DRDO AIP Plug: Late, But a Leap for Project-76 Indigenous Submarine Design

AIP Energy Module & Submarine Plug Diagram by Gemini

DRDO is reportedly poised to deliver its indigenously developed Air Independent Propulsion (AIP) plug in time for integration with INS Khanderi during its scheduled refit in 2026–27.

INS Khanderi is the second Kalvari-class (Project-75, Scorpene) submarine inducted into the Indian Navy (IN). It was commissioned on September 28, 2019.

The Indian Navy inducted six Kalvari-class Scorpene submarines under Project-75 between 2017 and 2024. Originally, it was planned to integrate DRDO-developed AIP plugs—designed to facilitate extended submerged endurance—into all Kalvari-class boats. However, the DRDO plug was not ready in time for installation on the first boat, INS Kalvari.

AIP Development Landmarks and Timeline

In June 2023, DRDO signed a contract with L&T to provide two AIP system modules for Kalvari-class submarines.

Under the contract, the Naval Materials Research Laboratory (NMRL), a DRDO laboratory, transferred AIP technology to L&T. The AIP modules are manufactured, integrated, and undergo factory acceptance trials at L&T’s AM Naik Heavy Engineering Complex in Surat.

The AIP modules, also called Energy Modules (EMs), are integrated into the AIP plug, which is then retrofitted into the submarine during refit. The refit will also include equipping the boat to launch DRDO-developed heavyweight torpedoes.

In December 2025, DRDO was expected to deliver the EM for integration with the plug that will be inserted into INS Khanderi during its refit.

“The system has undergone extensive shore-based trials and has met the required benchmarks. Integration work on the second submarine is expected to be completed before December 2026,” Times Now reported, quoting sources.

The submarine will need to undergo extensive trials following installation of the AIP plug, since the dimensions and buoyancy characteristics of the boat will change.

Sea trials are reportedly expected to commence between July and August 2027, with the full refit process expected to conclude by early 2028, the sources added.

Characteristics of the DRDO-Developed AIP

The DRDO-developed AIP uses phosphoric acid fuel cell (PAFC) technology.

A fuel cell converts chemical energy from a fuel into electricity through a chemical reaction between positively charged hydrogen ions and oxygen (or another oxidizing agent).

1. Several fuel cell types exist, including:
2. Alkaline Fuel Cell (AFC)
3. Proton Exchange Membrane Fuel Cell (PEMFC)
4. Direct Methanol Fuel Cell (DMFC)
5. Molten Carbonate Fuel Cell (MCFC)
6. Phosphoric Acid Fuel Cell (PAFC)
7. Solid Oxide Fuel Cell (SOFC)

A PAFC uses phosphoric acid (H₃PO₄) as the electrolyte. Hydrogen gas (H₂) is used as the fuel at the anode, while oxygen (O₂) from air is supplied at the cathode.

PAFC fuel cells offer several advantages over other fuel cell types. They provide greater fuel flexibility and are more tolerant of fuel impurities. They can operate using reformed hydrocarbon fuels such as methanol or even biogas.

PAFC operating temperatures (150–200°C) are relatively high. As a result, they generate steam as a byproduct in addition to electrical power for propulsion. The steam can be utilized for other onboard heating requirements, raising overall operating efficiency to as high as 70%.

INS Khanderi

DRDO AIP Critical for Project-76 Submarines

Successful integration of the DRDO AIP plug will not only augment the capabilities of Project-75 submarines but will also facilitate finalization of the design of Project-76 submarines.

Under Project-76, India has embarked on an ambitious design, development, and manufacturing program to deliver 12 next-generation diesel-electric attack submarines (SSKs) to the Indian Navy.

Project-76 is envisaged as the logical successor to the foreign-designed Project-75 (French Scorpène) and the upcoming Project-75I (Most likely German Type-214) programs.

Project-76 was initiated in late 2023 when the Indian Navy’s Warship Design Bureau (WDB) received formal authorization to begin the preliminary design phase.

In early 2024, the MoD allocated initial funding for the indigenous development of two pivotal enabling technologies for modern submarines: AIP systems and advanced lithium-ion batteries. As noted earlier, AIP offers increased submerged endurance, while lithium-ion batteries provide higher discharge rates and faster charging compared with traditional lead-acid batteries.

Project-76 aims for an unprecedented 90–95% indigenous content, including the Combat Management System (CMS), sonar suites, and periscopes.

Development Timeline

L&T is confirmed to be part of the design process along with the Navy’s Directorate of Naval Design (Submarine Design Group) (DND-SDG).

L&T’s credentials in submarine construction are impressive and extend beyond the development of the AIP plug for Project-75 submarines. The company previously carried out detailed engineering and hull construction for the Arihant-class SSBNs. It also designed and developed the SOV-400 Midget Submarine, a 400-tonne special operations vessel for commandos.

Additionally, L&T designed and built the Submarine Escape Training Tower (SETT) facility in Visakhapatnam, which is used to train naval crews in emergency escape procedures.

P-76 Progress

In September 2025, a senior L&T official reportedly stated that the design phase of the submarine could be completed by 2026–27.

As of March 2026, the project has moved into the detailed design phase. The Indian Navy is currently finalizing the Staff Requirements to ensure the P-76 can act as a bridge between conventional SSKs and nuclear-powered attack submarines (SSNs) being built under Project-77.

Initially, six submarines are proposed to be built. The first submarine could be delivered in six to seven years, with all six delivered within ten years.

As mentioned earlier, follow-on orders are likely to meet the Indian Navy’s expanding requirements.

P-76 Specifications

The P-76 submarine is envisioned as a 3,000-tonne class vessel, roughly 50% larger than the current Kalvari class.

It will feature a fully indigenous AIP system and incorporate advanced lithium-ion batteries, both designed and developed by DRDO in collaboration with L&T.

The submarine will be armed with indigenously developed torpedoes as well as torpedo-tube-launched anti-ship and land-attack cruise missiles.

 

When MR-SAM Is Available, Why Import Shtil-1?

Gemini generate image of a Shtil-1 interceptor launch from a IN warship

The MoD recently inked contracts worth ₹5,083 crore for the ALH Mk-III (MR) and VL-Shtil missiles.

According to the MoD press release on the Vertical Launch Shtil missiles:

“The contract for the procurement of Surface-to-Air Vertical Launch Shtil missiles and associated missile holding frames, valued at ₹2,182 crore, has been signed with JSC Rosoboronexport, Russian Federation. The acquisition is intended to substantially enhance the air defence capabilities of frontline warships against a wide spectrum of aerial threats.

The system will reinforce the layered air defence architecture onboard Indian Navy platforms by providing rapid-reaction, all-weather engagement capability and improved survivability in contested maritime environments.”

About Shtil-1

The Shtil-1 is an area air defence missile system developed by Russia's Almaz-Antey for light warships.

The Shtil-1 uses the 9M317ME semi-active radar homing (SARH) missile, a specialised naval variant of the missile used in the land-based Buk-M2 air defence system. The 9M317ME is a single-stage solid-fuel interceptor with folding fins to fit inside compact VLS canisters. During mid-course, the missile uses inertial guidance, 

The choice of a SARH system represents a well-considered engineering trade-off that prioritises cost, missile size, and terminal power over the “fire-and-forget” convenience of an Active Radar Homing (ARH) system like the MR-SAM.

The use of SARH enables strong target illumination using the ship’s high-power fire-control radars (such as the MR-90 Orekh). In contrast, an ARH missile relies on a small, battery-powered radio frequency (RF) transmitter, resulting in weaker target illumination.

SARH seekers are significantly cheaper and simpler to mass-produce than ARH seekers. Since a ship might need to carry 24–36 missiles, the cost savings are substantial.

By removing the radar transmitter and its associated cooling and power requirements from the missile, engineers can either reduce missile size or use the additional space for a larger warhead or more fuel.

An ARH missile is more susceptible to jamming due to its low-power RF transmitter. Since a SARH seeker is passive (it only listens), it is harder for a target to jam the missile directly. The target would have to overpower the ship’s high-power radar illuminating it.

However, SARH systems have limitations. They work best for shorter-range engagements. The ship must maintain line of sight to the target to keep it illuminated. This makes it difficult to engage sea-skimming missiles that are over the radar horizon.

Additionally, the further the target is from the ship, the weaker the reflected illumination becomes, in accordance with the inverse square law.

Shtil-1 Antecedents

The Shtil-1 system replaces the older Shtil/Uragan systems that used a single-arm rail launcher. In contrast, the Shtil-1 employs a modular, below-deck cellular Vertical Launch System (VLS).

This allows 360-degree omnidirectional defence without the need to rotate a heavy launcher toward the target.

Shtil-1 Performance

The system is capable of a high rate of fire, with the ability to launch a missile every 2–3 seconds.

The Shtil-1 is designed to intercept a wide spectrum of aerial threats, including supersonic aircraft, helicopters, drones, and high-speed anti-ship missiles. It can engage targets at ranges from 3.5 km to 50 km and at altitudes ranging from as low as 5 metres (sea-skimming missiles) up to 15 km.

A single installation can reportedly track and engage up to 12 targets simultaneously, making it effective against swarm or saturation attacks.

The Shtil-1 was developed for Project 11356R (Admiral Grigorovich-class) frigates in the Russian Navy. It currently equips Indian Navy Tushil-class frigates (Project 11356 derivatives).

Several Indian Navy warships previously equipped with Shtil/Uragan systems are now being fitted with Shtil-1 systems. These include:

Batch I & II Talwar-class frigates — INS Talwar, INS Trishul, INS Tabar, INS Teg, INS Tarkash, and INS Trikand — originally equipped with the 3S-90 single-arm launcher located forward of the bridge, carrying 24 missiles.

Delhi-class destroyers — INS Delhi, INS Mysore, and INS Mumbai — which feature two 3S-90 single-arm Shtil/Uragan launchers (one forward and one aft) firing 9M38M1 missiles. These are now slated for, or currently undergoing, Shtil-1 upgrades as part of their mid-life refits; they are also being equipped with improved Fregat-M2EM radars to handle contemporary saturation threats.

Shivalik-class stealth frigates — INS Shivalik, INS Satpura, and INS Sahyadri — originally fitted with the single-arm Shtil/Uragan launcher and now slated for, or undergoing, Shtil-1 upgrades like the Delhi class destroyer.

Conclusion

The Shtil-1 is one of the two principal area air defence systems fitted on Indian Navy warships, the other being the Israeli-Indian MR-SAM (Barak-8).

The Shtil-1 is both robust and cost-effective. As an evolution of the Buk family, it has an creditable operational track record. It relies on Semi-Active Radar Homing (SARH), wherein the ship continuously illuminates the target with dedicated radars until impact. The high power of the ship’s radar mitigates the effects of RF stealth techniques. The system’s relative simplicity and the availability of multiple vertical launch cells enable a high rate of fire.

In contrast, the MR-SAM is a more sophisticated and more expensive fire-and-forget system using Active Radar Homing (ARH). It offers a superior range of approximately 70 km and higher manoeuvrability due to its dual-pulse motor. The Shtil-1 (using the 9M317ME missile), by comparison, employs a more traditional single-stage, single-pulse solid-fuel motor.

The MR-SAM is better suited to high-value capital warships, while the Shtil-1 provides a more cost-effective solution for smaller platforms such as frigates.

Understanding the Strategic Importance of AS-HAPS Project

Days after the DAC in India accorded AoN to an IAF requirement for an Airship-based High Altitude Pseudo Satellite (AS-HAPS), Russia flight-tested a conceptually similar system.

India's AS-HAPS and the Russian system, named Barrage-1, are both based on lighter-than-air platforms that operate in the stratosphere.

However, while the AS-HAPS is being developed for the Indian Air Force to carry out "persistent Intelligence, Surveillance and Reconnaissance, Electronic Intelligence, telecommunication and remote sensing", Russia's Barrage is primarily focused on providing low-latency, high-bandwidth internet to its troops and field formations.

Another difference: the Russian system is not based on an airship platform; it is based on an aerostat platform.

Barrage System

The Russian system, named Barrage-1, will initially provide Starlink-like connectivity along the battlefront in Ukraine. Later, with increased deployment, the system will provide high-bandwidth, low-latency connectivity in remote areas and across the country.

Russia's Barrage-1 has been developed by the Russian company Aerodrommash in cooperation with Bauman Moscow State Technical University.

🚨⚡️ UNUSUAL: "Starlink" with 100% Russian Flavor.. 🇷🇺🛰️

Russia has officially begun flight tests for the "Barrage-1" platform, a stratospheric drone (flying in the upper atmospheric layers) designed to serve as a cost-effective alternative to satellites and global communication… pic.twitter.com/UJEuqasXjm

— RussiaNews 🇷🇺 (@mog_russEN) February 15, 2026

The first successful test flight was announced around February 12, 2026.

Most news outlets have reported an operating altitude of 20 km, but some reports allude to an altitude capability in the 20–40 km range.

The system, which can stay aloft for several weeks, features up to a 100 kg payload comprising communications, 5G relay, and other equipment.

The aerostat is made of translucent film material typical of high-altitude balloons. It keeps station and cruises using pneumatic ballasting that leverages differences in wind speed and direction at varying altitudes.

The operating altitude of the Barrage system facilitates low-latency broadband connectivity to Russian drones and hybrid cruise missile–drone combinations operating deep inside Ukrainian territory — the kind of connectivity that Ukrainian forces already enjoy using Starlink.

Allow me to explain latency.

Typically, satellite-based internet uses satellites parked in geostationary orbit (GSO) at an altitude of 35,786 km (22,236 miles) above Earth's mean sea level. Starlink uses a constellation of satellites in low Earth orbit (LEO) at an altitude of 550 km.

RF signals typically take 240 ms for a round trip to a GSO satellite. In contrast, a round trip to a Starlink satellite takes only 3.7 ms.

Guess what a round trip to a HAPS platform would take? 0.3 ms!

Low-latency connectivity facilitates remote piloting of drones. It also enables instantaneous, widespread distribution of footage relayed by the drone to command-and-control nodes for quick decision-making.

The Barrage-1 system will not only allow real-time control of Russian drones operating deep inside Ukrainian territory, it will also facilitate instantaneous dissemination of drone video footage to command-and-control nodes for a quick response.

Indian HAPS Development

India has been actively developing HAPS technology over the past five years.

NewSpace Research & Technologies (NRT), a Bengaluru-based private limited company, has been developing an autonomous, solar-powered unmanned aerial system (UAS) in collaboration with HAL, the prototype development partner.

According to the company, the aircraft is being designed to stay airborne for more than 90 days while cruising at an altitude of 65,000 ft. A scale model has already been tested.

In October 2022, the company spokesperson told Jane's, “The scale model, which was tested, has a wingspan of 8 m. The full-sized HAPS is planned to have a wingspan of 24 or 25 m.”

In February 2024, Jane's reported that India's Council of Scientific and Industrial Research – National Aerospace Laboratories (CSIR-NAL) had carried out a series of flight tests on a subscale model of its high-altitude pseudo-satellite (HAPS) platform.

The tests were conducted at the Defence Research and Development Organisation's (DRDO's) Aeronautical Test Range (ATR) at Challakere, Karnataka, from January 23, 2024, to February 2, 2024. During the tests, the subscale model, which has a wingspan of 12 m and a maximum take-off weight of 22 kg, conducted about 22 sorties and accumulated close to 37 flight hours.

L. Venkatakrishnan, NAL's chief scientist and high-altitude platform programme director, told Jane's, “The aircraft met or exceeded all the performance metrics set out for it, including a flight endurance of more than 8 hours 30 minutes and reaching an altitude of almost 3 km above mean sea level.” Venkatakrishnan added that metrics including climb rate, maximum bank angle, turn radius, and one-engine-inoperative performance were also assessed during the flight tests.

Mira Aerospace (UAE) and VEDA Aeronautics (India) have an active India-UAE collaboration on a fixed-wing, solar-powered HAPS.

The collaboration pivots around Mira's mature ApusNeo HAPS technology. VEDA serves as the “Make in India” front.

In March 2024, VEDA had committed to "deliver a HAPS platform specific to the Indian market within the first half of 2024."

Prior to that statement, the company's technology demonstrator HAPS unit flew in the Indian stratosphere — the only such flight in India to date.

The HAPS operates solely on solar energy and cruises autonomously at altitudes ranging from 16 to 20 km for extended periods. It cruises at 18,000 m with a 35 kg payload, with endurance varying from 30 to 45 days.

In January 2026, the Indian Army awarded a fast-track contract worth ₹168 crore (≈ USD 18.6 million) to Bengaluru-based NewSpace Research & Technologies (NRT) for its solar-powered Medium Altitude Persistent Surveillance System (MAPSS) UAV.

AS-HAPS

It appears that HAPS and AS-HAPS are two distinct projects. Only one of them, AS-HAPS, has received DAC AoN, indicating high development and procurement costs.

HAPS development has so far been privately funded, and the recent procurement contract is under the Indian Army's emergency purchase authorisation.

Conclusion

India in the past has focused solely on developing solar-powered high-altitude drones as pseudo-satellites. However, the focus has been on surveillance and communication relay.

The AoN for AS-HAPS appears to be a more ambitious project. Hopefully, Indian defence planners have factored in the enormous advantages that will accrue from integrating broadband internet capabilities into the planned AS-HAPS.

If the Barrage system delivers on its promise, it will likely do so at a very small fraction of the cost of deploying and maintaining the Starlink system. A similar spin-off could accrue to India from the AS-HAPS project.

Nirbhay’s Successors: Two Potent Naval Cruise Missiles Take Shape

ChatGPT generated image showing a submarine launching a cruise missile.

On February 12, 2026, The New Indian Express reported that the MoD has released a Request for Information (RFI) for procuring an undersea-launched missile capable of engaging land targets at ranges from a minimum of 50 km to beyond 500 km, with high accuracy and survivability. The missile is required to be compatible with standard 533 mm torpedo tubes used by the Navy’s existing conventional submarines and weigh under 1,500 kg, including the launch capsule.

The RFI states that the missile required is intended to provide “long-range strike capability against land targets” and stipulates that the missile should be capable of engaging targets “with high probability of kill” while being launched from conventional submarines.

The RFI further specifies that the missile should be capable of operating in contested environments, including GPS-denied conditions, and incorporate terrain-following capability, waypoint navigation, and anti-jamming features.

Indian Navy Requirement

The Indian Navy (IN) wants to procure a subsonic cruise missile that can be launched from a standard 533 mm torpedo tube of any conventional or nuclear submarine.

The IN had initially toyed with the idea of adapting the BrahMos for launch from a submarine. Indeed, a vertically launched submarine version of BrahMos was tested on March 20, 2013, from a submerged platform in the Bay of Bengal off the coast of Visakhapatnam.

However, to facilitate vertical launch from a submarine, an additional section would need to be plugged into the submarine. Plugging a new section would have been a risky proposition since it would have altered the buoyancy of an existing boat. Additionally, there would have been technical, financial, and timeline challenges.

A torpedo tube-launched cruise missile is a cheaper and more versatile option, though the missile would lack the destructive capability of the supersonic BrahMos.

The IN is currently equipped with Russian-origin Klub-S cruise missiles integrated with its Project 877EKM (Sindhughosh class) and HDW Type 209 (Shishumar class) submarines, and the French SM39 Exocet cruise missiles integrated with its HDW Type 209 (Shishumar class) submarines.

The SM39 Exocet missile does not have a land-attack variant. However, a land-attack variant of the missile called SM40 is under development in France.

The Klub-S has two variants — 3M54E1 anti-ship and 3M14E land-attack cruise missiles.

In July 2018, Russian shipbuilder Zvezdochka and Indian shipbuilder Larsen and Toubro announced their partnership to conduct medium refit and life certification (MRLC) upgrades on four of the Indian Navy's Sindhughosh-class submarines, which are the local designation for the Russian Project 877EKM Kilo-class diesel-electric attack submarines.

The partnership involved one submarine undergoing refit at Zvezdochka's facility in Severodvinsk, Russia, to facilitate technology transfer and training for Indian personnel. The remaining three would be handled at L&T's Kattupalli shipyard near Chennai, India.

The MRLC included integration of the Klub-S (3M-54E/3M-14E) missile system for anti-ship and land-attack capabilities, allowing strikes up to 220–300 km depending on the variant.

DRDO's SLCM

According to the DRDO Annual Report 2018, the MoD sanctioned the development of a Submarine-Launched Cruise Missile (SLCM) in 2017.

The SLCM is a derivative of the ITCM subsonic cruise missile.

ITCM

The ITCM, in turn, is a Nirbhay derivative. During DefExpo 2020, the DRDO announced completion and closure of the Nirbhay project and the launch of the Indigenous Technology Cruise Missile (ITCM) project based on technology developed for the Nirbhay project.

The ITCM differs from the Nirbhay in being powered by an indigenously developed small turbofan engine named Manik. Additionally, the ITCM features an RF seeker, something that the Nirbhay was never tested with.

The ITCM was last flight-tested successfully on April 17, 2024. The successful flight test established reliable performance of the Manik turbofan developed by the Gas Turbine Research Establishment (GTRE), Bengaluru, and all other subsystems, including the RF seeker.

According to the DRDO, the ITCM has a range of 1,000 km and a warhead of 300 kg. It weighs 1,500 kg and has a length of 6 m.

SLCM

The SLCM variant of the ITCM would need to be shorter and lighter to make it compatible for launch from a torpedo tube. Consequently, it will feature a 250-kilogram penetration-cum-blast or airburst warhead.

The SLCMs will be tested first on the Russian-origin Sindhughosh-class (Kilo-class) submarines as per the plan.

According to a media report, the DRDO successfully validated submarine launch capability in February 2023 during a developmental missile launch from an underwater platform. The missile tested covered a range of 402 kilometers.

The test was reportedly aimed at validating critical underwater launch processes such as wing deployment after surfacing and engine start during flight.

LR-LACM

Besides the SLCM, the DRDO is also developing a longer-range variant of the ITCM called the Long-Range Land-Attack Cruise Missile (LR-LACM) for precision attacks on static targets using its RF terminal seeker.

The LR-LACM flies a terrain-hugging/sea-skimming profile to avoid radar detection. It can navigate using waypoints and make flight profile changes to avoid adversary air defence zones, terrain, and other obstructions.

The missile can execute precision attacks on static targets using an RF seeker similar to the one developed for BrahMos for terminal homing.

The LR-LACM is being developed to meet the QRs projected by the IN to the DRDO. The missile is configured to launch from the ground (coastal batteries) using mobile articulated launchers and from frontline warships using a UVLM (Universal Vertical Launcher Module). Developed and patented by BrahMos Aerospace, the UVLM is already deployed on 30 ships of the Indian Navy.

Test of LR-LACM on November 12, 2024

The DRDO conducted the maiden flight test of the LR-LACM from the Integrated Test Range (ITR), Chandipur, off the coast of Odisha on November 12, 2024, from a mobile articulated launcher.

"The missile followed the desired path using waypoint navigation and demonstrated its capability to perform various manoeuvres while flying at various altitudes and speeds. The missile is also equipped with advanced avionics and software to ensure better and reliable performance."

Decoding the Lethal Upgrade in Russia’s Latest Su-57 Deliveries

A Su-57 from the batch delivered on February 9, 2026

On February 9, 2026, Russia's UAC delivered a large batch of Su-57s which, according to a UAC press release, were “in a new technical configuration.”

“The aircraft have received upgraded onboard systems and a new weapons complex.”

According to a TASS report that quoted experts, one of the main changes in the modernized Su-57 aircraft is the upgraded 101KS onboard optical-electronic self-defense system.

The new 101KS has an infrared channel, believed to operate in the medium and long-wave ranges, in contrast to the system of the previous batches. 

101KS Atoll Electro-Optical (EO) System

The 101KS Atoll Electro-Optical (EO) system is designed primarily for complete situational awareness. The system additionally assists the pilot in operation of the aircraft at all stages. It is used for air-to-air and air-to-surface target engagement, piloting & landing, and as a defensive suite.

The 101KS is a passive sensor suite that emits no radiation - IR or RF - thus providing the Su-57 with increased stealth and survivability. 

The suite includes the 

1. 4 x 101KS-U Omnidirectional UV based MAWS (U/01 - Dorsal aft & Ventral aft; U/02 Either side behind cockpit)

2. 2 x 101KS-O: DIRCM Laser-based counter-measures against infrared missiles (Dorsal fore, Ventral behind cockpit)

3. 101KS-P: Opto-electronic sensor

4. 101KS-V: Omnidirectional IRST for airborne targets

5. 101KS-N: Targeting pod

IRST 101KS-V

IRST is installed atop the aircraft's nose, near its windscreen. Photo: UAC Russia

The Su-57 sports an advanced infrared search and track sensor in the traditional position on Russian fighters—installed atop the aircraft's nose, near its windscreen. The positioning adversely impacts front aspect stealth of the aircraft but the ability of IRST to passively engage stealth aircraft from increasingly greater distances makes up for the LO erosion.

101KS-V forward looking IRST

The fore sensor suite on the Su-57 with elements of the N036 AESA and Atoll EO System

101KS-O, 101KS-U

Like the F-22, the Su-57 has a number of missile launch detector apertures scattered around the aircraft but the Su-57 also has turrets that fire modulated laser beams at an incoming missile's seeker to blind it and throw it off course. The IRST, and DIRCM turrets are mounted dorsally behind the cockpit and ventrally under the cockpit. 

Upper and lower 101KS-O bubbles are visible in the photo at the top.

The 101KS-O turrets on the Su-57 duplicate the functionality of the 101KS-V Opto-electronic (IRST) unit placed ahead of the cockpit but additionally feature IR homing suppression laser to blind an attacking missile providing DIRCM.

The 101KS-O system consists of two laser-emitting turrets, with one placed behind the cockpit on the dorsal side, and the other beneath the cockpit on the ventral side.

The Su-57 is the first fighter in the world to feature a DIRCM. Hitherto, the system has only been used on transports and helicopters only, invariably placed on the ventral side in the past as defense against MANPADS. The use of DIRCM to blind an air-to-air missile is unprecedented.

101KS-O turret on display at MAKS 2019

101KS-O turret on display at MAKS 2019

The 101KS-U MAWS UV sensors (below) of the Su-57 Atoll detect approaching IR missiles and the 101KS-O DIRCM blinds their IR homing sensors with laser.

101KS-U MAWS sensors on the Su-57

101KS-P Thermal Imager

The 101KS-P high resolution thermal imager of the Su-57 Atoll is installed on the wing leading edge & provides low altitude piloting and landing at night

101KS-P Thermal Imager

101KS-N Targeting Pod

101KS-N Optical Pod

The 101KS-N is a multi-channel optical sighting system designed to detect, identify and engage ground targe. The pod features its own thermal stabilization system. 

Situational Awareness

According to First Deputy Igor KRET Nasenkov, the Su-57 features a smart skin that provides the pilot 360-deg situational awareness.

The term "smart skin" refers to the fact that many of the surface of the aircraft are versatile antenna systems that facilitate integrated use of all resources of the aircraft. 

S-71 Integration

Since the UAC press release talks of a new weapons complex, it is possible that the fresh batch of Su-57s delivered is capable of carrying the newly developed air-launched stealthy combat UAV designated S-71, a weapon first unveiled during Army 2024.

The S-71 is an air-launched UAV that can be tasked with target identification, marking, or destruction. Deploying and controlling the Su-57 would require an upgrade of onboard systems. 

The S-71 began captive-carry trials in April 2024 at Russia’s Flight Research Centre in Zhukovsky, with test flights involving the Su-57 fighter.

You can read more details about the S-71 at my Thumkar blog post here.

On January 17, 2026, it was reported that an S-71K “Carpet” for the first time demonstrated its effectiveness by successfully destroying the highly mobile M142 HIMARS multiple launch rocket system.

The cruise missile–drone hybrid has been developed by GosMKB Raduga JSC and can be used by 4++ generation multirole fighters, including the Su-35S, Su-30SM/SM2, as well as Su-34 NVO fighter-bombers.