DESIGN SPECIFICATIONS
Establishing the engineering requirements, aerodynamic objectives, and design constraints for developing an endurance-optimized cranked-delta wing.
ONJECTIVES OF THE PROJECT
The objective of this project is to design and optimize a cranked-delta wing for a 15 kg VTOL (Vertical Take-Off and Landing) UAV to improve cruise efficiency while maintaining compatibility with vertical take-off and landing operations. The design focuses on achieving a high lift-to-drag ratio, delayed tip stall, reduced induced drag, and enhanced endurance through systematic optimization of the wing geometry and aerodynamic characteristics.
MISSION REQUIREMENTS
Aircraft Type: VTOL UAV
Maximum Take-Off Weight (MTOW): 15 kg
Primary Mission: Endurance-Optimized Cruise
Cruise Speed: 30 m/s
Flight Configuration: Vertical Take-off → Transition → Cruise → Vertical Landing
Design Altitude: Low to Medium Altitude
Atmospheric Properties (ISA)
The aerodynamic calculations in this project are based on the International Standard Atmosphere (ISA) at sea-level conditions, which provides standardized atmospheric properties for aircraft design and performance analysis.
Air Density (ρ): 1.225 kg/m³
This value represents the density of air at sea level under ISA conditions (15°C and 101.325 kPa). Air density directly influences lift, drag, and Reynolds number calculations. Since the UAV is intended to operate at low to medium altitudes, the sea-level ISA value is used during the conceptual design stage.
Dynamic Viscosity (μ): 1.81 × 10⁻⁵ kg/(m·s)
Dynamic viscosity represents the internal resistance of air to flow. This property is essential for calculating the Reynolds number, which determines the aerodynamic behavior of the selected airfoil. The adopted value corresponds to ISA conditions at 15°C.
Gravitational Acceleration (g): 9.81 m/s²
The standard gravitational acceleration recommended by the International System of Units (SI) is used to convert the aircraft mass into its corresponding weight.
Wing Configuration
(Selected Configuration: Cranked-Delta)
Based on the aerodynamic requirements, mission objectives, structural considerations, and VTOL integration requirements, the cranked-delta wing was selected as the optimal configuration for the proposed 15 kg VTOL UAV. Its dual-sweep planform enables improved cruise performance while maintaining sufficient lift, stability, and compatibility with distributed propulsion, making it well suited for endurance-oriented missions.
Wing Loading
(Selected Value: 60 N/m²)
The wing loading was selected as the initial conceptual design parameter. Wing loading is defined as the ratio of aircraft weight to wing planform area.
A relatively low wing loading was chosen to:
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Improve low-speed aerodynamic performance.
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Reduce stall speed.
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Enhance cruise endurance.
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Improve VTOL transition characteristics.
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Provide sufficient lift during take-off and landing.
[This selected value serves as the starting point for determining the required wing area.]
Wing Area
(Calculated Value: 2.45 m²)
The wing area was calculated using the relationship between aircraft weight and the selected wing loading.
This wing area satisfies the lift requirement for the selected mission profile.
Aspect Ratio
(Selected Value: 3.8)
The aspect ratio was selected after considering the aerodynamic and structural requirements of a medium-sized VTOL UAV.
An aspect ratio of 3.8 provides:
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Good aerodynamic efficiency during cruise.
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Reduced induced drag compared with lower aspect ratio delta wings.
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Sufficient structural stiffness.
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Adequate space for VTOL rotor placement.
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Compatibility with the selected cranked-delta planform.
Wingspan
(Calculated Value: 3.05 m)
The wingspan was calculated from the selected aspect ratio and wing area.
