Unmanned Fixed-Wing Aircraft:
Aerodynamic Design and Flight Testing
October 3rd, 2026
2. Enter:
- Required thrust (N)
- Motor RPM
- Flight altitude (m)
- Cruise airspeed (m/s)
- Propeller diameter (inch)
- Number of blades
- Blade material
- Motor aspect ratio
- Battery voltage (cell count)
The tool combines six methods from propeller and electric-motor design theory.
1. Blade Element Momentum (BEM) theory
The blade is divided into radial elements. At each element the axial and tangential induction factors are iterated until the momentum change in the slipstream balances the aerodynamic forces on the blade section. This produces the local inflow angle, angle of attack, and section loads.
2. Minimum-induced-loss design (Larrabee / Betz)
The chord and twist distributions are chosen so that the slipstream velocity is constant along the blade — the Betz condition for minimum induced power. This is the same optimization used by Eugene Larrabee (1979) for hand-built racing propellers and is still the standard for high-efficiency propellers today.
3. NeuralFoil airfoil polars
Lift and drag coefficients at each blade section are predicted by NeuralFoil — a neural-network surrogate trained on hundreds of thousands of XFOIL solutions. It provides accurate 2D polars across the Reynolds-number range typical of small propellers (Re = 5×10⁴ to 5×10⁵) in milliseconds instead of seconds.
4. Snel 3D stall correction
In the rotating reference frame, stall is delayed by centrifugal and Coriolis effects. The Snel correction (Snel et al., 1994) blends the 2D post-stall lift back toward its inviscid value using a factor f(c/r) that depends on the local chord-to-radius ratio. This produces realistic force predictions beyond the static stall angle.
5. Prandtl tip and root loss factors
The finite number of blades means the flow cannot produce full circulation at the tip and root. Prandtl's loss factor corrects the momentum equations for this effect — the same model used in classical propeller theory.
6. Essen's rule (D²L) for motor sizing
The electromagnetic torque capability of an electric motor scales with rotor volume D²·L. Essen's rule relates required shaft power to stator geometry through an empirical output coefficient. The tool uses a coefficient of 300 kW/(m³·rev/s), validated against real racing outrunner motors (T-Motor 2207, SunnySky 2216), and derives stator diameter, stack length, and required KV.
Technical notes
- Language: Python (Flask backend, vanilla JS frontend)
- Main dependencies: AeroSandbox, NeuralFoil, NumPy, SciPy, CasADi
- Hosting: Docker container, self-hosted
- Source: open, running locally or on a private server
Reference
Larrabee, E. E. (1979). Practical Design of Minimum Induced Loss Propellers. SAE Technical Paper 790585.
Snel, H., Houwink, R., Bosschers, J. (1994). Sectional prediction of lift coefficients on rotating wind turbine blades in stall. ECN-C-93-052.
Propeller-Electric Brushless Motor Sizing Tool
Models used
- Get:
- Pitch angle at 75% radius (degrees)
- Pitch distance (inches)
- Required shaft power (Watts)
- Propeller efficiency
- Thrust coefficient and advance ratio
- Estimated propeller mass (grams)
- Recommended motor stator diameter and stack length (mm)
- Recommended motor KV rating
- Chord and twist distributions along the blade
This tool is based on my working Python scripts. It takes flight conditions as input and returns propeller geometry and performance (at the design advance ratio), as well as stator diameter, height, and KV. My primary goal was to help students estimate the required pitch angle for a propeller and match motor size without needing to handle heavy, complex code or download dependencies—while still fully understanding how the code works. So, here it is (making me so proud and happy!), and I’d appreciate your feedback!
3. Enjoy! 😊
August 29, 2026
Welcome, guys!
On this page, you will find materials supporting our course, where we explore and hopefully enjoy the art and science of creating fixed‑wing UAVs — from the first sketch to the final flight test. But we don’t stop there: we also explore tiltrotors and multirotors, because real‑world design rarely fits into one box.
On this page, you will find materials supporting our course, where we explore and hopefully enjoy the art and science of creating fixed‑wing UAVs — from the first sketch to the final flight test. But we don’t stop there: we also explore tiltrotors and multirotors, because real‑world design rarely fits into one box.
Course Content
1) General UAV Design – Life cycle and design stages, project management (Gantt chart), technical requirements and quality function deployment (House of Quality), UAV types, calculation algorithms, design parameters (weight equation, wing loading, power-to-weight ratio, disk loading, constraint diagram, Breguet equation), propulsion and energy source selection, landing gear, flight performance calculation, parametric studies.
2) Aerodynamic Design of Fixed-wing UAVs – Flow parameters, flow models, streamlines, aerodynamic forces and moments, coefficients and their ranges, Reynolds number, boundary layer. Aerodynamic configuration. Wing: airfoils, wing planform, geometric parameters and aerodynamic characteristics, takeoff/landing devices. Tail and placement. Aerodynamic characteristics calculation: analytical methods, numerical methods (circulation, elementary flows, Kutta-Joukowski theorem, thin airfoil theory, lifting line theory, vortex lattice method), CFD. Effect of turbulent atmosphere.
3) Propeller Design and Optimization for Airplane UAVs, Propeller‑Airframe Interaction – Propeller geometry, types, required parameters and selection, thrust estimation, numerical methods for propeller calculation and optimization, propeller effect on airframe aerodynamics, distributed propulsion.
4) Tiltrotor UAV Design Features
5) Multirotor UAV Design
6) Flight Testing of UAVs – Goals and objectives, flight test planning.
7) UAV as a Scaled Model for Special Flight Tests – Similarity parameters and scaling principles, testing features.
1) General UAV Design – Life cycle and design stages, project management (Gantt chart), technical requirements and quality function deployment (House of Quality), UAV types, calculation algorithms, design parameters (weight equation, wing loading, power-to-weight ratio, disk loading, constraint diagram, Breguet equation), propulsion and energy source selection, landing gear, flight performance calculation, parametric studies.
2) Aerodynamic Design of Fixed-wing UAVs – Flow parameters, flow models, streamlines, aerodynamic forces and moments, coefficients and their ranges, Reynolds number, boundary layer. Aerodynamic configuration. Wing: airfoils, wing planform, geometric parameters and aerodynamic characteristics, takeoff/landing devices. Tail and placement. Aerodynamic characteristics calculation: analytical methods, numerical methods (circulation, elementary flows, Kutta-Joukowski theorem, thin airfoil theory, lifting line theory, vortex lattice method), CFD. Effect of turbulent atmosphere.
3) Propeller Design and Optimization for Airplane UAVs, Propeller‑Airframe Interaction – Propeller geometry, types, required parameters and selection, thrust estimation, numerical methods for propeller calculation and optimization, propeller effect on airframe aerodynamics, distributed propulsion.
4) Tiltrotor UAV Design Features
5) Multirotor UAV Design
6) Flight Testing of UAVs – Goals and objectives, flight test planning.
7) UAV as a Scaled Model for Special Flight Tests – Similarity parameters and scaling principles, testing features.
August 29, 2026
This Excel workbook is a practical, hands-on companion for the course “Unmanned Fixed-Wing Aircraft: Aerodynamic Design and Flight Testing.” It implements classical conceptual design methods (Raymer, Gudmundsson, Tyan, Hepperle, and others), as well as my historical sizing models in a structured, easy‑to‑follow spreadsheet format. You can use it to size, evaluate, and refine your own electric UAV – from initial requirements to performance maps and cost estimates.
The books in Russian and in English are slightly different, because I worked on them at different times. Still, both help size and evaluate a small electric UAV.
References and Methods
In each sheet, you’ll find citations to:
- Raymer (Aircraft Design: A Conceptual Approach)
- Gudmundsson (General Aviation Aircraft Design)
- Tyan et al. (Comprehensive preliminary sizing/resizing method for fixed‑wing VTOL UAV)
- Hepperle (Electric Flight – Potential and Limitations)
- Arepyev (Design of Light Passenger Aircraft)
- And many other sources.
Happy designing – and don’t forget to validate your results with real flight tests!
How to use this tool (based on the Russian version of the book; in the English version, the algorithm is identical, but the layout of the material is slightly different):
- Start with your mission requirements – enter payload, cruise speed, and endurance on the “ТЗ и данные прототипа” sheet.
- Run the mass iteration – the “Расчет взлетной массы_It_1 и 2” sheet will converge on a realistic take‑off mass.
- Define key parameters – the “Определение параметров завязки” sheet calculates wing area, wing loading, thrust‑to‑weight ratio, and battery weight.
- Check feasibility – use the “Диаграмма ограничений” to ensure your design meets climb, turn, take‑off, and ceiling constraints.
- Design the wing and tail – use the NACA airfoil generator, wing geometry, and tail sizing sheets.
- Evaluate performance – the range, speed, and climb sheets give you a full performance picture.
- Refine and explore – the parametric studies sheet lets you see how changing aspect ratio affects your design.
Excel-Based Design Tool for Electric UAVs
September 12, 2026
In the folder, you will find sample codes
- modeling unity equation,
- explaining measures of merit in aircraft design,
- designing and analyzing small aircrafts,
- conducting constraint analysis,
- exploring the sensitivity of range to the components of Breguet equation,
The folder is regularly updated.
The codes are in Jupyter notebook .ipynb format.
Useful Python codes for fixed-wing UAV design and analysis
