Jim Hall's Chaparral \(2 \mathrm{~F}\) sports-racing cars in the 1960s pioneered use of airfoils mounted above the rear suspension to enhance stability and improve braking performance. The airfoil was effectively \(6 \mathrm{ft}\) wide (span) and had a 1-ft chord. Its angle of attack was variable between \(0^{\circ}\) and \(-12^{\circ}\). Assume lift and drag coefficient data are given by curves in Fig. 9.17. Consider a car speed of \(120 \mathrm{mph}\) on a calm day. For an airfoil deflection of \(12^{\circ}\) down, calculate

(a) the maximum downward force 

(b) the maximum increase in deceleration force produced by the airfoil.

Data From Figure 9.17

Transcribed Image Text:

1.8 1.6 1.4 CL 1.2 1.0 0.8 1.8 C=1.72 max 1.6 CL = 1.50 1.4 1.2 CL 1.0 0.8 Laminar-flow section (NACA 662-215) 0.6 0.6 Conventional section (NACA 23015) 0.4 0.4 a a 0.2 4 8 12 16 20 Angle of attack, a (deg) 0.2 4 8 12 16 20 Angle of attack, a (deg)