250cc mx engine, and dyno

Components/Crankshaft.cs

@@ -8,21 +8,46 @@ namespace FluidSim.Components
         public float CrankAngle;        // rad, 0 … 4π
         public float PreviousAngle;
 
-        public float Inertia = 0.2f;
+        public float Inertia = 0.2f;     // kg·m²
         public float FrictionConstant;   // N·m
         public float FrictionViscous;    // N·m per rad/s
 
+        public float LastNetTorque { get; private set; }
+        public float AveragePower { get; private set; }     // smoothed, watts
+        public float AverageTorque { get; private set; }    // smoothed, Nm
+
         private float externalTorque;
+        private float _loadTorque;       // external brake torque (Nm)
+
+        // Power averaging buffer
+        private readonly float[] _powerBuffer;
+        private int _powerBufIdx;
+        private int _powerBufCount;
+        private float _powerBufSum;
+
+        // Torque averaging buffer (same size as power buffer)
+        private readonly float[] _torqueBuffer;
+        private int _torqueBufIdx;
+        private int _torqueBufCount;
+        private float _torqueBufSum;
 
         public Crankshaft(float initialRPM = 400f)
         {
             AngularVelocity = initialRPM * 2f * MathF.PI / 60f;
             CrankAngle = 0f;
             PreviousAngle = 0f;
+
+            _powerBuffer = new float[16384];
+            _torqueBuffer = new float[16384];
         }
 
         public void AddTorque(float torque) => externalTorque += torque;
 
+        public void SetLoadTorque(float torque)
+        {
+            _loadTorque = Math.Max(torque, 0f);
+        }
+
         public void Step(float dt)
         {
             if (float.IsNaN(AngularVelocity) || float.IsInfinity(AngularVelocity))
@@ -32,10 +57,17 @@ namespace FluidSim.Components
 
             PreviousAngle = CrankAngle;
 
+            // Internal friction torque
             float friction = FrictionConstant * MathF.Sign(AngularVelocity)
                            + FrictionViscous * AngularVelocity;
+
+            // Net torque from gas pressure minus friction (used for power/torque display)
             float netTorque = externalTorque - friction;
-            float alpha = netTorque / Inertia;
+            LastNetTorque = netTorque;
+
+            // Total torque after subtracting external load (brake)
+            float totalNetTorque = netTorque - _loadTorque;
+            float alpha = totalNetTorque / Inertia;
             AngularVelocity += alpha * dt;
 
             if (AngularVelocity < 0f) AngularVelocity = 0f;
@@ -46,6 +78,35 @@ namespace FluidSim.Components
             else if (CrankAngle < 0f)
                 CrankAngle += 4f * MathF.PI;
 
+            // ---- Power averaging ----
+            float instantPower = netTorque * AngularVelocity;
+            if (_powerBufCount == _powerBuffer.Length)
+            {
+                _powerBufSum -= _powerBuffer[_powerBufIdx];
+            }
+            else
+            {
+                _powerBufCount++;
+            }
+            _powerBuffer[_powerBufIdx] = instantPower;
+            _powerBufSum += instantPower;
+            _powerBufIdx = (_powerBufIdx + 1) % _powerBuffer.Length;
+            AveragePower = _powerBufSum / _powerBufCount;
+
+            // ---- Torque averaging ----
+            if (_torqueBufCount == _torqueBuffer.Length)
+            {
+                _torqueBufSum -= _torqueBuffer[_torqueBufIdx];
+            }
+            else
+            {
+                _torqueBufCount++;
+            }
+            _torqueBuffer[_torqueBufIdx] = netTorque;
+            _torqueBufSum += netTorque;
+            _torqueBufIdx = (_torqueBufIdx + 1) % _torqueBuffer.Length;
+            AverageTorque = _torqueBufSum / _torqueBufCount;
+
             externalTorque = 0f;
         }
     }