The F-35 Lightning II is the most complex and expensive weapon system in the history of military aviation. As a fifth-generation fighter jet, it embodies a fundamental paradigm shift: away from pure kinematic superiority toward information dominance and spectral superiority [1]. This article documents the ten central technical systems of the F-35 based on verified original sources.
The F-35 is produced in three variants based on a common basic design, yet differing significantly in their construction. Contrary to frequent claims, the actual commonality between the variants is only around 20% shared structural components [2].
The F-35A is the primary variant of the US Air Force and the export model for international partners, including Switzerland. It is designed for conventional takeoff and landing on paved runways.
| Parameter | Value |
|---|---|
| Maximum Speed | Mach 1.6 |
| Combat Radius | >1,093 km (590 nm) |
| Service Ceiling | >15,240 m (50,000 ft) |
| g-Limit | +9.0/-3.0 g |
| Internal Fuel Capacity | 8,278 kg (18,250 lbs) |
| Empty Weight | approx. 13,290 kg |
Source: USAF Fact Sheet F-35A [3], Lockheed Martin F-35 Brochure [4]
The F-35B is the variant of the US Marine Corps and the Royal Air Force. It features the Rolls-Royce LiftFan system and a swiveling nozzle that enable short takeoff and vertical landing.
| Parameter | Value |
|---|---|
| Combat Radius | >833 km (450 nm) |
| Vertical Thrust | >18,000 kg (combined) |
| g-Limit | +7.0 g |
| Special Feature | Smaller weapon bays than F-35A/C |
The F-35C is the carrier variant of the US Navy with a reinforced airframe, tailhook, and folding wings for aircraft carrier operations.
| Parameter | Value |
|---|---|
| Combat Radius | >1,111 km (600 nm) |
| Wingspan | 13.1 m (43 ft) -- larger than A/B |
| g-Limit | +7.5 g |
| Special Feature | Reinforced landing gear structure, larger wing area |
As of the end of 2024, over 1,000 F-35s have been delivered to international users. The annual production rate is approximately 150 aircraft, with a target of 156 per year [5].
The Pratt & Whitney F135 is the most powerful fighter jet engine ever to enter serial production. It exists in three sub-variants [6]:
| Parameter | Value |
|---|---|
| Dry Thrust | approx. 128 kN (28,000 lbf) |
| Afterburner Thrust | approx. 191 kN (43,000 lbf) |
| Engine Length | approx. 5.59 m (220 inches) |
| Inlet Diameter | approx. 1.09 m (43 inches) |
| Architecture | Three-stage fan, six-stage high-pressure compressor, annular combustor |
| Maintenance Concept | 6 hand tools for all Line Replaceable Components |
Sources: P&W F135 Fast Facts [7], P&W F135 Characteristics [8]
Over 1,300 engines have been delivered and have collectively accumulated more than 1 million flight hours [6].
The ECU modernizes the engine core and offers [9]:
The ECU contract amounts to 1.31 billion USD [10].
The Adaptive Engine Transition Program (AETP) with the demonstrators XA100 (GE) and XA101 (P&W) was not pursued further for the F-35, as the adaptive engines only fit the F-35A but not the B and C variants [11]. Instead, the AETP technology is flowing into the Next Generation Advanced Propulsion (NGAP) program for the F-47 (NGAD) with a total volume of 7 billion USD [12].
The avionics of the F-35 consist of four tightly integrated main systems that are linked by a central fusion engine into a unified tactical picture [13].
Developed by Northrop Grumman, the AN/APG-81 is a third-generation Active Electronically Scanned Array (AESA) with approximately 1,676 transmit/receive modules (TRMs) on a GaAs (gallium arsenide) basis [14].
Operating Modes:
The system received the David Packard Award for outstanding acquisition performance in 2010 [14].
Six MWIR sensors (Medium-Wave Infrared) distributed across the aircraft provide complete 360-degree infrared coverage [15]. Functions include:
Starting from Lot 15, the original Northrop Grumman system is being replaced by a next-gen version from RTX/Raytheon [16].
Developed by Lockheed Martin, the EOTS is the world's first conformally integrated electro-optical targeting system [17]. It combines:
The Advanced EOTS upgrade (starting with Block 4) introduces SWIR sensors (Short-Wave Infrared) and HDTV resolution [18].
The Communications, Navigation and Identification (CNI) suite from Northrop Grumman integrates over 27 avionics functions into a Software-Defined Radio system [19]. It includes:
The planned transition from the AN/APG-81 to the AN/APG-85 marks a fundamental technology change in the semiconductor basis of the transmit/receive modules [20]:
| Property | GaAs (APG-81) | GaN-on-SiC (APG-85) | Improvement |
|---|---|---|---|
| Bandgap | ~1.4 eV | ~3.4 eV | 2.4x |
| Breakdown Field Strength | ~0.4 MV/cm | ~3.3 MV/cm | ~8x |
| Power Density | ~1.5 W/mm | 5-12 W/mm | 3-8x |
| Power Added Efficiency | 25-40% | 50-65% | ~1.5-2x |
Sources: Qorvo GaN/GaAs Analysis [21], Military Embedded Systems [22]
The AN/APG-85, also developed by Northrop Grumman, is intended for F-35 Lot 17 and subsequent production lots [23]:
The full potential of the AN/APG-85 depends on the successful integration of the Technology Refresh 3 (TR-3) computer infrastructure. TR-3 software stabilization is ongoing until at least 2026 [24].
The Chinese J-20 features the Type 1475 AESA radar with an estimated 2,000-2,200 TRMs in a larger aperture [25]. The AN/APG-85 is the answer to this physical disadvantage: since the F-35 cannot enlarge its nose cone, it must increase the power per module.
According to current knowledge, the Swiss F-35As will be delivered with the AN/APG-81, not the AN/APG-85 [26]. This results in an estimated 33% lower initial detection range compared to APG-85-equipped allies.
The F-35 has internal and external weapon stations, the use of which directly affects the stealth signature [27].
Starting from Lot 15, the Sidekick adapter enables the internal carriage of 6 instead of 4 AIM-120 AMRAAM in the F-35A/C variants [28]. The adapter is not compatible with the F-35B.
6 external stations (3 per wing) with a total payload capacity of up to 8,160 kg (18,000 lbs) [27]. The use of external pylons significantly increases the radar cross-section.
Maximum external loading at the expense of stealth characteristics. Typical for scenarios with established air superiority.
| Weapon | Type | Status |
|---|---|---|
| AIM-120D AMRAAM | BVR air-to-air | Operational |
| AIM-9X Sidewinder | WVR air-to-air | Operational |
| GBU-31/32 JDAM | GPS-guided bomb | Operational |
| GBU-39 SDB I | Small Diameter Bomb | Operational |
| GBU-53/B StormBreaker | Tri-mode guided bomb | Operational |
| AGM-154 JSOW | Standoff glide bomb | Operational |
| AIM-260 JATM | Long-range air-to-air | In development (Block 4) |
| AGM-88G AARGM-ER | Anti-radiation missile | Internal integration planned |
| JSM (Joint Strike Missile) | Anti-ship/land attack | Norway/Australia |
The stealth characteristics of the F-35 are based on several complementary technologies [29].
The estimated RCS of the F-35 is ~0.001-0.01 m² in the frontal hemisphere -- comparable to the size of a golf ball [30]. This value applies to X-band frequencies, as used by most tactical radars.
The F-35 uses Fibermat technology -- radar-absorbing materials baked directly into the outer skin [29]. Compared to the F-22 with glued-on RAM coatings, this is more corrosion-resistant and requires less maintenance.
Instead of a conventional splitter plate, the F-35 uses a compression bump in front of the engine inlet [31]. Advantages:
For peacetime flights and exercises, 4 Luneburg lens reflectors (2 on top, 2 on bottom) are attached, which intentionally increase the RCS [32]. They are removed for combat missions.
Against VHF radars (Very High Frequency, wavelength ~1-3 m), stealth aircraft like the F-35 are significantly more visible due to resonance effects [33]. Russian systems such as the Nebo-M specifically exploit this.
Sensor fusion is the heart of the F-35 and the most important differentiator compared to fourth-generation fighter jets [34].
All sensor data -- radar (APG-81), infrared (DAS, EOTS), electronic intelligence (ASQ-239), and data links (MADL, Link-16) -- are correlated in a central fusion engine and linked into a unified tactical situational picture [34].
The 50x20 cm touchscreen display (20x8 inches) replaces conventional individual instruments and shows the fused situational picture in configurable views [35].
Developed by Collins Aerospace (RTX) and Elbit Systems, the Gen III helmet enables [36]:
The F-35 does not primarily operate as a kinematic weapons platform but as a sensor node in a networked "Kill Web" [37]. The ability to absorb, process, and distribute information is operationally more significant than speed or maneuverability alone.
MADL is the stealth-optimized data link of the F-35, operating in the Ku-band with directional phased-array antennas [38]:
The standardized NATO data link for broad interoperability [39]:
F-35 (MADL) and F-22 (IFDL) cannot communicate directly with each other [39]. Solution approaches:
The Block 4 modernization originally encompassed 66 new capabilities but has been reduced due to massive delays and cost overruns [43]:
| Parameter | Originally Planned | Current Status (2025) |
|---|---|---|
| Completion | 2026 | 2031+ |
| Cost | ~$12 billion | ~$18+ billion (+$6 billion over budget) |
| Capabilities | 66 | Reduced to "subset" |
Source: GAO-25-107632 [43]
TR-3 replaces the legacy Integrated Core Processor (ICP) with a new system featuring [35]:
Chronology of Delays:
ALIS (Autonomic Logistics Information System) was the original maintenance information system of the F-35 with severe problems [45]:
ODIN (Operational Data Integrated Network) replaces ALIS as a cloud-based system [45]:
Already in planning as the successor to the Block 4 modernization with additional capability enhancements [46].
The AN/ASQ-239, developed by BAE Systems, is the integrated electronic warfare system of the F-35 [47].
BAE Systems is developing the Digital Channelized Receiver Techniques Generator (DTIP) [48]:
Over 1,200 AN/ASQ-239 systems were delivered by the end of 2024 [47]. BAE Systems is investing 100 million USD in a new manufacturing facility (7,400 m²) with AI-powered automation and a capacity of 11 systems per month [49].
[1] Laird, R. F. & Timperlake, E.: The F-35 and the Future of Power Projection. NDU Press
[3] United States Air Force: F-35A Lightning II Fact Sheet
[4] Lockheed Martin: F-35 Lightning II Broschüre (PDF)
[5] GAO-25-107632: F-35 JSF: Actions Needed to Address Late Deliveries. 2025
[6] RTX / Pratt & Whitney: F135 Engine – Powering the F-35 Lightning II
[7] RTX / Pratt & Whitney: F135 Fast Facts 2025 (PDF)
[8] Pratt & Whitney: F135 Engine Characteristics
[9] Pratt & Whitney: F135 Engine Core Upgrade
[10] Air & Space Forces Magazine: Engine Core Upgrade for F-35 Passes PDR. 2024
[11] Air & Space Forces Magazine: Air Force Skips AETP Engines for F-35, Presses on with NGAP. 2024
[12] Air & Space Forces Magazine: Pentagon Hands Out $7 Billion for NGAP Engine. 2025
[13] Lockheed Martin: F-35 Mission Systems Design, Development, and Verification (PDF)
[14] Northrop Grumman: AN/APG-81 AESA Fire Control Radar
[15] Wikipedia: AN/AAQ-37 Distributed Aperture System
[16] RTX / Raytheon: Electro-Optical Distributed Aperture System
[17] Lockheed Martin: F-35 Electro Optical Targeting System (EOTS)
[18] Lockheed Martin: EOTS Product Card (PDF)
[19] Northrop Grumman: 100th Communications, Navigation, and Identification System Delivered. 2013
[20] Military Embedded Systems: GaN vs. GaAs for Next-Gen AESA Radar
[21] Qorvo: X-Band Radar: Driving Defense Applications with GaN and GaAs Technology
[22] Military Embedded Systems: GaN Technology in AESA Radar Systems
[23] Northrop Grumman: Developing the Next Generation Radar for the F-35. 2023
[24] Defense News: Key tests for latest F-35s will begin in 2026. 2025
[25] Air University / CASI: A Look at the J-20 AESA Radar
[26] Breaking Defense: Eyeing risk of radar delays, Lockheed proposes new F-35 fuselage design. 2025
[27] Aerospaceweb: F-35 Weapon Carriage Capacity
[28] The War Zone: F-35 Closer To Carrying Six AIM-120 Missiles Internally. 2023
[29] Wikipedia: Lockheed Martin F-35 Lightning II -- Design
[30] GlobalSecurity: Stealth / Low Observable Technology
[31] Wikipedia: Diverterless Supersonic Inlet
[32] The Aviation Geek Club: Luneburg Lens Radar Reflectors. 2022
[33] Fly a Jet Fighter: The F-35 Facing Russian and Chinese VHF Radars. 2023
[34] F35.com: Sensor Fusion in Focus
[35] Lockheed Martin / F35.com: Block 4 Capabilities
[36] Collins Aerospace / RTX: Gen III Helmet Mounted Display System; Elbit Systems of America: F-35 HMDS
[37] NDU Press: The F-35 and the Future of Power Projection
[38] Wikipedia: Multifunction Advanced Data Link
[39] Air & Space Forces Magazine: The F-22 and the F-35 Are Struggling to Talk
[40] The War Zone: F-22 And F-35 Datalinks Finally Talk via U-2 Gateway. 2021
[41] Air & Space Forces Magazine: F-35 Cues Ground Artillery with New Data Gateway. 2025
[42] Bulgarian Military: Danish F-35 fighters test DAGGR-2. 2025
[43] GAO-25-107632: F-35 JSF: Actions Needed to Address Late Deliveries (PDF). 2025
[44] Defense Security Monitor: A Sobering Report on the DoD's Largest Weapons Program. 2025
[45] Air & Space Forces Magazine: F-35 Program Dumps ALIS for ODIN
[46] Air & Space Forces Magazine: First F-35 Block 4 Updates, Block 5. 2025
[47] BAE Systems: AN/ASQ-239 F-35 EW Countermeasure System
[48] Military Embedded Systems: Block 4 work for F-35 EW system gets BAE Systems update. 2023
[49] Microwaves & RF: Enhanced EW Upgrades AN/ASQ-239 System. 2024