Adding free variables to README.

gpkitmodels/SP/SimPleAC/README.md

@@ -1,7 +1,7 @@
 SimPleAC
 ========
 
-In this example, we modify the simple wing model proposed by Prof. Warren Hoburg in his thesis to create a simple aircraft model incorporating signomial programming (SP). 
+In this example, we modify the simple wing model proposed by Prof. Warren Hoburg in his thesis to create a simple aircraft model incorporating signomial programming (SP). Firstly, we initialize the SimPleAC model, and define all of it its constants and free variables. 
 
 ```python
 from gpkit import Model, Variable, SignomialsEnabled, VarKey, units
@@ -10,7 +10,56 @@ import matplotlib.pyplot as plt
 
 class SimPleAC(Model):
     def setup(self):
-        # Variable definitions...
+        # Env. constants
+        g          = Variable("g", 9.81, "m/s^2", "gravitational acceleration")
+        mu         = Variable("\\mu", 1.775e-5, "kg/m/s", "viscosity of air", pr=4.)
+        rho        = Variable("\\rho", 1.23, "kg/m^3", "density of air", pr=5.)
+        rho_f      = Variable("\\rho_f", 817, "kg/m^3", "density of fuel")
+
+        # Non-dimensional constants
+        C_Lmax     = Variable("C_{L,max}", 1.6, "-", "max CL with flaps down", pr=5.)
+        e          = Variable("e", 0.92, "-", "Oswald efficiency factor", pr=3.)
+        k          = Variable("k", 1.17, "-", "form factor", pr=10.)
+        N_ult      = Variable("N_{ult}", 3.3, "-", "ultimate load factor", pr=15.)
+        S_wetratio = Variable("(\\frac{S}{S_{wet}})", 2.075, "-", "wetted area ratio", pr=3.)
+        tau        = Variable("\\tau", 0.12, "-", "airfoil thickness to chord ratio", pr=10.)
+        W_W_coeff1 = Variable("W_{W_{coeff1}}", 2e-5, "1/m",
+                              "wing weight coefficent 1", pr= 30.) #orig  12e-5
+        W_W_coeff2 = Variable("W_{W_{coeff2}}", 60., "Pa",
+                              "wing weight coefficent 2", pr=10.)
+        p_labor    = Variable('p_{labor}',1.,'1/min','cost of labor', pr = 20.)
+
+        # Dimensional constants
+        Range     = Variable("Range",3000, "km", "aircraft range")
+        # toz       = Variable("toz", 1, "-", pr=15.)
+        TSFC      = Variable("TSFC", 0.6, "1/hr", "thrust specific fuel consumption")
+        V_min     = Variable("V_{min}", 25, "m/s", "takeoff speed", pr=20.)
+        W_0       = Variable("W_0", 6250, "N", "aircraft weight excluding wing", pr=20.)
+
+        # Free Variables
+        LoD       = Variable('L/D','-','lift-to-drag ratio')
+        D         = Variable("D", "N", "total drag force")
+        V         = Variable("V", "m/s", "cruising speed")
+        W         = Variable("W", "N", "total aircraft weight")
+        Re        = Variable("Re", "-", "Reynold's number")
+        CDA0      = Variable("(CDA0)", "m^2", "fuselage drag area") #0.035 originally
+        C_D       = Variable("C_D", "-", "drag coefficient")
+        C_L       = Variable("C_L", "-", "lift coefficient of wing")
+        C_f       = Variable("C_f", "-", "skin friction coefficient")
+        W_f       = Variable("W_f", "N", "fuel weight")
+        V_f       = Variable("V_f", "m^3", "fuel volume")
+        V_f_avail = Variable("V_{f_{avail}}","m^3","fuel volume available")
+        T_flight  = Variable("T_{flight}", "hr", "flight time")
+
+        # Free variables (fixed for performance eval.)
+        A         = Variable("A", "-", "aspect ratio",fix = True)
+        S         = Variable("S", "m^2", "total wing area", fix = True)
+        W_w       = Variable("W_w", "N", "wing weight")#, fix = True)
+        W_w_strc  = Variable('W_w_strc','N','wing structural weight', fix = True)
+        W_w_surf  = Variable('W_w_surf','N','wing skin weight', fix = True)
+        V_f_wing  = Variable("V_f_wing",'m^3','fuel volume in the wing', fix = True)
+        V_f_fuse  = Variable('V_f_fuse','m^3','fuel volume in the fuselage', fix = True)
+        constraints = []
 ```
 
 
@@ -213,6 +262,21 @@ W_w \geq W_{w_{surf}} + W_{w_{strc}}
         return constraints
 ```
 
+Running the model
+-----------------
+
+The ```main``` method within ```SimPleAC.py```... allows the model to be run directly from a terminal with the command ```python SimPleAC.py```. 
+
+```python
+if __name__ == "__main__":
+    # Most basic way to execute the model 
+    m = SimPleAC()
+    m.cost = m['W_f'] 
+    sol = m.localsolve(verbosity = 4)
+    print sol.table()
+```
+
+
 Valid objective functions
 ---------