【正文】 plot a curve through these data points. The cruise speed was calculated by using Matlab’s fsolve function to solve the following equation for V: 2m i n __202 221 ???????? ??? ??????????? d r a gLDp CSV WKCSVVbhp ??? Equation 16 In Equation 16, ηp is the propeller efficiency, bhp is the horsepower of the engine (200), V is the cruise speed, ρ is the air density at cruise altitude, S is the area of the wing, CD0 is the zero lift drag coefficient, K is the aerodynamic constant, W is the aircraft GTOW, and CL_min_drag is the coefficient of lift which corresponds to the minimum drag coefficient. ηp, V, K, and CD0 were previously discussed. CL_min_drag is based upon the drag polar generated by the aerodynamic analysis and S is calculated by dividing the GTOW by the wing loading. It can be noted that the factor of in Equation 16 signifies that this velocity will be the cruise speed at 75% power. Climb rate is calculated using the Raymer’s equation : W VDWbhpV bcpv ????? lim_550 ? Equation 17 Where ηp_climb is the propeller efficiency during climb, bhp is the horsepower of the engine (200), V is the cruise speed, W is the GTOW, and D is the drag force of the aircraft during climb. ηp_climb is assumed to be based upon the propeller analysis (discussed later) and other than D all other parameters have been previously discussed. D is calculated using the equation: ?????? ???? 02 3421 DCSV? Equation 18 Where ρ is the density at sea level, V is the average speed during climb, S is the wing area, and CD0 is the zero lift drag coefficient. All of these values have been previously discussed. Takeoff distance was calculated using Raymer’s equation [10]: ?????????????????????????????????????????slavo b s t a c l ebcL UWThCg SWGB F L???lim_ Equation 19 Team V。 11 56WW represents a missed approach and climb to a 2020 ft divert altitude. It is calculated in the same manner as the fuel used to climb to cruise altitude ????????23WW . 67WW represents a divert distance, however, the team opted to use a 45 minute loiter/divert segment, thus this fuel fraction is 1. 78WW represents the fuel used during the 45 minute loiter/divert segment and is calculated using the loiter equation (also Raymer ): ??????????????????????DLCEWWii ex p1 Equation 15 where E is endurance time (in hours), C is SFC (same as before), and L/D is the lift to drag ratio at cruise conditions. The endurance time is specified as 45 minutes to acmodate IFR regulations and the L/D used in the loiter/divert segment is the same as that for cruise. 89WW is another descent segment and is assumed to be equal to45WW which should be conservative considering the aircraft is descending from a lower altitude. Finally 910WW represents the fuel used during landing and is assumed to be . This is based upon Raymer’s equation which simply states it should be between and [10]. The Wcrew and Wpayload were taken from the design requirement of having a 600 lb payload including crew. Once all of these sizing equations were piled together, it was possible to place them inside of two for loops. The first of these loops varied aspect ratio through a specified range。 9 G TO WWT p???? 550200 Equation 4 where ηp is the propeller efficiency, which is assumed to be based upon the propeller analysis discussed later. The SFC was calculated from the brake horsepower SFC (BSFC) which was calculated for the aircraft’s engine to be . Engine selection and SFC calculation is discussed later in this report. The equation used to calculate SFC from BSFC is: pVB S F CS F C ???? 550 Equation 5 where V is speed and ηp is the propeller efficiency. 12WW corresponds to the fuel used during takeoff and is also calculated using Equation 3 with 100% thrust. Duration for the takeoff segment is assumed to be one minute as specified in Raymer’s chapter 19 [10]. 23WW represents the fuel weight used in climbing to the cruise altitude of 8000 ft. It is calculated using Raymer’s equation : ?????????????????? ??????TDVhCWW eii1e xp1 Equation 6 where C is SFC (same as previously discussed), Δhe is the change in height energy, V is the average climb speed and D/T is the average drag divided by the average thrust during climb. It should be noted, however, that D/T is not actually calculated within the code, and is instead replaced by: 1??????? ?? WTDLTD Equation 7 In Equation 7, L/D is calculated implicitly by calculating CL/CD. CL is calculated using the equation: 221 VS WqSWC L ?? ???? ? Equation 8 where W/S is wing loading (an input parameter) and ρ is air density at sea level. CD is calculated using the curve fit for the plane’s drag polar: 0 2 0 7 2 ????? LLD CCC Equation 9 Δhe is calculated using Raymer’s equation : Team V。 8 Sizing Sizing and Carpet Plot Code Sizing of the Barn Owl was done through the use of carpet plots based on a weight fraction approach and its implementation in a Matlab script. The script was used to automatically generate the carpet plots with constraint lines, so that the lightest weight feasible design point could be determined. Since an existing engine was selected for the Barn Owl, as described below, fixedengine sizing was used. Thus, carpet plots sizing the aircraft with different aspect ratios over a range of wing loadings were used to set the design. The script uses an iteration scheme which assumes an initial guess for gross takeoff weight (GTOW), then calculates GTOW based upon that guess. It then iterates the guessed weight until the two weights are within % of ea