HENFOIL
An airfoil knowledge base for HENFOIL, in reading order: geometry and forces, analysis and design, boundary layers, theory and computation, then named families, wind-tunnel method, geometry repair, optimization, and the workflows that keep a polar traceable. Product field guides sit after the lessons. These are teaching notes, not certification reports.
220 articles · 38 topics
Product
HENFOIL and HENSYNTH product notes: what each workspace adds, who it is for, and what it does not claim.
How-to
Field guides for HENFOIL features and HENSYNTH loops — geometry, requirements, synthesis, Mission, Performance, Trades, Optimize and Reports.
Airfoil fundamentals
Chord, camber, thickness, NACA names, angle of attack, and how shape creates lift.
Airfoil analysis
Polars, Reynolds and Mach number, L/D, drag, pitching moment, and how to compare sections.
Airfoil design
Choosing, drawing, and optimizing a section for a UAV or another real mission.
Advanced aerodynamics
Boundary layers, stall types, roughness, icing, pressure plots, and airfoil noise.
Airfoil applications
Wind turbines, electric aircraft, CFD, and the step from a 2D section to a 3D wing.
Airfoil geometry
Coordinates, chord, camber, thickness distribution, leading-edge radius and named NACA profiles.
Lift and drag
How to calculate CL and CD, read the lift slope, zero-lift angle, CLmax and the best angle.
Analysis methods
Lift curves, low Reynolds number, Cp plots, potential flow, convergence and compressibility.
Design and modification
Editing a section, parameterization, design variables, optimizers and a comparison matrix.
Applications and validation
HALE and racing aircraft, altitude, gliders, wind-tunnel tests and checking a computation.
Boundary layers
Thickness, laminar bubbles, adverse gradients, transition, roughness and skin friction versus pressure drag.
Stall and flow control
Stall type, post-stall polars, slats, flaps, vortex generators and dynamic stall.
Coordinates and numerics
Bad points, interpolation, resampling, panel methods, resolution and why two codes disagree.
Operating conditions
Reynolds-number sweeps, temperature, yaw, critical Mach, shocks and off-design flight.
Design workflows
Databases, CAD sketches, performance maps, high-lift selection and the step from a polar to a wing.
Geometry models
NACA camber lines, 5-digit and 6-series sections, coordinate equations, CST and Bézier curves.
Aerodynamic theory
Thin-airfoil lift, the lift slope, the Kutta condition, circulation and the aerodynamic center.
Computational methods
Panel methods, viscous coupling, XFOIL settings, failed polars, CFD meshes and RANS.
Stability and integration
Pitching moment and stability, tailplanes, flaps, control surfaces and finite-wing effects.
Specialized applications
Solar UAVs, human-powered aircraft, wind-turbine stations, small electrics and performance maps.
Airfoil families
Clark Y, NACA 23012 and 4415, symmetric thicknesses, and Eppler and Selig low-Reynolds-number sections.
Flow phenomena
Pressure recovery, leading-edge suction, camber and zero lift, compressibility corrections and three-dimensional flow.
Wind-tunnel testing
Balances and wakes, data reduction, uncertainty, oil flow, pressure taps and a validation workflow.
Geometry processing
Self-intersections, area and ordering, transforms, DAT to DXF, and a quality check before the loft.
Optimization and workflows
Robust and multi-point design, surrogates, machine learning, morphing sections and an automated analysis loop.
Geometry parameters
Leading-edge radius, thickness ratio, trailing-edge thickness, reflex camber, and comparing two sections.
Performance reading
Best lift-to-drag angle, glide ratio, reading lift with drag and moment, hysteresis, and polar trade-offs.
Analysis workflows
Reynolds-number sweeps, consistent databases, sensitivity, outliers, solver benchmarks, and reproducible reports.
Aircraft and propulsion
Trainers, flying-wing UAVs, propeller blades, electric VTOL, high-altitude flight, and slow mapping aircraft.
Research methods
Uncertainty, Bayesian search, physics-informed models, flow control, bio-inspired sections, and digital twins.
Geometry models
The mean camber line is the midline between the upper and lower surfaces. For a NACA 4-digit section it is two parabolas. For a coordinate file it is the average of the two surfaces, done carefully.
Geometry models
A 5-digit NACA name puts the camber farther forward than a 4-digit section of similar design lift. NACA 23012 means a design lift coefficient of 0.3, maximum camber at 15% chord, and 12% thickness.
Geometry models
A 6-series section is drawn around a pressure distribution: a favorable gradient back to a chosen point, to hold a laminar run, and a design lift coefficient on a separate mean line.
Geometry models
Thickness is laid perpendicular to the camber line, not stacked vertically on the chord, except when the camber line is straight. The slope of the camber line is part of the coordinate.
Geometry models
CST writes each surface as a class function, which sets the nose and the trailing edge, times a shape function, which is a short polynomial. A handful of coefficients replaces a cloud of points.
Geometry models
A Bézier curve feels every control point globally. A B-spline feels only the nearby ones. Neither one knows what a leading-edge radius is unless you constrain it.