Fix regression for auto bail off

Author: cesarBLG

Source/Documentation/Manual/physics.rst

@@ -2924,11 +2924,10 @@ the following parameters will adjust the behaviour of air brakes:
 
 - ``Engine(DynamicBrakeHasAutoBailOff`` -- Set to 1 if brake cylinders are
   emptied while dynamic brake is active
-- ``Engine(ORTSDynamicBrakesHasPartialBailOff`` -- Only used if the parameter
-  above is set to 1. When ORTSDynamicBrakesHasPartialBailOff is set to 0 (default),
-  air brakes will be fully released when dynamic brake is providing at least the 85%
-  of the total train brake demand. When set to 1, only part of the air from the brake
-  cylinder is released, so the total air+dynamic brake force equals the total brake demand.
+- ``Engine(ORTSDynamicBrakesHasPartialBailOff`` -- If this parameter is set to 1,
+  air brakes are released while dynamic brakes satisfy the train brake demand.
+  If dynamic braking is not sufficient, air brakes will be partially applied
+  so the combination air+dynamic provides the required brake demand.
 
 
 Native Open Rails Braking Parameters

Source/Orts.Simulation/Simulation/RollingStocks/SubSystems/Brakes/MSTS/AirSinglePipe.cs

@@ -587,15 +587,15 @@ public override void Update(float elapsedClockSeconds)
                                 }
                             }
                         }
-                        if (loco.DynamicBrakeAutoBailOff && loco.DynamicBrakePercent > 0 && Car.MaxBrakeForceN > 0)
+                        if (loco.DynamicBrakePercent > 0 && Car.MaxBrakeForceN > 0)
                         {
-                            var requiredBrakeForceN = Math.Min(AutoCylPressurePSI / MaxCylPressurePSI, 1) * Car.MaxBrakeForceN;
-                            var localBrakeForceN = loco.DynamicBrakeForceN + Math.Min(CylPressurePSI / MaxCylPressurePSI, 1) * Car.MaxBrakeForceN;
-                            if (localBrakeForceN > requiredBrakeForceN - 0.15f * Car.MaxBrakeForceN)
+                            if (loco.DynamicBrakePartialBailOff)
                             {
-                                isolateAutoBrake = true;
-                                if (loco.DynamicBrakePartialBailOff)
+                                var requiredBrakeForceN = Math.Min(AutoCylPressurePSI / MaxCylPressurePSI, 1) * Car.MaxBrakeForceN;
+                                var localBrakeForceN = loco.DynamicBrakeForceN + Math.Min(CylPressurePSI / MaxCylPressurePSI, 1) * Car.MaxBrakeForceN;
+                                if (localBrakeForceN > requiredBrakeForceN - 0.15f * Car.MaxBrakeForceN)
                                 {
+                                    isolateAutoBrake = true;
                                     var compensatedPressurePSI = Math.Min(Math.Max((requiredBrakeForceN - loco.DynamicBrakeForceN)/Car.MaxBrakeForceN*MaxCylPressurePSI, 0), MaxCylPressurePSI);
                                     if (CylPressurePSI < BrakeLine3PressurePSI)
                                         CylPressurePSI = BrakeLine3PressurePSI;
@@ -614,10 +614,23 @@ public override void Update(float elapsedClockSeconds)
                                         CylPressurePSI += dp;
                                     }
                                 }
-                                else
+                            }
+                            else if (loco.DynamicBrakeAutoBailOff)
+                            {
+                                if (loco.DynamicBrakeForceCurves == null)
                                 {
+                                    isolateAutoBrake = true;
                                     CylPressurePSI = BrakeLine3PressurePSI;
                                 }
+                                else
+                                {
+                                    var dynforce = loco.DynamicBrakeForceCurves.Get(1.0f, loco.AbsSpeedMpS);
+                                    if ((loco.MaxDynamicBrakeForceN == 0 && dynforce > 0) || dynforce > loco.MaxDynamicBrakeForceN * 0.6)
+                                    {
+                                        isolateAutoBrake = true;
+                                        CylPressurePSI = BrakeLine3PressurePSI;
+                                    }
+                                }
                             }
                         }
                     }