Prop

TESTS

@@ -1,3 +1,4 @@
 gpkitmodels/GP/aircraft/wing/wing_test.py
 gpkitmodels/GP/aircraft/tail/tail_tests.py
 gpkitmodels/GP/aircraft/fuselage/test_fuselage.py
+gpkitmodels/GP/aircraft/prop/prop_test.py

gpkitmodels/GP/aircraft/prop/prop_test.py

@@ -0,0 +1,21 @@
+" propeller tests "
+from gpkitmodels.GP.aircraft.prop.propeller import Propeller
+from gpkitmodels.GP.aircraft.wing.wing_test import FlightState
+from gpkit import Model
+
+def simpleprop_test():
+    " test simple propeller model "
+    fs = FlightState()
+    p = Propeller()
+    pp = p.flight_model(p, fs)
+    m = Model(1/pp.eta, [fs, p, pp])
+    m.substitutions.update({"rho": 1.225, "V": 50, "T": 100})
+    m.solve()
+
+def test():
+    "tests"
+    simpleprop_test()
+
+if __name__ == "__main__":
+    test()
+

gpkitmodels/GP/aircraft/prop/propeller.py

@@ -0,0 +1,56 @@
+" propeller model "
+from numpy import pi
+from gpkit import Model, parse_variables
+
+class Propeller_Performance(Model):
+    """ Propeller Model
+
+    Variables
+    ---------
+    T                       [N]         thrust
+    Tc                      [-]         coefficient of thrust
+    etaadd     0.7          [-]         swirl and nonuniformity losses
+    etav       0.85         [-]         viscous losses
+    etai                    [-]         inviscid losses
+    eta                     [-]         overall efficiency
+    z1         self.helper  [-]         efficiency helper 1
+    z2                      [-]         efficiency helper 2
+    lam                     [-]         advance ratio
+    CT                      [-]         thrust coefficient
+    CP                      [-]         power coefficient
+    Q                       [N*m]       torque
+    omega                   [rpm]       propeller rotation rate
+
+    """
+
+    def helper(self, c):
+        " helper function to avoid signomial constraint "
+        return 2. - 1./c[self.etaadd]
+
+    def setup(self, static, state):
+        exec parse_variables(Propeller_Performance.__doc__)
+
+        V = state.V
+        rho = state.rho
+        R = static.R
+
+        return [eta <= etav*etai,
+                Tc == T/(0.5*rho*V**2*pi*R**2),
+                z2 >= Tc + 1,
+                etai*(z1 + z2**0.5/etaadd) <= 2,
+               ], static
+
+class Propeller(Model):
+    """ Propeller Model
+
+    Variables
+    ---------
+    R          1           [m]         prop radius
+
+    """
+    #TODO add weight model
+    flight_model = Propeller_Performance
+
+    def setup(self):
+        exec parse_variables(Propeller.__doc__)
+

gpkitmodels/GP/aircraft/wing/wing.py

@@ -41,12 +41,12 @@ class Planform(Model):
     deta        self.return_deta        [-]     \\Delta (2y/b)
 
     Upper Unbounded
-    ---------------  # bounding any pair of planform variables will work
-    cmac, b, tau
+    ---------------  # bounding any pair of variables will work
+    cave, b, tau
 
     Lower Unbounded
     ---------------
-    cmac, b, tau
+    cave, b, tau
 
     LaTex Strings
     -------------