Lesson Notes By Weeks and Term v4 - SHS 2
Design and Fabrication of UAVs
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Design and Fabrication of UAVs
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Subject: Aviation And Aerospace Engineering
Class: SHS 2
Term: 2nd Term
Week: 19
Grade code: 3.4.3.LI.2
Strand code: 4
Sub-strand code: 3
Content standard code: 3.4.3.CS.1
Indicator code: 3.4.3.LI.2
Theme: Unmanned Aerial Vehicles (UAVs)
Subtheme: Design and Fabrication of UAVs
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Unmanned Aerial Vehicles (UAVs), or drones, are becoming increasingly vital tools for solving some of Ghana's most pressing challenges. From monitoring cocoa farms in the Ahafo Region to delivering medical supplies to remote communities in the Oti Region, and even helping to map areas for urban planning in Accra, UAVs offer innovative solutions. However, not all UAVs are created equal. A drone designed for spraying crops is very different from one designed for long-range surveillance. As engineers, we must first generate several different ideas or "concepts" for a UAV that can solve a specific problem. The most critical next step is to choose the *best* concept to develop further.
This section breaks down the process of using an evaluation table to select the best UAV concept. A. What is a UAV Concept? A UAV concept is a high-level idea or a basic approach to a design problem. It is not a detailed engineering drawing but a general configuration. For any given problem, we can imagine several different concepts.
Common UAV Concepts: Concept 1: Multi-rotor (e.g., Quadcopter): Uses four or more rotors for vertical lift, like a helicopter. *Pros:* Excellent manoeuvrability, can hover in one spot, easy to fly. *Cons:* Short flight time (typically 15-30 minutes), lower payload capacity, inefficient for long-distance travel. Concept 2: Fixed-Wing: Looks like a traditional aeroplane. *Pros:* Long flight time (can fly for hours), can carry heavier payloads, very efficient for covering large areas. *Cons:* Cannot hover, requires a runway or catapult for launch and a net or open space for landing. Concept 3: Hybrid VTOL (Vertical Take-Off and Landing): A combination of the two. It has rotors for vertical take-off and landing, and wings for efficient forward flight. *Pros:* Best of both worlds—long flight time and the ability to hover/take off from anywhere. *Cons:* Very complex design, mechanically difficult, and significantly more expensive. B. The Decision Matrix (Evaluation Table) A decision matrix is a table used to evaluate and compare multiple options based on a set of specific criteria. It helps us to make an objective, data-driven choice instead of a subjective one.
Components of a Decision Matrix: Design Criteria: These are the specific requirements or features that the final design *must* have to be successful. They are derived from the mission goals. Examples: Flight Time, Cost, Payload Capacity, Ease of Manufacturing, Durability. Weight (W): This is a numerical value (e.g., on a scale of 1 to 5) that shows how important each criterion is. A higher weight means the criterion is more critical to the mission's success. 5 = Extremely Important 4 = Very Important 3 = Moderately Important 2 = Less Important 1 = Not Very Important Concepts: The different UAV designs you are comparing (e.g., Quadcopter, Fixed-Wing, Hybrid VTOL). Rating (R): This is a score (e.g., on a scale of 1 to 5) you give to each concept for how well it meets a specific criterion. 5 = Excellent 4 = Very Good 3 = Average 2 = Poor 1 = Very Poor Weighted Score (WS): This is the final score for each concept on a single criterion. It is calculated by multiplying the criterion's Weight by the concept's Rating. Formula: WS = W x R Total Score: The sum of all the weighted scores for a single concept. The concept with the highest total score is, on paper, the best choice. C. Worked Example: Selecting a UAV for Cocoa Farm Monitoring
Scenario: A farmers' cooperative in the Sefwi Wiawso district needs a UAV to monitor 100 hectares of cocoa farms for signs of Black Pod disease. The UAV must carry a high-resolution camera. The operators will be farmhands with basic training, and the budget is tight.