in which F = total drag or lift force on the object; Cd, CL = drag (d), lift (L) coefficient for the object; q = dynamic pressure; and A = projected area perpen dicular to the air flow for drag, or parallel to the air flow for hft. Dr.ag and lift coefficients for various structural shapes of infinite length are shown in FIg. 4.2. The data are for overpressures less than 20 psi (140kPa). For higher pressu.res, the drag coefficients can be adjusted by using the re~ults of a long plate tested m a free air flow. The drag coefficient for the long plate mcreases ~rom a value of 2.0 at an overpressure of 20 psi (140kPa) to a value of2.5 at approximately 60 pSI (410kPa), and drops to 1.8 at approximately 300 psi (2,100 kPa).