diff --git a/gpkitmodels/GP/aircraft/tail/empennage.py b/gpkitmodels/GP/aircraft/tail/empennage.py
index c7c190de..bfa86f31 100644
--- a/gpkitmodels/GP/aircraft/tail/empennage.py
+++ b/gpkitmodels/GP/aircraft/tail/empennage.py
@@ -11,21 +11,21 @@ def setup(self):
         mfac = Variable("m_{fac}", 1.0, "-", "Tail weight margin factor")
         W = Variable("W", "lbf", "empennage weight")
 
-        self.horizontaltail = HorizontalTail()
+        self.htail = HorizontalTail()
         self.verticaltail = VerticalTail()
         self.tailboom = TailBoom()
-        self.components = [self.horizontaltail, self.verticaltail,
+        self.components = [self.htail, self.verticaltail,
                            self.tailboom]
 
         state = TailBoomState()
-        loading = [self.tailboom.horizontalbending(self.horizontaltail, state),
+        loading = [self.tailboom.horizontalbending(self.htail, state),
                    self.tailboom.verticalbending(self.verticaltail, state),
                    self.tailboom.verticaltorsion(self.verticaltail, state)]
 
         constraints = [
-            W/mfac >= (self.horizontaltail["W"] + self.verticaltail["W"]
+            W/mfac >= (self.htail.topvar("W") + self.verticaltail["W"]
                        + self.tailboom["W"]),
-            self.tailboom["l"] >= self.horizontaltail["l_h"],
+            self.tailboom["l"] >= self.htail["l_h"],
             self.tailboom["l"] >= self.verticaltail["l_v"],
             ]
 
diff --git a/gpkitmodels/GP/aircraft/tail/horizontal_tail.py b/gpkitmodels/GP/aircraft/tail/horizontal_tail.py
index 48eb604f..46920141 100644
--- a/gpkitmodels/GP/aircraft/tail/horizontal_tail.py
+++ b/gpkitmodels/GP/aircraft/tail/horizontal_tail.py
@@ -2,47 +2,51 @@
 import numpy as np
 from gpkit import Model, Variable
 from tail_aero import TailAero
+from gpkitmodels.GP.aircraft.wing.wing import AeroSurf
+from gpkitmodels.GP.aircraft.wing.constant_taper_chord import c_bar
+from gpkitmodels.GP.aircraft.wing.wing_interior import WingInterior
+from gpkitmodels.GP.aircraft.wing.wing_skin import WingSkin
 
 class HorizontalTail(Model):
     "horizontal tail model"
-    def setup(self, lam=0.8):
-        Sh = Variable("S", "ft**2", "horizontal tail area")
+    def setup(self, N=3, lam=0.8):
+
         Vh = Variable("V_h", "-", "horizontal tail volume coefficient")
-        ARh = Variable("AR_h", "-", "horizontal tail aspect ratio")
-        Abar = Variable("\\bar{A}_{NACA0008}", 0.0548, "-",
-                        "cross sectional area of NACA 0008")
-        rhofoam = Variable("\\rho_{foam}", 1.5, "lbf/ft^3",
-                           "Density of formular 250")
-        rhoskin = Variable("\\rho_{skin}", 0.049, "g/cm**2",
-                           "horizontal tail skin density")
-        bh = Variable("b", "ft", "horizontal tail span")
         W = Variable("W", "lbf", "horizontal tail weight")
-        Vh = Variable("V_h", "-", "horizontal tail volume coefficient")
-        g = Variable("g", 9.81, "m/s^2", "Gravitational acceleration")
         lh = Variable("l_h", "ft", "horizontal tail moment arm")
         CLhmin = Variable("(C_{L_h})_{min}", 0.75, "-",
                           "max downlift coefficient")
         mh = Variable("m_h", "-", "horizontal tail span effectiveness")
-        cth = Variable("c_{t_h}", "ft", "horizontal tail tip chord")
-        crh = Variable("c_{r_h}", "ft", "horizontal tail root chord")
-        lamh = Variable("\\lambda", lam, "-", "horizontal tail taper ratio")
-        lamhfac = Variable("\\lambda_h/(\\lambda_h+1)", lam/(lam+1), "-",
-                           "horizontal tail taper ratio factor")
-        CLhtmax = Variable("C_{L_{max}}", 1.5, "-",
-                           "maximum CL of horizontal tail")
         mfac = Variable("m_{fac}", 1.1, "-", "horizontal tail margin factor")
-        tau = Variable("\\tau", 0.08, "-", "horizontal tail thickness ratio")
+
+        cb, eta, deta, cbarmac = c_bar(lam, N)
+        subdict = {"\\lambda": lam, "\\bar{c}": cb, "\\eta": eta,
+                   "\\bar{c}_{ave}": (cb[1:]+cb[:-1])/2, "\\tau": 0.08,
+                   "\\bar{c}_{MAC}": cbarmac, "d\\eta": deta, "C_{L_{max}}": 1.5}
+
+        self.surf = AeroSurf(N=N)
+        self.surf.substitutions.update(subdict)
+
+        self.skin = WingSkin()
+        self.skin.substitutions.update({"\\rho_{CFRP}": 0.049})
+        self.foam = WingInterior()
+        self.foam.substitutions.update({"\\bar{A}_{jh01}": 0.0548})
+        self.foam.substitutions.update({"\\rho_{foam}": 0.024})
+
+        self.components = [self.skin, self.foam]
 
         constraints = [
-            bh**2 == ARh*Sh,
-            mh*(1+2/ARh) <= 2*np.pi,
-            W/mfac >= g*rhoskin*Sh + rhofoam*Sh**2/bh*Abar,
-            cth == 2*Sh/bh*lamhfac,
-            crh == cth/lam,
-            lamh == lamh
+            W/mfac >= sum([c["W"] for c in self.components]),
+            mh*(1+2.0/self.surf["AR"]) <= 2*np.pi,
+            self.skin["W"] >= (self.skin["\\rho_{CFRP}"]*self.surf["S"]*2
+                               * self.skin["t"]*self.skin["g"]),
+            self.foam["W"] >= 2*(
+                self.foam["g"]*self.foam["\\rho_{foam}"]
+                *self.foam["\\bar{A}_{jh01}"]*self.surf["c_{ave}"]**2
+                * (self.surf["b"]/2)*self.surf["d\\eta"]).sum()
             ]
 
-        return constraints
+        return constraints, self.surf, self.components
 
     def flight_model(self, state):
         return TailAero(self, state)
diff --git a/gpkitmodels/GP/aircraft/wing/wing.py b/gpkitmodels/GP/aircraft/wing/wing.py
index 6ad4f22c..932bb24a 100644
--- a/gpkitmodels/GP/aircraft/wing/wing.py
+++ b/gpkitmodels/GP/aircraft/wing/wing.py
@@ -56,7 +56,7 @@ def setup(self, N=5, lam=0.5, hollow=False):
             self.components.extend([self.foam])
             constraints.extend([
                 self.foam["W"] >= 2*(
-                    self.foam["g"]*self.foam["\\rho"]
+                    self.foam["g"]*self.foam["\\rho_{foam}"]
                     * self.foam["\\bar{A}_{jh01}"]*self.surf["c_{ave}"]**2
                     * (self.surf["b"]/2)*self.surf["d\\eta"]).sum()])