fix: Update landing gear drag

.github/CHANGELOG.md

@@ -23,6 +23,7 @@
 1. [EFB] Added boarding time indication to Payload page - @ChristianLutzCL (Christian Lutz) @frankkopp (Frank Kopp)
 1. [EFB] Show correct runway numbers in landing calculator's runway widget when heading is between 0-5 degrees - @2hwk (2Cas#1022)
 1. [ADIRU/ND/PFD] Initial support for polar navigation - @tracernz (Mike)
+1. [FLIGHTMODEL] Update gear drag - @donstim (donbikes#4084)
 
 ## 0.9.0
 

flybywire-aircraft-a320-neo/SimObjects/AirPlanes/FlyByWire_A320_NEO/flight_model.cfg

@@ -238,7 +238,7 @@ lift_coef_flaps = 1.844 ; Change in lift due to flaps
 lift_coef_spoilers = -0.466875 ; Change in lift due to spoilers
 drag_coef_zero_lift = 0.01873 ; The zero lift drag polar
 drag_coef_flaps = 0.1316
-drag_coef_gear = 0.030
+drag_coef_gear = 0.0372
 drag_coef_spoilers = 0.05775;  Change in drag due to spoilers
 side_force_slip_angle = -3.252 ; (yaw angle) The change in side force per change in side slip angle
 side_force_roll_rate = 1.833 ; (roll velocity)  The change in side force per change in roll rate
@@ -441,8 +441,8 @@ flaps-position.0 =  0.00,  -1, 0, 0.0 ; CONF 0
 flaps-position.1 =  5.0,  -1, 0.33, 0.01 ; CONF 1
 flaps-position.2 = 10.00, 215, 0.63, 1.30 ; CONF 1+F
 flaps-position.3 = 15.00, 200, 0.85, 1.30 ; CONF 2
-flaps-position.4 = 20.00, 185, 1.08, 1.17 ; CONF 3
-flaps-position.5 = 40.00, 177, 1.00, 1.00 ; CONF FULL
+flaps-position.4 = 20.00, 185, 0.97, 1.17 ; CONF 3
+flaps-position.5 = 40.00, 177, 0.939, 1.00 ; CONF FULL
 
 [FLAPS.2]
 type = 2 ; Flap type 0 = None, 1 = trailing edge, 2 = leading edge
@@ -461,5 +461,5 @@ flaps-position.0 =  0.00,  -1, 1.00, 1.00 ; CONF 0
 flaps-position.1 = 18.00, 230, 0.33, 1.00 ; CONF 1
 flaps-position.2 = 18.01, 230, 0.63, 1.00 ; CONF 1+F
 flaps-position.3 = 22.00, 200, 0.85, 1.00 ; CONF 2
-flaps-position.4 = 22.01, 185, 1.08, 1.00 ; CONF 3
-flaps-position.5 = 27.00, 177, 1.00, 1.00 ; CONF FULL
+flaps-position.4 = 22.01, 185, 0.97, 1.00 ; CONF 3
+flaps-position.5 = 27.00, 177, 0.939, 1.00 ; CONF FULL

src/fmgc/src/guidance/vnav/FlightModel.ts

@@ -61,17 +61,17 @@ export class FlightModel {
             baseDrag = (0.0168 * Cl ** 3) - (0.0018 * Cl ** 2) - (0.0037 * Cl) + 0.0729;
             break;
         case FlapConf.CONF_3:
-            baseDrag = (0.0132 * Cl ** 3) - (0.0058 * Cl ** 2) + (0.0005 * Cl) + 0.0982;
+            baseDrag = (0.013 * Cl ** 3) - (0.0056 * Cl ** 2) + (0.0005 * Cl) + 0.0902;
             break;
         case FlapConf.CONF_FULL:
-            baseDrag = (0.0077 * Cl ** 3) - (0.0055 * Cl ** 2) - (0.0015 * Cl) + 0.1483;
+            baseDrag = (0.0077 * Cl ** 3) - (0.0056 * Cl ** 2) - (0.001 * Cl) + 0.1405;
             break;
         default:
             break;
         }
 
         const spdBrkIncrement = spdBrkDeflected ? 0.01008 : 0;
-        const gearIncrement = gearExtended ? 0.03 : 0;
+        const gearIncrement = gearExtended ? 0.0372 : 0;
         return baseDrag + spdBrkIncrement + gearIncrement;
     }