JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III Year UNMANNED AIR VEHICLES Previous Question Paper (August/September - 2021 - R18)

• Conceptual Design Phase: This is the initial stage where the feasibility of the UAV project is established. The primary focus is on defining the mission requirements, such as payload capacity, endurance, range, and operational altitude. Engineers perform trade-off studies to select the overall configuration (e.g., fixed-wing, multi-rotor, or VTOL). The output is typically a set of baseline specifications and a rough sizing estimate.
• Preliminary Design Phase: This stage follows the conceptual phase and involves a more rigorous analytical approach. The focus shifts to refining the configuration, performing detailed aerodynamic analysis (often using CFD or wind tunnel testing), and developing the structural layout. Key activities include weight and balance estimation, stability and control analysis, and preliminary selection of propulsion and avionics systems. The output is a frozen configuration ready for detailed engineering design.
• Key Differences: The conceptual phase is characterized by high uncertainty and low-fidelity tools, whereas the preliminary phase utilizes higher-fidelity models to validate the design against performance requirements. While the conceptual phase explores 'what' the UAV should be, the preliminary phase determines 'how' it will be built to meet those requirements.

Unmanned Aerial Vehicles (UAVs) have transformed modern operations. Their advantages and limitations are summarized below:

• Merits:
  • Risk Mitigation: UAVs eliminate the risk to human pilots in hazardous environments, such as combat zones, disaster areas, or regions with high radiation or chemical contamination.
  • Cost Efficiency: Generally, UAVs are smaller and cheaper to operate and maintain than manned aircraft, as they do not require life-support systems or pilot training overhead.
  • Endurance: Without the physical limitations of a human pilot (fatigue, physiological needs), UAVs can remain airborne for significantly longer durations, limited only by fuel or battery capacity.
  • Versatility: Their compact size allows for rapid deployment and operation in confined spaces where manned aircraft cannot maneuver.
• Demerits:
  • Communication Vulnerability: UAVs rely on data links that are susceptible to jamming, signal interference, or cyber-attacks, potentially leading to loss of control.
  • Regulatory and Ethical Challenges: Integrating UAVs into civilian airspace poses significant safety and legal concerns, particularly regarding privacy and collision avoidance.
  • Limited Situational Awareness: Even with advanced sensors, a remote operator lacks the 'seat-of-the-pants' sensory feedback and immediate peripheral vision available to an onboard pilot, which can complicate complex decision-making.
  • Technical Reliability: Dependence on complex software and autonomous algorithms introduces risks of system failure or unpredictable behavior in unforeseen environmental conditions.