (4.36m) Wingspan: 35ft (10.70m) Wing area: 460sqft (42.70m2) Maximum take-off weight: around 60,000lb (27,216kg) Combat radius on internal fuel: 500 miles Range on internal fuel: 1000 miles Internal fuel capacity: 13,100 pounds Weapons payload: 15,000 pounds Maximum speed: Mach 1.6 at altitude
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Boeing X-32, Wikipedia, https://en.wikipedia.org/wiki/Boeing_X-32
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Lockheed Martin X-35, Wikipedia, https://en.wikipedia.org/wiki/Lockheed_Martin_X-35
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Ultimate Fighter–Lockheed Martin F-35 Joint Strike Fighter, Bill Sweetman, Zenith Press, 2004
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Lockheed Martin F-35 Lightning II, Wikipedia, https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II
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F-35B Lightning II Joint Strike Fighter STOVL Variant, https://www.naval-technology.com/projects/f-35b-lightning-ii-joint-strike-fighter-stovl-variant/
- The F-35A vs F-35B: What Exactly is the Difference? https://nationalinterest.org/blog/buzz/f-35a-vs-f-35b-what-exactly-difference-30252
