With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements: I. All types of UAVs can do vertical landing. II. All types of UAVs can do automated hovering. III. All types of UAVs can use battery only as a source of power supply. How many of the statements given above are correct?
Contents12
- AOnly one
- BOnly two
- CAll the three
- DNone
Show answer
Answer: (D) None
The key word in all three statements is 'ALL types of UAVs' — this is an absolute claim, and if even one type of UAV fails the condition, the statement becomes false.
(I) 'All types of UAVs can do vertical landing' — FALSE.
Fixed-wing drones (like military Predator drones) have rigid wings, a fuselage, and a propeller, just like aeroplanes.
They need a runway or a net for landing and cannot land vertically.
Only multirotors (like quadcopters) and VTOL drones can do vertical landing.
(II) 'All types of UAVs can do automated hovering' — FALSE.
Again, fixed-wing drones cannot hover in one place.
They must keep moving forward to maintain lift, just like an aeroplane.
Only multirotors can hover.
(III) 'All types of UAVs can use battery only as power' — FALSE.
Many long-endurance and military UAVs (like the MQ-9 Reaper/Predator) use liquid fuel (gasoline, jet fuel) because batteries have lower energy density and cannot provide the range or endurance needed for long missions.
Since none of the three statements is universally true, the answer is (d) None.
UAVs have become critical in modern warfare and surveillance, with India developing indigenous drone capabilities and the military increasingly using different UAV types for specific missions.
The question tests understanding of fundamental UAV categories - fixed-wing drones operate like airplanes and need runways, while multirotor drones can hover and land vertically.
UPSC is checking if students can spot absolute statements as traps - when a statement says 'all types' of any technology, look for exceptions among different variants.
UAV Classification & Types
Science And Technology Unmanned Aerial Vehicles UAVs types
UAV Classification: Fixed-Wing vs Multirotor vs VTOL
Fixed-wing UAVs need runways like aeroplanes — cannot hover or land vertically
Multirotors (quadcopters) can hover and land vertically using multiple rotors
Power sources vary: batteries for small UAVs, liquid fuel for long-endurance missions
VTOL UAVs combine fixed-wing efficiency with vertical takeoff capability
UAVs come in fundamentally different designs, each with distinct capabilities and limitations. The question's trap lies in claiming ALL types can perform certain functions — understanding the basic classification reveals why this is false.
Major UAV Categories
Type | Wing Design | Vertical Landing | Hovering | Typical Power | Examples |
|---|---|---|---|---|---|
Fixed-Wing | Rigid wings like aircraft | No — needs runway | No — must keep moving | Liquid fuel for long missions | Predator, Reaper drones |
Multirotor | Multiple rotors (4, 6, 8) | Yes | Yes | Battery | Quadcopters, hexacopters |
VTOL | Wings + vertical rotors | Yes | Limited | Battery or hybrid | V-22 Osprey-style UAVs |
Helicopter | Main rotor + tail rotor | Yes | Yes | Liquid fuel or battery | Unmanned helicopters |
Question Analysis
Statement I fails because fixed-wing UAVs need runways — they generate lift through forward motion, not vertical thrust
Statement II fails because fixed-wing UAVs cannot hover — they must maintain forward speed to stay airborne
Statement III fails because long-endurance military UAVs use liquid fuel for better energy density and extended range
Absolute words trap: 'ALL types' makes statements vulnerable — even one exception makes them false
Aeroplane analogy: Fixed-wing UAVs behave like aeroplanes, not helicopters
Battery limitation: Small commercial drones use batteries, but military/industrial UAVs often need liquid fuel
UAV Flight Capabilities
Science And Technology vertical landing automated hovering
UAV Flight Capabilities: Landing & Hovering Mechanisms
Vertical landing requires downward thrust — only possible with rotors or vectored thrust
Hovering needs continuous vertical thrust to counteract gravity without forward motion
Fixed-wing design generates lift through forward motion — cannot hover or land vertically
Lift Generation Methods
%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
s1["`**Fixed-Wing Lift**
Air flows over curved wing surfaces → creates pressure difference → generates lift (needs forward motion)`"]
s2["`**Rotor Lift**
Spinning rotors push air downward → Newton's third law creates upward thrust → can hover in place`"]
s3["`**VTOL Hybrid**
Uses rotors for vertical movement + wings for efficient forward flight`"]
s1 --> s2
s2 --> s3Capability Limitations
Runway requirement: Fixed-wing UAVs need horizontal space for takeoff/landing — cannot operate from ships or confined spaces
Energy efficiency trade-off: Hovering consumes much more power than forward flight
Payload vs endurance: VTOL capability adds weight, reducing range or payload capacity
Don't confuse with manned aircraft: UAV capabilities mirror their manned counterparts — helicopters hover, aeroplanes don't
VTOL ≠ All UAVs: VTOL is a specific technology, not a universal UAV feature
UAV Power Systems
Science And Technology battery power supply
UAV Power Systems: Battery vs Liquid Fuel Trade-offs
Energy density: Liquid fuels provide much more energy per kg than batteries
Mission type determines power: Short surveillance uses batteries, long military missions need fuel
Reaper/Predator drones use jet fuel for 14+ hour endurance
Power System Comparison
Power Source | Energy Density | Flight Duration | UAV Types | Advantages | Limitations |
|---|---|---|---|---|---|
Battery (Li-ion) | Low (~250 Wh/kg) | 30 min - 2 hours | Commercial quadcopters | Clean, quiet, instant start | Limited endurance, weather sensitive |
Gasoline Engine | High (~12,000 Wh/kg) | 8-15 hours | Long-endurance UAVs | Extended range, proven technology | Heavier, needs maintenance |
Jet Fuel (Turbine) | Very High | 14+ hours | Military drones (Reaper) | Maximum endurance | Complex, expensive |
Hybrid (Battery+Fuel) | Medium | 4-8 hours | Commercial VTOL | Best of both worlds | Added complexity |
Mission Requirements
Surveillance missions need 8-15 hour endurance — impossible with current battery technology alone
Military operations prioritize range and loiter time over environmental concerns
Commercial delivery drones are moving toward hybrid systems for practical range
Battery myth: Not all UAVs are battery-powered — large military/industrial UAVs use liquid fuel
Energy density gap: Batteries are 50x less energy-dense than liquid fuels — physics limits battery-only endurance
Military UAVs in India
Science And Technology
Military UAV Programs & Procurement in India
India operates Israeli Heron and US Predator-class UAVs for border surveillance
DRDO Rustom series represents indigenous long-endurance UAV development
MQ-9B acquisition from US approved for maritime and border patrol
Key UAV Systems in India
Platform | Origin | Type | Primary Use | Power Source |
|---|---|---|---|---|
Heron | Israel | Fixed-wing MALE | Border surveillance | Liquid fuel |
Rustom-II | India (DRDO) | Fixed-wing MALE | ISR missions | Liquid fuel |
MQ-9B SeaGuardian | USA | Fixed-wing MALE | Maritime patrol | Jet fuel |
Nishant | India | Rotary-wing | Battlefield surveillance | Liquid fuel |
Strategic Applications
Border monitoring: LAC and LoC surveillance requires long-endurance fixed-wing platforms
Maritime domain: Arabian Sea and Bay of Bengal patrol needs fuel-powered systems for range
Indigenous development: Atmanirbhar Bharat push includes UAV manufacturing capabilities