Wing design starts from the weight and the slowest speed you want to fly, because the area needed is S = 2 × weight ÷ (air density × stall speed² × maximum lift coefficient), and the maximum lift coefficient has to come from published data for your aerofoil section. Everything else, the span, chord, planform, twist and structure, is chosen to deliver that area with acceptable drag, a safe stall and enough strength. The carrier’s first-aircraft recipe is a rectangular wing of 9-11 m span and 1.2-1.5 m chord.
Part of Aerodynamics and Flight
The decisions that make a wing: how big, what shape, how stiff, and what must be known before a rib is cut.
Size The Wing From The Slowest Speed You Need
Rearranging the stall equation (Stall Dynamics) gives the area: S = 2W ÷ (ρ × V² × CLmax). Worked example with the carrier’s figures: a 400 kg aircraft (W = 3,924 N) required to stall at 65 km/h (18.06 m/s) in air of 1.225 kg/m³. If CLmax were 1.3, S = 7,848 ÷ (1.225 × 326.1 × 1.3) = 7,848 ÷ 519.3 = 15.1 m²; if it were 1.6, S = 12.3 m². The coefficient is not mine to supply and 1.3 and 1.6 are placeholders to show the sensitivity: a 23% higher coefficient cuts the area by 19%, so a guess of the coefficient is a guess of the whole wing.
The Choices, In The Order They Should Be Made
- Area from the equation above.
- Section: take a published one (Airfoil Geometry).
- Planform and aspect ratio: span and chord for that area (Wing Planforms, Aspect Ratio).
- Twist: so the root stalls first (Wing Twist).
- Control surfaces and high-lift devices (Control Surfaces, Flaps and Slats).
- Structure: spar, ribs and skin, sized by arithmetic with known material properties (Structural Spars).
Doing this backwards, building the structure you can make and then asking what it can lift, is how an aircraft ends up that stalls faster than it can take off.
What The Corpus Can And Cannot Supply
The carrier (Aerodynamics and Flight) gives a recipe: a Clark Y section, a rectangular planform of 9-11 m span and 1.2-1.5 m chord, a laminated spruce main spar, plywood ribs every 20-30 cm and fabric skin. It does not give a lift coefficient, a strength for the spruce, or a calculation that these dimensions work together, and neither does any article here. Those are the three numbers that decide whether the wing flies and holds together.
Dihedral, Incidence And Washout
Tilting the wing tips up (dihedral) makes the aircraft roll back toward level after a gust. The incidence sets how the wing sits against the fuselage so that the fuselage flies level at cruise. Both are design values for a specific aircraft; copy a proven design’s values rather than choose.
Common Mistakes
- Fixing the wing size first — build a wing and compute the stall speed afterward, and you learn it too late.
- Using a coefficient from a picture or a different section — it must belong to the section, the Reynolds number and the surface you will actually have.
- Treating the carrier’s range as a proof — the carrier’s dimensions are a recipe from a hobby tradition, not a calculation.
Safety
A wing is both an aerodynamic and a structural claim
It must make enough lift and survive the loads that lift puts on it. Of the two, a structural failure in flight cannot be survived. If you cannot do the structural arithmetic with real material properties, you cannot build the wing.
What’s Next
- Learn next: Wing Planforms, the shape seen from above
- Combine with: Structural Spars, the arithmetic that decides strength