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The simplicity of flight
P A N E L   T W O
Weight & Velocity
For a jumbo jet with
a wing area of 511m²
flying at 900kph (250m/sec)
at an altitude of 12km, where the air
is one quarter the density of that
at ground level, we can
calculate its weight like this:
w = 0.3 x 1.25÷4 x 250² x 511m²
= 2,990,000 newtons
(300 tonnes)
This is roughly its weight
at level flight. Its maximum take-off weight is 394 tonnes.
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The Equations of Flight
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Alternatively, we could look at an albatross that weighs 87 newtons and has a wing area of 0.62m²
Here's how to calculate
its velocity:
v² = w ÷ (s x 0.3 x d)
= 87 ÷ (0.62 x 0.3 x 1.25)
= 19.2m/sec
(43mph)
w = weight
0.3 = lift coefficient
d = air density    v = velocity
s = wing area