Fixed issue with null references being thrown when the atmospheric slider on the build engineer is visible.
Fixed issue with null references being thrown when the atmospheric slider on the build engineer is visible.

 Binary files a/Assets/CurseLogo.png and b/Assets/CurseLogo.png differ
 Binary files a/Assets/CurseLogo.psd and b/Assets/CurseLogo.psd differ
--- a/Documents/CHANGES.txt
+++ b/Documents/CHANGES.txt
@@ -1,4 +1,41 @@
-1.0.14.0,
+1.0.16.3, 27-04-2015
+    Fixed issue with the toolbar icons not being created.
+    Removed superfluous 'm/s' on the mach slider in the build engineer.
+
+1.0.16.2, 27-04-2015
+    Changed the atmospheric slider on the build engineer to default to 0km when changing bodies.
+
+1.0.16.1, 26-04-2015, KSP Build #828
+    Merged Sarbian's mach adjustments.
+    Fixed bugs relating to thrust and atmosphere/velocity curves.
+    Changed the atmospheric slider on the Build Engineer to work based on altitude.
+    Changed the atmospheric slider to clamp to the maximum altitude for the selected body.
+    Changed the velocity slider to clamp to the maximum usable mach value for the current vessel.
+
+1.0.16.0, 25-04-2015, KSP Build #821
+    Fixed errors relating to KSP 1.0 update.
+    Fixed fuel simulation to account for new thrust system.
+    Fixed atmospheric engines to use the new velocity curve.
+    Fixed atmospheric readouts to work with the new atmospheric model.
+
+1.0.15.2, 13-02-2015
+    Padishar's Fixes:
+        Fixed: Calculation of per-stage resource mass.
+
+1.0.15.1, 13-02-2015
+    Rebuild
+    
+1.0.15.0, 08-02-2015
+    Padishar's Fixes:
+        Added: Support KIDS ISP thrust correction.
+        Fixed: Log spam for stage priority mode.
+        Fixed: Locked tanks preventing simulation from staging.
+        Fixed: No flow and all vessel modes to respect flow states.
+
+1.0.14.1, 28-12-2014
+    Fixed: Missing texture on the ER-7500 model.
+    
+1.0.14.0, 28-12-2014
     Added: Career mode that limits the Flight Engineer by:
         - Requiring an Engineer Kerbal of any level, or placement of an Engineer Chip or ER-7500 part.
         - Tracking station level 3 enables Flight Engineer everywhere.
@@ -13,6 +50,7 @@
     Changed: Editor Overlay Tabs start position moved over as to not overlap the parts menu.
     Fixed: Bug where STAGE_PRIORITY_FLOW resources would not be corrently disabled/enabled.
     Fixed: Issue with the formatting large Mass and Cost values.
+    Fixed: Error when loading the Engineer7500 part model.
 
 1.0.13.1, 16-12-2014
     Fixed: Issue with manoeuvre node readouts and low tier tracking station.

--- a/KerbalEngineer/CelestialBodies.cs
+++ b/KerbalEngineer/CelestialBodies.cs
@@ -17,16 +17,12 @@
 //     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // 
 
-#region Using Directives
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-
-#endregion
-
 namespace KerbalEngineer
 {
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+
     /*
      * 
      * With thanks to Nathaniel R. Lewis (aka. Teknoman117) (linux.robotdude@gmail.com) for working out
@@ -36,8 +32,6 @@
 
     public static class CelestialBodies
     {
-        #region Constructors
-
         static CelestialBodies()
         {
             try
@@ -55,16 +49,8 @@
             }
         }
 
-        #endregion
-
-        #region Properties
-
         public static BodyInfo SelectedBody { get; private set; }
         public static BodyInfo SystemBody { get; private set; }
-
-        #endregion
-
-        #region Public Methods
 
         /// <summary>
         ///     Gets a body given a supplied body name.
@@ -89,7 +75,7 @@
         {
             try
             {
-                var body = GetBodyInfo(bodyName);
+                BodyInfo body = GetBodyInfo(bodyName);
                 if (body != null)
                 {
                     if (SelectedBody != null)
@@ -108,33 +94,26 @@
             return false;
         }
 
-        #endregion
-
-        #region Nested type: BodyInfo
-
         public class BodyInfo
         {
-            #region Constructors
-
             public BodyInfo(CelestialBody body, BodyInfo parent = null)
             {
                 try
                 {
                     // Set the body information.
-                    this.CelestialBody = body;
-                    this.Name = body.bodyName;
-                    this.Gravity = 9.81 * body.GeeASL;
-                    this.Atmosphere = body.atmosphere ? 101.325 * body.atmosphereMultiplier : 0;
-                    this.Parent = parent;
+                    CelestialBody = body;
+                    Name = body.bodyName;
+                    Gravity = 9.81 * body.GeeASL;
+                    Parent = parent;
 
                     // Set orbiting bodies information.
-                    this.Children = new List<BodyInfo>();
-                    foreach (var orbitingBody in body.orbitingBodies)
-                    {
-                        this.Children.Add(new BodyInfo(orbitingBody, this));
-                    }
-
-                    this.SelectedDepth = 0;
+                    Children = new List<BodyInfo>();
+                    foreach (CelestialBody orbitingBody in body.orbitingBodies)
+                    {
+                        Children.Add(new BodyInfo(orbitingBody, this));
+                    }
+
+                    SelectedDepth = 0;
                 }
                 catch (Exception ex)
                 {
@@ -142,37 +121,28 @@
                 }
             }
 
-            #endregion
-
-            #region Properties
-
+            public CelestialBody CelestialBody { get; private set; }
+            public List<BodyInfo> Children { get; private set; }
+            public double Gravity { get; private set; }
             public string Name { get; private set; }
-            public double Gravity { get; private set; }
-            public double Atmosphere { get; private set; }
             public BodyInfo Parent { get; private set; }
-            public List<BodyInfo> Children { get; private set; }
-            public CelestialBody CelestialBody { get; private set; }
             public bool Selected { get; private set; }
             public int SelectedDepth { get; private set; }
 
-            #endregion
-
-            #region Public Methods
-
             public BodyInfo GetBodyInfo(string bodyName)
             {
                 try
                 {
                     // This is the searched body.
-                    if (String.Equals(this.Name, bodyName, StringComparison.CurrentCultureIgnoreCase))
+                    if (String.Equals(Name, bodyName, StringComparison.CurrentCultureIgnoreCase))
                     {
                         return this;
                     }
 
                     // Check to see if any of this bodies children are the searched body.
-                    foreach (var child in this.Children)
-                    {
-                        var body = child.GetBodyInfo(bodyName);
+                    foreach (BodyInfo child in Children)
+                    {
+                        BodyInfo body = child.GetBodyInfo(bodyName);
                         if (body != null)
                         {
                             return body;
@@ -188,33 +158,44 @@
                 return null;
             }
 
+            public double GetDensity(double altitude)
+            {
+                return CelestialBody.GetDensity(GetPressure(altitude), GetTemperature(altitude));
+            }
+
+            public double GetPressure(double altitude)
+            {
+                return CelestialBody.GetPressure(altitude);
+            }
+
+            public double GetTemperature(double altitude)
+            {
+                return CelestialBody.GetTemperature(altitude);
+            }
+
+            public double GetAtmospheres(double altitude)
+            {
+                return GetPressure(altitude) * PhysicsGlobals.KpaToAtmospheres;
+            }
+
             public void SetSelected(bool state, int depth = 0)
             {
-                this.Selected = state;
-                this.SelectedDepth = depth;
-                if (this.Parent != null)
-                {
-                    this.Parent.SetSelected(state, depth + 1);
-                }
-            }
-
-            #endregion
-
-            #region Debugging
+                Selected = state;
+                SelectedDepth = depth;
+                if (Parent != null)
+                {
+                    Parent.SetSelected(state, depth + 1);
+                }
+            }
 
             public override string ToString()
             {
-                var log = "\n" + this.Name +
-                          "\n\tGravity: " + this.Gravity +
-                          "\n\tAtmosphere: " + this.Atmosphere +
-                          "\n\tSelected: " + this.Selected;
-
-                return this.Children.Aggregate(log, (current, child) => current + "\n" + child);
-            }
-
-            #endregion
-        }
-
-        #endregion
+                string log = "\n" + Name +
+                             "\n\tGravity: " + Gravity +
+                             "\n\tSelected: " + Selected;
+
+                return Children.Aggregate(log, (current, child) => current + "\n" + child);
+            }
+        }
     }
 }

--- a/KerbalEngineer/Editor/BuildAdvanced.cs
+++ b/KerbalEngineer/Editor/BuildAdvanced.cs
@@ -37,11 +37,11 @@
     public class BuildAdvanced : MonoBehaviour
     {
         #region Fields
+        public static float Altitude = 0.0f;
 
         private GUIStyle areaSettingStyle;
         private GUIStyle areaStyle;
-        private float atmosphericPercentage = 1.0f;
-        private float atmosphericVelocity;
+        private float atmosphericMach;
         private GUIStyle bodiesButtonActiveStyle;
         private GUIStyle bodiesButtonStyle;
         private DropDown bodiesList;
@@ -65,6 +65,7 @@
         private GUIStyle titleStyle;
         private bool visible = true;
         private GUIStyle windowStyle;
+        private float maxMach;
 
         #endregion
 
@@ -133,12 +134,13 @@
                 this.bodiesList.DrawCallback = this.DrawBodiesList;
                 this.Load();
 
+                SimManager.UpdateModSettings();
                 SimManager.OnReady -= this.GetStageInfo;
                 SimManager.OnReady += this.GetStageInfo;
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex);
+                Logger.Exception(ex, "BuildAdvanced.Awake()");
             }
         }
 
@@ -164,7 +166,7 @@
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex);
+                Logger.Exception(ex, "BuildAdvanced.OnDestroy()");
             }
         }
 
@@ -214,7 +216,7 @@
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex);
+                Logger.Exception(ex, "BuildAdvanced.OnGUI()");
             }
         }
 
@@ -227,7 +229,7 @@
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex);
+                Logger.Exception(ex, "BuildAdvanced.Start()");
             }
         }
 
@@ -255,21 +257,21 @@
 
                 if (this.showAtmosphericDetails)
                 {
-                    SimManager.Atmosphere = CelestialBodies.SelectedBody.Atmosphere * 0.01d * this.atmosphericPercentage;
+                    SimManager.Atmosphere = CelestialBodies.SelectedBody.GetAtmospheres(Altitude);
                 }
                 else
                 {
                     SimManager.Atmosphere = 0;
                 }
 
-                SimManager.Velocity = this.atmosphericVelocity;
+                SimManager.Mach = this.atmosphericMach;
 
                 SimManager.RequestSimulation();
                 SimManager.TryStartSimulation();
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex, "BuildAdvanced->Update");
+                Logger.Exception(ex, "BuildAdvanced.Update()");
             }
         }
 
@@ -293,23 +295,30 @@
         /// </summary>
         private void DrawAtmosphericDetails()
         {
-            GUILayout.BeginHorizontal();
-            GUILayout.BeginVertical();
-            GUILayout.Label("Pressure: " + (this.atmosphericPercentage * 100.0f).ToString("F1") + "%", this.settingAtmoStyle, GUILayout.Width(125.0f * GuiDisplaySize.Offset));
-            GUI.skin = HighLogic.Skin;
-            this.atmosphericPercentage = GUILayout.HorizontalSlider(this.atmosphericPercentage, 0, 1.0f);
-            GUI.skin = null;
-            GUILayout.EndVertical();
-
-            GUILayout.Space(5.0f);
-
-            GUILayout.BeginVertical();
-            GUILayout.Label("Velocity: " + this.atmosphericVelocity.ToString("F1") + "m/s", this.settingAtmoStyle, GUILayout.Width(125.0f * GuiDisplaySize.Offset));
-            GUI.skin = HighLogic.Skin;
-            this.atmosphericVelocity = GUILayout.HorizontalSlider(this.atmosphericVelocity, 0, 2500f);
-            GUI.skin = null;
-            GUILayout.EndVertical();
-            GUILayout.EndHorizontal();
+            try
+            {
+                GUILayout.BeginHorizontal();
+                GUILayout.BeginVertical();
+                GUILayout.Label("Altitude: " + (Altitude * 0.001f).ToString("F1") + "km", this.settingAtmoStyle, GUILayout.Width(125.0f * GuiDisplaySize.Offset));
+                GUI.skin = HighLogic.Skin;
+                Altitude = GUILayout.HorizontalSlider(Altitude, 0.0f, (float)(CelestialBodies.SelectedBody.CelestialBody.atmosphereDepth));
+                GUI.skin = null;
+                GUILayout.EndVertical();
+
+                GUILayout.Space(5.0f);
+
+                GUILayout.BeginVertical();
+                GUILayout.Label("Mach: " + this.atmosphericMach.ToString("F1"), this.settingAtmoStyle, GUILayout.Width(125.0f * GuiDisplaySize.Offset));
+                GUI.skin = HighLogic.Skin;
+                atmosphericMach = GUILayout.HorizontalSlider(Mathf.Clamp(atmosphericMach, 0.0f, maxMach), 0.0f, maxMach);
+                GUI.skin = null;
+                GUILayout.EndVertical();
+                GUILayout.EndHorizontal();
+            }
+            catch (Exception ex)
+            {
+                Logger.Exception(ex, "BuildAdvanced.DrawAtmosphericDetails()");
+            }
         }
 
         private void DrawBodiesList()
@@ -334,6 +343,7 @@
             if (GUILayout.Button(bodyInfo.Children.Count > 0 ? bodyInfo.Name + " [" + bodyInfo.Children.Count + "]" : bodyInfo.Name, bodyInfo.Selected && bodyInfo.SelectedDepth == 0 ? this.bodiesButtonActiveStyle : this.bodiesButtonStyle))
             {
                 CelestialBodies.SetSelectedBody(bodyInfo.Name);
+                Altitude = 0.0f;
                 this.bodiesList.Resize = true;
             }
             GUILayout.EndHorizontal();
@@ -588,7 +598,11 @@
 
         private void GetStageInfo()
         {
-            this.stages = SimManager.Stages;
+            stages = SimManager.Stages;
+            if (stages != null && stages.Length > 0)
+            {
+                maxMach = stages[stages.Length - 1].maxMach;
+            }
         }
 
         /// <summary>
@@ -701,7 +715,7 @@
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex, "BuildAdvanced->Load");
+                Logger.Exception(ex, "BuildAdvanced.Load()");
             }
         }
 
@@ -796,7 +810,7 @@
             }
             catch (Exception ex)
             {
-                Logger.Exception(ex);
+                Logger.Exception(ex, "BuildAdvanced.Window()");
             }
         }
 

--- a/KerbalEngineer/Editor/BuildOverlayVessel.cs
+++ b/KerbalEngineer/Editor/BuildOverlayVessel.cs
@@ -58,7 +58,7 @@
         #endregion
 
         #region Properties
-       
+
         public static bool Visible
         {
             get { return visible; }
@@ -188,7 +188,7 @@
 
             if (BuildAdvanced.Instance.ShowAtmosphericDetails)
             {
-                SimManager.Atmosphere = CelestialBodies.SelectedBody.Atmosphere * 0.01;
+                SimManager.Atmosphere = CelestialBodies.SelectedBody.GetAtmospheres(BuildAdvanced.Altitude);
             }
             else
             {

--- a/KerbalEngineer/Editor/BuildToolbar.cs
+++ b/KerbalEngineer/Editor/BuildToolbar.cs
@@ -42,6 +42,14 @@
         {
             GameEvents.onGUIApplicationLauncherReady.Add(this.OnGuiAppLauncherReady);
             Logger.Log("BuildToolbar->Awake");
+        }
+
+        private void Start()
+        {
+            if (button == null)
+            {
+                OnGuiAppLauncherReady();
+            }
         }
 
         private void OnDestroy()

--- a/KerbalEngineer/EngineerGlobals.cs
+++ b/KerbalEngineer/EngineerGlobals.cs
@@ -33,7 +33,7 @@
         /// <summary>
         ///     Current version of the Kerbal Engineer assembly.
         /// </summary>
-        public const string AssemblyVersion = "1.0.13.1";
+        public const string AssemblyVersion = "1.0.16.3";
 
         #endregion
 

--- a/KerbalEngineer/Extensions/PartExtensions.cs
+++ b/KerbalEngineer/Extensions/PartExtensions.cs
@@ -464,7 +464,7 @@
         /// </summary>
         public static bool IsSolidRocket(this Part part)
         {
-            return part.HasModule<ModuleEngines>() && part.GetModuleEngines().throttleLocked;
+            return (part.HasModule<ModuleEngines>() && part.GetModuleEngines().throttleLocked) || (part.HasModule<ModuleEnginesFX>() && part.GetModuleEnginesFx().throttleLocked);
         }
 
         #endregion

--- a/KerbalEngineer/Flight/ActionMenu.cs
+++ b/KerbalEngineer/Flight/ActionMenu.cs
@@ -55,6 +55,14 @@
             Logger.Log("ActionMenu was created.");
         }
 
+        protected void Start()
+        {
+            if (button == null)
+            {
+                OnGuiAppLauncherReady();
+            }
+        }
+
         protected void OnDestroy()
         {
             try
@@ -62,7 +70,10 @@
                 GameEvents.onGUIApplicationLauncherReady.Remove(this.OnGuiAppLauncherReady);
                 GameEvents.onHideUI.Remove(this.OnHide);
                 GameEvents.onShowUI.Remove(this.OnShow);
-                ApplicationLauncher.Instance.RemoveModApplication(this.button);
+                if (button != null)
+                {
+                    ApplicationLauncher.Instance.RemoveModApplication(this.button);
+                }
             }
             catch (Exception ex)
             {

--- a/KerbalEngineer/Flight/FlightEngineerCore.cs
+++ b/KerbalEngineer/Flight/FlightEngineerCore.cs
@@ -33,6 +33,7 @@
     using Sections;
     using Settings;
     using UnityEngine;
+    using VesselSimulator;
 
     #endregion
 
@@ -268,6 +269,9 @@
                 this.SectionWindows = new List<SectionWindow>();
                 this.SectionEditors = new List<SectionEditor>();
                 this.UpdatableModules = new List<IUpdatable>();
+
+                SimManager.UpdateModSettings();
+
                 Logger.Log("FlightEngineerCore->Awake");
             }
             catch (Exception ex)

--- a/KerbalEngineer/Flight/Readouts/Surface/AtmosphericProcessor.cs
+++ b/KerbalEngineer/Flight/Readouts/Surface/AtmosphericProcessor.cs
@@ -29,6 +29,8 @@
 
 namespace KerbalEngineer.Flight.Readouts.Surface
 {
+    using UnityEngine;
+
     public class AtmosphericProcessor : IUpdatable, IUpdateRequest
     {
         #region Instance
@@ -46,7 +48,10 @@
         /// </summary>
         public static AtmosphericProcessor Instance
         {
-            get { return instance; }
+            get
+            {
+                return instance;
+            }
         }
 
         #endregion
@@ -122,13 +127,13 @@
                 }
                 else
                 {
-                    var mass = FlightGlobals.ActiveVessel.parts.Sum(p => p.GetWetMass());
-                    var drag = FlightGlobals.ActiveVessel.parts.Sum(p => p.GetWetMass() * p.maximum_drag);
-                    var grav = FlightGlobals.getGeeForceAtPosition(FlightGlobals.ship_position).magnitude;
-                    var atmo = FlightGlobals.ActiveVessel.atmDensity;
-                    var coef = FlightGlobals.DragMultiplier;
-
-                    TerminalVelocity = Math.Sqrt((2 * mass * grav) / (atmo * drag * coef));
+                    var m = FlightGlobals.ActiveVessel.parts.Sum(part => part.GetWetMass()) * 1000.0;
+                    var g = FlightGlobals.getGeeForceAtPosition(FlightGlobals.ship_position).magnitude;
+                    var a = FlightGlobals.ActiveVessel.parts.Sum(part => part.DragCubes.AreaDrag) * PhysicsGlobals.DragCubeMultiplier;
+                    var p = FlightGlobals.ActiveVessel.atmDensity;
+                    var c = PhysicsGlobals.DragMultiplier;
+
+                    TerminalVelocity = Math.Sqrt((2.0 * m * g) / (p * a * c));
                 }
 
                 Efficiency = FlightGlobals.ship_srfSpeed / TerminalVelocity;

--- a/KerbalEngineer/Flight/Readouts/Vessel/AttitudeProcessor.cs
+++ b/KerbalEngineer/Flight/Readouts/Vessel/AttitudeProcessor.cs
@@ -123,7 +123,8 @@
             // This code was derived from MechJeb2's implementation for getting the vessel's surface relative rotation.
             this.centreOfMass = FlightGlobals.ActiveVessel.findWorldCenterOfMass();
             this.up = (this.centreOfMass - FlightGlobals.ActiveVessel.mainBody.position).normalized;
-            this.north = Vector3.Exclude(this.up, (FlightGlobals.ActiveVessel.mainBody.position + FlightGlobals.ActiveVessel.mainBody.transform.up * (float)FlightGlobals.ActiveVessel.mainBody.Radius) - this.centreOfMass).normalized;
+            this.north = Vector3.ProjectOnPlane((FlightGlobals.ActiveVessel.mainBody.position + FlightGlobals.ActiveVessel.mainBody.transform.up * (float)FlightGlobals.ActiveVessel.mainBody.Radius) - this.centreOfMass, this.up).normalized;
+
             return Quaternion.Inverse(Quaternion.Euler(90.0f, 0.0f, 0.0f) * Quaternion.Inverse(FlightGlobals.ActiveVessel.transform.rotation) * Quaternion.LookRotation(this.north, this.up));
         }
 

--- a/KerbalEngineer/Flight/Readouts/Vessel/SimulationProcessor.cs
+++ b/KerbalEngineer/Flight/Readouts/Vessel/SimulationProcessor.cs
@@ -119,7 +119,7 @@
                 SimManager.Gravity = FlightGlobals.ActiveVessel.mainBody.gravParameter /
                                      Math.Pow(FlightGlobals.ActiveVessel.mainBody.Radius +
                                               FlightGlobals.ActiveVessel.mainBody.GetAltitude(FlightGlobals.ActiveVessel.CoM), 2);
-                SimManager.Velocity = FlightGlobals.ActiveVessel.srfSpeed;
+                SimManager.Mach = FlightGlobals.ActiveVessel.mach;
             }
         }
 

--- /dev/null
+++ b/KerbalEngineer/Helpers/Pool.cs
@@ -1,1 +1,53 @@
+namespace KerbalEngineer.VesselSimulator
+{
+    using System.Collections.Generic;
 
+    public class Pool<T> where T : new()
+    {
+        private static List<T> available = new List<T>();
+        private static List<T> inUse = new List<T>();
+
+        public static int PoolCount
+        {
+            get
+            {
+                return available.Count + inUse.Count;
+            }
+        }
+
+        public static T GetPoolObject()
+        {
+            T obj;
+            if (available.Count > 0)
+            {
+                obj = available[0];
+                available.RemoveAt(0);
+            }
+            else
+            {
+                obj = new T();
+            }
+
+            inUse.Add(obj);
+            return obj;
+        }
+
+        public static void Release(T obj)
+        {
+            if (inUse.Contains(obj))
+            {
+                inUse.Remove(obj);
+                available.Add(obj);
+            }
+        }
+
+        public static void ReleaseAll()
+        {
+            for (int i = 0; i < inUse.Count; ++i)
+            {
+                available.Add(inUse[i]);
+            }
+            inUse.Clear();
+        }
+    }
+}

--- a/KerbalEngineer/Helpers/Units.cs
+++ b/KerbalEngineer/Helpers/Units.cs
@@ -20,7 +20,6 @@
 namespace KerbalEngineer.Helpers
 {
     #region Using Directives
-
     using System;
 
     #endregion
@@ -28,6 +27,7 @@
     public static class Units
     {
         #region Methods
+        public const double GRAVITY = 9.80665;
 
         public static string Concat(int value1, int value2)
         {
@@ -65,9 +65,9 @@
 
         public static string Cost(double value1, double value2, int decimals = 1)
         {
-            if (value1 >= 1e6 || value2 >= 1e6)
+            if (value1 >= 1000000.0 || value2 >= 1000000.0)
             {
-                return (value1 / 1000.0).ToString("N" + decimals) + " / " + (value2 / 1000.0f).ToString("N" + decimals) + "K";
+                return (value1 / 1000.0).ToString("N" + decimals) + " / " + (value2 / 1000.0).ToString("N" + decimals) + "K";
             }
             return value1.ToString("N" + decimals) + " / " + value2.ToString("N" + decimals);
         }
@@ -123,8 +123,8 @@
 
         public static string ToForce(double value1, double value2)
         {
-            var format1 = (value1 < 100000.0) ? (value1 < 10000.0) ? (value1 < 100.0) ? (Math.Abs(value1) < Double.Epsilon) ? "N0" : "N3" : "N2" : "N1" : "N0";
-            var format2 = (value2 < 100000.0) ? (value2 < 10000.0) ? (value2 < 100.0) ? (Math.Abs(value2) < Double.Epsilon) ? "N0" : "N3" : "N2" : "N1" : "N0";
+            string format1 = (value1 < 100000.0) ? (value1 < 10000.0) ? (value1 < 100.0) ? (Math.Abs(value1) < Double.Epsilon) ? "N0" : "N3" : "N2" : "N1" : "N0";
+            string format2 = (value2 < 100000.0) ? (value2 < 10000.0) ? (value2 < 100.0) ? (Math.Abs(value2) < Double.Epsilon) ? "N0" : "N3" : "N2" : "N1" : "N0";
             return value1.ToString(format1) + " / " + value2.ToString(format2) + "kN";
         }
 
@@ -135,9 +135,8 @@
                 return value.ToString("N" + decimals + 2) + "t";
             }
 
-                value *= 1000.0;
-                return value.ToString("N" + decimals) + "kg";
-
+            value *= 1000.0;
+            return value.ToString("N" + decimals) + "kg";
         }
 
         public static string ToMass(double value1, double value2, int decimals = 0)
@@ -146,11 +145,10 @@
             {
                 return value1.ToString("N" + decimals + 2) + " / " + value2.ToString("N" + decimals + 2) + "t";
             }
-   
-                value1 *= 1000.0;
-                value2 *= 1000.0;
-                return value1.ToString("N" + decimals) + " / " + value2.ToString("N" + decimals) + "kg";
-  
+
+            value1 *= 1000.0;
+            value2 *= 1000.0;
+            return value1.ToString("N" + decimals) + " / " + value2.ToString("N" + decimals) + "kg";
         }
 
         public static string ToPercent(double value, int decimals = 2)
@@ -182,7 +180,6 @@
         {
             return value.ToString((value < 100.0) ? (Math.Abs(value) < Double.Epsilon) ? "N0" : "N1" : "N0") + "kNm";
         }
-
         #endregion
     }
 }

--- a/KerbalEngineer/KerbalEngineer.csproj
+++ b/KerbalEngineer/KerbalEngineer.csproj
@@ -199,6 +199,7 @@
     <Compile Include="UIControls\WindowObject.cs" />
     <Compile Include="VesselSimulator\AttachNodeSim.cs" />
     <Compile Include="VesselSimulator\EngineSim.cs" />
+    <Compile Include="Helpers\Pool.cs" />
     <Compile Include="VesselSimulator\PartSim.cs" />
     <Compile Include="VesselSimulator\ResourceContainer.cs" />
     <Compile Include="VesselSimulator\SimManager.cs" />

--- a/KerbalEngineer/VesselSimulator/AttachNodeSim.cs
+++ b/KerbalEngineer/VesselSimulator/AttachNodeSim.cs
@@ -19,42 +19,44 @@
 
 #region Using Directives
 
-using System;
-using System.Text;
-
 #endregion
 
 namespace KerbalEngineer.VesselSimulator
 {
-    internal class AttachNodeSim
+    using System;
+    using System.Text;
+
+    internal class AttachNodeSim : Pool<AttachNodeSim>
     {
         public PartSim attachedPartSim;
         public String id;
         public AttachNode.NodeType nodeType;
 
-        public AttachNodeSim(PartSim partSim, String newId, AttachNode.NodeType newNodeType)
-        {
-            this.attachedPartSim = partSim;
-            this.nodeType = newNodeType;
-            this.id = newId;
-        }
-
         public void DumpToBuffer(StringBuilder buffer)
         {
-            if (this.attachedPartSim == null)
+            if (attachedPartSim == null)
             {
                 buffer.Append("<staged>:<n>");
             }
             else
             {
-                buffer.Append(this.attachedPartSim.name);
+                buffer.Append(attachedPartSim.name);
                 buffer.Append(":");
-                buffer.Append(this.attachedPartSim.partId);
+                buffer.Append(attachedPartSim.partId);
             }
             buffer.Append("#");
-            buffer.Append(this.nodeType);
+            buffer.Append(nodeType);
             buffer.Append(":");
-            buffer.Append(this.id);
+            buffer.Append(id);
+        }
+
+        public AttachNodeSim Initialise(PartSim partSim, String newId, AttachNode.NodeType newNodeType)
+        {
+            attachedPartSim = partSim;
+            nodeType = newNodeType;
+            id = newId;
+
+            return this;
         }
     }
 }

--- a/KerbalEngineer/VesselSimulator/EngineSim.cs
+++ b/KerbalEngineer/VesselSimulator/EngineSim.cs
@@ -17,217 +17,175 @@
 //     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // 
 
-#region Using Directives
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-using UnityEngine;
-
-#endregion
-
 namespace KerbalEngineer.VesselSimulator
 {
-    public class EngineSim
+    using System;
+    using System.Collections.Generic;
+    using System.Text;
+    using Editor;
+    using Helpers;
+    using UnityEngine;
+
+    public class EngineSim : Pool<EngineSim>
     {
-        private readonly ResourceContainer resourceConsumptions = new ResourceContainer();
-
-        public double actualThrust = 0;
+        public double actualThrust = 0.0;
+        public List<AppliedForce> appliedForces = new List<AppliedForce>();
         public bool isActive = false;
         public double isp = 0;
         public PartSim partSim;
-        public List<AppliedForce> appliedForces;
+        public float maxMach;
 
         public double thrust = 0;
 
         // Add thrust vector to account for directional losses
         public Vector3 thrustVec;
-
-        public EngineSim(PartSim theEngine,
-                         double atmosphere,
-                         double velocity,
-                         float maxThrust,
-                         float minThrust,
-                         float thrustPercentage,
-                         float requestedThrust,
-                         Vector3 vecThrust,
-                         float realIsp,
-                         FloatCurve atmosphereCurve,
-                         FloatCurve velocityCurve,
-                         bool throttleLocked,
-                         List<Propellant> propellants,
-                         bool active,
-                         bool correctThrust,
-                         List<Transform> thrustTransforms)
+        private readonly ResourceContainer resourceConsumptions = new ResourceContainer();
+
+        public EngineSim Initialise(PartSim theEngine,
+            double atmosphere,
+            float machNumber,
+            float maxFuelFlow,
+            float minFuelFlow,
+            float thrustPercentage,
+            Vector3 vecThrust,
+            FloatCurve atmosphereCurve,
+            bool atmChangeFlow,
+            FloatCurve atmCurve,
+            FloatCurve velCurve,
+            float currentThrottle,
+            bool throttleLocked,
+            List<Propellant> propellants,
+            bool active,
+            float resultingThrust,
+            List<Transform> thrustTransforms)
         {
             StringBuilder buffer = null;
-            //MonoBehaviour.print("Create EngineSim for " + theEngine.name);
-            //MonoBehaviour.print("maxThrust = " + maxThrust);
-            //MonoBehaviour.print("minThrust = " + minThrust);
-            //MonoBehaviour.print("thrustPercentage = " + thrustPercentage);
-            //MonoBehaviour.print("requestedThrust = " + requestedThrust);
-            //MonoBehaviour.print("velocity = " + velocity);
-
-            this.partSim = theEngine;
-
-            this.isActive = active;
-            this.thrust = (maxThrust - minThrust) * (thrustPercentage / 100f) + minThrust;
-            //MonoBehaviour.print("thrust = " + thrust);
-
-            this.thrustVec = vecThrust;
-
-            double flowRate = 0d;
-            if (this.partSim.hasVessel)
-            {
-                //MonoBehaviour.print("hasVessel is true");
-                this.actualThrust = isActive ? requestedThrust : 0.0;
-                if (velocityCurve != null)
-                {
-                    this.actualThrust *= velocityCurve.Evaluate((float)velocity);
-                    //MonoBehaviour.print("actualThrust at velocity = " + actualThrust);
-                }
-
-                this.isp = atmosphereCurve.Evaluate((float)this.partSim.part.staticPressureAtm);
-                if (this.isp == 0d)
-                {
-                    MonoBehaviour.print("Isp at " + this.partSim.part.staticPressureAtm + " is zero. Flow rate will be NaN");
-                }
-
-                if (correctThrust && realIsp == 0)
-                {
-                    float ispsl = atmosphereCurve.Evaluate(0);
-                    if (ispsl != 0)
-                    {
-                        this.thrust = this.thrust * this.isp / ispsl;
+
+            isp = 0.0;
+            maxMach = 0.0f;
+            actualThrust = 0.0;
+            partSim = theEngine;
+            isActive = active;
+            thrustVec = vecThrust;
+            resourceConsumptions.Reset();
+            appliedForces.Clear();
+
+            double flowRate = 0.0;
+            if (partSim.hasVessel)
+            {
+                float flowModifier = GetFlowModifier(atmChangeFlow, atmCurve, partSim.part.atmDensity, velCurve, machNumber, ref maxMach);
+                isp = atmosphereCurve.Evaluate((float)atmosphere);
+                thrust = GetThrust(Mathf.Lerp(minFuelFlow, maxFuelFlow, GetThrustPercent(thrustPercentage)) * flowModifier, isp);
+                actualThrust = isActive ? resultingThrust : 0.0;
+
+                if (throttleLocked)
+                {
+                    flowRate = GetFlowRate(thrust, isp);
+                }
+                else
+                {
+                    if (currentThrottle > 0.0f && partSim.isLanded == false)
+                    {
+                        flowRate = GetFlowRate(actualThrust, isp);
                     }
                     else
                     {
-                        MonoBehaviour.print("Isp at sea level is zero. Unable to correct thrust.");
-                    }
-                    //MonoBehaviour.print("corrected thrust = " + thrust);
-                }
-
-                if (velocityCurve != null)
-                {
-                    this.thrust *= velocityCurve.Evaluate((float)velocity);
-                    //MonoBehaviour.print("thrust at velocity = " + thrust);
-                }
-
-                if (throttleLocked)
-                {
-                    //MonoBehaviour.print("throttleLocked is true");
-                    flowRate = this.thrust / (this.isp * 9.82);
-                }
-                else
-                {
-                    if (this.partSim.isLanded)
-                    {
-                        //MonoBehaviour.print("partSim.isLanded is true, mainThrottle = " + FlightInputHandler.state.mainThrottle);
-                        flowRate = Math.Max(0.000001d, this.thrust * FlightInputHandler.state.mainThrottle) / (this.isp * 9.82);
-                    }
-                    else
-                    {
-                        if (requestedThrust > 0)
-                        {
-                            if (velocityCurve != null)
-                            {
-                                requestedThrust *= velocityCurve.Evaluate((float)velocity);
-                                //MonoBehaviour.print("requestedThrust at velocity = " + requestedThrust);
-                            }
-
-                            //MonoBehaviour.print("requestedThrust > 0");
-                            flowRate = requestedThrust / (this.isp * 9.82);
-                        }
-                        else
-                        {
-                            //MonoBehaviour.print("requestedThrust <= 0");
-                            flowRate = this.thrust / (this.isp * 9.82);
-                        }
+                        flowRate = GetFlowRate(thrust, isp);
                     }
                 }
             }
             else
             {
-                //MonoBehaviour.print("hasVessel is false");
-                this.isp = atmosphereCurve.Evaluate((float)atmosphere);
-                if (this.isp == 0d)
-                {
-                    MonoBehaviour.print("Isp at " + atmosphere + " is zero. Flow rate will be NaN");
-                }
-                if (correctThrust)
-                {
-                    float ispsl = atmosphereCurve.Evaluate(0);
-                    if (ispsl != 0)
-                    {
-                        this.thrust = this.thrust * this.isp / ispsl;
-                    }
-                    else
-                    {
-                        MonoBehaviour.print("Isp at sea level is zero. Unable to correct thrust.");
-                    }
-                    //MonoBehaviour.print("corrected thrust = " + thrust);
-                }
-
-                if (velocityCurve != null)
-                {
-                    this.thrust *= velocityCurve.Evaluate((float)velocity);
-                    //MonoBehaviour.print("thrust at velocity = " + thrust);
-                }
-
-                flowRate = this.thrust / (this.isp * 9.82);
-            }
-
-            if (SimManager.logOutput)
-            {
-                buffer = new StringBuilder(1024);
-                buffer.AppendFormat("flowRate = {0:g6}\n", flowRate);
-            }
-
-            float flowMass = 0f;
-            foreach (Propellant propellant in propellants)
-            {
+                float flowModifier = GetFlowModifier(atmChangeFlow, atmCurve, CelestialBodies.SelectedBody.GetDensity(BuildAdvanced.Altitude), velCurve, machNumber, ref maxMach);
+                isp = atmosphereCurve.Evaluate((float)atmosphere);
+                thrust = GetThrust(Mathf.Lerp(minFuelFlow, maxFuelFlow, GetThrustPercent(thrustPercentage)) * flowModifier, isp);
+                flowRate = GetFlowRate(thrust, isp);
+            }
+
+            float flowMass = 0.0f;
+
+            for (int i = 0; i < propellants.Count; ++i)
+            {
+                Propellant propellant = propellants[i];
                 flowMass += propellant.ratio * ResourceContainer.GetResourceDensity(propellant.id);
-            }
-
-            if (SimManager.logOutput)
-            {
-                buffer.AppendFormat("flowMass = {0:g6}\n", flowMass);
-            }
-
-            foreach (Propellant propellant in propellants)
-            {
-                if (propellant.name == "ElectricCharge" || propellant.name == "IntakeAir")
-                {
-                    continue;
-                }
 
                 double consumptionRate = propellant.ratio * flowRate / flowMass;
-                if (SimManager.logOutput)
-                {
-                    buffer.AppendFormat("Add consumption({0}, {1}:{2:d}) = {3:g6}\n", ResourceContainer.GetResourceName(propellant.id), theEngine.name, theEngine.partId, consumptionRate);
-                }
-                this.resourceConsumptions.Add(propellant.id, consumptionRate);
-            }
-
-            if (SimManager.logOutput)
-            {
-                MonoBehaviour.print(buffer);
-            }
-
-            appliedForces = new List<AppliedForce>();
+                resourceConsumptions.Add(propellant.id, consumptionRate);
+            }
+
             double thrustPerThrustTransform = thrust / thrustTransforms.Count;
-            foreach (Transform thrustTransform in thrustTransforms) {
+            for (int i = 0; i < thrustTransforms.Count; ++i)
+            {
+                Transform thrustTransform = thrustTransforms[i];
+
                 Vector3d direction = thrustTransform.forward.normalized;
                 Vector3d position = thrustTransform.position;
                 appliedForces.Add(new AppliedForce(direction * thrustPerThrustTransform, position));
             }
+
+            return this;
         }
 
         public ResourceContainer ResourceConsumptions
         {
-            get { return this.resourceConsumptions; }
+            get
+            {
+                return resourceConsumptions;
+            }
+        }
+
+        public static double GetExhaustVelocity(double isp)
+        {
+            return isp * Units.GRAVITY;
+        }
+
+        public static float GetFlowModifier(bool atmChangeFlow, FloatCurve atmCurve, double atmDensity, FloatCurve velCurve, float machNumber, ref float maxMach)
+        {
+            float flowModifier = 1.0f;
+            if (atmChangeFlow)
+            {
+                flowModifier = (float)(atmDensity / 1.225);
+                if (atmCurve != null)
+                {
+                    flowModifier = atmCurve.Evaluate(flowModifier);
+                }
+            }
+            if (velCurve != null)
+            {
+                flowModifier = flowModifier * velCurve.Evaluate(machNumber);
+                maxMach = velCurve.maxTime;
+            }
+            if (flowModifier < float.Epsilon)
+            {
+                flowModifier = float.Epsilon;
+            }
+            return flowModifier;
+        }
+
+        public static double GetFlowRate(double thrust, double isp)
+        {
+            return thrust / GetExhaustVelocity(isp);
+        }
+
+        public static float GetThrottlePercent(float currentThrottle, float thrustPercentage)
+        {
+            return currentThrottle * GetThrustPercent(thrustPercentage);
+        }
+
+        public static double GetThrust(double flowRate, double isp)
+        {
+            return flowRate * GetExhaustVelocity(isp);
+        }
+
+        public static float GetThrustPercent(float thrustPercentage)
+        {
+            return thrustPercentage * 0.01f;
+        }
+
+        public void DumpEngineToBuffer(StringBuilder buffer, String prefix)
+        {
+            buffer.Append(prefix);
+            buffer.AppendFormat("[thrust = {0:g6}, actual = {1:g6}, isp = {2:g6}\n", thrust, actualThrust, isp);
         }
 
         public bool SetResourceDrains(List<PartSim> allParts, List<PartSim> allFuelLines, HashSet<PartSim> drainingParts)
@@ -237,24 +195,27 @@
             // A dictionary to hold a set of parts for each resource
             Dictionary<int, HashSet<PartSim>> sourcePartSets = new Dictionary<int, HashSet<PartSim>>();
 
-            foreach (int type in this.resourceConsumptions.Types)
-            {
+            for (int i = 0; i < resourceConsumptions.Types.Count; ++i)
+            {
+                int type = resourceConsumptions.Types[i];
                 HashSet<PartSim> sourcePartSet = null;
                 switch (ResourceContainer.GetResourceFlowMode(type))
                 {
                     case ResourceFlowMode.NO_FLOW:
-                        if (this.partSim.resources[type] > SimManager.RESOURCE_MIN)
+                        if (partSim.resources[type] > SimManager.RESOURCE_MIN && partSim.resourceFlowStates[type] != 0)
                         {
                             sourcePartSet = new HashSet<PartSim>();
                             //MonoBehaviour.print("SetResourceDrains(" + name + ":" + partId + ") setting sources to just this");
-                            sourcePartSet.Add(this.partSim);
+                            sourcePartSet.Add(partSim);
                         }
                         break;
 
                     case ResourceFlowMode.ALL_VESSEL:
-                        foreach (PartSim aPartSim in allParts)
-                        {
-                            if (aPartSim.resources[type] > SimManager.RESOURCE_MIN)
+                        for (int j = 0; j < allParts.Count; ++j)
+                        {
+                            PartSim aPartSim = allParts[j];
+
+                            if (aPartSim.resources[type] > SimManager.RESOURCE_MIN && aPartSim.resourceFlowStates[type] != 0)
                             {
                                 if (sourcePartSet == null)
                                 {
@@ -267,15 +228,19 @@
                         break;
 
                     case ResourceFlowMode.STAGE_PRIORITY_FLOW:
-                        var stagePartSets = new Dictionary<int, HashSet<PartSim>>();
-                        var maxStage = -1;
-
-                        Logger.Log(type);
-                        foreach (var aPartSim in allParts)
-                        {
-                            if (aPartSim.resources[type] <= SimManager.RESOURCE_MIN || aPartSim.resourceFlowStates[type] == 0) continue;
-
-                            var stage = aPartSim.DecouplerCount();
+                        Dictionary<int, HashSet<PartSim>> stagePartSets = new Dictionary<int, HashSet<PartSim>>();
+                        int maxStage = -1;
+
+                        for (int j = 0; j < allParts.Count; ++j)
+                        {
+                            PartSim aPartSim = allParts[j];
+
+                            if (aPartSim.resources[type] <= SimManager.RESOURCE_MIN || aPartSim.resourceFlowStates[type] == 0)
+                            {
+                                continue;
+                            }
+
+                            int stage = aPartSim.DecouplerCount();
                             if (stage > maxStage)
                             {
                                 maxStage = stage;
@@ -289,10 +254,10 @@
                             sourcePartSet.Add(aPartSim);
                         }
 
-                        for (var i = 0; i <= maxStage; i++)
+                        for (int j = 0; j <= maxStage; j++)
                         {
                             HashSet<PartSim> stagePartSet;
-                            if (stagePartSets.TryGetValue(i, out stagePartSet) && stagePartSet.Count > 0)
+                            if (stagePartSets.TryGetValue(j, out stagePartSet) && stagePartSet.Count > 0)
                             {
                                 sourcePartSet = stagePartSet;
                             }
@@ -305,9 +270,9 @@
                         if (SimManager.logOutput)
                         {
                             log = new LogMsg();
-                            log.buf.AppendLine("Find " + ResourceContainer.GetResourceName(type) + " sources for " + this.partSim.name + ":" + this.partSim.partId);
-                        }
-                        sourcePartSet = this.partSim.GetSourceSet(type, allParts, visited, log, "");
+                            log.buf.AppendLine("Find " + ResourceContainer.GetResourceName(type) + " sources for " + partSim.name + ":" + partSim.partId);
+                        }
+                        sourcePartSet = partSim.GetSourceSet(type, allParts, visited, log, "");
                         if (SimManager.logOutput)
                         {
                             MonoBehaviour.print(log.buf);
@@ -315,7 +280,7 @@
                         break;
 
                     default:
-                        MonoBehaviour.print("SetResourceDrains(" + this.partSim.name + ":" + this.partSim.partId + ") Unexpected flow type for " + ResourceContainer.GetResourceName(type) + ")");
+                        MonoBehaviour.print("SetResourceDrains(" + partSim.name + ":" + partSim.partId + ") Unexpected flow type for " + ResourceContainer.GetResourceName(type) + ")");
                         break;
                 }
 
@@ -336,8 +301,10 @@
             }
 
             // If we don't have sources for all the needed resources then return false without setting up any drains
-            foreach (int type in this.resourceConsumptions.Types)
-            {
+            for(int i = 0; i < resourceConsumptions.Types.Count; ++i)
+            {
+                int type = resourceConsumptions.Types[i];
+
                 if (!sourcePartSets.ContainsKey(type))
                 {
                     if (SimManager.logOutput)
@@ -345,17 +312,19 @@
                         MonoBehaviour.print("No source of " + ResourceContainer.GetResourceName(type));
                     }
 
-                    this.isActive = false;
+                    isActive = false;
                     return false;
                 }
             }
 
             // Now we set the drains on the members of the sets and update the draining parts set
-            foreach (int type in this.resourceConsumptions.Types)
-            {
+            for (int i = 0; i < resourceConsumptions.Types.Count; ++i)
+            {
+                int type = resourceConsumptions.Types[i];
+
                 HashSet<PartSim> sourcePartSet = sourcePartSets[type];
                 // Loop through the members of the set 
-                double amount = this.resourceConsumptions[type] / sourcePartSet.Count;
+                double amount = resourceConsumptions[type] / sourcePartSet.Count;
                 foreach (PartSim partSim in sourcePartSet)
                 {
                     if (SimManager.logOutput)
@@ -370,11 +339,5 @@
 
             return true;
         }
-
-        public void DumpEngineToBuffer(StringBuilder buffer, String prefix)
-        {
-            buffer.Append(prefix);
-            buffer.AppendFormat("[thrust = {0:g6}, actual = {1:g6}, isp = {2:g6}\n", this.thrust, this.actualThrust, this.isp);
-        }
     }
 }

--- a/KerbalEngineer/VesselSimulator/PartSim.cs
+++ b/KerbalEngineer/VesselSimulator/PartSim.cs
@@ -34,11 +34,11 @@
 {
     using CompoundParts;
 
-    public class PartSim
+    public class PartSim : Pool<PartSim>
     {
         private readonly List<AttachNodeSim> attachNodes = new List<AttachNodeSim>();
         public Vector3d centerOfMass;
-        public double baseMass = 0d;
+        public double baseMass;
         public double cost;
         public int decoupledInStage;
         public bool fuelCrossFeed;
@@ -71,8 +71,47 @@
         public String vesselName;
         public VesselType vesselType;
 
-        public PartSim(Part thePart, int id, double atmosphere, LogMsg log)
-        {
+        private static void Reset(PartSim partSim)
+        {
+            partSim.attachNodes.Clear();
+            partSim.fuelTargets.Clear();
+            partSim.resourceDrains.Reset();
+            partSim.resourceFlowStates.Reset();
+            partSim.resources.Reset();
+            partSim.baseMass = 0.0;
+            partSim.startMass = 0.0;
+            partSim.centerOfMass = Vector3d.zero;
+            partSim.cost = 0.0;
+            partSim.decoupledInStage = 0;
+            partSim.fuelCrossFeed = false;
+            partSim.hasModuleEngines = false;
+            partSim.hasModuleEnginesFX = false;
+            partSim.hasMultiModeEngine = false;
+            partSim.hasVessel = false;
+            partSim.initialVesselName = null;
+            partSim.inverseStage = 0;
+            partSim.isDecoupler = false;
+            partSim.isEngine = false;
+            partSim.isFuelLine = false;
+            partSim.isFuelTank = false;
+            partSim.isLanded = false;
+            partSim.isNoPhysics = false;
+            partSim.isSepratron = false;
+            partSim.localCorrectThrust = false;
+            partSim.name = null;
+            partSim.noCrossFeedNodeKey = null;
+            partSim.parent = null;
+            partSim.parentAttach = AttachModes.SRF_ATTACH;
+            partSim.part = null;
+            partSim.partId = 0;
+            partSim.vesselName = null;
+            partSim.vesselType = VesselType.Base;
+        }
+
+        public PartSim Initialise(Part thePart, int id, double atmosphere, LogMsg log)
+        {
+            Reset(this);
+
             this.part = thePart;
             this.centerOfMass = thePart.transform.TransformPoint(thePart.CoMOffset);
             this.partId = id;
@@ -97,13 +136,11 @@
             this.cost = this.part.GetCostWet();
 
             // Work out if the part should have no physical significance
-            this.isNoPhysics = this.part.HasModule<LaunchClamp>() ||
-                               this.part.physicalSignificance == Part.PhysicalSignificance.NONE ||
-                               this.part.PhysicsSignificance == 1;
-
-            if (!this.isNoPhysics)
-            {
-                this.baseMass = this.part.mass;
+            this.isNoPhysics = this.part.HasModule<LaunchClamp>();
+
+            if (isNoPhysics == false)
+            {
+                baseMass = part.mass;
             }
 
             if (SimManager.logOutput)
@@ -111,8 +148,10 @@
                 MonoBehaviour.print((this.isNoPhysics ? "Ignoring" : "Using") + " part.mass of " + this.part.mass);
             }
 
-            foreach (PartResource resource in this.part.Resources)
-            {
+            for (int i = 0; i < part.Resources.Count; ++i)
+            {
+                PartResource resource = part.Resources[i];
+
                 // Make sure it isn't NaN as this messes up the part mass and hence most of the values
                 // This can happen if a resource capacity is 0 and tweakable
                 if (!Double.IsNaN(resource.amount))
@@ -152,6 +191,8 @@
             {
                 MonoBehaviour.print("Created " + this.name + ". Decoupled in stage " + this.decoupledInStage);
             }
+
+            return this;
         }
 
         public ResourceContainer Resources
@@ -164,7 +205,7 @@
             get { return this.resourceDrains; }
         }
 
-        public void CreateEngineSims(List<EngineSim> allEngines, double atmosphere, double velocity, bool vectoredThrust, LogMsg log)
+        public void CreateEngineSims(List<EngineSim> allEngines, double atmosphere, double mach, bool vectoredThrust, bool fullThrust, LogMsg log)
         {
             bool correctThrust = SimManager.DoesEngineUseCorrectedThrust(this.part);
             if (log != null)
@@ -185,8 +226,12 @@
                 // The mode of the engine is the engineID of the ModuleEnginesFX that is active
                 string mode = this.part.GetModule<MultiModeEngine>().mode;
 
-                foreach (ModuleEnginesFX engine in this.part.GetModules<ModuleEnginesFX>())
-                {
+                List<ModuleEnginesFX> engines = part.GetModules<ModuleEnginesFX>();
+
+                for (int i = 0; i < engines.Count; ++i)
+                {
+                    ModuleEnginesFX engine = engines[i];
+
                     if (engine.engineID == mode)
                     {
                         if (log != null)
@@ -196,32 +241,35 @@
 
                         Vector3 thrustvec = this.CalculateThrustVector(vectoredThrust ? engine.thrustTransforms : null, log);
 
-                        EngineSim engineSim = new EngineSim(this,
-                                                            atmosphere,
-                                                            velocity,
-                                                            engine.maxThrust,
-                                                            engine.minThrust,
-                                                            engine.thrustPercentage,
-                                                            engine.requestedThrust,
-                                                            thrustvec,
-                                                            engine.realIsp,
-                                                            engine.atmosphereCurve,
-                                                            engine.useVelocityCurve ? engine.velocityCurve : null,
-                                                            engine.throttleLocked,
-                                                            engine.propellants,
-                                                            engine.isOperational,
-                                                            correctThrust,
-                                                            engine.thrustTransforms);
+                        EngineSim engineSim = EngineSim.GetPoolObject().Initialise(this,
+                            atmosphere,
+                            (float)mach,
+                            engine.maxFuelFlow,
+                            engine.minFuelFlow,
+                            engine.thrustPercentage,
+                            thrustvec,
+                            engine.atmosphereCurve,
+                            engine.atmChangeFlow,
+                            engine.useAtmCurve ? engine.atmCurve : null,
+                            engine.useVelCurve ? engine.velCurve : null,
+                            engine.currentThrottle,
+                            engine.throttleLocked || fullThrust,
+                            engine.propellants,
+                            engine.isOperational,
+                            engine.resultingThrust,
+                            engine.thrustTransforms);
                         allEngines.Add(engineSim);
                     }
                 }
             }
             else
             {
-                if (this.hasModuleEnginesFX)
-                {
-                    foreach (ModuleEnginesFX engine in this.part.GetModules<ModuleEnginesFX>())
-                    {
+                if (this.hasModuleEngines)
+                {
+                    List<ModuleEngines> engines = part.GetModules<ModuleEngines>();
+                    for (int i = 0; i < engines.Count; ++i)
+                    {
+                        ModuleEngines engine = engines[i];
                         if (log != null)
                         {
                             log.buf.AppendLine("Module: " + engine.moduleName);
@@ -229,56 +277,26 @@
 
                         Vector3 thrustvec = this.CalculateThrustVector(vectoredThrust ? engine.thrustTransforms : null, log);
 
-                        EngineSim engineSim = new EngineSim(this,
-                                                            atmosphere,
-                                                            velocity,
-                                                            engine.maxThrust,
-                                                            engine.minThrust,
-                                                            engine.thrustPercentage,
-                                                            engine.requestedThrust,
-                                                            thrustvec,
-                                                            engine.realIsp,
-                                                            engine.atmosphereCurve,
-                                                            engine.useVelocityCurve ? engine.velocityCurve : null,
-                                                            engine.throttleLocked,
-                                                            engine.propellants,
-                                                            engine.isOperational,
-                                                            correctThrust,
-                                                            engine.thrustTransforms);
+                        EngineSim engineSim = EngineSim.GetPoolObject().Initialise(this,
+                            atmosphere,
+                            (float)mach,
+                            engine.maxFuelFlow,
+                            engine.minFuelFlow,
+                            engine.thrustPercentage,
+                            thrustvec,
+                            engine.atmosphereCurve,
+                            engine.atmChangeFlow,
+                            engine.useAtmCurve ? engine.atmCurve : null,
+                            engine.useVelCurve ? engine.velCurve : null,
+                            engine.currentThrottle,
+                            engine.throttleLocked || fullThrust,
+                            engine.propellants,
+                            engine.isOperational,
+                            engine.resultingThrust,
+                            engine.thrustTransforms);
                         allEngines.Add(engineSim);
                     }
                 }
-
-                if (this.hasModuleEngines)
-                {
-                    foreach (ModuleEngines engine in this.part.GetModules<ModuleEngines>())
-                    {
-                        if (log != null)
-                        {
-                            log.buf.AppendLine("Module: " + engine.moduleName);
-                        }
-
-                        Vector3 thrustvec = this.CalculateThrustVector(vectoredThrust ? engine.thrustTransforms : null, log);
-
-                        EngineSim engineSim = new EngineSim(this,
-                                                            atmosphere,
-                                                            velocity,
-                                                            engine.maxThrust,
-                                                            engine.minThrust,
-                                                            engine.thrustPercentage,
-                                                            engine.requestedThrust,
-                                                            thrustvec,
-                                                            engine.realIsp,
-                                                            engine.atmosphereCurve,
-                                                            engine.useVelocityCurve ? engine.velocityCurve : null,
-                                                            engine.throttleLocked,
-                                                            engine.propellants,
-                                                            engine.isOperational,
-                                                            correctThrust,
-                                                            engine.thrustTransforms);
-                        allEngines.Add(engineSim);
-                    }
-                }
             }
 
             if (log != null)
@@ -295,8 +313,10 @@
             }
 
             Vector3 thrustvec = Vector3.zero;
-            foreach (Transform trans in thrustTransforms)
-            {
+            for (int i = 0; i < thrustTransforms.Count; ++i)
+            {
+                Transform trans = thrustTransforms[i];
+
                 if (log != null)
                 {
                     log.buf.AppendFormat("Transform = ({0:g6}, {1:g6}, {2:g6})   length = {3:g6}\n", trans.forward.x, trans.forward.y, trans.forward.z, trans.forward.magnitude);
@@ -349,9 +369,12 @@
                 log.buf.AppendLine("SetupAttachNodes for " + this.name + ":" + this.partId + "");
             }
 
-            this.attachNodes.Clear();
-            foreach (AttachNode attachNode in this.part.attachNodes)
-            {
+            attachNodes.Clear();
+
+            for (int i = 0; i < part.attachNodes.Count; ++i)
+            {
+                AttachNode attachNode = part.attachNodes[i];
+
                 if (log != null)
                 {
                     log.buf.AppendLine("AttachNode " + attachNode.id + " = " + (attachNode.attachedPart != null ? attachNode.attachedPart.partInfo.name : "null"));
@@ -367,7 +390,7 @@
                             log.buf.AppendLine("Adding attached node " + attachedSim.name + ":" + attachedSim.partId + "");
                         }
 
-                        this.attachNodes.Add(new AttachNodeSim(attachedSim, attachNode.id, attachNode.nodeType));
+                        attachNodes.Add(AttachNodeSim.GetPoolObject().Initialise(attachedSim, attachNode.id, attachNode.nodeType));
                     }
                     else
                     {
@@ -379,8 +402,10 @@
                 }
             }
 
-            foreach (Part p in this.part.fuelLookupTargets)
-            {
+            for (int i = 0; i < part.fuelLookupTargets.Count; ++i)
+            {
+                Part p = part.fuelLookupTargets[i];
+
                 if (p != null)
                 {
                     PartSim targetSim;
@@ -498,9 +523,10 @@
             // Rule 2: Part performs scan on start of every fuel pipe ending in it. This scan is done in order in which pipes were installed.
             // Then it makes an union of fuel tank sets each pipe scan returned. If the resulting list is not empty, it is returned as result.
             //MonoBehaviour.print("foreach fuel line");
-
-            foreach (PartSim partSim in this.fuelTargets)
-            {
+            for (int i = 0; i < fuelTargets.Count; ++i)
+            {
+                PartSim partSim = fuelTargets[i];
+
                 if (visited.Contains(partSim))
                 {
                     //if (log != null)
@@ -540,8 +566,10 @@
             if (this.fuelCrossFeed)
             {
                 //MonoBehaviour.print("foreach attach node");
-                foreach (AttachNodeSim attachSim in this.attachNodes)
-                {
+                for (int i = 0; i < attachNodes.Count; ++i)
+                {
+                    AttachNodeSim attachSim = attachNodes[i];
+
                     if (attachSim.attachedPartSim != null)
                     {
                         if (attachSim.nodeType == AttachNode.NodeType.Stack)
@@ -637,8 +665,10 @@
         public void RemoveAttachedParts(HashSet<PartSim> partSims)
         {
             // Loop through the attached parts
-            foreach (AttachNodeSim attachSim in this.attachNodes)
-            {
+            for (int i = 0; i < attachNodes.Count; ++i)
+            {
+                AttachNodeSim attachSim = attachNodes[i];
+
                 // If the part is in the set then "remove" it by clearing the PartSim reference
                 if (partSims.Contains(attachSim.attachedPartSim))
                 {
@@ -650,8 +680,10 @@
         public void DrainResources(double time)
         {
             //MonoBehaviour.print("DrainResources(" + name + ":" + partId + ", " + time + ")");
-            foreach (int type in this.resourceDrains.Types)
-            {
+            for (int i = 0; i < resourceDrains.Types.Count; ++i)
+            {
+                int type = resourceDrains.Types[i];
+
                 //MonoBehaviour.print("draining " + (time * resourceDrains[type]) + " " + ResourceContainer.GetResourceName(type));
                 this.resources.Add(type, -time * this.resourceDrains[type]);
                 //MonoBehaviour.print(ResourceContainer.GetResourceName(type) + " left = " + resources[type]);
@@ -663,8 +695,10 @@
             //MonoBehaviour.print("TimeToDrainResource(" + name + ":" + partId + ")");
             double time = double.MaxValue;
 
-            foreach (int type in this.resourceDrains.Types)
-            {
+            for (int i = 0; i < resourceDrains.Types.Count; ++i)
+            {
+                int type = resourceDrains.Types[i];
+
                 if (this.resourceDrains[type] > 0)
                 {
                     time = Math.Min(time, this.resources[type] / this.resourceDrains[type]);
@@ -677,6 +711,19 @@
             return time;
         }
 
+        public bool EmptyOf(HashSet<int> types)
+        {
+            foreach (int type in types)
+            {
+                if (this.resources.HasType(type) && this.resourceFlowStates[type] != 0 && (double)this.resources[type] > SimManager.RESOURCE_MIN)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
         public int DecouplerCount()
         {
             int count = 0;
@@ -702,9 +749,9 @@
         {
             double mass = this.baseMass;
 
-            foreach (int type in this.resources.Types)
-            {
-                mass += this.resources.GetResourceMass(type);
+            for (int i = 0; i < resources.Types.Count; ++i)
+            {
+                mass += this.resources.GetResourceMass(resources.Types[i]);
             }
 
             return mass;

--- a/KerbalEngineer/VesselSimulator/ResourceContainer.cs
+++ b/KerbalEngineer/VesselSimulator/ResourceContainer.cs
@@ -134,7 +134,7 @@
 
         public void Reset()
         {
-            this.resources = new Hashtable();
+            this.resources.Clear();
         }
 
         public void Debug()

--- a/KerbalEngineer/VesselSimulator/SimManager.cs
+++ b/KerbalEngineer/VesselSimulator/SimManager.cs
@@ -22,6 +22,7 @@
     #region Using Directives
 
     using System;
+    using System.Collections.Generic;
     using System.Diagnostics;
     using System.Reflection;
     using System.Threading;
@@ -46,17 +47,23 @@
         private static readonly object locker = new object();
         private static readonly Stopwatch timer = new Stopwatch();
 
-        // Support for RealFuels using reflection to check localCorrectThrust without dependency
-
-        private static FieldInfo RF_ModuleEngineConfigs_locaCorrectThrust;
-        private static FieldInfo RF_ModuleHybridEngine_locaCorrectThrust;
-        private static FieldInfo RF_ModuleHybridEngines_locaCorrectThrust;
         private static bool bRequested;
         private static bool bRunning;
         private static TimeSpan delayBetweenSims;
-        private static bool hasCheckedForRealFuels;
+
+        // Support for RealFuels using reflection to check localCorrectThrust without dependency
+
+        private static bool hasCheckedForMods;
         private static bool hasInstalledRealFuels;
-
+        private static FieldInfo RF_ModuleEngineConfigs_localCorrectThrust;
+        private static FieldInfo RF_ModuleHybridEngine_localCorrectThrust;
+        private static FieldInfo RF_ModuleHybridEngines_localCorrectThrust;
+        private static bool hasInstalledKIDS;
+        private static MethodInfo KIDS_Utils_GetIspMultiplier;
+        private static bool bKIDSThrustISP = false;
+        private static List<Part> parts = new List<Part>(); 
+
+        private static Simulation simulation = new Simulation();
         #endregion
 
         #region Delegates
@@ -81,7 +88,7 @@
 
         public static Stage[] Stages { get; private set; }
 
-        public static double Velocity { get; set; }
+        public static double Mach { get; set; }
 
         public static String failMessage { get; private set; }
 
@@ -89,54 +96,112 @@
 
         #region Methods
 
+        private static void CheckForMods()
+        {
+            hasCheckedForMods = true;
+
+            foreach (var assembly in AssemblyLoader.loadedAssemblies)
+            {
+                MonoBehaviour.print("Assembly:" + assembly.assembly);
+
+                var name = assembly.assembly.ToString().Split(',')[0];
+
+                if (name == "RealFuels")
+                {
+                    MonoBehaviour.print("Found RealFuels mod");
+
+                    var RF_ModuleEngineConfigs_Type = assembly.assembly.GetType("RealFuels.ModuleEngineConfigs");
+                    if (RF_ModuleEngineConfigs_Type != null)
+                    {
+                        RF_ModuleEngineConfigs_localCorrectThrust = RF_ModuleEngineConfigs_Type.GetField("localCorrectThrust");
+                    }
+
+                    var RF_ModuleHybridEngine_Type = assembly.assembly.GetType("RealFuels.ModuleHybridEngine");
+                    if (RF_ModuleHybridEngine_Type != null)
+                    {
+                        RF_ModuleHybridEngine_localCorrectThrust = RF_ModuleHybridEngine_Type.GetField("localCorrectThrust");
+                    }
+
+                    var RF_ModuleHybridEngines_Type = assembly.assembly.GetType("RealFuels.ModuleHybridEngines");
+                    if (RF_ModuleHybridEngines_Type != null)
+                    {
+                        RF_ModuleHybridEngines_localCorrectThrust = RF_ModuleHybridEngines_Type.GetField("localCorrectThrust");
+                    }
+
+                    hasInstalledRealFuels = true;
+                    break;
+                }
+                else if (name == "KerbalIspDifficultyScaler")
+                {
+                    var KIDS_Utils_Type = assembly.assembly.GetType("KerbalIspDifficultyScaler.KerbalIspDifficultyScalerUtils");
+                    if (KIDS_Utils_Type != null)
+                    {
+                        KIDS_Utils_GetIspMultiplier = KIDS_Utils_Type.GetMethod("GetIspMultiplier");
+                    }
+
+                    hasInstalledKIDS = true;
+                }
+            }
+        }
+
         public static bool DoesEngineUseCorrectedThrust(Part theEngine)
         {
-            if (!hasInstalledRealFuels /*|| HighLogic.LoadedSceneIsFlight*/)
-            {
-                return false;
-            }
-
-            // Look for any of the Real Fuels engine modules and call the relevant method to find out
-            if (RF_ModuleEngineConfigs_locaCorrectThrust != null && theEngine.Modules.Contains("ModuleEngineConfigs"))
-            {
-                var modEngineConfigs = theEngine.Modules["ModuleEngineConfigs"];
-                if (modEngineConfigs != null)
-                {
-                    // Check the localCorrectThrust
-                    if ((bool)RF_ModuleEngineConfigs_locaCorrectThrust.GetValue(modEngineConfigs))
-                    {
-                        return true;
-                    }
-                }
-            }
-
-            if (RF_ModuleHybridEngine_locaCorrectThrust != null && theEngine.Modules.Contains("ModuleHybridEngine"))
-            {
-                var modHybridEngine = theEngine.Modules["ModuleHybridEngine"];
-                if (modHybridEngine != null)
-                {
-                    // Check the localCorrectThrust
-                    if ((bool)RF_ModuleHybridEngine_locaCorrectThrust.GetValue(modHybridEngine))
-                    {
-                        return true;
-                    }
-                }
-            }
-
-            if (RF_ModuleHybridEngines_locaCorrectThrust != null && theEngine.Modules.Contains("ModuleHybridEngines"))
-            {
-                var modHybridEngines = theEngine.Modules["ModuleHybridEngines"];
-                if (modHybridEngines != null)
-                {
-                    // Check the localCorrectThrust
-                    if ((bool)RF_ModuleHybridEngines_locaCorrectThrust.GetValue(modHybridEngines))
-                    {
-                        return true;
-                    }
-                }
+            if (hasInstalledRealFuels)
+            {
+                // Look for any of the Real Fuels engine modules and call the relevant method to find out
+                if (RF_ModuleEngineConfigs_localCorrectThrust != null && theEngine.Modules.Contains("ModuleEngineConfigs"))
+                {
+                    var modEngineConfigs = theEngine.Modules["ModuleEngineConfigs"];
+                    if (modEngineConfigs != null)
+                    {
+                        // Return the localCorrectThrust
+                        return (bool)RF_ModuleEngineConfigs_localCorrectThrust.GetValue(modEngineConfigs);
+                    }
+                }
+
+                if (RF_ModuleHybridEngine_localCorrectThrust != null && theEngine.Modules.Contains("ModuleHybridEngine"))
+                {
+                    var modHybridEngine = theEngine.Modules["ModuleHybridEngine"];
+                    if (modHybridEngine != null)
+                    {
+                        // Return the localCorrectThrust
+                        return (bool)RF_ModuleHybridEngine_localCorrectThrust.GetValue(modHybridEngine);
+                    }
+                }
+
+                if (RF_ModuleHybridEngines_localCorrectThrust != null && theEngine.Modules.Contains("ModuleHybridEngines"))
+                {
+                    var modHybridEngines = theEngine.Modules["ModuleHybridEngines"];
+                    if (modHybridEngines != null)
+                    {
+                        // Return the localCorrectThrust
+                        return (bool)RF_ModuleHybridEngines_localCorrectThrust.GetValue(modHybridEngines);
+                    }
+                }
+            }
+
+            if (hasInstalledKIDS && HighLogic.LoadedSceneIsEditor)
+            {
+                return bKIDSThrustISP;
             }
 
             return false;
+        }
+
+        public static void UpdateModSettings()
+        {
+            if (!hasCheckedForMods)
+            {
+                CheckForMods();
+            }
+
+            if (hasInstalledKIDS)
+            {
+                // (out ispMultiplierVac, out ispMultiplierAtm, out extendToZeroIsp, out thrustCorrection, out ispCutoff, out thrustCutoff);
+                object[] parameters = new object[6];
+                KIDS_Utils_GetIspMultiplier.Invoke(null, parameters);
+                bKIDSThrustISP = (bool)parameters[3];
+            }
         }
 
         public static String GetVesselTypeString(VesselType vesselType)
@@ -171,9 +236,9 @@
 
         public static void RequestSimulation()
         {
-            if (!hasCheckedForRealFuels)
-            {
-                GetRealFuelsTypes();
+            if (!hasCheckedForMods)
+            {
+                CheckForMods();
             }
 
             lock (locker)
@@ -217,47 +282,12 @@
             LastStage = null;
         }
 
-        private static void GetRealFuelsTypes()
-        {
-            hasCheckedForRealFuels = true;
-
-            foreach (var assembly in AssemblyLoader.loadedAssemblies)
-            {
-                MonoBehaviour.print("Assembly:" + assembly.assembly);
-
-                if (assembly.assembly.ToString().Split(',')[0] == "RealFuels")
-                {
-                    MonoBehaviour.print("Found RealFuels mod");
-
-                    var RF_ModuleEngineConfigs_Type = assembly.assembly.GetType("RealFuels.ModuleEngineConfigs");
-                    if (RF_ModuleEngineConfigs_Type != null)
-                    {
-                        RF_ModuleEngineConfigs_locaCorrectThrust = RF_ModuleEngineConfigs_Type.GetField("localCorrectThrust");
-                    }
-
-                    var RF_ModuleHybridEngine_Type = assembly.assembly.GetType("RealFuels.ModuleHybridEngine");
-                    if (RF_ModuleHybridEngine_Type != null)
-                    {
-                        RF_ModuleHybridEngine_locaCorrectThrust = RF_ModuleHybridEngine_Type.GetField("localCorrectThrust");
-                    }
-
-                    var RF_ModuleHybridEngines_Type = assembly.assembly.GetType("RealFuels.ModuleHybridEngines");
-                    if (RF_ModuleHybridEngines_Type != null)
-                    {
-                        RF_ModuleHybridEngines_locaCorrectThrust = RF_ModuleHybridEngines_Type.GetField("localCorrectThrust");
-                    }
-
-                    hasInstalledRealFuels = true;
-                    break;
-                }
-            }
-        }
-
         private static void RunSimulation(object simObject)
         {
             try
             {
                 Stages = (simObject as Simulation).RunSimulation();
+
                 if (Stages != null && Stages.Length > 0)
                 {
                     if (logOutput)
@@ -272,8 +302,7 @@
             }
             catch (Exception e)
             {
-                MonoBehaviour.print("Exception in RunSimulation: " + e);
-                Logger.Exception(e);
+                Logger.Exception(e, "SimManager.RunSimulation()");
                 Stages = null;
                 LastStage = null;
                 failMessage = e.ToString();
@@ -325,15 +354,21 @@
                     timer.Start();
                 }
 
-                var parts = HighLogic.LoadedSceneIsEditor ? EditorLogic.fetch.ship.parts : FlightGlobals.ActiveVessel.Parts;
-
-                // Create the Simulation object in this thread
-                var sim = new Simulation();
+                if (HighLogic.LoadedSceneIsEditor)
+                {
+                    parts = EditorLogic.fetch.ship.parts;
+                }
+                else
+                {
+                    parts = FlightGlobals.ActiveVessel.Parts;
+                    Atmosphere = FlightGlobals.ActiveVessel.staticPressurekPa * PhysicsGlobals.KpaToAtmospheres;
+                }
 
                 // This call doesn't ever fail at the moment but we'll check and return a sensible error for display
-                if (sim.PrepareSimulation(parts, Gravity, Atmosphere, Velocity, dumpTree, vectoredThrust))
-                {
-                    ThreadPool.QueueUserWorkItem(RunSimulation, sim);
+                if (simulation.PrepareSimulation(parts, Gravity, Atmosphere, Mach, dumpTree, vectoredThrust))
+                {
+                    ThreadPool.QueueUserWorkItem(RunSimulation, simulation);
+                    //RunSimulation(simulation);
                 }
                 else
                 {
@@ -347,8 +382,7 @@
             }
             catch (Exception e)
             {
-                MonoBehaviour.print("Exception in StartSimulation: " + e);
-                Logger.Exception(e);
+                Logger.Exception(e, "SimManager.StartSimulation()");
                 failMessage = e.ToString();
                 lock (locker)
                 {

--- a/KerbalEngineer/VesselSimulator/Simulation.cs
+++ b/KerbalEngineer/VesselSimulator/Simulation.cs
@@ -32,27 +32,30 @@
 {
     using CompoundParts;
     using Extensions;
+    using Helpers;
 
     public class Simulation
     {
-        private const double STD_GRAVITY = 9.82;
         private const double SECONDS_PER_DAY = 86400;
         private readonly Stopwatch _timer = new Stopwatch();
-        private List<EngineSim> activeEngines;
-        private List<EngineSim> allEngines;
-        private List<PartSim> allFuelLines;
-        private List<PartSim> allParts;
+        private List<EngineSim> activeEngines = new List<EngineSim>();
+        private List<EngineSim> allEngines = new List<EngineSim>();
+        private List<PartSim> allFuelLines = new List<PartSim>();
+        private List<PartSim> allParts = new List<PartSim>();
+        private Dictionary<Part, PartSim> partSimLookup = new Dictionary<Part, PartSim>();
         private double atmosphere;
         private int currentStage;
         private double currentisp;
         private bool doingCurrent;
-        private List<PartSim> dontStageParts;
-        private HashSet<PartSim> drainingParts;
-        private HashSet<int> drainingResources;
+        private List<PartSim> dontStageParts = new List<PartSim>();
+        List<List<PartSim>> dontStagePartsLists = new List<List<PartSim>>();
+        private HashSet<PartSim> drainingParts = new HashSet<PartSim>();
+        private HashSet<int> drainingResources = new HashSet<int>();
+        private HashSet<PartSim> decoupledParts = new HashSet<PartSim>();
         private double gravity;
 
         private int lastStage;
-        private List<Part> partList;
+        private List<Part> partList = new List<Part>();
         private double simpleTotalThrust;
         private double stageStartMass;
         private Vector3d stageStartCom;
@@ -67,7 +70,8 @@
         private Vector3 vecActualThrust;
         private Vector3 vecStageDeltaV;
         private Vector3 vecThrust;
-        private double velocity;
+        private double mach;
+        private float maxMach;
         public String vesselName;
         public VesselType vesselType;
 
@@ -113,7 +117,7 @@
         // need during the simulation.  All required data is copied from the core game data structures 
         // so that the simulation itself can be run in a background thread without having issues with 
         // the core game changing the data while the simulation is running.
-        public bool PrepareSimulation(List<Part> parts, double theGravity, double theAtmosphere = 0, double theVelocity = 0, bool dumpTree = false, bool vectoredThrust = false)
+        public bool PrepareSimulation(List<Part> parts, double theGravity, double theAtmosphere = 0, double theMach = 0, bool dumpTree = false, bool vectoredThrust = false, bool fullThrust = false)
         {
             LogMsg log = null;
             if (SimManager.logOutput)
@@ -128,20 +132,24 @@
             this.partList = parts;
             this.gravity = theGravity;
             this.atmosphere = theAtmosphere;
-            this.velocity = theVelocity;
+            this.mach = theMach;
             this.lastStage = Staging.lastStage;
             //MonoBehaviour.print("lastStage = " + lastStage);
 
-            // Create the lists for our simulation parts
-            this.allParts = new List<PartSim>();
-            this.allFuelLines = new List<PartSim>();
-            this.drainingParts = new HashSet<PartSim>();
-            this.allEngines = new List<EngineSim>();
-            this.activeEngines = new List<EngineSim>();
-            this.drainingResources = new HashSet<int>();
+            // Clear the lists for our simulation parts
+            allParts.Clear();
+            allFuelLines.Clear();
+            drainingParts.Clear();
+            allEngines.Clear();
+            activeEngines.Clear();
+            drainingResources.Clear();
+
+            PartSim.ReleaseAll();
+            EngineSim.ReleaseAll();
+            AttachNodeSim.ReleaseAll();
 
             // A dictionary for fast lookup of Part->PartSim during the preparation phase
-            Dictionary<Part, PartSim> partSimLookup = new Dictionary<Part, PartSim>();
+            partSimLookup.Clear();
 
             if (this.partList.Count > 0 && this.partList[0].vessel != null)
             {
@@ -164,7 +172,7 @@
                 }
 
                 // Create the PartSim
-                PartSim partSim = new PartSim(part, partId, this.atmosphere, log);
+                PartSim partSim = PartSim.GetPoolObject().Initialise(part, partId, this.atmosphere, log);
 
                 // Add it to the Part lookup dictionary and the necessary lists
                 partSimLookup.Add(part, partSim);
@@ -175,10 +183,15 @@
                 }
                 if (partSim.isEngine)
                 {
-                    partSim.CreateEngineSims(this.allEngines, this.atmosphere, this.velocity, vectoredThrust, log);
+                    partSim.CreateEngineSims(this.allEngines, this.atmosphere, this.mach, vectoredThrust, fullThrust, log);
                 }
 
                 partId++;
+            }
+
+            for (int i = 0; i < allEngines.Count; ++i)
+            {
+                maxMach = Mathf.Max(maxMach, allEngines[i].maxMach);
             }
 
             this.UpdateActiveEngines();
@@ -341,7 +354,7 @@
             }
 
             // Create a list of lists of PartSims that prevent decoupling
-            List<List<PartSim>> dontStagePartsLists = this.BuildDontStageLists(log);
+            BuildDontStageLists(log);
 
             if (log != null)
             {
@@ -493,7 +506,7 @@
                     // If we have drained anything and the masses make sense then add this step's deltaV to the stage total
                     if (resourceDrainTime > 0d && this.stepStartMass > this.stepEndMass && this.stepStartMass > 0d && this.stepEndMass > 0d)
                     {
-                        this.vecStageDeltaV += this.vecThrust * (float)((this.currentisp * STD_GRAVITY * Math.Log(this.stepStartMass / this.stepEndMass)) / this.simpleTotalThrust);
+                        this.vecStageDeltaV += this.vecThrust * (float)((this.currentisp * Units.GRAVITY * Math.Log(this.stepStartMass / this.stepEndMass)) / this.simpleTotalThrust);
                     }
 
                     // Update the active engines and resource drains for the next step
@@ -531,13 +544,13 @@
 
                 // Store the magnitude of the deltaV vector
                 stage.deltaV = this.vecStageDeltaV.magnitude;
-                stage.resourceMass = this.stepStartMass - this.stepEndMass;
+                stage.resourceMass = this.stageStartMass - this.stepEndMass;
 
                 // Recalculate effective stage isp from the stage deltaV (flip the standard deltaV calculation around)
                 // Note: If the mass doesn't change then this is a divide by zero
                 if (this.stageStartMass != this.stepStartMass)
                 {
-                    stage.isp = stage.deltaV / (STD_GRAVITY * Math.Log(this.stageStartMass / this.stepStartMass));
+                    stage.isp = stage.deltaV / (Units.GRAVITY * Math.Log(this.stageStartMass / this.stepStartMass));
                 }
                 else
                 {
@@ -548,6 +561,7 @@
                 stage.time = (this.stageTime < SECONDS_PER_DAY) ? this.stageTime : 0d;
                 stage.number = this.doingCurrent ? -1 : this.currentStage; // Set the stage number to -1 if doing current engines
                 stage.totalPartCount = this.allParts.Count;
+                stage.maxMach = maxMach;
                 stages[this.currentStage] = stage;
 
                 // Now activate the next stage
@@ -610,16 +624,24 @@
             return stages;
         }
 
-        private List<List<PartSim>> BuildDontStageLists(LogMsg log)
+        private void BuildDontStageLists(LogMsg log)
         {
             if (log != null)
             {
                 log.buf.AppendLine("Creating list with capacity of " + (this.currentStage + 1));
             }
-            List<List<PartSim>> lists = new List<List<PartSim>>();
+
+            dontStagePartsLists.Clear();
             for (int i = 0; i <= this.currentStage; i++)
             {
-                lists.Add(new List<PartSim>());
+                if (i < dontStagePartsLists.Count)
+                {
+                    dontStagePartsLists[i].Clear();
+                }
+                else
+                {
+                    dontStagePartsLists.Add(new List<PartSim>());
+                }
             }
 
             foreach (PartSim partSim in this.allParts)
@@ -640,20 +662,18 @@
                     }
                     else
                     {
-                        lists[partSim.decoupledInStage + 1].Add(partSim);
+                        dontStagePartsLists[partSim.decoupledInStage + 1].Add(partSim);
                     }
                 }
             }
 
             for (int i = 1; i <= this.lastStage; i++)
             {
-                if (lists[i].Count == 0)
-                {
-                    lists[i] = lists[i - 1];
-                }
-            }
-
-            return lists;
+                if (dontStagePartsLists[i].Count == 0)
+                {
+                    dontStagePartsLists[i] = dontStagePartsLists[i - 1];
+                }
+            }
         }
 
         // This function simply rebuilds the active engines by testing the isActive flag of all the engines
@@ -783,7 +803,7 @@
                     }
                     //buffer.AppendFormat("isSepratron = {0}\n", partSim.isSepratron ? "true" : "false");
 
-                    if (!partSim.isSepratron && !partSim.Resources.EmptyOf(this.drainingResources))
+                    if (!partSim.isSepratron && !partSim.EmptyOf(this.drainingResources))
                     {
                         if (SimManager.logOutput)
                         {
@@ -834,7 +854,7 @@
         private void ActivateStage()
         {
             // Build a set of all the parts that will be decoupled
-            HashSet<PartSim> decoupledParts = new HashSet<PartSim>();
+            decoupledParts.Clear();
             foreach (PartSim partSim in this.allParts)
             {
                 if (partSim.decoupledInStage >= this.currentStage)

--- a/KerbalEngineer/VesselSimulator/Stage.cs
+++ b/KerbalEngineer/VesselSimulator/Stage.cs
@@ -29,27 +29,29 @@
 {
     public class Stage
     {
-        public double actualThrust = 0f;
-        public double actualThrustToWeight = 0f;
-        public double cost = 0d;
-        public double deltaV = 0f;
-        public double inverseTotalDeltaV = 0f;
-        public double isp = 0f;
-        public double mass = 0f;
-        public double maxThrustToWeight = 0f;
+        public double actualThrust = 0.0;
+        public double actualThrustToWeight = 0.0;
+        public double cost = 0.0;
+        public double deltaV = 0.0;
+        public double inverseTotalDeltaV = 0.0;
+        public double isp = 0.0;
+        public double mass = 0.0;
+        public double rcsMass = 0.0;
+        public double maxThrustToWeight = 0.0;
         public int number = 0;
-        public double thrust = 0f;
-        public double thrustToWeight = 0f;
-        public double time = 0f;
-        public double totalCost = 0;
-        public double totalDeltaV = 0f;
-        public double totalMass = 0f;
-        public double totalTime = 0f;
+        public double thrust = 0.0;
+        public double thrustToWeight = 0.0;
+        public double time = 0.0;
+        public double totalCost = 0.0;
+        public double totalDeltaV = 0.0;
+        public double totalMass = 0.0;
+        public double totalTime = 0.0;
         public int totalPartCount = 0;
         public int partCount = 0;
         public double resourceMass = 0.0;
-        public double maxThrustTorque = 0f;
-        public double thrustOffsetAngle = 0f;
+        public double maxThrustTorque = 0.0;
+        public double thrustOffsetAngle = 0.0;
+        public float maxMach = 0.0f;
 
         public void Dump()
         {

 Binary files a/Output/KerbalEngineer/KerbalEngineer.dll and b/Output/KerbalEngineer/KerbalEngineer.dll differ
--- a/Output/KerbalEngineer/KerbalEngineer.version
+++ b/Output/KerbalEngineer/KerbalEngineer.version
@@ -5,13 +5,13 @@
 	{
 		"MAJOR":1,
 		"MINOR":0,
-		"PATCH":13,
-		"BUILD":1
+		"PATCH":16,
+		"BUILD":3
 	},
 	"KSP_VERSION":
 	{
-		"MAJOR":0,
-		"MINOR":90,
+		"MAJOR":1,
+		"MINOR":0,
 		"PATCH":0
 	}
 }

 Binary files /dev/null and b/Output/KerbalEngineer/Parts/Engineer7500/model000.mbm differ
--- a/Output/KerbalEngineer/Parts/Engineer7500/part.cfg
+++ b/Output/KerbalEngineer/Parts/Engineer7500/part.cfg
@@ -7,7 +7,6 @@
 	
 	// --- asset parameters ---
 	mesh = model.mu
-	texture = model000.mbm
 	rescaleFactor = 0.8
 
 	PhysicsSignificance = 1

 Binary files a/Output/KerbalEngineer/Parts/Engineer7500/textures/model000.mbm and /dev/null differ