📌 The Question:

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?

(a) Only one
(b) Only two
(c) All the three
(d) None

✅ Correct Answer: (d) None

🧠 Classroom Explanation (Lightning Mode):

First, lock the core idea:

✈️ UAVs = a broad family, not just quadcopters. UPSC loves this trap.

🔹 Statement I: Vertical Take-off & Landing (VTOL) ❌

• Multi-rotor drones → can do vertical take-off & landing
• Fixed-wing UAVs → ❌ cannot

• Require runways, catapults, nets, or recovery systems

👉 Since all UAVs cannot do VTOL, the statement is incorrect.

🔹 Statement II: Automated Hovering ❌

• Hovering requires lift without forward motion
• Fixed-wing UAVs generate lift only when moving forward
• Hence, no hovering capability

👉 Again, “all UAVs” makes the statement wrong.

🔹 Statement III: Battery-only Power Source ❌

UAV power sources include:
• Batteries (small drones)
• Internal combustion engines
• Hybrid systems
• Hydrogen fuel cells
• Solar-assisted propulsion

⚡ High-endurance & military UAVs cannot rely on batteries alone due to low energy density.

👉 Statement III is also incorrect.

📌 Therefore:
None of the three statements is correct.

🔍 Curiosity Raiser:
🛰️ Predator-class military drones can fly for more than 24 hours — something no battery-powered drone can currently achieve.

📚 Enrich Notes (UPSC Edge):

• Multi-rotor UAVs → VTOL + hover + battery
• Fixed-wing UAVs → long range + fuel-powered
• Hybrid VTOL UAVs → combine both, but still not “all”
• Keywords UPSC loves:
VTOL, endurance, energy density, hybrid propulsion

🪶 IAS Monk Whisper:
When UPSC says “all”, pause — absolutes are usually false.