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

287.70

345.24

SHPunistall = Figure 10.43a x 1,075

413

440

462

484

J = 0.00533 x knots

0.528

1.055

1.320

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).

Leave a reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>