Problem 15: A frequently quoted rule of thumb in aircraft design is that wings s
ID: 1781218 • Letter: P
Question
Problem 15: A frequently quoted rule of thumb in aircraft design is that wings should produce about 1000 N oflft pe square meter of wing. (The fact that a wing has a top and bottom surface does not double its area.) Part (a) At takeoff, an aircraft travels at 61 m s, so that the air speed relative to the bottom of the wing is 61 m/s. Given the sea level density of air to be 1.29 kg/m, how fast must it move over the upper surface to create the ideal lift? Numeric :A numeric value is expected and not an expression 12- Part (b) How fast must air move over the upper surface at a cruising speed of 249 m s and at an altitude where air density is one-fourth that at sea level? Numeric :A numeric value is expected and not an expression. Y2=Explanation / Answer
15)
part a)
let the speed of air at the upper surface is v
Now , FOrce = Pressure * area
1000 = 1 * 0.50 * 1.29 * (v^2 - 61^2)
solving for v
v = 72.6 m/s
the speed at the upper suraface is 72.6 m/s
b)
FOrce = Pressure * area
1000 = 1 * 0.50 * 1.29 * (249^2 - v^2)
solving for v
v = 245.8 m/s
the speed at the lower wing is 245.8 m/s