Python CreateFDM.set_property_value方法代码示例

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def testOrbit(self):
        script_name = 'ball_orbit.xml'
        script_path = self.sandbox.path_to_jsbsim_file('scripts', script_name)
        self.AddAccelerometersToAircraft(script_path)

        # The time step is too small in ball_orbit so let's increase it to 0.1s
        # for a quicker run
        tree = et.parse(self.sandbox.elude(script_path))
        run_tag = tree.getroot().find('./run')
        run_tag.attrib['dt'] = '0.1'
        tree.write(self.sandbox(script_name))

        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path('aircraft')
        fdm.load_script(script_name)
        # Switch the accel on
        fdm.set_property_value('fcs/accelerometer/on', 1.0)
        fdm.run_ic()

        while fdm.run():
            self.assertAlmostEqual(fdm.get_property_value('fcs/accelerometer/X'),
                                   0.0, delta=1E-8)
            self.assertAlmostEqual(fdm.get_property_value('fcs/accelerometer/Y'),
                                   0.0, delta=1E-8)
            self.assertAlmostEqual(fdm.get_property_value('fcs/accelerometer/Z'),
                                   0.0, delta=1E-8)
            self.assertAlmostEqual(fdm.get_property_value('accelerations/a-pilot-x-ft_sec2'),
                                   0.0, delta=1E-8)
            self.assertAlmostEqual(fdm.get_property_value('accelerations/a-pilot-y-ft_sec2'),
                                   0.0, delta=1E-8)
            self.assertAlmostEqual(fdm.get_property_value('accelerations/a-pilot-z-ft_sec2'),
                                   0.0, delta=1E-8)

        del fdm

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def test_fuel_tanks_inertia(self):
        script_path = self.sandbox.path_to_jsbsim_file('scripts', 'c1722.xml')

        # The aircraft c172x does not contain an <inertia_factor> tag so we need
        # to add one.
        tree, aircraft_name, b = CopyAircraftDef(script_path, self.sandbox)
        tank_tag = tree.getroot().find('./propulsion/tank')
        inertia_factor = et.SubElement(tank_tag, 'inertia_factor')
        inertia_factor.text = '1.0'
        tree.write(self.sandbox('aircraft', aircraft_name,  aircraft_name+'.xml'))

        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path('aircraft')
        fdm.load_script(script_path)
        fdm.run_ic()

        contents0 = fdm.get_property_value('propulsion/tank/contents-lbs')
        ixx0 = fdm.get_property_value('propulsion/tank/local-ixx-slug_ft2')
        iyy0 = fdm.get_property_value('propulsion/tank/local-iyy-slug_ft2')
        izz0 = fdm.get_property_value('propulsion/tank/local-izz-slug_ft2')

        # Remove half of the tank contents and check that the inertias are
        # updated accordingly
        fdm.set_property_value('propulsion/tank/contents-lbs', 0.5*contents0)
        contents = fdm.get_property_value('propulsion/tank/contents-lbs')
        ixx = fdm.get_property_value('propulsion/tank/local-ixx-slug_ft2')
        iyy = fdm.get_property_value('propulsion/tank/local-iyy-slug_ft2')
        izz = fdm.get_property_value('propulsion/tank/local-izz-slug_ft2')

        self.assertTrue(abs(contents-0.5*contents0) < 1E-7,
                        msg="The tank content (%f lbs) should be %f lbs" % (contents, 0.5*contents0))
        self.assertTrue(abs(ixx-0.5*ixx0) < 1E-7,
                        msg="The tank inertia Ixx (%f slug*ft^2) should be %f slug*ft^2" % (ixx, 0.5*ixx0))
        self.assertTrue(abs(iyy-0.5*iyy0) < 1E-7,
                        msg="The tank inertia Iyy (%f slug*ft^2) should be %f slug*ft^2" % (iyy, 0.5*iyy0))
        self.assertTrue(abs(izz-0.5*izz0) < 1E-7,
                        msg="The tank inertia Izz (%f slug*ft^2) should be %f slug*ft^2" % (izz, 0.5*izz0))

        # Execute the script and check that the fuel inertias have been updated
        # along with the consumption.
        ExecuteUntil(fdm, 200.0)

        contents = fdm.get_property_value('propulsion/tank/contents-lbs')
        ixx = fdm.get_property_value('propulsion/tank/local-ixx-slug_ft2')
        iyy = fdm.get_property_value('propulsion/tank/local-iyy-slug_ft2')
        izz = fdm.get_property_value('propulsion/tank/local-izz-slug_ft2')

        contents_ratio = contents / contents0
        ixx_ratio = ixx / ixx0
        iyy_ratio = iyy / iyy0
        izz_ratio = izz / izz0

        self.assertTrue(abs(contents_ratio - ixx_ratio) < 1E-7,
                        msg="Ixx does not vary as the tank content does\nIxx ratio=%f\nContents ratio=%f" % (ixx_ratio, contents_ratio))
        self.assertTrue(abs(contents_ratio - iyy_ratio) < 1E-7,
                        msg="Iyy does not vary as the tank content does\nIyy ratio=%f\nContents ratio=%f" % (iyy_ratio, contents_ratio))
        self.assertTrue(abs(contents_ratio - izz_ratio) < 1E-7,
                        msg="Izz does not vary as the tank content does\nIzz ratio=%f\nContents ratio=%f" % (izz_ratio, contents_ratio))

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
def CheckRateLimit(script_path, input_prop, output_prop, incr_limit, decr_limit):
    fdm = CreateFDM(sandbox)
    fdm.set_aircraft_path('aircraft')

    ScriptExecution(fdm, script_path, 1.0)

    fdm.set_property_value(input_prop, 1.0)

    CheckRateValue(fdm, output_prop, incr_limit)

    fdm.set_property_value(input_prop, 0.0)
    CheckRateValue(fdm, output_prop, decr_limit)

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def test_static_hold_down(self):
        fdm = CreateFDM(self.sandbox)
        fdm.load_model('J246')
        aircraft_path = self.sandbox.elude(self.sandbox.path_to_jsbsim_file('aircraft'))
        fdm.load_ic(os.path.join(aircraft_path, 'J246', 'LC39'), False)
        fdm.set_property_value('forces/hold-down', 1.0)
        fdm.run_ic()
        h0 = fdm.get_property_value('position/h-sl-ft')
        t = 0.0

        while t < 420.0:
            fdm.run()
            t = fdm.get_property_value('simulation/sim-time-sec')
            self.assertAlmostEqual(fdm.get_property_value('position/h-sl-ft'),
                                   h0, delta=1E-5)

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def CheckRateLimit(self, input_prop, output_prop, incr_limit, decr_limit):
        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path("aircraft")

        self.ScriptExecution(fdm, 1.0)

        fdm.set_property_value(input_prop, 1.0)

        self.CheckRateValue(fdm, output_prop, incr_limit)

        fdm.set_property_value(input_prop, 0.0)
        self.CheckRateValue(fdm, output_prop, decr_limit)

        # Because JSBSim internals use static pointers, we cannot rely on Python
        # garbage collector to decide when the FDM is destroyed otherwise we can
        # get dangling pointers.
        del fdm

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def test_moments_update(self):
        script_path = self.sandbox.path_to_jsbsim_file('scripts', 'weather-balloon.xml')
        fdm = CreateFDM(self.sandbox)

        fdm.load_script(script_path)
        fdm.run_ic()

        # Moves the radio sonde to modify the CG location
        fdm.set_property_value('inertia/pointmass-location-X-inches', 5.0)

        # Check that the moment is immediately updated accordingly
        fdm.run()
        Fbz = fdm.get_property_value('forces/fbz-buoyancy-lbs')
        CGx = fdm.get_property_value('inertia/cg-x-in') / 12.0 # Converts from in to ft
        Mby = fdm.get_property_value('moments/m-buoyancy-lbsft')
        self.assertTrue(abs(Fbz * CGx + Mby) < 1E-7,
                        msg="Fbz*CGx = %f and Mby = %f do not match" % (-Fbz*CGx, Mby))

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def testSpinningBodyOnOrbit(self):
        script_name = 'ball_orbit.xml'
        script_path = self.sandbox.path_to_jsbsim_file('scripts', script_name)
        self.AddAccelerometersToAircraft(script_path)

        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path('aircraft')
        fdm.load_model('ball')
        # Offset the CG along Y (by 30")
        fdm.set_property_value('inertia/pointmass-weight-lbs[1]', 50.0)

        aircraft_path = self.sandbox.elude(self.sandbox.path_to_jsbsim_file('aircraft', 'ball'))
        fdm.load_ic(os.path.join(aircraft_path, 'reset00.xml'), False)
        # Switch the accel on
        fdm.set_property_value('fcs/accelerometer/on', 1.0)
        # Set the orientation such that the spinning axis is Z.
        fdm.set_property_value('ic/phi-rad', 0.5*math.pi)

        # Set the angular velocities to 0.0 in the ECEF frame. The angular
        # velocity R_{inertial} will therefore be equal to the Earth rotation
        # rate 7.292115E-5 rad/sec
        fdm.set_property_value('ic/p-rad_sec', 0.0)
        fdm.set_property_value('ic/q-rad_sec', 0.0)
        fdm.set_property_value('ic/r-rad_sec', 0.0)
        fdm.run_ic()

        fax = fdm.get_property_value('fcs/accelerometer/X')
        fay = fdm.get_property_value('fcs/accelerometer/Y')
        faz = fdm.get_property_value('fcs/accelerometer/Z')
        cgy_ft = fdm.get_property_value('inertia/cg-y-in') / 12.
        omega = 0.00007292115 # Earth rotation rate in rad/sec

        self.assertAlmostEqual(fdm.get_property_value('accelerations/a-pilot-x-ft_sec2'),
                               fax, delta=1E-8)
        self.assertAlmostEqual(fdm.get_property_value('accelerations/a-pilot-y-ft_sec2'),
                               fay, delta=1E-8)
        self.assertAlmostEqual(fdm.get_property_value('accelerations/a-pilot-z-ft_sec2'),
                               faz, delta=1E-8)

        # Acceleration along X should be zero
        self.assertAlmostEqual(fax, 0.0, delta=1E-8)
        # Acceleration along Y should be equal to r*omega^2
        self.assertAlmostEqual(fay / (cgy_ft * omega * omega), 1.0, delta=1E-7)
        # Acceleration along Z should be zero
        self.assertAlmostEqual(faz, 0.0, delta=1E-8)

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def test_gust_reset(self):
        fdm = CreateFDM(self.sandbox)
        fdm.load_script(self.sandbox.path_to_jsbsim_file('scripts', 'c172_cruise_8K.xml'))
        fdm.set_property_value('simulation/randomseed', 0.0)
        fdm.set_output_directive(self.sandbox.path_to_jsbsim_file('tests', 'output.xml'))

        fdm.run_ic()
        ExecuteUntil(fdm, 15.5)

        ref, current = Table(), Table()
        ref.ReadCSV(self.sandbox('output.csv'))

        fdm.set_property_value('simulation/randomseed', 0.0)
        fdm.reset_to_initial_conditions(1)
        ExecuteUntil(fdm, 15.5)

        current.ReadCSV(self.sandbox('output_0.csv'))

        diff = ref.compare(current)
        self.longMessage = True
        self.assertTrue(diff.empty(), msg='\n'+repr(diff))

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def test_no_script(self):
        fdm = CreateFDM(self.sandbox)
        aircraft_path = self.sandbox.path_to_jsbsim_file('aircraft')
        fdm.set_aircraft_path(aircraft_path)
        fdm.load_model('c172x')

        aircraft_path = os.path.join(self.sandbox.elude(aircraft_path), 'c172x')
        fdm.load_ic(os.path.join(aircraft_path, 'reset01.xml'), False)
        fdm.run_ic()

        self.assertEqual(fdm.get_property_value('simulation/sim-time-sec'), 0.0)
        ExecuteUntil(fdm, 5.0)

        t = fdm.get_property_value('simulation/sim-time-sec')
        fdm.set_property_value('simulation/do_simple_trim', 1)
        self.assertEqual(fdm.get_property_value('simulation/sim-time-sec'), t)

        fdm.reset_to_initial_conditions(1)
        self.assertEqual(fdm.get_property_value('simulation/sim-time-sec'), 0.0)

        del fdm

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def BuildReference(self, script_name):
        # Run the script
        self.script = self.sandbox.path_to_jsbsim_file(os.path.join('scripts',
                                                               script_name))
        self.sandbox.delete_csv_files()
        fdm = CreateFDM(self.sandbox)
        fdm.set_output_directive(self.sandbox.path_to_jsbsim_file('tests',
                                                                  'output.xml'))
        fdm.load_script(self.script)
        fdm.set_property_value('simulation/randomseed', 0.0)

        fdm.run_ic()
        ExecuteUntil(fdm, 50.0)

        self.ref = Table()
        self.ref.ReadCSV(self.sandbox("output.csv"))

        # Since the script will work with modified versions of the aircraft XML
        # definition file, we need to make a copy of the directory that contains
        # all the input data of that aircraft

        tree, self.aircraft_name, self.path_to_jsbsim_aircrafts = CopyAircraftDef(self.script, self.sandbox)
        self.aircraft_path = self.sandbox('aircraft', self.aircraft_name)

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def Compare(self, section):
        # Rerun the script with the modified aircraft definition
        self.sandbox.delete_csv_files()
        fdm = CreateFDM(self.sandbox)
        # We need to tell JSBSim that the aircraft definition is located in the
        # directory build/.../aircraft
        fdm.set_aircraft_path('aircraft')
        fdm.set_output_directive(self.sandbox.path_to_jsbsim_file('tests', 'output.xml'))
        fdm.load_script(self.script)
        fdm.set_property_value('simulation/randomseed', 0.0)

        fdm.run_ic()
        ExecuteUntil(fdm, 50.0)

        mod = Table()
        mod.ReadCSV(self.sandbox('output.csv'))

        # Whether the data is read from the aircraft definition file or from an
        # external file, the results shall be exactly identical. Hence the
        # precision set to 0.0.
        diff = self.ref.compare(mod, 0.0)
        self.assertTrue(diff.empty(),
                        msg='\nTesting section "'+section+'"\n'+repr(diff))

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def testSteadyFlight(self):
        script_name = 'c1722.xml'
        script_path = self.sandbox.path_to_jsbsim_file('scripts', script_name)
        self.AddAccelerometersToAircraft(script_path)

        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path('aircraft')
        fdm.load_script(script_path)
        # Switch the accel on
        fdm.set_property_value('fcs/accelerometer/on', 1.0)
        # Use the standard gravity (i.e. GM/r^2)
        fdm.set_property_value('simulation/gravity-model', 0)
        # Simplifies the transformation to compare the accelerometer with the
        # gravity
        fdm.set_property_value('ic/psi-true-rad', 0.0)
        fdm.run_ic()

        while fdm.get_property_value('simulation/sim-time-sec') <= 0.5:
            fdm.run()

        fdm.set_property_value('simulation/do_simple_trim', 1)
        ax = fdm.get_property_value('accelerations/udot-ft_sec2')
        ay = fdm.get_property_value('accelerations/vdot-ft_sec2')
        az = fdm.get_property_value('accelerations/wdot-ft_sec2')
        g = fdm.get_property_value('accelerations/gravity-ft_sec2')
        theta = fdm.get_property_value('attitude/theta-rad')

        # There is a lag of one time step between the computations of the
        # accelerations and the update of the accelerometer
        fdm.run()
        fax = fdm.get_property_value('fcs/accelerometer/X')
        fay = fdm.get_property_value('fcs/accelerometer/Y')
        faz = fdm.get_property_value('fcs/accelerometer/Z')

        fax -= ax
        fay -= ay
        faz -= az

        # Deltas are relaxed because the tolerances of the trimming algorithm
        # are quite relaxed themselves.
        self.assertAlmostEqual(faz / (g * math.cos(theta)), -1.0, delta=1E-5)
        self.assertAlmostEqual(fax / (g * math.sin(theta)), 1.0, delta=1E-5)
        self.assertAlmostEqual(math.sqrt(fax*fax+fay*fay+faz*faz)/g, 1.0, delta=1E-6)

        del fdm

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def testOnGround(self):
        script_name = 'c1721.xml'
        script_path = self.sandbox.path_to_jsbsim_file('scripts', script_name)
        self.AddAccelerometersToAircraft(script_path)

        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path('aircraft')
        fdm.load_script(script_path)

        # Switch the accel on
        fdm.set_property_value('fcs/accelerometer/on', 1.0)
        # Use the standard gravity (i.e. GM/r^2)
        fdm.set_property_value('simulation/gravity-model', 0)
        # Simplifies the transformation to compare the accelerometer with the
        # gravity
        fdm.set_property_value('ic/psi-true-rad', 0.0)
        fdm.run_ic()

        for i in xrange(500):
            fdm.run()

        ax = fdm.get_property_value('accelerations/udot-ft_sec2')
        ay = fdm.get_property_value('accelerations/vdot-ft_sec2')
        az = fdm.get_property_value('accelerations/wdot-ft_sec2')
        g = fdm.get_property_value('accelerations/gravity-ft_sec2')
        theta = fdm.get_property_value('attitude/theta-rad')

        # There is a lag of one time step between the computations of the
        # accelerations and the update of the accelerometer
        fdm.run()
        fax = fdm.get_property_value('fcs/accelerometer/X')
        fay = fdm.get_property_value('fcs/accelerometer/Y')
        faz = fdm.get_property_value('fcs/accelerometer/Z')

        fax -= ax
        faz -= az

        self.assertAlmostEqual(fay, 0.0, delta=1E-6)
        self.assertAlmostEqual(fax / (g * math.sin(theta)), 1.0, delta=1E-5)
        self.assertAlmostEqual(faz / (g * math.cos(theta)), -1.0, delta=1E-7)

        del fdm

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
class CheckMomentsUpdate(unittest.TestCase):
    def setUp(self):
        self.sandbox = SandBox()

    def tearDown(self):
        self.sandbox.erase()

    def CheckCGPosition(self):
        weight = self.fdm.get_property_value('inertia/weight-lbs')
        empty_weight = self.fdm.get_property_value('inertia/empty-weight-lbs')
        contents = self.fdm.get_property_value('buoyant_forces/gas-cell/contents-mol')
        radiosonde_weight = weight - empty_weight - contents * mol2lbs

        CGx = self.fdm.get_property_value('inertia/cg-x-in')
        CGy = self.fdm.get_property_value('inertia/cg-y-in')
        CGz = self.fdm.get_property_value('inertia/cg-z-in')
        X = self.fdm.get_property_value('inertia/pointmass-location-X-inches')
        Y = self.fdm.get_property_value('inertia/pointmass-location-Y-inches')
        Z = self.fdm.get_property_value('inertia/pointmass-location-Z-inches')

        self.assertAlmostEqual(CGx, X * radiosonde_weight / weight, delta = 1E-7)
        self.assertAlmostEqual(CGy, Y * radiosonde_weight / weight, delta = 1E-7)
        self.assertAlmostEqual(CGz, Z * radiosonde_weight / weight, delta = 1E-7)

    def test_moments_update(self):
        script_path = self.sandbox.path_to_jsbsim_file('scripts', 'weather-balloon.xml')
        self.fdm = CreateFDM(self.sandbox)

        self.fdm.load_script(script_path)
        self.fdm.set_output_directive(self.sandbox.path_to_jsbsim_file('tests', 'output.xml'))
        self.fdm.run_ic()

        self.CheckCGPosition()

        dt = self.fdm.get_property_value('simulation/dt')
        ExecuteUntil(self.fdm, 1.0-2.0*dt)

        self.CheckCGPosition()

        # Moves the radio sonde to modify the CG location
        self.fdm.set_property_value('inertia/pointmass-location-X-inches', 5.0)

        # Check that the moment is immediately updated accordingly
        self.fdm.run()
        self.CheckCGPosition()

        Fbx = self.fdm.get_property_value('forces/fbx-buoyancy-lbs')
        Fbz = self.fdm.get_property_value('forces/fbz-buoyancy-lbs')
        CGx = self.fdm.get_property_value('inertia/cg-x-in') / 12.0 # Converts from in to ft
        CGz = self.fdm.get_property_value('inertia/cg-z-in') / 12.0
        Mby = self.fdm.get_property_value('moments/m-buoyancy-lbsft')

        self.assertAlmostEqual(Fbx * CGz - Fbz * CGx, Mby, delta=1E-7,
                               msg="Fbx*CGz-Fbz*CGx = %f and Mby = %f do not match" % (Fbx*CGz-Fbz*CGx, Mby))

        # One further step to log the same results in the output file
        self.fdm.run()
        self.CheckCGPosition()

        csv = Table()
        csv.ReadCSV(self.sandbox('output.csv'))
        Mby = csv.get_column('M_{Buoyant} (ft-lbs)')[-1]
        Fbx = csv.get_column('F_{Buoyant x} (lbs)')[-1]
        Fbz = csv.get_column('F_{Buoyant z} (lbs)')[-1]

        self.assertAlmostEqual(Fbx * CGz - Fbz * CGx, Mby, delta=1E-7,
                               msg="Fbx*CGz-Fbz*CGx = %f and Mby = %f do not match" % (Fbx*CGz-Fbz*CGx, Mby))

# 需要导入模块: from JSBSim_utils import CreateFDM [as 别名]
# 或者: from JSBSim_utils.CreateFDM import set_property_value [as 别名]
    def test_pitot_angle(self):
        script_name = 'ball_chute.xml'
        script_path = self.sandbox.path_to_jsbsim_file('scripts', script_name)

        # Add a Pitot angle to the Cessna 172
        tree, aircraft_name, path_to_jsbsim_aircrafts = CopyAircraftDef(script_path, self.sandbox)
        root = tree.getroot()
        metrics_tag = root.find('./metrics')
        pitot_tag = et.SubElement(metrics_tag, 'pitot_angle')
        pitot_tag.attrib['unit'] = 'DEG'
        pitot_tag.text = '5.0'
        contact_tag = root.find('./ground_reactions/contact')
        contact_tag.attrib['type'] = 'STRUCTURE'
        tree.write(self.sandbox('aircraft', aircraft_name,
                                aircraft_name+'.xml'))

        fdm = CreateFDM(self.sandbox)
        fdm.set_aircraft_path('aircraft')
        fdm.load_model('ball')
        pitot_angle = float(pitot_tag.text) * math.pi / 180.
        weight = fdm.get_property_value('inertia/weight-lbs')
        spring_tag = contact_tag.find('./spring_coeff')
        spring_coeff = float(spring_tag.text)
        print "Weight=%d Spring=%d" % (weight, spring_coeff)
        fdm.set_property_value('ic/h-sl-ft', weight / spring_coeff)
        fdm.set_property_value('forces/hold-down', 1.0)
        fdm.run_ic()

        ExecuteUntil(fdm, 10.)

        for i in xrange(36):
            for j in xrange(-9, 10):
                angle = math.pi * i / 18.0
                angle2 = math.pi * j / 18.0
                ca2 = math.cos(angle2)
                fdm.set_property_value('atmosphere/wind-north-fps',
                                       10. * math.cos(angle) * ca2)
                fdm.set_property_value('atmosphere/wind-east-fps',
                                       10. * math.sin(angle) * ca2)
                fdm.set_property_value('atmosphere/wind-down-fps',
                                       10. * math.sin(angle2))
                fdm.run()

                vg = fdm.get_property_value('velocities/vg-fps')
                self.assertAlmostEqual(vg, 0.0, delta=1E-7)

                vt = fdm.get_property_value('velocities/vt-fps')
                self.assertAlmostEqual(vt, 10., delta=1E-7)

                mach = vt / fdm.get_property_value('atmosphere/a-fps')
                P = fdm.get_property_value('atmosphere/P-psf')
                pt = P * math.pow(1+0.2*mach*mach, 3.5)
                psl = fdm.get_property_value('atmosphere/P-sl-psf')
                rhosl = fdm.get_property_value('atmosphere/rho-sl-slugs_ft3')
                A = math.pow((pt-P)/psl+1.0, 1.0/3.5)
                alpha = fdm.get_property_value('aero/alpha-rad')
                beta = fdm.get_property_value('aero/beta-rad')
                vc = math.sqrt(7.0*psl/rhosl*(A-1.0))*math.cos(alpha+pitot_angle)*math.cos(beta)

                self.assertAlmostEqual(fdm.get_property_value('velocities/vc-kts'),
                                       max(0.0, vc) / 1.68781, delta=1E-7)