Most fighter jets have a stall speed—the slowest they can go before falling from the sky. But two fighter jets currently in service can get around their stall speed and go even slower. One is the Lockheed Martin F-35B Lightning II, and the other is versions of the Harrier jump jet still used by the USMC and others. These are the slowest fighters possible because they’re the only fighter jets currently able to hover—making their slowest speed literally zero. The F-35B can hover for about nine minutes in terms of fuel consumption.
These jets are designed to operate in environments where space is limited, such as aircraft carriers and forward, unimproved air bases. The F-35B is classified as a Short Take-Off and Vertical Landing (STOVL) aircraft, while the Harrier is a Vertical/Short Take-Off and Landing (V/STOL) aircraft. While both are technically able to take off vertically, they can carry greater loads if they get a short running start.
How the F-35B achieves the impossible
The F-35B uses a dedicated vertical thrust system located behind the cockpit. This Rolls-Royce-built LiftSystem includes a flap behind the cockpit with a fan underneath. Once the flap rises, the LiftSystem fan’s contra-rotating sets of blades drive air downward enough to generate 20,000 pounds of thrust. Another 20,000 pounds of thrust comes from thrust nozzles connected to the main engine, so the aircraft produces thrust from two points. Combined, the 40,000 pounds of thrust enables the jet to move vertically or hover in place.
The F-35B is primarily considered a ground attack aircraft, but it can hold its own against enemy aircraft. The fighter jet can carry two AIM-120C/D air-to-air missiles internally. It can also carry a 4-barrel 25mm GAU-22/A cannon in a pod under the centerline of the fuselage. However, the aircraft cannot hover and fire simultaneously.
The Harrier’s legacy continues
The F-35B builds on decades of experience by the US Marine Corps and Royal Navy utilizing the Harrier series of jet attack fighters since the 1970s. The Sea Harrier was an important component of the UK’s arsenal in the Falklands War, downing Argentinean aircraft and losing none in air-to-air combat. Later versions proved themselves in combat ranging from Mediterranean no-fly zones to Central Asia. When designing the LiftSystem for the F-35B, Rolls-Royce leaned heavily on lessons learned from developing the Pegasus engine that powered Harriers through the current AV-8B.
Compared to the Harrier, the F-35B is easier to fly and stealthier. As the Marine Corps and other armed forces retire their Harrier fleets, countries such as Indonesia are looking to acquire the aircraft. Despite their differences in age and price tag, the desire of armed forces to purchase both the F-35B and AV-8B demonstrates that there is genuine need for fighter jets whose ultimate slow speed is zero.
