Stealthy

The U.S. Navy and U.S. Air Force are working on a new “Compact Variant” of the AIM-9X Sidewinder. The smaller Sidewinder is being developed with a focus on increased magazine depth when carried internally by “advanced aircraft,” while also offering improved range and performance.

The Navy manages the Sidewinder program in cooperation with the Air Force. The Navy is asking for $83.3 million for work on the AIM-9X Compact Variant (CV) in its 2027 Fiscal Year budget request. The AIM-9X CV is also mentioned in the Air Force’s proposed budget for the 2027 Fiscal Year, but with the caveat that it does not plan to contribute funding explicitly toward its development until Fiscal Year 2028.

Current-generation Block II and Block II+ subvariants AIM-9X are already highly capable imaging infrared (IIR) guided anti-air missiles. They have thrust-vectoring, high-off-boresight targeting, lock-on-after-launch, and other capabilities that you can read more about in detail here.

Risk reduction work on the AIM-9X CV has already been underway since Fiscal Year 2025. However, the new version does not appear to have been mentioned by name in prior Navy or Air Force budgets. Previous funding was contained under the umbrella of the larger System Improvement Plan IV (SIP IV) upgrade effort.

“The AIM-9X CV repackages the SIP IV technology into a compact airframe optimized for internal carriage on advanced aircraft with improved kinematic performance,” according to the Navy’s Fiscal Year 2027 budget request. “The program will deliver increased capability to the warfighter with greater standoff range, increased aircraft weapon station capacity, and maintains inner boundary performance.”

In Fiscal Year 2027, the goal is that “the program will advance hardware and software designs. This effort will focus on design and development of critical hardware components and compatibility with advanced platforms,” the budget documents add. “The overall scope includes platform integration, material and energetics studies, and extensive modeling, simulation, and analysis. Activities will also incorporate system safety analysis, the establishment of requisite integration and test environments, risk- reduction testing, and other engineering efforts necessary to mature the complete system baseline.”

The Navy and Air Force budget documents do not offer any further details about the AIM-9X CV’s configuration, or how it will achieve “greater standoff range” and “improved kinematic performance” in a more compact package. How truncated the AIM-9X CV’s airframe, as well as its control surfaces, might be compared to existing versions is also unknown. The core AIM-9X design is already relatively short and narrow by anti-air missile standards at just under 10 feet long and five inches in diameter (not including its fins). For comparison, all variants of the AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM) are some 12 feet long and have bodies that are around seven inches in diameter.

The Navy and the Air Force previously considered developing a Block III variant of the AIM-9X, which could have included a highly loaded grain rocket motor. Though the Block III effort was shelved, at least publicly, the Navy has continued to make significant investments in this kind of rocket technology with a general eye toward improved range and performance for future missiles.

“The Next-Generation Highly Loaded Grain project team has matured the technology and seeded the development of future mission-modular propulsion systems that can increase weapon ranges by up to 1.5x while maintaining inner boundaries for short-range and time-critical missions,” according to one factsheet detailing notable achievements by NAVAIR’s Naval Air Warfare Center Weapons Division (NAWCAD) in 2023.

The benefits of greater reach and better kinematic performance, even in the AIM-9X’s existing form factor, are clear-cut. As the Navy and Air Force budget documents highlight, putting all that in a smaller package offers additional value from a magazine depth perspective. If an aircraft can carry multiple AIM-9X CVs on stations that can only accommodate one standard-size version, that means more engagement opportunities per sortie without any change to the rest of the loadout.

This is all especially important for stealthy aircraft that carry stores in internal bays with rigid dimensions when flying in their most low-observable configurations. As an example of what this means in practical terms, Lockheed Martin has spent years now working to develop a capability called Sidekick to increase the total number of AIM-120s that F-35s can carry in their weapons bays from four to six. Even so, that upgrade will only apply to A and C variants of the jet, as the bays on the B model are smaller to begin with.

The expectation that the AIM-9X CV will offer improved capabilities over its predecessors is also significant. The Air Force, in particular, has explored several concepts for air-to-air missiles that are smaller than Sidewinder, but which have generally been understood to trade range and/or performance for added magazine depth.

All of this brings us to the matter of Collaborative Combat Aircraft (CCA) type drones, which impose additional constraints on weapons integration simply by virtue of their overall size and maximum takeoff weight. As described now, the AIM-9X CV might be well-suited for arming CCAs, which will have more limited internal and external stores capacity, overall, compared to traditional crewed tactical jets. Being able to load them with more total missiles per sortie, and increase their reach at the same time, would be a major boon.

The Air Force just recently started weapons integration work as part of its CCA program using Anduril’s YFQ-44A Fury, which does not have an internal bay. Fury has been seen so far conducting flight tests loaded with a pair of inert AIM-120s, one under each wing.

The YFQ-44A is one of two designs the Air Force is currently flight testing under the first phase, or Increment 1, of its CCA program. The other is General Atomics YFQ-42A Dark Merlin, which can carry stores internally. The Air Force has also been experimenting with other relevant drone designs in recent years, including Kratos XQ-58A and Boeing’s MQ-28 Ghost Bat, the former of which also has an internal payload bay. More recently, the service assigned the YFQ-48A designation to Northrop Grumman’s Talon Blue drone.

It is worth noting here that the development of the MQ-28 originally began for the Royal Australian Air Force, which has conducted at least one live-fire AIM-120 shot from one of those drones. The Ghost Bat carried the missile externally in that test. Future versions of the design are set to include internal weapons bays.

Uncrewed MQ-28 Ghost Bat showcases its combat capability

Back in the United States, the Marine Corps’ first CCA is set to be a variant of the XQ-58, and the service is also leveraging the YFQ-42A to support its CCA plans. The Navy is still early in the process of exploring potential carrier-based CCA designs.

The AIM-9X CV might also open up other kinds of new operational possibilities. A compact anti-air missile could provide defensive capability against incoming missiles for larger aircraft. This is something the Air Force has been particularly interested in, including as a way to help better protect aerial refueling tankers.

The compact version’s overall benefits could make it attractive for employment as a surface-to-air weapon, as well. Full-size AIM-9Xs are already an interceptor option for several ground-based air defense systems in service or otherwise on the market globally today, including the U.S. Army’s Enduring Shield.

With the development of the AIM-9X CV now fully out in the open, more details about the missile’s design, as well as how the Navy and Air Force might plan to field it, may now begin to emerge.

Contact the author: joe@twz.com

Ukraine has released more details of Russia’s S-71K Kovyor — translated as Carpet — an air-launched missile that Kyiv says has been used in combat since late last year. The continued development of weapons in this class highlights the fact that Russia is looking for alternatives to its more established — and more costly — legacy air-launched cruise missiles, with current production levels struggling to meet wartime needs.

The Ukrainian Ministry of Defense’s Main Directorate of Intelligence (GUR) today publicly released new information on the S-71K, including an interactive 3D model. The GUR had previously released details of companies involved in the manufacture of Russia’s Su-57 Felon fighter, and notes that the new missile was specifically developed for this platform.

“The new missile was first deployed by the enemy late last year and appears to represent the United Aircraft Corporation’s (UAC) initial venture into missile manufacturing,” the GUR says.

The GUR adds that the warhead of the S-71K utilizes a 551-pound OFAB-250-270 high-explosive fragmentation bomb. This bomb, which was developed in the Cold War as a free-fall air-launched weapon, is integrated into the structure of the S-71K, which otherwise features a low-observable airframe.

The S-71K’s airframe is made from “a multi-layer fiberglass material with additional reinforcement,” with other internal elements made of aluminum alloys. The airframe has a low-observable shape, with a trapezoidal cross section, chined nose, pop-out swept wings, and an inverted V-tail. Available imagery of the wreckage reveals details of the top-mounted conformal engine intake, feeding a pentagon-shaped intake duct. There are, however, no signs of any low-observable coatings, such as radar-absorbent material, likely to keep costs down.

The GUR also provides information on various electronic components, of which it says “the vast majority” are of foreign origin, including items manufactured in China, Germany, Ireland, Japan, Switzerland, Taiwan, and the United States. As the GUR says, “Continued access to foreign technologies and components allows the aggressor state to develop new weapons and scale their use in the war against Ukraine.”

This makes it one of many Russian weapons relying on foreign parts. For instance, a Russian Shahed-136 strike drone obtained by the GUR contained numerous components from the U.S. as well as parts from Iran, Taiwan, and other nations. Previously, we noted that the GUR found multiple foreign components in a Russian S-70 Okhotnik-B (Hunter-B) flying-wing uncrewed combat air vehicle (UCAV) downed in a case of friendly fire.

The S-71K is powered by a compact R500 turbojet engine, also produced by UAC, and features what the GUR describes as “an inertial navigation system based on simple sensors.”

With three separate internal fuel tanks, Ukraine assesses that the S-71K has an operational range of up to 186 miles. Earlier reports suggest that the missile flies at a speed of Mach 0.6 and at altitudes of up to 27,000 feet.

In 2024, it was reported that Sukhoi had received approval from the Russian Defense Ministry to begin producing the S-71, after it underwent “significant design changes” based on lessons from the Ukraine conflict.

These changes apparently included increasing the range and reducing the radar cross-section to improve survivability against air defenses.

The GUR has not said what platform or platforms are understood to have employed the S-71K in the war in Ukraine. As mentioned, the S-71K is known to have been developed with the Su-57 in mind and has at least been tested on this aircraft, with captive-carry trials in April 2024 at the Russian flight research center in Zhukovsky. There is no reason that it couldn’t also be carried by other Russian tactical jets; this would be necessary for large-volume employment, if significant production numbers are actually realized.

It is also expected that Russia will explore the integration of the S-71K with its S-70 Okhotnik UCAV.

Interestingly, there have also been reports that the S-71K may be complemented by a more advanced weapon, known as the S-71M Monokhrom. While described as a kamikaze drone, this is essentially an air-to-ground missile expected to have a “human-in-the-loop” capability, to allow dynamic targeting, including against moving targets, via a controller on the ground. In this way, it differs from the S-71K, which apparently features a fairly basic inertial guidance system, likely backed up by satellite navigation. The S-71M is also said to feature electro-optical sensors for day and night operations, and multiple warhead options, including high-explosive and shaped charges.

While the S-71K is externally carried by launch aircraft, the S-71M can reportedly also be accommodated in the weapons bay of a Su-57 or S-70 UCAV. So far, we have not seen S-71s with folding tailfins, which would be required for internal carriage.

Earlier this year, unconfirmed reports from Russia suggested that the S-71M Monokhrom may have been used in an attack on a Ukrainian HIMARS launcher in the Chernihiv region, although the Russian military stressed that the target was destroyed by a Geran loitering munition. Images released of S-71M test rounds indicate a missile design that is notably less stealthy than the latest S-71K, but the M-version may also have been refined in the meantime.

In March of this year, the GUR revealed details of another new Russian air-launched cruise missile, the Izdeliye 30, which you can read more about here.

The Defence Intelligence of Ukraine has published an interactive 3D model, the main assemblies, and components of the enemy’s new cruise missile “izdeliye-30,” as well as data on 20 enterprises involved in its production cooperation chain.

🔗: https://t.co/shMagPCZHE pic.twitter.com/6XgEsxVatf

— Defence Intelligence of Ukraine (@DI_Ukraine) March 2, 2026

This missile also has folding wings, but offers a much longer range of at least 930 miles. It is similarly powered by a compact turbojet engine but does not have a stealthy airframe.

Various components in the Izdeliye 30 appear to have been reused from existing weapons, reducing cost and complexity and speeding development.

Based on its range, the Izdeliye is likely intended as a cheaper, simpler alternative to the air-launched cruise missiles otherwise used by Tu-95MS and Tu-160 bombers, namely the Kh-101 and Kh-555 (the Kh-55 carries a nuclear warhead).

Meanwhile, the S-71K appears to be tailored for tactical crewed and uncrewed aircraft, while its more limited range is partly compensated for by the fact that it has low-observable features (and is intended for launch from low-observable platforms).

The S-71K should also offer a cheaper alternative to the Kh-69, a weapon widely associated with the Su-57, although it can also be launched by ‘legacy’ Russian tactical aircraft. You can read about this air-to-surface missile here.

1/ TASS reports that KTRV will display (a mock-up of) its Kh-69 air-launched cruise missile (ALCM) at the upcoming “Army-2022” forum.

Specifications:
– Max range (km): 290
– Cruise speed (km/h): 700 – 1,000
– Warhead (kg): 300 – 310 (depending on configuration) pic.twitter.com/UD38MsNNpG

— Guy Plopsky (@GuyPlopsky) August 11, 2022

While it remains to be seen exactly how the S-71 series will be used in an operational context, it’s clear that Russia has a need for cheaper, easier-to-produce air-launched missiles for its combat aircraft fleet. 

Just as the U.S. military is facing the challenge of limited munitions stocks as it prepares for a potential future conflict with China, Russia has a requirement today for strike weapons that can be manufactured cost-effectively and in large numbers.

At minimum, the deployment of the S-71 poses an additional challenge for Ukraine’s already strained air defense forces, especially given the continued scarcity of Western-supplied ground-based air defense systems.

Contact the author: thomas@thewarzone.com