The GE F118 is a military jet engine that powers reconnaissance and electronic warfare aircraft

The General Electric F118 is a turbofan jet engine built for the U.S. Air Force and used in specific military aircraft that need high performance at low noise levels. Unlike fighter jet engines designed for speed and combat, the F118 was engineered for long-duration missions where fuel efficiency and quiet operation matter more than raw power. The engine powers the B-2 Spirit stealth bomber and the U-2 Dragon Lady reconnaissance aircraft, two of the most specialized planes in the military inventory.

The F118 is a derivative of the F404 engine, which powers the F/A-18 Super Hornet fighter jet. General Electric modified the F404 design to create an engine that could meet the specific demands of aircraft that fly at high altitudes, carry heavy sensor payloads, or need to operate with minimal acoustic signature. The result is an engine that trades some of the raw thrust of a fighter engine for better fuel economy and lower noise output.

Key Takeaways

  • The F118 powers the B-2 stealth bomber and the U-2 reconnaissance aircraft, both of which require specialized engine performance rather than maximum speed.
  • The engine is based on the F404 turbofan but was modified to prioritize fuel efficiency and quiet operation over raw thrust.
  • The F118 produces approximately 12,000 pounds of thrust per engine, and the B-2 uses two of them.
  • The engine entered service in the late 1980s and remains in active use with no announced retirement date.
  • Maintenance and parts for the F118 are handled exclusively by the U.S. military and General Electric through classified or restricted contracts.

How the F118 differs from other military jet engines

Military jet engines fall into two broad categories: high-thrust engines designed for fighter jets, and specialized engines built for specific mission types. The F118 belongs to the second group. A fighter engine like the F100 (used in the F-15 and F-16) prioritizes maximum afterburner thrust and rapid acceleration. The F118 does not have an afterburner and instead focuses on sustained performance over long flight times.

The F118 produces approximately 12,000 pounds of thrust per engine without afterburner. By comparison, the F100 produces around 14,500 pounds with afterburner engaged. That difference reflects the mission: the B-2 does not need to outrun an opponent in a dogfight. It needs to fly thousands of miles, loiter over a target area, and return to base on a single fuel load. The U-2 needs to climb to extreme altitudes (above 70,000 feet) and stay there for hours while carrying reconnaissance sensors. Both missions demand efficiency over peak power.

The F118 also operates more quietly than a fighter engine. Noise reduction matters for the U-2 because it flies at high altitude where sound carries far, and for the B-2 because acoustic signature is part of the overall stealth design. The engine achieves this through a larger fan diameter and lower pressure ratio compared to fighter engines, which means air moves through the engine at lower speeds and generates less noise.

The B-2 Spirit and U-2 Dragon Lady: the two aircraft that use the F118

The B-2 Spirit stealth bomber carries two F118 engines and has been in service since 1997. The B-2 is designed to penetrate defended airspace undetected, deliver ordnance, and return to base without fighter escort. The two F118 engines provide enough power to lift a 336,500-pound aircraft (maximum takeoff weight) and cruise at subsonic speeds for intercontinental distances. The B-2 can fly from the continental United States to targets overseas and back without refueling, though it typically uses aerial refueling to extend range and reduce fuel burn.

The U-2 Dragon Lady reconnaissance aircraft also uses the F118 (in a variant called the F118-GE-100). The U-2 is a single-engine aircraft that has been flying reconnaissance missions since 1955, though the airframe has been continuously upgraded. The U-2 needs an engine that can push the aircraft to extreme altitudes where the air is so thin that conventional engines cannot function. The F118 achieves this through a high-altitude optimized design that maintains thrust even as air density drops. A U-2 can reach altitudes above 70,000 feet and stay there for over 12 hours on a single fuel load.

Both aircraft are operated by the U.S. Air Force and are among the most classified military systems in existence. The specific performance characteristics, operational procedures, and maintenance protocols for the F118 are restricted information. Public information about the engine comes from declassified military documents, congressional testimony, and General Electric's limited public statements.

When the F118 entered service and its operational history

The F118 was developed in the 1980s as part of the Advanced Technology Bomber program, which led to the B-2 Spirit. General Electric began work on the engine in the early 1980s, and the first F118 engines were installed in B-2 test aircraft in the mid-1980s. The engine underwent extensive testing and refinement before the B-2 entered operational service in 1997. The U-2 began receiving F118 engines in the 1990s as part of a modernization program that replaced the older TF33 turbofan engines.

Since entering service, the F118 has accumulated thousands of flight hours across both the B-2 and U-2 fleets. The engine has proven reliable in operation, though like all military systems it requires regular maintenance and periodic overhaul. The U.S. Air Force has not announced any plans to retire the F118 or replace it with a newer engine. Both the B-2 and U-2 are expected to remain in service for at least another decade, which means the F118 will continue operating through the 2030s.

Maintenance, support, and who works on F118 engines

The F118 is maintained exclusively by the U.S. Air Force and General Electric through contracts that are often classified or restricted to cleared personnel. Unlike commercial jet engines, which are overhauled by third-party maintenance shops and documented in public records, F118 maintenance is handled by military depots and GE facilities with security clearances. The specific maintenance intervals, overhaul procedures, and parts specifications are not publicly disclosed.

General Electric maintains a dedicated support organization for the F118, including spare parts inventory, technical documentation, and engineering support. The company has facilities at its aviation division headquarters in Ohio and at other locations that handle F118 work. Military personnel who work on the F118 must hold appropriate security clearances and complete specialized training. The engine is not available for civilian use, and no civilian aircraft have ever been powered by the F118.

Technical specifications and performance characteristics

The F118 is a two-spool, high-bypass turbofan engine with a single-stage fan, nine-stage compressor, and two-stage turbine. The engine does not have an afterburner, which distinguishes it from most fighter jet engines. Maximum thrust is approximately 12,000 pounds per engine, and the engine can operate continuously at cruise thrust settings for extended periods without thermal stress.

The F118 is optimized for high-altitude performance, which means it maintains thrust efficiency even as air density decreases. This characteristic is essential for the U-2, which operates at altitudes where most conventional engines lose significant thrust. The engine also features low fuel consumption per pound of thrust, which translates to longer range and endurance for both the B-2 and U-2.

The F118 weighs approximately 2,700 pounds per engine, making it relatively light for its thrust class. The engine is approximately 10 feet long and 3 feet in diameter. These dimensions were designed to fit within the B-2's airframe while maintaining the aircraft's aerodynamic shape and stealth characteristics.

Frequently Asked Questions

Can you buy an F118 engine or parts for it?

No. The F118 is exclusively military equipment and is not sold to civilians or foreign governments. The engine is controlled under U.S. export regulations and international arms treaties. Even retired F118 engines are typically destroyed or retained by the military rather than sold on the open market.

How does the F118 compare to the engines in modern fighter jets?

Fighter engines like the F135 (in the F-35) produce more thrust and include afterburners for supersonic flight. The F118 trades peak power for fuel efficiency and altitude performance. A fighter needs to accelerate quickly and reach high speeds; the B-2 and U-2 need to fly long distances and operate in specific altitude regimes. Different missions require different engines.

Why does the U-2 still use the F118 instead of a newer engine?

The F118 was specifically designed for high-altitude performance and has proven reliable over decades of operation. Replacing it would require redesigning the U-2's air intake, fuel system, and airframe structure. The cost and risk of such a modification outweigh the benefit of a newer engine, especially since the F118 continues to meet the U-2's performance requirements.

Is the F118 related to the F404 engine used in the F/A-18?

Yes. The F118 is derived from the F404 turbofan but was significantly modified for the B-2 and U-2 missions. The F404 is a fighter engine with an afterburner; the F118 removed the afterburner and optimized the core for efficiency and altitude performance. They share some design heritage but are distinct engines built for different purposes.

How long does an F118 engine last before it needs to be overhauled?

The specific overhaul intervals are classified information. Military jet engines typically require overhaul every 2,000 to 4,000 flight hours, but the exact schedule for the F118 depends on mission profile, operating conditions, and maintenance procedures that are not publicly disclosed.