Like Lockheed Martin F-35 The Lightning II is a stealth fighter and needs to carry ammunition inside its bays. The presence of external ammunition and fuel tanks significantly increases its radar signature and visibility. Its internal compartments were designed in the early 2000s and now guide engineering decisions in the design of next-generation air-to-air missiles and other munitions intended for use on the platform.
The new Joint Advanced Tactical Missile, the AIM-260, is one example of a next-generation air-to-air missile specifically designed to be bayed on the F-35. Although the F-35 can function as a “missile truck” in beast mode, in practice it rarely, if ever, does so. Instead it’s transfers this role to other fighters (such as the F-15EX and Eurofighter Typhoon). He has a lot to know about the new four-meter rocket developed for the F-35.
Internal weapons bay limitations
Credit: Ministry of Defense.
The F-35 has a major limitation: it needs to carry weapons internally to maintain its stealth. This means that missiles must fit into its weapons bay, a problem for longer missiles that cannot fit. The F-35’s internal compartment is just over four meters long. It is only capable of carrying approximately 5,700 lb (2,585 kg) lb of ammunition internally.
With that said, The F-35A can carry approximately 22,000 pounds (9,980 kg) of ordnance externally in “beast mode”.bringing the total payload to 27,700 lb (12,565 kg), although it does sacrifice stealth. By comparison, the F-15EX Eagle II carries no ordnance internally and carries up to 29,500 lb (13,381 kg) of ordnance externally.
In practice, the F-35 rarely flies in beast mode in combat, at least as publicly reported. In March 2025, after the type had been in service for about seven years and flown thousands of combat missions, The War Zone reported that Israel had become the first publicly known operator to use them in brutal fashion. This may have been done for missions over the Gaza Strip or Lebanon, where the F-35 faces no credible threats or faces limited threats.
Internal weapon bays are here to stay
Credit: US Air Force.
While the F-35’s internal weapons bays may be seen as a major limitation, they are here to stay. Although they are one of the reasons why the F-35 works well when paired with 4.5 generation fighters such as F-15EX (for which the USAF is increasing its order)Eurofighter Typhoon and other aircraft. In the RAF, F-35s are informally referred to as “killers” and Eurofighter crews are referred to as “bandits”.
The F-35 wasn’t the first fighter to have internal compartments: those were the F-117 Nighthawk and the F-22 Raptor. Because the Raptor is an air superiority fighter, its payload limitation is not as important as for ground-based aircraft. Russia has since developed its Su-57 Felon with internal compartments, although it is unclear whether they will enter service in mid-2026. The South Korean KF-21 is designed with internal compartments that will enter service during subsequent block upgrades.
The Chinese J-20 relies on internal weapons bays and even abandoned the usual internal automatic cannon. Next generation prototypes in China (such as the J-50 and J-36) also appear to have internal weapons bays. The Anglo-Japanese-Italian fighter GCAP/Tempest has them. Aviation Week, which was allowed to look at the demonstrator under construction, reported that:
“The size suggests the demonstrator could carry twice the internal weapons capacity of the F-35’s relatively shallow bays and potentially accommodate larger-diameter magazines.“
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F-35A Compartment Dimensions
Credit: Ministry of Defense.
However, the US Air Force, Marine Corps and Navy will have to make do with the relatively shallow compartments of the F-35 in the 2060s and beyond. Regular F-35A (used by the Air Force) and carrier-based F-35C (used by Marines and Navy) have the same internal geometry of the weapons compartment.
Commonly accepted dimensions are about 14 feet (4.27 meters) long, 25 inches (0.64 meters) wide, and 25 inches (0.64 meters) deep. The STOVL variant used by the Marine Corps is noticeably shorter. It is 12.5 to 13 feet (3.8 to 4.0 meters) long, making it six to 12 inches shorter. The width is believed to be slightly smaller at about 24 inches (0.61 meters), and the depth is likely about the same at 25 inches (0.64 meters).
Internal compartment dimensions of the F-35 (according to various estimates) | F-35A and F-35S | F-35B |
|---|---|---|
Length | 14 feet (4.27 meters) | 12.5 to 13 feet long (3.8 to 4.0 meters) |
Width | 25 inches (0.64 meters) | 24 inches (0.61 meters) |
Depth | 25 inches (0.64 meters) | 25 inches (0.64 meters) |
In its normal stealth configuration, the F-35A can carry combinations such as four AIM-120 AMRAAM or two 2000 lb (907 kg) and two AIM-120 or eight GBU-53/B StormBreakers and two to four air-to-air missiles. The latter configuration will become possible after the modernization of Block 4. In the future, it will be able to carry AIM-260 JATM. The European air-to-air missile MBDA Meteor is also being tested for integration.
Joint advanced tactical missile AIM-260
Credit: Ministry of Defense.
The four-meter rocket mentioned in the title of this article Joint advanced tactical missile AIM-260. It was designed specifically to fit into the bays of the F-35, although it may not fit into the bays of the F-35B variant. The missile is a US-developed air-launched cruise missile (developed from the Naval Strike Missile).
The War Zone reported that the missile first broke cover in May 2026 on an F/A-18F Super Hornet assigned to the 31st Air Test and Evaluation Squadron. It is known that flight tests began many years ago. It is expected to complement and eventually replace the AIM-120 AMRAAM in US service. The publication wrote that “unlike the AIM-120, it does not have middle steering surfaces or even straps running down the sides. The overall JATM configuration reflects optimization for maximum speed and range.“
The US Navy is developing the AIM-260 in collaboration with the Air Force. The military is known to be nervous that the growing reach of Chinese air-to-air missiles such as the PL-15 is eroding their advantages.
The missile is reportedly designed to hit targets at a range of at least 120 miles (200 kilometers) and even further. Alex Hollings of Sandboxx News recently reported that a notice released by the Air Force Life Cycle Management Center said the service is seeking to develop an air-to-air missile capable of hitting targets out to 1,000 nautical miles (about 11 times that of the AIM-120).
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Meteor vs AIM-260
Credit: Ministry of Defense.
The European MBDA Meteor is widely considered the world’s best air-to-air missile.or at least belonging to the highest echelon of such missiles. However, it is also limited by what aircraft it is integrated into, with integration work with the F-35 still ongoing. Comparing the missile to the AIM-260 is difficult, since much more is known about the mature Meteor than the highly classified AIM-260.
However, the AIM-260 is said to be slightly longer (13 feet or 4.0 meters versus 12 feet or 3.66 meters). The Meteor uses a new solid rocket booster and a throttled ramjet engine, allowing it to reach longer ranges. Meanwhile, it is widely believed that the AIM-260 uses an advanced solid rocket motor rather than a ramjet, although few official details have been released.
The Meteor’s speed exceeds Mach 4. The AIM-260 is widely believed to be somewhat faster, with many reports estimating the speed to be closer to Mach 5. However, the Meteor’s range is officially reported to be over 62 miles (100 kilometers), but it is widely believed to be significantly greater.
This is important to note when making air-to-air comparisons. rocket the ranges they reach are heavily influenced by factors such as how high and fast the fighter flies, how high or low the missile flies, the degree to which the missile is aimed outboard, and other factors. The ranges are highly classified, and companies may use different criteria to measure distances.
How AIM-260 addresses 2002 decisions
Credit: Ministry of Defense.
There is still much to learn about the new AIM-260, including its exclusion zone. For example, the Meteor’s throttled ramjet engine allows it to maintain thrust throughout most of the flight, rather than simply coasting after the engine burns out. This allows him to maintain unusually high energy during the final stages of combat and contributes to the creation of one of the largest known no-exit zones. A missile’s no-exit zone is not the same as its range.
The two missiles may have a range of 150 miles, but the practical no-evasion zones may differ dramatically. The true range and zone of no return of the AIM-260 remains to be seen. The AIM-260 highlights several factors. One is the eternal cat-and-mouse game of innovation, counter-innovation and adaptation. China may have developed a long-range missile, but this is encouraging the US to develop an even bigger missile.
Another factor is how engineering decisions made 25 years ago dictate engineering decisions now and decades into the future. Around 2002, engineers largely overhauled the F-35’s internal compartments, decisions that now influence missile design. WITH The US only gets about a third from F-35 purchasesit will serve as the basis for rocket development for decades to come.