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.
Stability and integration
A nose-down section moment changes the tail load required to trim. It does not, by itself, make the airplane stable. Stability is the slope of moment with angle, set by where the center of gravity sits.
Stability and integration
A tailplane usually wants a symmetric section, because it must lift both ways. Its Reynolds number is not the wing’s, and its stall is a control failure, not just a drag item.
Stability and integration
Small flap angles move lift, drag and moment almost together. Larger angles keep adding drag and moment after the lift increment has flattened, because the flap itself has separated.
Stability and integration
A control surface is a flap on a particular section. Ailerons change wing lift asymmetrically. Elevators change tail lift. The hinge moment and the stall of that flap are the control limits.
Stability and integration
A preliminary performance model reads CL and CD from the section polar at the lift the wing is flying, then adds induced drag. Using the section L/D as the airplane L/D skips that second term.
Stability and integration
A finite wing flies at a lower effective angle than the geometric angle, pays an induced drag the section never had, and stalls where some station reaches its section limit first.