A jet airplane in level flight has a mass of 8.69 x 10 4 kg, and the two wings h

Question

A jet airplane in level flight has a mass of 8.69 x 104 kg, and the two wings havean estimated total area of 88.0m2. (a) What is the pressure difference between thelower and upper surfaces of the wings?
1 Pa

(b) If the speed of air under the wings is 229 m/s, what is the speed of the air over thewings? Assume air has a density of 1.29 kg/m3.
2 m/s

(c) Explain why all aircraft have a "ceiling," a maximumoperational altitude.
The density of air 3---Select---decreasesincreases with 4---Select---decreasingincreasing height, resulting in a 5---Select---greatersmaller pressure difference. Beyond the maximum operationalaltitude, the pressure difference can no longer support theaircraft. (a) What is the pressure difference between thelower and upper surfaces of the wings?
1 Pa

(b) If the speed of air under the wings is 229 m/s, what is the speed of the air over thewings? Assume air has a density of 1.29 kg/m3.
2 m/s

(c) Explain why all aircraft have a "ceiling," a maximumoperational altitude.
The density of air 3---Select---decreasesincreases with 4---Select---decreasingincreasing height, resulting in a 5---Select---greatersmaller pressure difference. Beyond the maximum operationalaltitude, the pressure difference can no longer support theaircraft.

Explanation / Answer

(a) What is the pressure difference between thelower and upper surfaces of the wings?
Pressure difference between the two surfaces of the wings should besuch that the weight of the plane is balanced by this difference inpressure.

Force = Pressure difference * Total wing area = P*88 = Mg =8.69*104*9.8 N

So, P = 9677.5 Pa

(b) If the speed of air under the wings is 229 m/s, what is the speed of the air over thewings? Assume air has a density of 1.29 kg/m3.

Using Bernoulli's equation for constant altitude,

P + 0.5*d*(v2 - 2292) = 9677.5 +0.5*d*(v2 - 2292) = 0

d = 1.29 kg/m3 (as per question)

So, v = 259.70 m/s


(c) Explain why all aircraft have a "ceiling," a maximumoperational altitude.
The density of air decreases withincreasing height, resulting in a smaller pressure difference. Beyond the maximumoperational altitude, the pressure difference can no longer supportthe aircraft.

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