diff --git a/QtRocket.ui b/QtRocket.ui
index 91751eb..9cfd349 100644
--- a/QtRocket.ui
+++ b/QtRocket.ui
@@ -13,6 +13,10 @@
   <property name="windowTitle">
    <string>QtRocket</string>
   </property>
+  <property name="windowIcon">
+   <iconset>
+    <normaloff>resources/qtrocket.png</normaloff>resources/qtrocket.png</iconset>
+  </property>
   <widget class="QWidget" name="centralwidget">
    <layout class="QVBoxLayout" name="verticalLayout" stretch="2">
     <item>
diff --git a/main.cpp b/main.cpp
index ed45820..845cef4 100644
--- a/main.cpp
+++ b/main.cpp
@@ -12,9 +12,11 @@ int main(int argc, char *argv[])
    // TODO: Only support US English at the moment. Anyone want to help translate?
    QTranslator translator;
    const QStringList uiLanguages = QLocale::system().uiLanguages();
-   for (const QString &locale : uiLanguages) {
+   for (const QString &locale : uiLanguages)
+   {
       const QString baseName = "qtrocket_" + QLocale(locale).name();
-      if (translator.load(":/i18n/" + baseName)) {
+      if (translator.load(":/i18n/" + baseName))
+      {
          a.installTranslator(&translator);
          break;
       }
diff --git a/qtrocket.pro b/qtrocket.pro
index 5ec3737..c3c5d16 100644
--- a/qtrocket.pro
+++ b/qtrocket.pro
@@ -17,13 +17,17 @@ SOURCES += \
     qcustomplot.cpp \
     sim/AtmosphericModel.cpp \
     sim/GravityModel.cpp \
+    sim/Propagator.cpp \
+    sim/RK4Solver.cpp \
     sim/SphericalGeoidModel.cpp \
     sim/SphericalGravityModel.cpp \
     sim/USStandardAtmosphere.cpp \
     sim/WindModel.cpp \
     utils/BinMap.cpp \
     utils/CurlConnection.cpp \
-    utils/ThrustCurveAPI.cpp
+    utils/ThrustCurveAPI.cpp \
+    utils/math/Quaternion.cpp \
+    utils/math/Vector3.cpp
 
 HEADERS += \
     QtRocket.h \
@@ -32,8 +36,11 @@ HEADERS += \
     model/Thrustcurve.h \
     qcustomplot.h \
     sim/AtmosphericModel.h \
+    sim/DESolver.h \
     sim/GeoidModel.h \
     sim/GravityModel.h \
+    sim/Propagator.h \
+    sim/RK4Solver.h \
     sim/SphericalGeoidModel.h \
     sim/SphericalGravityModel.h \
     sim/USStandardAtmosphere.h \
@@ -41,7 +48,9 @@ HEADERS += \
     utils/BinMap.h \
     utils/CurlConnection.h \
     utils/ThrustCurveAPI.h \
-    utils/math/Constants.h
+    utils/math/Constants.h \
+    utils/math/Quaternion.h \
+    utils/math/Vector3.h
 
 FORMS += \
     QtRocket.ui
diff --git a/resources/qtrocket.png b/resources/qtrocket.png
new file mode 100644
index 0000000..b41bf2b
Binary files /dev/null and b/resources/qtrocket.png differ
diff --git a/sim/DESolver.h b/sim/DESolver.h
new file mode 100644
index 0000000..46b979d
--- /dev/null
+++ b/sim/DESolver.h
@@ -0,0 +1,18 @@
+#ifndef SIM_DESOLVER_H
+#define SIM_DESOLVER_H
+
+namespace sim
+{
+
+class DESolver
+{
+public:
+   DESolver() {}
+   virtual ~DESolver() {}
+
+   virtual double step(double curVal, double t, double dt) = 0;
+};
+
+} // namespace sim
+
+#endif // SIM_DESOLVER_H
diff --git a/sim/Propagator.cpp b/sim/Propagator.cpp
new file mode 100644
index 0000000..43cdaef
--- /dev/null
+++ b/sim/Propagator.cpp
@@ -0,0 +1,10 @@
+#include "Propagator.h"
+
+namespace sim {
+
+Propagator::Propagator()
+{
+
+}
+
+} // namespace sim
diff --git a/sim/Propagator.h b/sim/Propagator.h
new file mode 100644
index 0000000..0662b0b
--- /dev/null
+++ b/sim/Propagator.h
@@ -0,0 +1,18 @@
+#ifndef SIM_PROPAGATOR_H
+#define SIM_PROPAGATOR_H
+
+
+namespace sim
+{
+
+class Propagator
+{
+public:
+    Propagator();
+
+private:
+};
+
+} // namespace sim
+
+#endif // SIM_PROPAGATOR_H
diff --git a/sim/RK4Solver.cpp b/sim/RK4Solver.cpp
new file mode 100644
index 0000000..c6ef857
--- /dev/null
+++ b/sim/RK4Solver.cpp
@@ -0,0 +1,19 @@
+#include "RK4Solver.h"
+
+namespace sim {
+
+double RK4Solver::step(double curVal, double t, double dt)
+{
+   double retVal(0.0);
+
+   k1 = de(t, curVal);
+   k2 = de(t + dt / 2.0, curVal + (dt * k1 / 2.0));
+   k3 = de(t + dt / 2.0, curVal + (dt * k2 / 2.0));
+   k4 = de(t + dt, curVal + dt * k3);
+   retVal = curVal + (1.0 / 6.0)*dt*(k1 + 2.0*k2 + 2.0*k3 + k4);
+
+   return retVal;
+}
+
+
+} // namespace sim
diff --git a/sim/RK4Solver.h b/sim/RK4Solver.h
new file mode 100644
index 0000000..2c89a5e
--- /dev/null
+++ b/sim/RK4Solver.h
@@ -0,0 +1,27 @@
+#ifndef SIM_RK4SOLVER_H
+#define SIM_RK4SOLVER_H
+
+#include "DESolver.h"
+
+#include <functional>
+
+namespace sim {
+
+class RK4Solver : public DESolver
+{
+public:
+   RK4Solver(const std::function<double(double, double)>& d) : de(d) {}
+   virtual ~RK4Solver() {}
+
+   virtual double step(double curVal, double t, double dt) override;
+
+private:
+   std::function<double(double, double)> de;
+
+   double k1, k2, k3, k4;
+
+};
+
+} // namespace sim
+
+#endif // SIM_RK4SOLVER_H
diff --git a/utils/math/Quaternion.cpp b/utils/math/Quaternion.cpp
new file mode 100644
index 0000000..4c23d11
--- /dev/null
+++ b/utils/math/Quaternion.cpp
@@ -0,0 +1,11 @@
+#include "Quaternion.h"
+
+namespace math
+{
+
+Quaternion::Quaternion()
+{
+
+}
+
+} // namespace math
diff --git a/utils/math/Quaternion.h b/utils/math/Quaternion.h
new file mode 100644
index 0000000..25fd934
--- /dev/null
+++ b/utils/math/Quaternion.h
@@ -0,0 +1,32 @@
+#ifndef MATH_QUATERNION_H
+#define MATH_QUATERNION_H
+
+#include "Vector3.h"
+
+namespace math
+{
+
+class Quaternion
+{
+public:
+    Quaternion();
+
+    Quaternion(double r, const Vector3& i);
+    Quaternion(double r, double i1, double i2, double i3);
+
+    ~Quaternion();
+
+    Quaternion operator-();
+    Quaternion operator-(const Quaternion& rhs);
+    Quaternion operator+(const Quaternion& rhs);
+    Quaternion operator*(double s);
+    Quaternion operator*(const Quaternion& rhs);
+
+private:
+    double real;
+    Vector3 imag;
+};
+
+} // namespace math
+
+#endif // MATH_QUATERNION_H
diff --git a/utils/math/Vector3.cpp b/utils/math/Vector3.cpp
new file mode 100644
index 0000000..05282ad
--- /dev/null
+++ b/utils/math/Vector3.cpp
@@ -0,0 +1,66 @@
+#include "Vector3.h"
+
+namespace math
+{
+
+Vector3::Vector3()
+   : x1(0.0),
+     x2(0.0),
+     x3(0.0)
+{
+
+}
+
+Vector3::Vector3(const double& inX1,
+                 const double& inX2,
+                 const double& inX3)
+   : x1(inX1),
+     x2(inX2),
+     x3(inX3)
+{
+
+}
+
+Vector3::Vector3(const Vector3& o)
+   : x1(o.x1),
+     x2(o.x2),
+     x3(o.x3)
+{
+
+}
+
+Vector3::~Vector3()
+{}
+
+Vector3 Vector3::operator=(const Vector3& rhs)
+{
+    return Vector3(rhs.x1, rhs.x2, rhs.x3);
+}
+
+Vector3 Vector3::operator-()
+{
+    return Vector3(-x1, -x2, -x3);
+}
+
+Vector3 Vector3::operator-(const Vector3& rhs)
+{
+    return Vector3(x1 - rhs.x1,
+                   x2 - rhs.x2,
+                   x3 - rhs.x3);
+}
+
+Vector3 Vector3::operator+(const Vector3& rhs)
+{
+    return Vector3(x1 + rhs.x1,
+                   x2 + rhs.x2,
+                   x3 + rhs.x3);
+}
+
+Vector3 Vector3::operator*(const double& s)
+{
+    return Vector3(x1 * s,
+                   x2 * s,
+                   x3 * s);
+}
+
+} // namespace math
diff --git a/utils/math/Vector3.h b/utils/math/Vector3.h
new file mode 100644
index 0000000..5dc7f39
--- /dev/null
+++ b/utils/math/Vector3.h
@@ -0,0 +1,40 @@
+#ifndef MATH_VECTOR3_H
+#define MATH_VECTOR3_H
+
+
+namespace math
+{
+
+class Vector3
+{
+public:
+   Vector3();
+   Vector3(const double& inX1,
+           const double& inX2,
+           const double& inX3);
+
+   Vector3(const Vector3& o);
+
+   ~Vector3();
+
+   Vector3 operator=(const Vector3& rhs);
+
+   Vector3 operator-();
+   Vector3 operator-(const Vector3& rhs);
+   Vector3 operator+(const Vector3& rhs);
+   Vector3 operator*(const double& s);
+
+   double getX1() { return x1; }
+   double getX2() { return x2; }
+   double getX3() { return x3; }
+
+
+private:
+   double x1;
+   double x2;
+   double x3;
+};
+
+} // namespace math
+
+#endif // MATH_VECTOR3_H