Lockheed Martin F-35 Lightning II

Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, supersonic stealth attack aircraft. It is a multirole war aircraft designed for both air superiority and strike missions, and also possesses intelligence, surveillance, and reconnaissance capabilities. Lockheed Martin is the prime contractor for the F-35, working with main partners Northrop Grumman and BAE Systems. The aircraft has three main variants:

1. F-35A: conventional takeoff and landing (CTOL),

2. F-35B: short takeoff and vertical landing (STOVL),

3. F-35C: carrier variant (CV) with catapult-assisted takeoff and arrested recovery (CATOBAR).

The F-35 is a continuation of the Lockheed Martin X-35. The X-35 won the Joint Strike Fighter (JSF) program in 2001 by defeating the Boeing X-32, and was designed to replace the F-16 Fighting Falcon, F/A-18 Hornet, and McDonnell Douglas AV-8B Harrier II "jump jet" like aircraft. Development of the F-35 is primarily funded by the United States, with additional financial contributions from member states of the North Atlantic Treaty Organization (NATO) and allied nations.

These countries include Australia, Canada, Denmark, Italy, Netherlands, Norway, the United Kingdom, and Türkiye, a former partner. Additionally, many other country have ordered or are considering ordering the F-35. The program has faced criticism due to its unprecedented scale, complexity, rising costs, and delayed deliveries. The strategy of concurrent production during development and testing has led to expensive design changes and retrofits. July As of 2024, the average unit costs for the aircraft are as follows: $82.5 million for the F-35A, $109 million for the F-35B, and $102.1 million for the F-35C.

The F-35 made its first flight in 2006 and entered service with the US Marine Corps in July 2015 using the F-35B variant. This was followed by the US Air Force’s F-35A in 2016 and the US Navy’s F-35C in 2019. The aircraft was first used in combat by the Israeli Air Force in 2018. The United States plans to purchase 2,456 F-35s by 2044. These aircraft are expected to form a major portion of the US Air Force, Navy, and Marine Corps’ manned tactical aviation fleet over the next several decades and remain in service until 2070 as the cornerstone of NATO and US allied air power.

Program History

The F-35 emerged as a product of the Joint Strike Fighter (JSF) program, which consolidated various fighter aircraft projects. The program’s roots trace back to the Advanced Short Takeoff/Vertical Landing (ASTOVL) project initiated in the 1980s, which aimed to develop a supersonic STOVL fighter to replace the Harrier for the US Marine Corps (USMC) and the UK Royal Navy.

In 1993, ASTOVL was renamed the Common Affordable Lightweight Fighter (CALF), and major aerospace companies such as Lockheed, McDonnell Douglas, and Boeing joined the program. At the same time, due to the end of Cold War and defense budget cuts, the US Air Force’s Multi-Role Fighter (MRF) and the US Navy’s Advanced Attack/Fighter (A/F-X) projects were canceled.

Following these cancellations, in 1993 the US Department of Defense launched the Joint Advanced Strike Technology (JAST) program. Initially focused on developing concepts and technologies for advanced strike systems rather than a new aircraft, JAST was merged with ASTOVL/CALF in 1994 to form the JSF program, establishing a common fighter aircraft goal for air forces, navies, and marine corps.

The JSF program officially began in 1995, with major companies including Lockheed Martin, Boeing, McDonnell Douglas, and Northrop Grumman participating. The goal of JSF was to replace diverse aircraft such as the Harrier, F-16, F/A-18, A-10, and F-117 with a single platform. The program also had an international dimension: the United Kingdom became the first and only Tier 1 partner, while Italy and the Netherlands joined as Tier 2 partners, and countries including Türkiye as Tier 3 partners.

In 1997, Lockheed Martin and Boeing were selected for the concept demonstration phase. Lockheed Martin’s X-35 demonstrated STOVL capability using a shaft-driven lift fan (SDLF) system, while Boeing’s X-32 favored a direct-lift system. The X-35A made its first flight on 24 October 2000, and the X-35B successfully demonstrated STOVL performance. The X-35C underwent carrier landing tests.

On 26 October 2001, Lockheed Martin was declared the winner, and the F-35 program’s System System Development and Demonstration (SDD) phase began. Thus, the production process of the F-35 Lightning II, one of the world’s most advanced multirole fighter aircraft, was formally launched.

Design and Production

During the transition from the X-35 prototype to the F-35 fighter, several design modifications were made:

1. The nose was extended by 13 cm.

2. The horizontal stabilizers were repositioned 5 cm rearward.

3. Weapons bays were enlarged.

4. The air intake (Diverterless Supersonic Inlet, DSI) was redesigned.

The first F-35A prototype, designated AA-1, underwent flight testing. Despite delays caused by cost increases and technical challenges, the program continued with the F-35A (CTOL), F-35B (STOVL), and F-35C (CV) variants.

Overview

The F-35 is a platform distinguished among fifth-generation fighter aircraft by its low radar signature, advanced avionics, and sensor fusion. It is the second fifth-generation fighter to enter US inventory and the first stealth fighter capable of supersonic flight with short takeoff and vertical landing (STOVL). The US Air Force (USAF) positions the F-35 as its primary strike aircraft for missions such as enemy air defense suppression (SEAD) and air interdiction.

Aerodynamic Design and Structural Features

1. Wing and Tail Structure: Canted vertical stabilizers reduce radar cross-section, while flight control surfaces (flaperons, rudders, and stabilators) provide high maneuverability.

2. Air Inlets: The Fixed Diverterless Supersonic Inlet (DSI) design enhances engine efficiency by managing boundary layer airflow.

3. Composite Materials: Thirty-five percent of the airframe’s weight consists of composite materials, reinforced with nanotube-enhanced epoxy for increased durability.

4. Internal Weapons Bay: Integrating weapons internally reduces drag caused by external stores, improving performance.

Engine and Performance

1. Speed and Power: Powered by the Pratt & Whitney F135 engine, it can reach a maximum speed of Mach 1.6. With afterburner, it can sustain Mach 1.2 supersonic cruise for 150 inch (240 km).

2. Fuel Capacity: Internal fuel capacity exceeds twice that of the F-16, enabling long range operations.

Maneuverability and Control System

1. High Angle-of-Attack Performance: Capable of controlled flight up to 50° angle of attack.

2. Fly-by-Wire Flight Control: A triply redundant system provides high resistance to departures and superior controllability.

The F-35 assumes a dominant role in air combat through high situational awareness, long-range strike capability, and advanced mission systems. Its operational effectiveness will be continuously enhanced through future software and hardware upgrades.

Sensors and Avionics

The F-35 is a modern fighter aircraft that enhances pilot situational awareness through advanced sensors and avionics, enabling network-centric warfare capabilities. These systems comprise various components such as radar, electronic warfare, electro-optical targeting, and communications.

Main Sensors and Mission Systems

AN/APG-81 AESA Radar (Northrop Grumman)

1. The active electronically scanned array radar provides multi-target tracking and synthetic aperture radar (SAR) capabilities beyond 150 km.

2. Integrated with electronic warfare systems, it supports both passive and active air-to-air modes.

AN/ASQ-239 Barracuda Electronic Warfare System (BAE Systems)

1. Detects enemy radars, provides jamming, and protects against guided missiles.

2. Antennas integrated into wing and tail edges function as a 360-degree radar warning receiver (RWR).

AN/AAQ-37 Electro-Optical Distributed Aperture System (DAS) (Northrop Grumman/Raytheon)

1. Uses six infrared sensors to provide 360 degree missile launch warning and target tracking.

2. Projects night vision and global infrared imagery onto the pilot’s helmet, enhancing awareness.

AN/AAQ-40 Electro-Optical Targeting System (EOTS) (Lockheed Martin)

1. Features infrared search and track (FLIR), targeting, and long-range target tracking (IRST) capabilities.

AN/ASQ-242 CNI Package (Northrop Grumman)

1. Provides low-observable secure communication via the Multifunction Advanced Data Link (MADL).

2. Supports Link 16 for compatibility with legacy platforms.

Sensor Fusion and Network-Centric Warfare

The F-35 integrates data from its sensors to create a unified battlefield picture for the pilot. Sensor fusion converts information from radio frequency receivers and infrared sensors into a single tactical display, accelerating the pilot’s decision-making process.

Future Upgrades and Technology Refreshes

Technology Refresh 3 (TR-3): Will introduce new processors and an advanced cockpit display, to be implemented on Lot 15 aircraft.

Block 4 Upgrades:

1. Enhanced EOTS (Advanced EOTS) for improved targeting precision.

2. Integration of the AN/APG-85 radar for improved threat detection.

Unmanned Combat Aerial Vehicle (UCAV) Management: The US Air Force is testing the F-35’s ability to direct UCAVs using its sensor and communication systems.

The F-35 is designed to evolve through continuous avionics, sensor, and software upgrades, ensuring it maintains competition capability in modern combat environments and adapts to future threats.

Cockpit

The F-35’s glass cockpit is designed to provide the pilot with high situational awareness. The primary display is a 20x8 inch (50x20 cm) panoramic touchscreen that presents flight instruments, weapons systems, communications, and warning data, offering a customizable interface. The cockpit also features a voice recognition system developed by Adacel.

The F-35 replaces the traditional head-up display (HUD) with a Helmet-Mounted Display System (HMDS) that projects all flight and combat data onto the pilot’s visor. Thanks to the Distributed Aperture System (DAS), the pilot can view infrared imagery and 360-degree visual data directly on the helmet screen, observing surroundings without looking outside the aircraft. This system allows the pilot to launch missiles even when the aircraft’s nose is pointed in a different direction. Each HMDS helmet costs $400,000 and is heavier than traditional helmets, potentially posing a safety risk for lighter pilots.

Cockpit features include:

1. A single-piece, forward-hinged canopy with an internal frame.

2. The Martin-Baker US16E ejection seat is launched via a dual catapult system mounted on side rails.

3. A hands-on throttle-and-stick (HOTAS) system provides control via linked control stick and throttle.

4. Oxygen support is provided by the Integrated Power Package (IPP), which includes an onboard oxygen generation system (OBOGS) and a backup oxygen source.

During development, alternative helmet designs were considered due to issues with vibration, night vision, and sensor display in the HMDS, but in 2013, improvements to the baseline helmet led to cancellation of the alternative project. The third-generation helmet introduced in 2016 features an upgraded night vision camera, new liquid crystal displays, and automatic alignment.

Engine

The F-35 is powered by the Pratt & Whitney F135 low-bypass turbofan engine, producing 28,000 lbf (125 kN) military thrust and 43,000 lbf (191 kN) with afterburner. It is an enhanced version of the F119 engine used in the F-22, though not optimized for sustained supersonic cruise. The engine features a radar-invisible afterburner design, serpentine fuel injectors, and ceramic radar-absorbent coatings. Early development stages experienced pressure oscillation issues known as “screech.” The stealth exhaust nozzle contains 15 teeth to reduce radar visibility and infrared signature.

The F-35B variant uses the F135-PW-600 engine, which incorporates a Shaft Shaft-Driven Lift Fan (SDLF) to enable STOVL (short takeoff and vertical landing) operations. The Rolls-Royce LiftSystem consists of a lift fan, drive shaft, two roll posts, and a three-bearing swivel module (3BSM). The 3BSM nozzle directs exhaust downward to assist in takeoff. It uses “fueldraulic” actuators powered by fuel pressure. Unlike the Harrier’s Pegasus engine, the F-35B receives additional lift from the lift fan, providing more balanced takeoff performance. Roll post nozzles on the wingtips provide roll control during slow flight.

An alternative engine development effort, the General Electric/Allison/Rolls-Royce F136, was planned but canceled in 2011 due to budget inadequacy. In 2016, the Adaptive Engine Transition Program (AETP) initiated development of GE’s XA100 and P&W’s XA101 adaptive engine prototypes. However, in 2023, P&W’s F135 Engine Core Upgrade (ECU) was selected due to higher cost and risk, resulting in improved fuel efficiency, thrust, and cooling capacity.

(Translated and edited by Beyza Nur Türkü)[1]

(Translated and edited by Beyza Nur Türkü)[1]

(Translated and edited by Beyza Nur Türkü)[1]

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