EVALUATION REPORT
NAME : M.ZAOREZ
SEMESTER: THIRD
SUBMITTED TO: MECH LEAD@ NUST AIRWORKS
DUE DATE: October 6, 2024
REQUIRED TASK:
Your task is to determine the (i) aircraft configuration, and (ii) wing area and engine sizing via
the design point of a UAV keeping in mind the following aircraft profile:
A prop-driven, fixed-wing aircraft should be capable of a high degree of stability, as well as a
certain amount of maneuverability (should be able to fly in a pattern resembling figure 8). The
aircraft must contain only conventional control surfaces and no HLDs.
1. Introduction and Mission Description
This report presents the conceptual design and preliminary calculations for a small propeller-
driven, fixed-wing UAV. The primary mission of this UAV is to perform stable, maneuverable
flight patterns, specifically the capability to fly in a figure-8 pattern while maintaining high
stability. The aircraft will rely on conventional control surfaces without the use of high-lift
devices (HLDs).
The UAV is designed to meet the following mission requirements:
Maximum Take-off Mass: 3 kg
Stall Speed: ≤ 12 m/s
Maximum Height (Ceiling): 120 m
Runway Length: 15 m
Additional design requirements include a wing span of ≤ 1.5 meters and a power consumption
limit of ≤ 900 W to ensure efficiency and longevity during flight.
2. Wing Configuration and Characteristics
The chosen wing configuration for this UAV is a high-aspect-ratio, fixed-wing design. This
configuration offers excellent aerodynamic efficiency by providing a good lift-to-drag ratio
(L/Dmax = 11.5), which is essential for a UAV of this scale that must meet the stability and
maneuverability criteria of the mission. The wing's high aspect ratio of 13.33 ensures reduced
induced drag, leading to better performance during cruise and other phases of flight.
The characteristics of the wing are:
Wing Area (S):
0.343 m^2
Aspect Ratio (A): 13.33
Wing Span (b): To be calculated from aspect ratio and area in subsequent stages.
The airfoil selected is one optimized for low-speed performance with a maximum lift coefficient
(CLmax) of 1.4, allowing for better takeoff and landing characteristics while maintaining a stall
speed of 10 m/s, which is well below the 12 m/s requirement.
3. Tail Configuration
The tail configuration chosen for this UAV is a conventional tail with horizontal and vertical
stabilizers. This tail type is common in fixed-wing designs and provides good stability and control
at various speeds, ensuring the aircraft can complete its figure-8 pattern and other maneuvers.
The horizontal stabilizer is designed to prevent excessive pitch motion during takeoff and
landing, contributing to overall stability.
4. Motor Configuration
For this UAV, a tractor motor configuration is chosen. This is a forward-facing propeller system,
commonly used in UAVs of this scale. The tractor motor configuration offers several benefits,
such as improved cooling of the motor and higher efficiency in converting engine power into
thrust due to the airflow being undisturbed by the fuselage. Additionally, this setup enhances
the UAV's forward stability and improves thrust during takeoff.
A pusher motor configuration was considered but was ruled out due to the following reasons:
The airflow over the wing and fuselage could be disturbed, leading to less efficient lift
generation.
The pusher configuration may also lead to reduced efficiency in cooling the motor, especially at
low speeds.
Thus, the tractor motor configuration provides a more stable and efficient design for the
intended mission profile.
5. Justification for Design Parameters
The values for key design parameters were selected based on UAV design principles, mission
requirements, and industry norms. Below is a justification for the choices of each of the 5
parameters in Topic 4.3.
1. Stall Speed (Vs = 10 m/s)
The chosen stall speed of 10 m/s ensures the UAV can maintain stable flight at low speeds,
which is essential for safe takeoff and landing within a confined runway length of 15 meters. A
lower stall speed provides better low-speed handling and reduces the risk of stalling during
takeoff and approach.
2. Maximum Speed (Vmax = 26 m/s)
A maximum speed of 26 m/s was selected to provide enough performance margin for the UAV
to complete rapid maneuvers, such as the figure-8 pattern, while also allowing for efficient
cruise performance. This speed ensures that the UAV can operate efficiently across a wide
speed range, including climb and descent phases.
3. Maximum Lift Coefficient (CLmax = 1.4)
The chosen CLmax of 1.4 reflects a balance between aerodynamic efficiency and practical
considerations for the UAV's wing design. This value ensures sufficient lift is generated at low
speeds without requiring a large wing area, which helps to minimize overall weight and drag.
4. Lift-to-Drag Ratio (L/Dmax = 11.5)
The L/Dmax of 11.5 represents a reasonable lift-to-drag ratio for a small, efficient UAV. This
value provides a good compromise between aerodynamic performance and structural
simplicity, allowing the UAV to achieve stable, long-endurance flight while minimizing power
consumption.
5. Propeller Efficiency (n = 0.55)
A propeller efficiency of 0.55 was chosen, reflecting typical values for small UAVs with fixed-
pitch propellers. This efficiency accounts for the losses in power conversion and ensures that
the motor produces sufficient thrust to meet the performance requirements, particularly during
takeoff and climb.
6. Assumptions for Fixed Values
In addition to the design parameters mentioned above, several fixed values were assumed
based on standard references for UAV designs and aerodynamic theory:
Oswald Efficiency Factor (e₀ = 0.8): A typical value for small UAVs, indicating a relatively efficient
wing with minimal drag due to the wing's aspect ratio.
Air Density (p = 1.225 kg/m³ at sea level and PAC = 1.217 kg/m³ at 300m): Standard atmospheric
conditions were assumed for air density, influencing aerodynamic calculations such as lift and
drag.
Coefficient of Zero-Lift Drag (Cd₀ = 0.0323): A typical value for streamlined UAV designs,
accounting for the drag when no lift is being generated.
Coefficient of Friction (u = 0.04): This accounts for the friction between the tires and the runway
during takeoff.
Take-off Distance (Sₜₒ = 10 m): A short takeoff distance was assumed based on the UAV’s weight,
power, and the need for operation from restricted runways.
Conclusion
The design of this UAV adheres to the mission requirements and performance constraints, with
careful consideration given to the wing configuration, tail type, and motor setup. The calculated
wing area of 0.343 m² and engine power of 1118 W reflect a highly efficient design but require
optimization to reduce power consumption below the 900 W limit. The chosen values for the
key design parameters strike a balance between stability, maneuverability, and efficiency,
ensuring that the UAV will perform well under the specified conditions. Further refinement of
the design will focus on improving power efficiency while maintaining overall performance.
UAV Design Summary
1. Design Constraints:
• Maximum Take-off Mass (W): 3 kg (29.43 N)
• Stall Speed (Vs): 10 m/s
• Maximum Speed (Vmax): 26 m/s
• Rotation Speed (Vr): 11 m/s
• Maximum Height (Ceiling): 120 m
• Runway Length: 15 m
• Wing Span (b): ≤ 1.5 m
• Power Limit: ≤ 900 W (including factor of safety)
• 2. Assumed and Given Values:
• Maximum Lift Coefficient (CLmax): 1.4
• Propeller Efficiency (n): 0.55
• Oswald Efficiency Factor (e₀): 0.8
• Air Density at Sea Level (p₀): 1.225 kg/m³
• Air Density at 300m (PAC): 1.217 kg/m³
• Aspect Ratio (A): 13.33
• Coefficient of Friction (u): 0.04
• Gravitational Acceleration (g): 9.81 m/s²
• Coefficient of Zero-Lift Drag of Landing Gear (Cd₀lg): 0.03
• Cruise Lift Coefficient (Clc): 0.4
• Coefficient of Zero-Lift Drag (Cd₀): 0.0323
• Take-off Distance (Sₜₒ): 10 m
• Rate of Climb (R): 1.5 m/s
• Lift-to-Drag Ratio (L/Dmax): 11.5
3. Design Point from Desmos:
• (x-coordinate): 85.75
• (y-coordinate): 0.038
https://www.desmos.com/calculator/nawivlpcd0
FROM ABOVE WE CAN FIND WING AREA AND ENGINE POWER AS:
WING AREA:
𝑾
𝑺=
𝒙
𝟐𝟗. 𝟒𝟑
𝑺=
𝟖𝟓. 𝟕𝟓
S=0.343 𝑚2
ENGINE POWER:
𝑾
𝑷=
𝒚
𝟐𝟗. 𝟒𝟑
𝑷=
𝟎. 𝟎𝟑𝟖
POWER= 775 kW
WING SPAN:
𝑺𝒑𝒂𝒏 = √𝑨𝒔𝒑𝒆𝒄𝒕 𝒓𝒂𝒕𝒊𝒐 × 𝒘𝒊𝒏𝒈 𝒂𝒓𝒆𝒂
𝒔𝒑𝒂𝒏 = √𝟏𝟑. 𝟑𝟑 × 𝟎. 𝟑𝟒𝟑
SPAN= 2.14m
REFRENCES AND TABLES
