Defence Technology: UPSC Previous Year Questions (Science and Technology)

Explanation

Statement 1 is incorrect: Only Vertical Takeoff and Landing (VTOL) UAVs, like multi-rotor drones (e.g., DJI Phantom, Skydio quadcopters/hexacopters, 2014) and certain hybrid tilt-rotor drones, can land vertically. Fixed-wing UAVs (e.g., NASA Global Hawk, MQ-1 Predator, Wing Loong, 1994) require runways, catapults, or recovery systems (e.g., net, parachute) and cannot land vertically. Hybrid UAVs vary by design. Fixed-wing UAVs excel in energy efficiency, endurance, and speed, ideal for surveillance and long-range missions, unlike multi-rotor drones suited for precision tasks.

Statement 2 is incorrect: Only rotary-wing and multi-rotor UAVs (e.g., DJI Phantom, Skydio, 2014) hover, using vertical thrust from propellers with GPS/stabilization systems can do automated hovering. Fixed-wing UAVs (e.g., MQ-9 Reaper, Global Hawk, 2001) require forward motion for lift and cannot hover. Some VTOL-capable fixed-wing UAVs (e.g., tilt-rotor) can hover, but not universally. Hovering suits aerial photography, surveillance, delivery, and rescue.

Statement 3 is incorrect: UAVs use diverse power sources: batteries (Lithium-ion/LiPo for small/medium multi-rotor drones, e.g., DJI Mavic Air, Skydio, 2018), gasoline (military drones like MQ-9 Reaper, DRDO Rustom, Nishant, 2008), hybrid systems, solar (HALE UAVs like AeroVironment’s, 2010), or hydrogen fuel cells. Power choice depends on mission, endurance, range, and payload. Hence, option (d) is correct.

Explanation

CL-20 (Chemical Formula C₆H₆N₁₂O₁₂), HMX (High Melting Explosive Chemical Formula C₄H₈N₈O₈), and LLM-105 (2,6-Diamino-3,5-dinitropyrazine-1-oxide) are High-Energy Materials (HEMs)--specifically military explosives used in warheads, missiles, artillery shells, and detonators. They are not refrigerants or fuels, but nitroamine (CL-20, HMX) or nitro-substituted (LLM-105) compounds with high detonation velocities, thermal stability, and armor-penetration capability. CL-20: Developed in 1987 by U.S. Naval Air Warfare Center, it has 20% more energy than HMX. Indian variant (ICL-20) is made by DRDO’s High Energy Materials Research Laboratory (HEMRL). Used in Switchblade drones, AGM-158C missiles, and Arjun MBT shaped charges. HMX: It is one of the Standard explosives used in Agni, Prithvi, and nuclear weapons. Used in Plastic Bonded Explosives (PBX), torpedoes, and detonators. LLM-105: Designed for Insensitive Munitions (IM), Ideal for naval/aircraft munitions, explored by HEMRL.

Explanation

Pair 1 is correctly matched: Dornier -228 is known for their versatility, they are equipped for a range of missions, including maritime patrol, surveillance, pollution control, search and rescue, and medical evacuation.

Pair 2 is not correctly matched: The Ilyushin Il-76 is a strategic/heavy military transport aircraft, not a supersonic combat aircraft. HAL Tejas, MiG-21, Sukhoi Su-30MKI and Dassault Rafale are examples of supersonic combat aircraft.

Pair 3 is correctly matched: The C-17 Globemaster III is a large military transport aircraft used for airlift and cargo missions. The Indian Air Force (IAF) has received its third Boeing C-17 Globemaster III, a large, versatile military transport aircraft capable of carrying heavy, oversize loads long distances and landing on rough and unprepared surfaces.

Explanation

Fifth-generation fighter aircraft typically have features like stealth, advanced avionics, sensor fusion, and supercruise capability. Examples include the F-35 Lightning II (USA), F-22 Raptor (USA), Su-57 (Russia), and J-20 (China). They differ from fourth-generation aircraft primarily in their stealth features. Fifth-generation aircraft have a low electromagnetic signature, which makes it difficult for enemy radar to detect them. At the same time, fifth-generation aircraft have powerful sensors and new weapons, so they are able to register the signature of enemy aircraft and take them out.

Option 1 is incorrect: Rafale is a 4.5-generation multirole fighter developed by Dassault Aviation (France). It features advanced avionics, stealth enhancements, and superior maneuverability but lacks full stealth and sensor fusion, which are key traits of fifth-generation aircraft.

Option 2 is incorrect: MiG-29 is a fourth-generation fighter developed by Russia, primarily designed for air superiority with high agility but lacks stealth technology.

Option 3 is incorrect: Tejas MK-1 is an indigenously developed fourth-generation light combat aircraft (LCA) by India with modern avionics but does not meet fifth-generation requirements.

Explanation

Statement 1 is not correct: Ballistic missiles are rocket-powered only during the initial (boost) phase of flight, following an arcing trajectory to the target after that. Ballistic missiles travel well outside earth’s atmosphere. In contrast, cruise missiles are jet-propelled at subsonic speeds throughout their journeys. Cruise missile flies within the earth’s atmosphere and uses jet engine technology.

Statement 2 is not correct: The Defence Research and Development Organisation (DRDO) of India developed the land-based intercontinental ballistic missile known as Agni-V. The BrahMos is a medium-range Ramjet Supersonic Cruise Missile that may be fired from a submarine, ship, aircraft, or land. The BrahMos is undoubtedly the world’s fastest supersonic cruise missile.

Explanation

The Shourya is a canisterised missile system that can be easily handled, transported and stored within the canister for longer shelf-life. The high manoeuvrability of the missile makes it less vulnerable to available anti-missile defence systems.

Statement 1 is incorrect: The Can carry a payload of 200 to 1000 kg.Propellant - Solid fuel is a hypersonic surface-to-surface tactical missile. It is known to travel at speeds of up to Mach 7.5, which is slightly less than Mach 8.

Statement 2 is incorrect: The range of the Shourya missile is approximately 750-1900 km, depending on its payload, but its operational range typically does not exceed 1600 km in standard configurations.

Explanation

Statement 1 is incorrect: INS Sindhughosh is not an aircraft carrier. It is a diesel-electric submarine of the Sindhughosh class, which is based on the Russian Kilo-class submarines. It is used for anti-submarine warfare, reconnaissance, and intelligence gathering.

Statement 2 is incorrect: INS Viraat is not a submarine. It was an aircraft carrier and served as the flagship of the Indian Navy for many years. It played a significant role in enhancing India’s naval power before being decommissioned in 2017.

Explanation

India purchased the Barak anti-missile defence systems from Israel. The Barak system is developed by Israel Aerospace Industries (IAI) in collaboration with Rafael Advanced Defense Systems, is a surface-to-air missile designed to intercept and destroy incoming threats such as anti-ship missiles, aircraft, and drones. It is part of India’s naval defence system and is installed on various Indian Navy warships to enhance their anti-missile capabilities.

Explanation

5.5 ton class helicopter with twin engines. is an Advanced Light Helicopter (ALH) developed by Hindustan Aeronautics Limited (HAL) for military and civilian applications. Equipped with twin Shakti engines, it operates at altitudes up to 20,000 feet, making it suitable for diverse terrains. Dhruv is used for troop transport, search and rescue, reconnaissance, medical evacuation, and disaster relief. Its variants include the armed Rudra and the upgraded Mark III. As a symbol of India’s self-reliance in defense, Dhruv has been exported to countries like Nepal and Mauritius, enhancing India’s defense diplomacy.

Explanation

Statement 1 is correct: In November 2006, the Defence Research and Development Organisation (DRDO) of India conducted a successful test of the Prithvi Air Defence (PAD) system, which used the Prithvi-II missile as an interceptor to destroy an incoming target missile. The Prithvi-II missile has been instrumental in validating India’s BMD technologies, ensuring readiness to protect against ballistic missile threats. This test marked a significant milestone in India’s ballistic missile defence program.

Statement 2 is correct: While the primary role of the Prithvi-II is as a surface-to-surface missile but it has been adapted for air defense purposes also. It is part of India’s Ballistic Missile Defense (BMD) system, which is designed to protect major cities from ballistic missile attacks.