Validation Report

The deviation is higher for a lighter flight weight and overall it decreases when headwind is added. The rotation time should be within a range of values (1s to 3s) according to the literature and should be adjusted for a given aircraft in order to obtain a good accuracy in the takeoff distance. The value chosen will be the same for every takeoff since it is assumed that the force applied on the elevator by the pilot is the same. An explanation for the large deviation when the flight weight is reduced can be that a given aircraft with a lighter weight might rotate faster than if it has a heavier weight since it reacts faster to pilot’s inputs. Validation Report Copyright(c) 2007-2021 Optimal Aircraft Design srl (OAD) - All rights reserved 5/9 Maximum Rate of Climb The RCMx and its associated flight speed (Vy), are presented in Table 6 for a flight weight of 1429kg and in Table 7Erreur ! Source du renvoi introuvable. for a flight weight of 1179kg. Table 6 – RCMx @ 1429kg, CG @ 27% MAC, Alt @SL FM ADS Δ [%] Vy [km/h] 180 180 0 RC [m/s] 4.39 4.40 0.3 Table 7 – RCMx @ 1179kg, CG @ 27% MAC, Alt @SL FM ADS Δ [%] Vy [km/h] 180 158 -12.2 RC [m/s] 5.89 5.99 1.5 The RC @ 180km/h (Vy) is presented in Table 8 for a flight weight of 1179kg. Table 8 – RC @ 1179kg, CG @ 27% MAC, Alt @SL, Vy = 180km/h FM ADS Δ [%] RC [m/s] 5.89 5.887 -0.05 Validation Report Copyright(c) 2007-2021 Optimal Aircraft Design srl (OAD) - All rights reserved 6/9 Cruise Speed The computed cruise speed (ADS) for different altitudes and power settings is presented in Table 9. Table 9 – Vcr @ 1179kg, CG @ 27% MAC FM ADS Δ Alt [m] PS [%] Vcr [km/h] Vcr [km/h] [%] 610 90 289 292 1.0 1219 84 287 289 0.7 1829 78 285 286 0.4 2438 72 282 283 0.4 3048 67 278 280 0.7 3658 62 272 277 1.8 4267 57 267 272 1.9 Both computed values (ADS) and values taken from the flight manual (FM) are presented in Figure 3. The maximum deviation is less than 2%. Figure 3 – Cruise speed (taken from FM and computed with ADS) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 265 270 275 280 285 290 295 Altitude [m] Vcruise [km/h] FM ADS Validation Report Copyright(c) 2007-2021 Optimal Aircraft Design srl (OAD) - All rights reserved 7/9 Landing The landing distance depends on the runway surface, touchdown speed (VTD) and flare time (Flr. T). The RFC (Rolling Friction Coefficient, brakes on) controls the brake action during the landing. This parameter can have a range of values [0.15 - 0.50] according to the runway surface and the pilot action on the brakes. The flare time is the time required for the aircraft to be rolling on the runway with all wheels on the surface. It starts when the main wheels hit the ground and ends as soon as the nosewheel touches the runway. The landing distance is calculated according to the runway slope and surface, headwind speed, flap deflection, CG position, flight weight and for a RFC equal to 0.39 which represents the friction coefficient on a paved runway and moderate action on the brakes. The conditions used to obtain the landing distance for an asphalt runway are presented in Table 10. Table 10 – Landing distance for a flight weight of 1429kg and RFC=0.39 FM ADS Δ Rwy Alt [m] Flap dflct [º] HW [km/h] VTD [km/h] Flr T [s] RFC Ld run [m] Ld run [m] Ld Run [%] 0 32 0 144 1 0.39 260 270 3.85 0 32 24 144 1 0.39 234 234 0.00 0 16 0 156 1 0.39 331 323 -2.42 0 16 24 156 1 0.39 298 283 -5.03 0 0 0 165 1 0.39 381 368 -3.41 0 0 24 165 1 0.39 343 325 -5.25 914 32 0 151 1 0.39 284 296 4.23 914 32 24 151 1 0.39 256 258 0.78 914 16 0 163 1 0.39 361 351 -2.77 914 16 24 163 1 0.39 325 310 -4.62 914 0 0 172 1 0.39 416 398 -4.33 914 0 24 172 1 0.39 375 353 -5.87 The deviation is influenced by the headwind and flap setting, as shown in Figure 4. The deviation depends slightly on the altitude and increases as the headwind increases for flap settings 50% and 0%. In contrast, for flaps at 100% increasing the headwind speed will result in a lower deviation. Figure 4 – Deviation in function of headwind and flap setting flap 100% flap100% flap 50% flap 50% flap up flap up flap 100% flap 100% flap 50% flap 50% flap up flap up 0 5 10 15 20 25 30 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 Headwind speed [km/h] Deviation [%] Asphalt runway, h=0m / 914m and M=1429kg h=0m h=914m Validation Report Copyright(c) 2007-2021 Optimal Aircraft Design srl (OAD) - All rights reserved 8/9 Comments The maximum lift is computed from the lift distribution over the lifting surface using the lifting line theory. The lift increment due to flap deflection is computed from the flap type and geometry The total drag is computed making the sum of the drag of each component of the Aircraft, including the interference drag. The empty weight is computed making the sum of the weight of each component of the aircraft. The weight of each component is computed from its geometry. A fudge factor may be used to take into account the material and the skills of the manufacturer. The Center of Gravity position of the aircraft is computed from the mass and position of each component. The center of gravity is computed for different loading configuration. The CG range is computed to ensure stability and maneuverability. The engine performance are computed from an engine database taking into account the flight conditions The takeoff run is the distance between the brake release point and the point where the speed is equal to the liftoff speed and the plane lifts off. The mean acceleration is computed at several speeds, between these two limits, taking into account the engine thrust, the total drag, the wheel friction and the slope of the runway. The length of each segment is computed from the mean acceleration and the speed. The total distance is the sum of the distances travelled in each segment. The rate of climb is computed at a given speed taking into account the engine thrust and the total drag of the airplane. The engine thrust is computed from the engine nominal power and takes into account the effects of altitude, the propeller efficiency and the installation efficiency. The total drag is the sum of the zero lift drag, induced drag and trim drag. The zero lift drag is computed by summing the drag of each component of the aircraft, including the interference drag. The cruising speed is computed for a given flight condition taking into account the power setting, the flight weight, the center of gravity position and the flight altitude. The stall speed is computed flaps up and flaps down taking into account the lift distribution on the wing. The stall is reached when one local lift coefficient reaches its maximum value. The lift distribution is computed from the lifting line theory and takes into account the airfoil profiles and the planform of the lifting surface. The aerodynamic data of each airfoil profile have been computed with XFoil. Not included in this report but processed by ADS: - Static stability - Dynamic stability (free response (eigenmode), step response, harmonic response) - Cost analysis (R&D, Operating, Breakeven, Market price) - Optimization (performance, cost, shape) - Sizing and location of each component/system - Checking for interference between components Sources The ADSV4 computation engine is a compilation of the best algorithms, chosen for their excellent accuracy / time-to-compute ratio. The algorithms are extracted from academic & scientific publications and reference books such as USAF DATCOM, Roskam, Raymer, Torenbeek… Technical notes written by OAD complete them and are directly accessible via the software's interface Validation Report Copyright(c) 2007-2021 Optimal Aircraft Design srl (OAD) - All rights reserved 9/9 List of Symbols ADS Result computed by ADS Cdint Airplane equivalent interference drag coefficient Cfe Airplane friction coefficient CG Center of Gravity % MAC ClMx Maximum lift coefficient FFClMx Fudge factor maximum lift coefficient FFΔClMx Fudge factor maximum lift increment Flap dflct Flap deflection ° Flr. T Landing flare time s FM Value taken from the Flight Manual HW Headwind speed km/h LdRun Landing run m PS Engine Power Setting % RCMx Maximum Rate of Climb m/s RCF Rolling friction coefficient Rot. T Rotation time during takeoff s Rwy Alt Runway altitude m TORun Takeoff run m Vcr Cruise Speed km/h VLO Liftoff Speed km/h VS Stall Speed km/h VTD Touchdown Speed km/h VY Speed for best rate of climb km/h Δ (ADS-FM)/FM % ClMx Maximum lift increment