Glossary term

Wing Taper Ratio

Dimensionless wing planform ratio comparing tip chord with root chord, used in tapered-wing geometry, MAC and aerodynamic tradeoffs.

Branch: Aerospace Engineering
Glossary type: quantity
Content: Glossary term
Updated: Jun 24, 2026
Revision: v1.0.0 · reviewed

Definition

quantity

Wing taper ratio is the tip chord divided by the root chord of a tapered wing planform.

Wing taper ratio is commonly written lambda = c_t/c_r for a trapezoidal wing, where c_t is tip chord and c_r is root chord. It controls how wing area is distributed between root and tip for a given span and area. Taper affects mean aerodynamic chord, spanwise lift distribution, local Reynolds number, stall progression, spar depth, structural bending efficiency, aileron environment and manufacturability. It is a planform geometry ratio, not a performance metric by itself.

Wing taper ratio is the ratio of tip chord to root chord:

\displaystyle \lambda=\frac{c_t}{c_r}

where $c_t$ is tip chord and $c_r$ is root chord. For a conventional tapered wing, $0<\lambda<1$ . A rectangular wing has $\lambda=1$ . A reverse-tapered wing has $\lambda>1$ and requires explicit justification because it moves more area outboard.

For a straight trapezoidal wing with full span $b$ , root chord $c_r$ and tip chord $c_t$ , reference area is:

\displaystyle S=\frac{b}{2}(c_r+c_t)

The taper ratio therefore controls how the same span and area can be distributed between inboard and outboard chord.

Engineering Role

Wing taper ratio shapes the spanwise chord distribution. That affects mean aerodynamic chord, pitching-moment reference geometry, local Reynolds number, stall progression, aileron environment, structural spar depth, fuel volume, wing bending efficiency, manufacturing complexity and aeroelastic behavior.

Taper is not automatically good or bad. Moderate taper can move area inboard and reduce structural penalty, but too much taper can make the tip chord small, lower local Reynolds number, reduce control-surface volume and increase the risk of unfavorable tip stall unless twist, airfoil selection, washout, leading-edge devices or planform details are coordinated.

Worked Example: Same Span and Area, Different Planform

A rectangular reference wing has:

b=12.0\ \text{m}

and constant chord:

c=2.25\ \text{m}

Its area is:

S=bc=12.0(2.25)=27.0\ \text{m}^2

and its aspect ratio is:

\displaystyle AR=\frac{b^2}{S}=\frac{12.0^2}{27.0}=5.33

Now review a tapered wing with the same span and area:

c_r=3.00\ \text{m},\quad c_t=1.50\ \text{m}

The taper ratio is:

\displaystyle \lambda=\frac{1.50}{3.00}=0.50

Its area is:

\displaystyle S=\frac{12.0}{2}(3.00+1.50)=27.0\ \text{m}^2

so the aspect ratio is still:

AR=5.33

The two wings have the same span, area and aspect ratio, but they do not have the same chord distribution. For the tapered wing, the mean aerodynamic chord is:

\displaystyle \bar{c}=\frac{2}{3}c_r\frac{1+\lambda+\lambda^2}{1+\lambda}

\displaystyle \bar{c}=\frac{2}{3}(3.00)\frac{1+0.50+0.50^2}{1+0.50}=2.33\ \text{m}

The rectangular wing MAC is simply:

\bar{c}=2.25\ \text{m}

The tapered wing therefore has a MAC that is:

\displaystyle \frac{2.33}{2.25}-1=0.037

or about $3.7\%$ larger than the rectangular chord, even though the two wings have the same area and span.

The local chord ratio also changes local Reynolds number at the same speed and air properties. If Reynolds number is proportional to chord, then:

\displaystyle \frac{Re_{tip}}{Re_{root}}=\frac{c_t}{c_r}=0.50

Engineering comment: the taper ratio changes local aerodynamic and structural conditions without changing total wing area or aspect ratio in this example. A real planform review would also check twist, airfoil variation, high-lift devices, aileron sizing, stall pattern, spar depth, fuel volume, manufacturing constraints and aeroelastic margins.

Wing taper ratio is not wing aspect ratio. Aspect ratio compares span with area; taper ratio compares tip chord with root chord.

Wing taper ratio is not mean aerodynamic chord. Taper ratio is one input to MAC for a simple trapezoidal wing; MAC is the reference chord that represents the planform for moment and center-of-gravity normalization.

Wing taper ratio is not wing loading. Wing loading uses weight and reference area. Taper ratio describes how that area is distributed along the span.

Wing taper ratio is not a stall guarantee. Taper changes local chord and loading tendencies, but stall behavior also depends on airfoil selection, twist, Reynolds number, roughness, sweep, high-lift devices and control deflection.

Validation and Common Mistakes

A defensible taper-ratio value states the root chord definition, tip chord definition, span station limits, whether extensions or winglets are included, whether the wing is straight, swept, cranked or multi-panel, and which configuration-controlled geometry revision is being used.

Common mistakes include:

using exposed wing chord in one calculation and reference-planform chord in another;
applying a single trapezoidal formula to a cranked or multi-panel wing without segmenting the planform;
confusing taper ratio with aspect ratio or wing loading;
ignoring local Reynolds-number effects at a small tip chord;
changing taper without updating MAC, LEMAC, aerodynamic center and percent-MAC data;
assuming taper alone fixes lift distribution without twist, airfoil and sweep review;
comparing wind-tunnel and flight-test data sets that use different planform conventions.

REF

Disciplines

Wing Taper Ratio

Definition

Engineering Role

Worked Example: Same Span and Area, Different Planform

Validation and Common Mistakes

See also

Engineering Role

Worked Example: Same Span and Area, Different Planform

Distinction from Related Terms

Validation and Common Mistakes