A wing develops 10,000N of lift at 100knots. Assuming the wing remains at the same angle of attack and remains at the same altitude, how much lift will it develop at 300knots?
- 900,000N.
- 90,000N.
- 30,000N.
Explanation
Lift is proportional to the square of the airspeed when angle of attack and density are unchanged. Tripling the speed from 100 to 300 knots multiplies the lift by three squared, that is nine. So 10,000 N times 9 gives 90,000 N. The 30,000 N answer wrongly assumes lift varies directly with speed rather than its square.
arifadli8 asking:
how to calculate??
Community Comments (2)
S
sauravkatwal Posts: 14 06.10.2013 / 08:15
L= (density*Coefficient of lift*square of velocity)/2
since velocity is tripled i.e square of 3 is 9 so the answer is 90000N!
since velocity is tripled i.e square of 3 is 9 so the answer is 90000N!
J
Jordi Posts: 198 26.06.2020 / 18:16
can i ask somethin?Why dont we do it the cross way?I mean we say for 100 knots we have 10000N for 300Knots how much? it is 30000N .I try to understand why it is 90000 but we dont have the Cl we dont have the ρ .To use the formula for L.
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