SME
Aircraft Design · Problem type
Wing loading from stall speed
Use this for “The approach needs a stall speed of 60 m/s with CLmax = 2.2 at sea level. What is the largest wing loading?”
Chart
W/S(60) = 4,851
This is an example. Type your own values to start a new problem.
W/S (Pa)
=
0.5
×
ρ (kg/m³)
×
(
Vₛ (m/s)
)
2
×
CLmax
Formulas
W/S
=
0.5
×
ρ
×
Vₛ
2
×
CLmax
4,851
=
0.5
×
1.225
×
60
2
×
2.2
Assumptions
•
At the stall the wing flies at CLmax, flaps down for landing, and lift equals weight.
•
Sea-level ρ = 1.225 kg/m³ unless the field is high.
•
The design W/S must be at or below this: a vertical line on the constraint diagram.
Step-by-step
WE KNOW
ρ = 1.225 kg/m³, Vₛ = 60 m/s, CLmax = 2.2
FIND
wing loading (W/S)
Step 1 · Find wing loading (W/S)
Use W/S = 0.5 × ρ × Vₛ² × CLmax
Lift
equals
weight
at
the
stall,
L
=
1
2
ρVₛ²SCLmax;
divide
both
by
S.
W/S
=
0.5
×
1.225
×
60
2
×
2.2
W/S = 0.5 × 1.225 × 3,600 × 2.2
W/S = 0.6125 × 3,600 × 2.2
W/S = 2,205 × 2.2
W/S = 4,851 Pa
Check
Put the numbers back in. Both sides should match.
4,851
=
0.5
×
1.225
×
60
2
×
2.2
✓
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Wing loading and thrust-to-weight (constraint diagram)
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Wing loading for the least thrust
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