Lift and Drag Analysis Flight Test database Air data Engine Data JINS IS Data Air Data Computations Gross Weight, Vint P In-Flight Thrust Model Wind Axis Accelerations FE A = G RAM.DRAG XW,YW2ZW Fry=GW*A Predicted Performance Performance Model (outside vortex influence) D=cos(aestFG-FRAM-FEr DRAGEX LD,D Vortex effect= Vortex-Baseline %△Cn,%△Cn,%△WFT Performance data was determined using classical techniques. A force balance along the flight path was used to determine drag while a force balance perpendicular to that was used to determine lift D= cos(aest)FG-FRAM-FEDRAGGWAXW); L=sin(aest)FG+(GW"NXW). Three primary data reduction areas feed the performance mode: 1)Air Data, 2)IFT, and 3 )Accelerations. tal fuel accounting for crew weight. It also includes a calculation of an estimated alpha, aest, which is based on the trailing aircraft s pitch angle and the lead aircraft's flight path angle(aest= gtrail-ylead). This was required because the trailing aircraft's alpha probes are unusable during formation flight due to localized upwash influences of the lead aircraft. Because the lead aircraft flew at steady-state conditions(constant speed and altitude ), the flight path angle, lead, was always close model. The model calculated gross thrust (FG), ram drag(FRAM) and engine throttle dependent drag. (FEDRAG). Gross thrust is the primary force the engine produces out the tail pipe, FRAl The engine manufacturer's IFT model was used to calculate thrust on the F404-GE-400 engines installed in the trailing F/A-18 Aircraft The next chart describes the measurements used to run t presents the force loss due to the mom air, W1, entering the inlet, and FEDRAG accounts for the extemal drag forces associated with the engine nozzle and inlet spillage flow The INS was used to obtain vehicle acceleration data. This data was corrected for rotation effects due to not being mounted exactly on the center of gravity. It then was translated into the flight path (wind axis)coordinate system. Axial acceleration was used to compute vehicle excess thrust: FEX= GW'AXW The performance model used the information from the three paths described above to obtain lift, drag and respective coefficients. To obtain drag reduction values, data obtained during formation flight (vortex) was compared to baseline(non-vortex) points completed in a back-to-back fashion. Some formation flight test points did not include a slide-out maneuver to obtain baseline conditions For these few points, baseline data were estimated based on data trends in drag related to gross weight. A simple prediction model was used to calculate baseline lift and drag values to evaluate the reasonableness of the baseline dataPage 2 Autonomous Formation Flight Program NAS4-00041 TO-104 Lift and Drag Analysis Flight Test Database Air Data Engine Data INS Data In-Flight Thrust Model FG, FRAM, FEDRAG Wind Axis Accelerations AXW, AYW, AZW Air Data Computations Gross Weight, Vinf, Po Dest. = TTrail.- JLead Performance Model D = cos(Dest) FG – FRAM – FEDRAG - FEX CL, CD , CDi = CD– CD0 Vortex Effect = Vortex – Baseline %'CD, %'CDi, %'WFT Predicted Performance (outside vortex influence) CL, CD , CD0 FEX=GW*AXW Performance data was determined using classical techniques. A force balance along the flight path was used to determine drag while a force balance perpendicular to that was used to determine lift: D = cos(Dest) FG – FRAM – FEDRAG-(GW*AXW); L = sin(Dest) FG + (GW*NXW). Three primary data reduction areas feed the performance mode; 1) Air Data, 2) IFT, and 3) Accelerations. The Air Data model computes gross weight (GW) using empty weight and the remaining total fuel accounting for crew weight. It also includes a calculation of an estimated alpha, Dest, which is based on the trailing aircraft’s pitch angle and the lead aircraft’s flight path angle (Dest = qtrail-Jlead). This was required because the trailing aircraft’s alpha probes are unusable during formation flight due to localized upwash influences of the lead aircraft. Because the lead aircraft flew at steady-state conditions (constant speed and altitude), the flight path angle, Jlead, was always close to zero. The engine manufacturer’s IFT model was used to calculate thrust on the F404-GE-400 engines installed in the trailing F/A-18 Aircraft. The next chart describes the measurements used to run this model. The model calculated gross thrust (FG), ram drag (FRAM) and engine throttle dependent drag, (FEDRAG). Gross thrust is the primary force the engine produces out the tail pipe, FRAM represents the force loss due to the momentum of air, W1, entering the inlet, and FEDRAG accounts for the external drag forces associated with the engine nozzle and inlet spillage flow. The INS was used to obtain vehicle acceleration data. This data was corrected for rotation effects due to not being mounted exactly on the center of gravity. It then was translated into the flight path (wind axis) coordinate system. Axial acceleration was used to compute vehicle excess thrust: FEX = GW*AXW The performance model used the information from the three paths described above to obtain lift, drag and respective coefficients. To obtain drag reduction values, data obtained during formation flight (vortex) was compared to baseline (non-vortex) points completed in a back-to-back fashion. Some formation flight test points did not include a slide-out maneuver to obtain baseline conditions. For these few points, baseline data were estimated based on data trends in drag related to gross weight. A simple prediction model was used to calculate baseline lift and drag values to evaluate the reasonableness of the baseline data