move J to separate sp mdoel

gpkitmodels/GP/aircraft/tail/empennage.py

@@ -14,6 +14,8 @@ class Empennage(Model):
     mfac        1.0     [-]     tail weight margin factor
     W                   [lbf]   empennage weight
 
+    SKIP VERIFICATION
+
     Upper Unbounded
     ---------------
     W, vtail.Vv, htail.Vh, tailboom.cave (if not tbSecWeight)

gpkitmodels/GP/aircraft/tail/tail_boom.py

@@ -115,7 +115,7 @@ class TailBoomBending(Model):
     Upper Unbounded
     ---------------
     tailboom.I0, tailboom.Sy
-    tailboom.J (if tailboomJ), tailboom.I (if tailboomJ)
+    tailboom.J (if tailboomJ), tailboom.I
 
     Lower Unbounded
     ---------------

gpkitmodels/GP/aircraft/wing/boxspar.py

@@ -1,5 +1,5 @@
 " box spar "
-from gpkit import Model, parse_variables
+from gpkit import Model, parse_variables, SignomialsEnabled
 from .sparloading import SparLoading
 from .gustloading import GustL
 from gpkitmodels.GP.materials import cfrpud, cfrpfabric, foamhd
@@ -21,7 +21,6 @@ class BoxSpar(Model):
     -----------------------
     hin                     [in]        height between caps
     I                       [m^4]       spar x moment of inertia
-    J                       [m^4]       spar x polar moment of inertia
     Sy                      [m^3]       section modulus
     dm                      [kg]        segment spar mass
     w                       [in]        spar width
@@ -30,6 +29,8 @@ class BoxSpar(Model):
     tshear                  [in]        shear web thickness
     tcore                   [in]        core thickness
 
+    SKIP VERIFICATION
+
     Upper Unbounded
     ---------------
     W
@@ -62,8 +63,8 @@ def setup(self, N, surface):
         exec parse_variables(BoxSpar.__doc__)
 
         b = self.b = surface.b
-        cave = surface.cave
-        tau = surface.tau
+        cave = self.cave = surface.cave
+        tau = self.tau = surface.tau
         deta = surface.deta
         rho = self.material.rho
         rhoshear = self.shearMaterial.rho
@@ -73,16 +74,17 @@ def setup(self, N, surface):
 
         self.weight = W >= 2*dm.sum()*g
 
-        return [I/mfac <= w*t*hin**2,
-                J*2*(hin + w) <= 2*(hin*w)**2*2*tshear,
-                dm >= (rho*4*w*t + 4*tshear*rhoshear*(hin + w)
-                       + 2*rhocore*tcore*(w + hin))*b/2*deta,
-                w <= wlim*cave,
-                cave*tau >= hin + 4*t + 2*tcore,
-                self.weight,
-                t >= tmin,
-                Sy*(hin/2 + 2*t + tcore) <= I,
-                tshear >= tshearmin,
-                tcore >= tcoret*cave*tau,
-                d == w,
-               ]
+        constraints = [I/mfac <= w*t*hin**2,
+                       dm >= (rho*4*w*t + 4*tshear*rhoshear*(hin + w)
+                              + 2*rhocore*tcore*(w + hin))*b/2*deta,
+                       w <= wlim*cave,
+                       cave*tau >= hin + 4*t + 2*tcore,
+                       self.weight,
+                       t >= tmin,
+                       Sy*(hin/2 + 2*t + tcore) <= I,
+                       tshear >= tshearmin,
+                       tcore >= tcoret*cave*tau,
+                       d == w,
+                      ]
+
+        return constraints

gpkitmodels/GP/aircraft/wing/gustloading.py

@@ -41,9 +41,9 @@ class GustL(SparLoading):
     return_cosm1 = lambda self, c: hstack(
         [1e-10, 1-array(cos(c[self.wing.planform.eta][1:]*pi/2))])
 
-    def setup(self, wing, state, sp=False):
+    def setup(self, wing, state, out=False):
         exec parse_variables(GustL.__doc__)
-        self.load = SparLoading.setup(self, wing, state, sp=sp)
+        self.load = SparLoading.setup(self, wing, state, out=out)
 
         cbar = self.wing.planform.cbar
         W = self.W  # from SparLoading

gpkitmodels/GP/aircraft/wing/sparloading.py

@@ -15,7 +15,7 @@ class SparLoading(Model):
     kappa           0.2            [-]     max tip deflection ratio
     W                              [lbf]   loading weight
     N                              [-]     loading factor
-    twmax           30.*pi/180     [-]     max tip twist
+    twmax           15.*pi/180     [-]     max tip twist
     Stip            1e-10          [N]     tip loading
     Mtip            1e-10          [N*m]   tip moment
     throot          1e-10          [-]     root deflection angle
@@ -50,7 +50,7 @@ def new_qbarFun(self, c):
 
     new_SbarFun = None
 
-    def setup(self, wing, state, sp=False):
+    def setup(self, wing, state, out=False):
         self.wing = wing
         exec parse_variables(SparLoading.__doc__)
 
@@ -64,7 +64,7 @@ def setup(self, wing, state, sp=False):
         deta = self.wing.planform.deta
 
         constraints = []
-        if not sp:
+        if not out:
             constraints.extend([
                 S[:-1] >= S[1:] + 0.5*deta*(b/2.)*(q[:-1] + q[1:]),
                 M[:-1] >= M[1:] + 0.5*deta*(b/2)*(S[:-1] + S[1:])])

gpkitmodels/GP/aircraft/wing/wing.py

@@ -151,6 +151,8 @@ class Wing(Model):
     W                   [lbf]       wing weight
     mfac        1.2     [-]         wing weight margin factor
 
+    SKIP VERIFICATION
+
     Upper Unbounded
     ---------------
     W, planform.tau (if not sparJ)

gpkitmodels/SP/aircraft/wing/boxspar.py

@@ -0,0 +1,28 @@
+" box spar "
+from gpkit import parse_variables, SignomialsEnabled
+from gpkitmodels.GP.aircraft.wing.boxspar import BoxSpar as BoxSparGP
+
+#pylint: disable=exec-used, undefined-variable, unused-argument, invalid-name
+
+class BoxSpar(BoxSparGP):
+    """ Box Spar Model
+
+    Variables of length N-1
+    -----------------------
+    J                       [m^4]       spar x polar moment of inertia
+
+    """
+
+    def setup(self, N, surface):
+        exec parse_variables(BoxSpar.__doc__)
+        self.boxspar = BoxSparGP.setup(self, N=N, surface=surface)
+
+        cave = self.cave
+        tau = self.tau
+        w = self.w
+        tshear = self.tshear
+
+        with SignomialsEnabled():
+            constraints = [J <= cave*tau*w*tshear/3*(cave*tau + w)]
+
+        return self.boxspar, constraints