The free-stream velocity in the test section during an early morning windtunnel test was 100 km/h and the temperature was 280 K (use ρ = 1.2 kg/m3, μ = 1.8 × 10-5 N s/m2). The same test is repeated in the afternoon but now the temperature was 310 K (to calculate ρ, use the ideal-gas relation, μ = 2.0 × 10-5 N s/m2).
(a) Calculate the desirable free-stream speed to maintain the Reynolds number of the morning test.
(b) At what speed will the forces (e.g., lift and drag) be the same as in the morning?