On January 11, 2025, Hindustan Aeronautics Limited (HAL) announced via an X.com post a significant milestone for its Combat Air Teaming System (CATS): the successful Engine Ground Run of the full-scale demonstrator, the CATS Warrior drone.
While the announcement was met with enthusiasm from defense aficionados online, a closer examination of the full-scale model raises concerns about the current state of the project.
The CATS Concept
HAL unveiled its CATS concept at Aero India 2021 in Bengaluru, displaying models of the system components
CATS is an advanced concept akin to the U.S. Skyborg program. It envisions a mother ship operating in uncontested airspace, coordinating a team of four autonomous unmanned aerial vehicles (UAVs) – CATS Warrior, CATS Hunter, CATS Alpha-S, and CATS Infinity – with specific roles.
Let’s take a look at the four CATS components.
CATS Warrior
The flagship drone of the system, CATS Warrior, is designed for autonomous operations up to 700 km from the mother ship in contested airspace. It can strike targets as would a cruise missile or deliver weapons such as SAAW up to 350 km into hostile territory.
Key specifications of the Warrior include:
Maximum Take-Off Weight: 1,300 kg
Speed: ~850 km/h
Range: 800 km
Flight Duration: 80 minutes
Payload Capacity: 250 kg (carried internally and under the wings)
Armament: Includes air-to-air and air-to-ground missiles.
The Warrior features a radar and sensor suite linked to the mothership, which assigns specific tasks and relays target coordinates.
Other CATS Components include:
CATS Hunter: A cruise missile launched by the mother ship, capable of penetrating deep into contested airspace to execute precision strikes.
CATS Alpha-S: A glider system designed to carry and release swarms of quadcopter drones (ranging from 4 to 20) into enemy territory, 50–100 km beyond the frontlines.
CATS Infinity: A high-altitude, solar-powered UAV designed for extended intelligence, surveillance, and reconnaissance (ISR) missions. Operating at altitudes of ~70,000 feet, it can remain airborne for 2–3 months, providing satellite-like coverage.
Stealth Characteristics
The CATS concept is critically dependent on radio frequency (RF) stealth to safely operate in contested airspace.
The Warrior drone airframe is shaped to minimize radar cross-section (RCS) to enhance its survivability in contested airspace.
Other CATS Warrior features designed to reduce RCS include
1. A serpentine air intake on top of the fuselage that hides the engine compressor from ground-based radar emissions. Engine compressor blades reflect radar waves copiously. Also, the reflected radio energy can help in identifying the aircraft.
2. The use of composite materials to minimize RF reflection.
3. Internal weapons bay to completely eliminate the high RF reflectivity of weapons slung under the fuselage or wings. The drone can carry both air-to-air and air-to-ground weapons internally to maintain its stealth profile.
4. V-shaped tail surfaces to reduce RF reflections.
5. Use of conformal data link antennas, designed to blend with the drone’s shape, reducing any protrusions that might increase radar reflection.
6. A Chevron exhaust similar to that found on the Lockheed Martin F-35 Lightning II, which helps in reducing both jet blast noise and radar emissions.
Warrior V-Tail
Conventional aircraft and drones feature aerodynamic surfaces at the rear of the fuselage for stability and control – usually a large vertical fin and a horizontal tailplane. These surfaces readily reflect RF energy, resulting in an increase in the RCS.
The increase in RCS can be minimized by using two smaller fins angled outwards towards the horizontal.
The CATS Warrior uses two large fins angled outwards towards the horizontal and eliminates the horizontal tail plane completely.
It may be noted that a pure stealth design eliminates tail surfaces completely and is often referred to as a flying wing design. Directional stability and control in a flying wing design is achieved by small computer-controlled surfaces on the wing.
China recently unveiled two sixth-generation fighters, both of which feature a flying wing design to achieve pure stealth.
Powerplant
The CATS Warrior is envisioned to be powered by HAL’s HTFE-25 engine, a 25 kN turbofan which is still under development. It is likely that the demonstrator unveiled likely uses two PTAE-7 engines.
Developed by HAL in the 1980s for Pilotless Target Aircraft, the PTAE-7 is a 400 kg, 3.43 kN single-spool turbojet engine.
Interestingly, the CATS Warrior demonstrator’s dorsal engine air intake differs significantly from the stealthy air intakes on models showcased at airshows. The location of the air intake is stealthy, but not its shaping.
Analysis
The following analysis is based on what is discernible from the photograph of the CATS Warrior posted by HAL to announce the successful completion of the drone’s first ground run. It assumes that the drone is powered by PTAE-7 engines.
The most striking feature appears to be the larger-than-expected size of the drone, which in the photograph appears to be as large as a small fighter, even after factoring in the distortion caused by the wide-angle lens used to capture the photograph.
Going by its size, it’s hard to believe that the drone will feature an all-up weight of just 1,300 kg, as published by HAL earlier. The weight will likely be much more. We are possibly dealing with a weight spiral even before the drone has done a taxi run!
Weight spirals have plagued all HAL airframe designs and their impact on performance has been worsened by thrust shortfalls of respective power plants. Using two PTAE-7 engines, even a new thrust augmented variant, if it exists, there is no way the Warrior will reach its design speed of 850 kph!
Stealth shaping of CATS Warrior has infirmities that will reduce RCS, but not to the extent where the drone could be classified as a stealth drone. The infirmities include the design of the canted rudders, non-stealthy dorsal air intake, appendages like the large pitot tube, and non-stealthy exhaust.
Conclusion
The promise of CATS will only be realized if the Warrior and Hunter drones are adequately stealthy, feature fuel-efficient aero engines with thrust-to-weight ratios that guarantee good cruise, loiter, and maneuver performance, capable lightweight sensors, and adequate onboard computing horsepower for networking, navigation, and weapon operations.
It’s difficult to be enthused by the CATS Warrior drone, considering its unproven stealth design, inadequate power plant, unproven sensors, and computing horsepower capabilities.
Having said that, it’s essential that HAL increase the pace of development of the CATS concept and work harder to realize its promised capabilities.
What HAL has developed so far is a technology demonstrator that will allow HAL to develop and test the sensors, networking and weapon system management capabilities required for an operational system.
Engine ground run on a full-scale model with an interim engine is really not a landmark worthy of fanfare. HAL likely hyped the ground run to create a buzz before Aero India 2025. This is fine, but only if HAL doesn’t project the CATS as an operational weapon system.
At the current state of its development, under no circumstances should the IAF be coerced into committing and placing orders for the CATS because that could perilously further weaken the IAF.
- Vijainder K Thakur is a retired IAF Jaguar pilot, author, software architect, entrepreneur, and military analyst.
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