Concept Selection

Concept Selection

Generating solution concepts is the fundamental aspect of design. Understanding the mission requirements as a basis for generating them will result in a quality product. Selecting a concept design for this project was done using two different techniques: weighted objectives and Pugh’s Method.

For the weighted objectives, twelve objectives were selected which affected the mission requirements. Rankings and percentages were then assigned to each objective as shown in Figure 1. Each objective was ranked either 1 – Poor, 3 – Average, or 9 – Excellent for the nine design concepts. Each objective score was then multiplied by its corresponding weighted average and added together to give a total score for each design (Figure 2).

The next step was Pugh’s Method, where the concept which scored highest in the weighted objectives was set as the datum, a standard for which all other designs were compared. To compare each design, a score of “+” (better), “-“ (worse), or “s” (same) was assigned for each objective. The sum of each scoring criteria (“+”, “-“, or “s”) was taken and design strengths and weaknesses were determined. Design 6, a three fuselage design with canard and high aspect ratio wing, was selected from the weighted objectives and Pugh’s Method results.

Objectives / Team Ranking / % of votes
Endurance (high AR, fuselage - batteries) / 6 / 8.85
Maneuverability (position of control surfaces) / 4 / 9.69
Lightweight / 7 / 8.75
Robust/Accessibility / 5 / 9.48
Low Speed / 3 / 10.10
Cost / 12a / 5.00
Stylish / 2 / 10.21
Stable (CG. vs. AC) / 8 / 8.54
Easy To Fly (size) / 10 / 6.56
Technically Simple / 1 / 10.31
High Lift (wing area/lift distribution) / 9 / 7.50
Ground Clearance (props, tail) / 12b / 5.00

Figure 1: Weighted Objectives

Objectives / 1 / 2 / 3 / 4 / 5 / 6 / 7
Technically Simple / 9 / 9 / 3 / 3 / 1 / 3 / 3
Stylish / 3 / 9 / 3 / 3 / 9 / 9 / 3
Low Speed / 3 / 3 / 9 / 1 / 3 / 3 / 3
Maneuverability (position of control surfaces) / 9 / 1 / 3 / 9 / 1 / 3 / 3
Robust / Accessibility / 9 / 9 / 9 / 3 / 3 / 3 / 9
Endurance (high AR, fuselage - batteries) / 3 / 3 / 3 / 9 / 3 / 9 / 3
Lightweight / 9 / 9 / 1 / 3 / 1 / 3 / 9
Stable (CG vs. AC) / 9 / 3 / 3 / 9 / 1 / 9 / 9
High Lift (wing area/lift distribution) / 9 / 9 / 3 / 3 / 9 / 9 / 9
Easy To Fly (size) / 3 / 9 / 3 / 3 / 9 / 9 / 3
Cost / 3 / 3 / 3 / 3 / 1 / 3 / 3
Ground Clearance (props, tail) / 9 / 9 / 3 / 1 / 9 / 9 / 9
Total / 53.86 / 53.34 / 33.33 / 35.24 / 33.63 / 49.12 / 44.64

Figure 2: Weighted Objective design concept scores

Concepts
Objectives / 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9
Technically Simple / D
A
T
U
M / S / - / - / - / - / - / S / S
Stylish / + / - / S / + / + / S / S / +
Low Speed / S / - / S / + / + / - / - / -
Robust/Accessibility / S / S / S / + / + / S / S / +
Endurance (high AR, fuselage - batteries) / S / - / S / + / + / S / S / -
Lightweight / S / - / - / - / - / S / S / +
Stable (CG vs. AC) / S / - / + / - / S / S / + / +
Maneuverability (position of control surfaces) / - / S / S / - / S / S / S / -
Easy To Fly (size) / + / S / S / + / + / S / S / -
High Lift (wing area/lift distribution) / S / - / S / + / + / - / - / -
Ground Clearance (props, tail) / S / - / S / - / + / S / S / -
Σ + / 2 / 0 / 1 / 6 / 7 / 0 / 1 / 4
Σ - / 1 / 8 / 2 / 5 / 2 / 3 / 2 / 6
Σ S / 8 / 3 / 8 / 0 / 2 / 8 / 8 / 1
Total / 1 / -8 / -1 / 1 / 5 / -3 / -1 / -2

Figure 3: Pugh's Method