JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III UNMANNED AIR VEHICLE (UAV) SYSTEMS Previous Question Paper (November/December - 2020 - R16)

The selection of an Unmanned Aircraft System (UAS) is a multi-disciplinary process requiring a balance between mission requirements, operational constraints, and technical capabilities. The primary parameters involved in this selection process are categorized as follows:

1. Mission Profile and Operational Requirements: The most critical factor is the intended application, such as surveillance, mapping, agricultural spraying, or cargo delivery. This dictates the required endurance, range, payload capacity, and operating altitude. The environment, whether urban, maritime, or rural, determines the necessity for specific sensors and communication resilience.

2. Payload Specifications: The selection must accommodate the weight, power consumption, and data bandwidth requirements of the sensors or equipment. High-resolution cameras, LiDAR, or multispectral sensors impose different integration challenges regarding stabilization and power management.

3. Performance Parameters: Key performance indicators include:

• Endurance and Range: Determined by battery capacity or fuel efficiency and the aerodynamic efficiency of the airframe.
• Speed and Maneuverability: Essential for tracking moving targets or operating in high-wind conditions.
• Payload Fraction: The ratio of payload weight to the total take-off weight (MTOW), which indicates the efficiency of the platform.

4. Communication and Data Link: The selection depends on the required command and control (C2) range and data throughput. Factors include frequency spectrum availability, latency requirements, and the necessity for beyond-line-of-sight (BLOS) capabilities via satellite or cellular networks.

5. Launch and Recovery Systems: Depending on the airframe type (VTOL, fixed-wing, or hybrid), the selection must consider the available infrastructure. VTOL systems offer flexibility in confined spaces, whereas catapult or runway-dependent fixed-wing systems may offer superior endurance.

6. Reliability and Safety: This involves assessing the redundancy of critical systems (flight controller, GPS, power systems) and the inclusion of fail-safe mechanisms like parachute recovery or return-to-home (RTH) protocols. Compliance with regulatory standards (e.g., FAA, EASA) is mandatory.

7. Lifecycle Cost and Maintainability: The total cost of ownership includes the initial acquisition, training, spare parts, and maintenance schedules. Systems with modular designs are generally preferred for easier field repairs and sensor upgrades.

8. Environmental Compatibility: The UAS must be rated for the operating climate, considering factors such as operating temperature ranges, ingress protection (IP) ratings for dust and moisture, and electromagnetic interference (EMI) shielding.

The conceptual design phase is the initial stage of the Unmanned Aerial System (UAS) development process, where the primary objective is to define the system's mission requirements, establish overall feasibility, and determine the fundamental configuration that best meets the operational needs. This phase transforms abstract mission requirements into a tangible, high-level design concept.

Key activities in this phase include:

• Mission Definition: Identifying the primary purpose of the UAV, including payload capacity, range, endurance, operating altitude, and speed.
• Constraint Analysis: Establishing technical and regulatory boundaries, such as takeoff weight limits, launch and recovery methods, and communication link requirements.
• Configuration Selection: Evaluating different airframe layouts (e.g., fixed-wing, rotary-wing, or VTOL) to determine the most efficient aerodynamic and structural approach.
• Sizing and Weight Estimation: Performing initial calculations for takeoff gross weight (TOGW) and wing loading to ensure the design can physically perform the mission.

The conceptual design process follows an iterative loop:

In terms of sketching the process, a conceptual design block diagram would show a feedback loop where the Mission Requirements feed into the Design Synthesis block, which then outputs a Preliminary Configuration. This configuration is subjected to Performance Estimation. If the performance does not meet the requirements, the design parameters are adjusted, and the loop repeats until convergence is reached. The final output of this phase is a set of baseline specifications, a rough general arrangement drawing, and a preliminary cost and schedule estimate, providing the foundation for the subsequent Preliminary Design Review (PDR).