added weights model hopefully

Model/Propulsion/cruise_comp.py

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+from openmdao.api import ExplicitComponent
+
+rho = 1.225 #density, [kg/m**3]
+
+
+class   WeightComp(ExplicitComponent):  
+
+
+    def setup(self):
+        self.add_input('W',desc='Weight of aircraft')
+        self.add_input('Cd',desc='coefficient of drag')
+        self.add_input('Cl',desc='coefficient of lift')
+        self.add_input('AR',desc='Aspect Ratio')
+        self.add_input('S',desc='Refernce Area')
+        self.add_input('V',desc='Airspeed')
+
+        self.add_output('P_C',desc='Power required for cruise')
+
+        self.declare_partials(of='*', wrt='*', method='fd')
+
+
+
+    def compute(self,inputs,outputs):
+        outputs['P_C'] = (( (2*(inputs['W']**3)*(inputs['Cd']**2))/(inputs['S']*rho*(inputs['Cl']**3)) )**.5)/1000

Model/Propulsion/range_comp.py

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+from openmdao.api import ExplicitComponent
+
+B_density = 400     # [Wh/kg]
+FAA = 0.5           # [hr], flight time required by FAA for emergency
+LO_time = 90/3600   # [hr], time to reach cruise alt
+res = 0.80          # 20% battery reserve for healthy and happy battery :)
+class   RangeComp(ExplicitComponent):  
+
+
+    def setup(self):
+        self.add_input('B_W',desc='Battery Weight')
+        self.add_input('P_L',desc='Power Required @ Liftoff')
+        self.add_input('P_C',desc='Power Required  @ Cruise')
+        self.add_input('V',desc='Speed flying @ cruise')
+
+        self.add_output('R',desc='Max Range W/Reserve & Emergency 30min')
+        self.add_output('t',desc='Time flying @ max range')
+
+        self.declare_partials(of='*', wrt='*', method='fd')
+
+    def compute(self,inputs,outputs):
+        LO_Wh = inputs['P_L']*LO_time*1000  # Energy spent on liftoff
+        time = ( (B_density*inputs['B_W']*res)-LO_Wh-(LO_Wh/2) ) / (1000*inputs['P_C'])
+        dist = (time-FAA)*inputs['V']
+
+        outputs['R'] = dist
+        outputs['t'] = time

Model/Weight/gross_weight_comp.py

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+from openmdao.api import ExplicitComponent
+
+
+class GrossWeightComp(ExplicitComponent):
+
+    def setup(self):
+        self.add_input('Wp')   # weight of payload (passangers)
+        self.add_input('Wb')   # weight of battery
+        self.add_input('We/W0')   # empty over gross
+        self.add_output('W0') # gross weight
+        self.declare_partials('*', '*')
+
+    def compute(self, inputs, outputs):
+        Wp = inputs['Wp']
+        Wb = inputs['Wb']
+        We_W0 = inputs['We/W0']
+        outputs['W0'] = (Wp + Wb) / (1 - We_W0)
+
+    def compute_partials(self, inputs, partials):
+        Wp = inputs['Wp']
+        Wb = inputs['Wb']
+        We_W0 = inputs['We/W0']
+        partials['W0', 'Wp'] = 1. / (1 - We_W0)
+        partials['W0', 'Wb'] = 1. / (1 - We_W0)
+        partials['W0', 'We/W0'] = (Wp + Wb) / (1 - We_W0) ** 2