【正文】 n estimated time to descend. Team V。 Stability ................................................................................................ 50 Propulsion .................................................................................................................................... 55 Cost ............................................................................................................................................... 61 Final Design Comparisons ......................................................................................................... 72 References .................................................................................................................................... 75 Appendix A – Additional Barn Owl Pictures ........................................................................... 76 Appendix B – Sizing/Carpet Plot Code ..................................................................................... 79 Appendix C – Drag Polar Data .................................................................................................. 87 Appendix D – Wing Structure Optimization Code.................................................................. 88 Appendix E – Wing Optimization Code Outputs .................................................................... 96 Appendix F – Empty Weight Calculation Code ....................................................................... 99 Appendix G – Aluminum Equivalent Inputs for Appendix C .............................................. 101 Appendix H– Fiberglass Property Calculation Code ............................................................ 102 Appendix I – Vn Diagram Code ............................................................................................. 105 Appendix J – Flight Envelope Code ........................................................................................ 107 Team V。 4 Introduction This team’s system requirements review [14] described a plan to target the general aviation market with a singleengine, fourseat aircraft – the Barn Owl. It was the goal of Team V to design a product running on an alternative fuel that will be marketable to hobbyists, fixed base operators, and training fleets in the phaseout of 100 octane lowlead (100LL) aviation gasoline and the transitional times of “peakoil.” The system requirements review also included an estimate of the potential market. It was determined that sales of 500 aircraft per year, or more, could be expected in the wake of the 100LL phaseout. A system definition review was conducted to develop the concept of the aircraft [13]. Biodiesel was selected as the alternative fuel for the Barn Owl. The configuration was set as a lowwing, conventional tail aircraft with a piston engine powering a tractor propeller. The following report describes the method used to determine the preliminary design. 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。s E f f i c i e n c t F a c t o r 0 . 6 7 0 4 2 Team V。 was needed for takeoff. Thus, the fuselage and landing gear were arranged so this rotation angle was possible (see Figure 4). Figure 4 Takeoff rotation Engine Mounting Room Using an engine CAD model obtained from the engine manufacturer website, the engine was integrated into the plane CAD model to determine if its position as required by the center of gravity and stability requirements would interfere with the fuselage. It was found that the nose of the aircraft has adequate room for the engine and all related ponents. Figure 5 Mounted engine Fuel Volume Concerns were raised that there might not be enough room inside the wing for 54 gal of fuel. Calculations from the Catia model showed that the wing had enough room for 240 gal. 15176。 12 In order to find the optimal aircraft design (. the one with the minimum GTOW), Team V calculated and plotted various constraints along the aspect ratio curves. The constraints used were stall speed, cruise speed, climb rate, takeoff distance, and turn load factor (n) value. For each aspect ratio and wing loading bination, cruise speed, climb rate, takeoff distance, and the turn load factor (n) value were calculated as discussed below and placed into an individual matrix for each constraint. Then for each row in the matrix (which corresponded to a constant aspect ratio) the value