# Takeoff Rating (Turboprop): Standard Day

The installed takeoff thrust of a turboprop is plotted in Figure 10.40. It is repeated in this section as Figure 13.5 to keep all available thrust graphs in one section. At the takeoff rating, engine power is kept nearly constant at a speed when the en – route climb can start at a reduced power setting of the maximum climb rating. The psfc of the turboprop at takeoff is 0.5 lb/hr/shp, based on uninstalled power. There­fore, at SHPsls, the fuel-flow rate is 0.5 x 1,075 = 537.5 lb/hr. The intake airmass

Table 13.3. 30,000-ft altitude (p = 0.00088 slug/ft3, a = 0.37) maximum cruise

 True air speed in knots 100 200 250 300 V in mph 115.08 230.16 287.7 345.24 SHPunistall = Figure 10.43a x 1,075 413 440 462 484 J = 0.00533 x knots 0.528 1.055 1.32 1.583 Cp = 0.000116 x shp 0.123 0.131 0.138 0.144 nprop (from Figure 10.35) 0.66 0.81 0.82 0.81 Uninstalled thrust, T (lb) 888 582 494 426 Installed thrust (lb) 852 558 474 409 Sfc (lb/hr/SHP) (Figure 10.44b) 0.46 0.45 0.44 0.43 Fuel flow rate (lb/hr) 190 198 204 208

Figure 13.5. Available turboprop thrust at take­off rating from a 1,100-SHP engine

flow at SHPsls is 0.011 x 1,075 = 11.83 lb/s (the specific power of 0.11 lb/s/SHP is provided in Section 10.2.2).