Weight estimate-prelim.xls - PDF document

Weight estimate-prelim.xls Mission profile: Takeoff, climb, cruise, loiter x hrs, land; y% fuel reserve + z lbs additional fuel Input specific problem variables in green shaded boxes Misssion specs Passengers 150 Ave_Pass_Wt 175 lbf Ave_Pass_Bagg 60 lbf Crew_num 5 Pilots + flight attendants/on-board cargo handlers Ave_Crew_Wt 175 lbf Ave_Crew_Bagg 30 lbf Add_Cargo 0 lbf Additional cargo capacity Range 1500 nmi 9114000 ft fuel_margin 3% Add_fuel 200 lbf Technology Assumptions tsfc 0.537 (lbm/hr)/lbf SFC during cruise 4.64E-06 (slug/s)/lbf tsfc2 0.537 (lbm/hr)/lbf SFC during loiter 4.64E-06 (slug/s)/lbf V 798 ft/s Cruise duration 3.2 hrs LOD_max 15 LOD_CR 13.5 LOD_loiter 15 Endurance 0.25 hr 900 s Stat. weight fractions Warm-up, taxi, take-off Initial guess Payload wt Crew wt Calculated weight fractions From Breguet type equation From Breguet type equation Weight fraction burned as fuel includes reserve fuel margin (%) but not absolute reserve Roskam constants for commercial transports His correlation is of the form Wo=10^A * We^B We vs Wo correlation We= cc*Wo^dd cc = 10^(-A/B); dd=1/B Newton-Raphson Iteration f_Wo=Woguess*(1-wFuel)-Add_fuel-PL-crew-We(Woguess); We=cc*Woguess^dd Iteration No. Initial guess delta Wo Next guess Final converged weight estimate (probably no better than +/- 5%) Estimated gross take-off weight Estimated empty weight Empty weight fraction includes all reserves (%+abs) Page 1