Question 1 (10 marks)

(2022 Paper)

You are working as a flight test engineer at SUSS Research Flight Test Centre. During the

low speed phase of the test program for a UAV program, pressure at two locations were

measured.

The first pressure is known to be at the stagnation point, and the second is at the edge of

the boundary layer above the wing.

You know that the UAV is flying at an altitude of 500 m under the ISA condition. The two

pressure readings are:

Point 1: Stagnation Pressure, pi=96,920.125 N/m²

Point 2: Static Pressure just outside boundary layer, p2=94,454.204 N/m²

Question la

Apply the flight test data provided to calculate the velocity of the UAV, and determine the

Mach number and the Reynolds Number of the UAV (assume that the characteristic length

is 0.2 m and the Dynamic Viscosity is 1.7737 X 10³ kg/ms).

Question lb

Verify the compressibility of the flow over the UAV, and state whether the density can be

treated as a constant.

Question le

Examine if Bernoulli's equation could be applied to determine the local flow velocity at

point 2, and state the reason(s).

Question Id

Appraise the flow velocity at the point 2.

Question le

Appraise the flow around the point 2 to determine the surface pressure on the wing, directly

below point 2.