Add prop structure and performance models

gpkitmodels/GP/aircraft/prop/prop_test.py

@@ -9,7 +9,8 @@ def eta_test():
     p = Propeller(fs)
     p.substitutions[p.T] = 100
     p.cost = 1/p.eta
-    p.solve()
+    sol = p.solve()
+    print sol.table()
 
 def qprop_test():
 
@@ -23,7 +24,7 @@ def qprop_test():
 def test():
     "tests"
     eta_test()
-    qprop_test()
+    #qprop_test()
 
 if __name__ == "__main__":
     test()

gpkitmodels/GP/aircraft/prop/propeller.py

@@ -1,15 +1,28 @@
 " propeller model "
 from numpy import pi
-from gpkit import Model, parse_variables
+from gpkit import Model, parse_variables, SignomialsEnabled, SignomialEquality
 
 class Propeller(Model):
     """ Propeller Model
 
+    Variables
+    ---------
+    R          10           [m]         prop radius
+
+    """
+    def setup(self):
+        exec parse_variables(Propeller.__doc__)
+
+    def performance(state):
+        return Propeller_Performance(self, state)
+
+class Propeller_Performance(Model):
+    """ Propeller Model
+
     Variables
     ---------
     T                       [N]         thrust
     Tc                      [-]         coefficient of thrust
-    R          0.3          [m]         prop radius
     etaadd     0.7          [-]         swirl and nonuniformity losses
     etav       0.85         [-]         viscous losses
     etai                    [-]         inviscid losses
@@ -27,8 +40,10 @@ def setup(self, state):
 
         V = state.V
         rho = state.rho
+
 
-        return [eta <= etav*etai,
+        constraints = [eta <= etav*etai,
                 Tc == T/(0.5*rho*V**2*pi*R**2),
-                z2 >= 1 + Tc,
+                z2 >= Tc + 1,
                 etai*(z1 + z2**0.5/etaadd) <= 2]
+        return constraints