def gps2stall(GS,
TK,
Hp,
T,
temp_units='C',
alt_units=default_alt_units,
speed_units=default_speed_units,
GPS_units=default_speed_units):
"""
Return the CAS at the stall, given four GPS ground speeds, GPS tracks,
altitude and temperature.
speed_units = CAS units. May be 'kt', 'mph', 'km/h', 'm/s' and 'ft/s'.
GS_units = GPS ground speed units. 'kt', 'mph', 'km/h', 'm/s' and 'ft/s'.
HP = pressure altitude. May be feet ('ft'), metres ('m'), kilometres ('km'),
statute miles, ('sm') or nautical miles ('nm').
The temperature may be in deg C, F, K or R.
If the units are not specified, the units in default_units.py are used.
Conduct four stalls, in a four sided box pattern, with all stalls at the same
pressure altitude. The data reduction algorithm calculates the TAS using Doug
Gray's GPS to TAS method, using four different combinations of three legs. If
the data quality is high, all four TAS values will be similar, with a low standard
deviation.
The TAS at the stall is converted to CAS, using pressure altitude and
temperature.
Returns CAS and standard deviation of the CAS value.
Examples:
>>> gps2stall([44, 104, 157, 131], [258, 29, 91, 150], 7000, 14, temp_units='F', GPS_units='km/h')
(50.322235245211225, 0.6583323098888626)
"""
tas, std_dev = SSEC.gps2tas(GS, TK, verbose=1)
tas = U.speed_conv(tas, from_units=GPS_units, to_units=speed_units)
std_dev = U.speed_conv(std_dev, from_units=GPS_units, to_units=speed_units)
cas = A.tas2cas(tas,
Hp,
T,
temp_units=temp_units,
alt_units=alt_units,
speed_units=speed_units)
std_dev = std_dev * cas / tas # factor standard deviation to reference CAS vs TAS
return cas, std_dev
def temp2speed_of_sound(temp, temp_units=default_temp_units,
speed_units=default_speed_units):
"""
Return the speed of sound, given the air temperature.
The temperature units may be deg C, F, K or R ('C', 'F', 'K' or 'R').
The speed units may be 'kt', 'mph', 'km/h', 'm/s' and 'ft/s'.
If the units are not specified, the units in default_units.py are used.
Examples:
Determine speed of sound in knots at 15 deg (default temperature units):
>>> temp2speed_of_sound(15)
661.47882487301808
Determine speed of sound in mph at 120 deg F:
>>> temp2speed_of_sound(120, speed_units = 'mph', temp_units = 'F')
804.73500154991291
"""
# function tested in tests/test_std_atm.py
temp = U.temp_conv(temp, from_units=temp_units, to_units='K')
speed_of_sound = M.sqrt((1.4 * Rd) * temp)
speed_of_sound = U.speed_conv(speed_of_sound, from_units='m/s',
to_units=speed_units)
return speed_of_sound
def cd2drag(
Cd,
eas,
wing_area,
speed_units=default_speed_units,
area_units=default_area_units,
drag_units=default_weight_units,
):
"""
Returns the drag, given coefficient of drag, equivalent airspeed, and wing
area.
Example:
>>> cd2drag(.138, 100, 10, speed_units='km/h', area_units='m**2',\
drag_units='N')
652.1990740740742
"""
eas = U.speed_conv(eas, from_units=speed_units, to_units='m/s')
wing_area = U.area_conv(wing_area, from_units=area_units, to_units='m**2')
drag = (((0.5 * Rho0) * eas**2) * wing_area) * Cd
drag = U.force_conv(drag, from_units='N', to_units=drag_units)
return drag
def _pwr_error(eas_guess,
altitude,
weight,
power,
rpm,
temp='std',
temp_units='C',
rv='F1',
wing_area=102,
speed_units='kt',
flap=0,
prop_eff=0.78):
tas_guess = A.eas2tas(eas_guess,
altitude,
temp=temp,
speed_units=speed_units)
tas_guess_fts = U.speed_conv(tas_guess,
from_units=speed_units,
to_units='ft/s')
power_avail = power * prop_eff
drag = F.eas2drag(eas_guess,
weight,
wing_area,
rv=rv,
flap=flap,
speed_units=speed_units)
power_req = tas_guess_fts * drag / 550.
error = power_avail - power_req
return error, tas_guess
def cl2cas(
Cl,
altitude,
weight,
wing_area,
load_factor=1,
speed_units=default_speed_units,
alt_units=default_alt_units,
weight_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the calibrated airspeed, given coefficient of lift, altitude,
weight, and wing area.
Load factor is an optional input. The load factor, if not provided,
defaults to 1.
"""
weight = U.wt_conv(weight, from_units=weight_units, to_units='kg')
wing_area = U.area_conv(wing_area, from_units=area_units, to_units='m**2')
eas = ((((2. * weight) * g) * load_factor) /
((Rho0 * wing_area) * Cl))**0.5
eas = U.speed_conv(eas, from_units='m/s', to_units=speed_units)
cas = A.eas2cas(eas, altitude, speed_units, alt_units)
return cas
def cd2drag(
Cd,
eas,
wing_area,
speed_units=default_speed_units,
area_units=default_area_units,
drag_units=default_weight_units,
):
"""
Returns the drag, given coefficient of drag, equivalent airspeed, and wing
area.
Example:
>>> cd2drag(.138, 100, 10, speed_units='km/h', area_units='m**2',\
drag_units='N')
652.19907407407425
"""
eas = U.speed_conv(eas, from_units=speed_units, to_units='m/s')
wing_area = U.area_conv(wing_area, from_units=area_units,
to_units='m**2')
drag = (((0.5 * Rho0) * eas ** 2) * wing_area) * Cd
drag = U.force_conv(drag, from_units='N', to_units=drag_units)
return drag
def aoc(prop, altitude, eas, weight, power, rpm, temp = 'std', temp_units = 'C', \
rv = '8', wing_area = 110, speed_units = 'kt', flap = 0):
"""
Returns the climb or descent gradient.
Runs with zero power at 1800 lb show best glide speed for RV-8 of:
98 kt at 1800 lb
86 kt at 1400 lb
best angle of climb:
66 kt at 1800 lb
"""
tas = A.eas2tas(eas, altitude, temp = temp, speed_units = speed_units)
tas_fts = U.speed_conv(tas, from_units = speed_units, to_units = 'ft/s')
prop_eff = PM.prop_eff(prop, power, rpm, tas, altitude, temp = temp, \
temp_units = 'C', speed_units = speed_units)
power_avail = power * prop_eff
drag = FT.eas2drag(eas, weight, wing_area, rv = rv, flap = flap, \
speed_units = speed_units)
power_req = tas_fts * drag / 550.
excess_power = power_avail - power_req
roc = excess_power * 550 / weight
gradient = roc / tas_fts
return gradient
def tip_mach(tas,
rpm,
temperature,
dia,
speed_units='kt',
temp_units='C',
dia_units='in'):
"""
Returns the mach number of the propeller blade tip, given the
true airspeed (tas), revolutions per minute (rpm), temperature and
propeller diameter.
The speed units may be specified as "kt", "mph", "km/h" or "ft/s", but
default to "kt" if not specified.
The temperature units may be specified as "C", "F", "K" or "R", but
default to deg C if not specified.
The diameter units may be specified as "in", "ft", or "m", but default
to inches if not specified.
"""
dia = U.length_conv(dia, from_units=dia_units, to_units='m')
tas = U.speed_conv(tas, from_units=speed_units, to_units='m/s')
speed_of_sound = SA.temp2speed_of_sound(temperature,
temp_units=temp_units,
speed_units='m/s')
rotation_speed = dia * rpm * M.pi / 60
tip_speed = M.sqrt(tas**2 + rotation_speed**2)
tip_mach = tip_speed / speed_of_sound
return tip_mach
def run_tests(cd0 = 0.0221, e = 0.825):
"""
Run all test cases to compare drag polar model against CAFE results.
"""
sum_sq = 0
wt_value_tot = 0
wing_area = 110
prop = PM.Prop('7666-4RV')
for n, test in enumerate(level_test_cases):
tas = test[0]
dalt = test[1]
wt = test[2]
rpm = test[3]
mp = test[4]
wt_value = test[5]
eas = A.tas2eas(tas, dalt, speed_units = 'mph')
tas_fts = U.speed_conv(tas, from_units = 'mph', to_units = 'ft/s')
cl = FT.eas2cl(eas, wt, wing_area, speed_units = 'mph')
cd = FT.cl2cd_test(cl, cd0, e, flap = 0)
drag = FT.cd2drag(cd, eas, wing_area, speed_units = 'mph')
drag_power = drag * tas_fts / 550.
power = IO.pwr(rpm, mp, dalt)
prop_eff = PM.prop_eff(prop, power, rpm, tas, dalt, speed_units = 'mph')
thrust_power = power * prop_eff
excess_power = thrust_power - drag_power
print 'Case', n, 'Altitude =', dalt, 'TAS =', tas, 'EAS =', eas, 'Excess power =', excess_power
sum_sq += wt_value * excess_power ** 2
wt_value_tot += wt_value
print 'Average sum of squares of excess power =', \
(sum_sq / wt_value_tot) ** 0.5
def temp2speed_of_sound(temp,
temp_units=default_temp_units,
speed_units=default_speed_units):
"""
Return the speed of sound, given the air temperature.
The temperature units may be deg C, F, K or R ('C', 'F', 'K' or 'R').
The speed units may be 'kt', 'mph', 'km/h', 'm/s' and 'ft/s'.
If the units are not specified, the units in default_units.py are used.
Examples:
Determine speed of sound in knots at 15 deg (default temperature units):
>>> temp2speed_of_sound(15)
661.47882487301808
Determine speed of sound in mph at 120 deg F:
>>> temp2speed_of_sound(120, speed_units = 'mph', temp_units = 'F')
804.73500154991291
"""
# function tested in tests/test_std_atm.py
temp = U.temp_conv(temp, from_units=temp_units, to_units='K')
speed_of_sound = M.sqrt((1.4 * Rd) * temp)
speed_of_sound = U.speed_conv(speed_of_sound,
from_units='m/s',
to_units=speed_units)
return speed_of_sound
def cl2lift(
Cl,
eas,
wing_area,
speed_units=default_speed_units,
lift_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the lift, given coefficient of lift, equivalent airspeed, and wing
area.
"""
eas = U.speed_conv(eas, from_units=speed_units, to_units='m/s')
wing_area = U.area_conv(wing_area, from_units=area_units,
to_units='m**2')
lift = (((0.5 * Rho0) * eas ** 2.) * wing_area) * Cl
if lift_units == 'kg':
lift = U.force_conv(lift, 'N', 'lb')
lift = U.mass_conv(lift, 'lb', 'kg')
else:
lift = U.force_conv(lift, 'N', lift_units)
return lift
def aoc(prop, altitude, eas, weight, power, rpm, temp = 'std', temp_units = 'C', \
rv = '8', wing_area = 110, speed_units = 'kt', flap = 0):
"""
Returns the climb or descent gradient.
Runs with zero power at 1800 lb show best glide speed for RV-8 of:
98 kt at 1800 lb
86 kt at 1400 lb
best angle of climb:
66 kt at 1800 lb
"""
tas = A.eas2tas(eas, altitude, temp=temp, speed_units=speed_units)
tas_fts = U.speed_conv(tas, from_units=speed_units, to_units='ft/s')
prop_eff = PM.prop_eff(prop, power, rpm, tas, altitude, temp = temp, \
temp_units = 'C', speed_units = speed_units)
power_avail = power * prop_eff
drag = FT.eas2drag(eas, weight, wing_area, rv = rv, flap = flap, \
speed_units = speed_units)
power_req = tas_fts * drag / 550.
excess_power = power_avail - power_req
roc = excess_power * 550 / weight
gradient = roc / tas_fts
return gradient
def cl2cas(
Cl,
altitude,
weight,
wing_area,
load_factor=1,
speed_units=default_speed_units,
alt_units=default_alt_units,
weight_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the calibrated airspeed, given coefficient of lift, altitude,
weight, and wing area.
Load factor is an optional input. The load factor, if not provided,
defaults to 1.
"""
weight = U.wt_conv(weight, from_units=weight_units, to_units='kg')
wing_area = U.area_conv(wing_area, from_units=area_units,
to_units='m**2')
eas = ((((2. * weight) * g) * load_factor) / ((Rho0 * wing_area)
* Cl)) ** 0.5
eas = U.speed_conv(eas, from_units='m/s', to_units=speed_units)
cas = A.eas2cas(eas, altitude, speed_units, alt_units)
return cas
def eff2thrust(eff, bhp, TAS, power_units="hp", speed_units="kt", thrust_units="lb"):
"""
Returns thrust, given prop efficiency, true airspeed and brake power.
Matches the results from the Hartzell prop map program fairly closely.
"""
TAS = U.speed_conv(TAS, from_units=speed_units, to_units="m/s")
bhp = U.power_conv(bhp, from_units=power_units, to_units="W")
thrust = eff * bhp / TAS
return U.force_conv(thrust, from_units="N", to_units=thrust_units)
def gps2stall(GS, TK, Hp, T, temp_units='C', alt_units=default_alt_units, speed_units=default_speed_units, GPS_units=default_speed_units):
"""
Return the CAS at the stall, given four GPS ground speeds, GPS tracks,
altitude and temperature.
speed_units = CAS units. May be 'kt', 'mph', 'km/h', 'm/s' and 'ft/s'.
GS_units = GPS ground speed units. 'kt', 'mph', 'km/h', 'm/s' and 'ft/s'.
HP = pressure altitude. May be feet ('ft'), metres ('m'), kilometres ('km'),
statute miles, ('sm') or nautical miles ('nm').
The temperature may be in deg C, F, K or R.
If the units are not specified, the units in default_units.py are used.
Conduct four stalls, in a four sided box pattern, with all stalls at the same
pressure altitude. The data reduction algorithm calculates the TAS using Doug
Gray's GPS to TAS method, using four different combinations of three legs. If
the data quality is high, all four TAS values will be similar, with a low standard
deviation.
The TAS at the stall is converted to CAS, using pressure altitude and
temperature.
Returns CAS and standard deviation of the CAS value.
Examples:
>>> gps2stall([44, 104, 157, 131], [258, 29, 91, 150], 7000, 14, temp_units='F', GPS_units='km/h')
(50.322235245211225, 0.6583323098888626)
"""
tas, std_dev = SSEC.gps2tas(GS, TK, verbose=1)
tas = U.speed_conv(tas, from_units=GPS_units, to_units=speed_units)
std_dev = U.speed_conv(std_dev, from_units=GPS_units, to_units=speed_units)
cas = A.tas2cas(tas, Hp, T, temp_units=temp_units, alt_units=alt_units, speed_units=speed_units)
std_dev = std_dev * cas / tas # factor standard deviation to reference CAS vs TAS
return cas, std_dev
def eff2thrust(eff,
bhp,
TAS,
power_units='hp',
speed_units='kt',
thrust_units='lb'):
"""
Returns thrust, given prop efficiency, true airspeed and brake power.
Matches the results from the Hartzell prop map program fairly closely.
"""
TAS = U.speed_conv(TAS, from_units=speed_units, to_units='m/s')
bhp = U.power_conv(bhp, from_units=power_units, to_units='W')
thrust = eff * bhp / TAS
return U.force_conv(thrust, from_units='N', to_units=thrust_units)
def _pwr_error(eas_guess, altitude, weight, power, rpm, temp = 'std', \
temp_units = 'C', rv = 'F1', wing_area = 102, speed_units = 'kt', \
flap = 0, prop_eff=0.78):
tas_guess = A.eas2tas(eas_guess, altitude, temp = temp, \
speed_units = speed_units)
tas_guess_fts = U.speed_conv(tas_guess, from_units = speed_units, \
to_units = 'ft/s')
power_avail = power * prop_eff
drag = F.eas2drag(eas_guess, weight, wing_area, rv = rv, flap = flap,\
speed_units = speed_units)
power_req = tas_guess_fts * drag / 550.
error = power_avail - power_req
return error, tas_guess
def _pwr_error(prop, eas_guess, altitude, weight, power, rpm, temp = 'std', \
temp_units = 'C', rv = '8', wing_area = 110, speed_units = 'kt', \
flap = 0, wheel_pants = 1):
tas_guess = A.eas2tas(eas_guess, altitude, temp = temp, \
speed_units = speed_units, temp_units = temp_units)
tas_guess_fts = U.speed_conv(tas_guess, from_units = speed_units, \
to_units = 'ft/s')
prop_eff = PM.prop_eff(prop, power, rpm, tas_guess, altitude, temp = temp,\
temp_units = temp_units, speed_units = speed_units)
power_avail = power * prop_eff
drag = FT.eas2drag(eas_guess, weight, wing_area, rv = rv, flap = flap,\
speed_units = speed_units, wheel_pants = wheel_pants)
power_req = tas_guess_fts * drag / 550.
error = power_avail - power_req
return error, tas_guess
def Re(V, L, KV, speed_units=default_speed_units, length_units=default_length_units,
#kinematic_viscosity_units=default_kinematic_viscosity_units
):
"""
Return Reynold's number, given velocity, characteristic length and kinematic viscosity'
V = velocity
L = characteristic length
KV = kinematic viscosity
"""
V = U.speed_conv(V, speed_units, 'm/s')
L = U.length_conv(L, length_units, 'm')
# KV = U.kinematic_viscosity_conv(KV, kinematic_viscosity_units, '??')
Re = V * L / KV
return Re
def advance_ratio(tas, rpm, dia, speed_units="kt", dia_units="in"):
"""
Returns the propeller advance ratio, J, given the
revolutions per minute (rpm), true airspeed (tas), temperature and
propeller diameter.
The advance ratio is the forward distance that the propeller advances
during one revolution, divided by the diameter of the propeller.
The diameter units may be specified as "in", "ft", or "m", but default
to inches if not specified.
"""
tas = U.speed_conv(tas, from_units=speed_units, to_units="m/s")
dia = U.length_conv(dia, from_units=dia_units, to_units="m")
advance_ratio = tas * 60.0 / (rpm * dia)
return advance_ratio
def _pwr_error(prop, eas_guess, altitude, weight, power, rpm, temp = 'std', \
temp_units = 'C', rv = '8', wing_area = 110, speed_units = 'kt', \
flap = 0, wheel_pants = 1):
tas_guess = A.eas2tas(eas_guess, altitude, temp = temp, \
speed_units = speed_units, temp_units = temp_units)
tas_guess_fts = U.speed_conv(tas_guess, from_units = speed_units, \
to_units = 'ft/s')
prop_eff = PM.prop_eff(prop, power, rpm, tas_guess, altitude, temp = temp,\
temp_units = temp_units, speed_units = speed_units)
power_avail = power * prop_eff
drag = FT.eas2drag(eas_guess, weight, wing_area, rv = rv, flap = flap,\
speed_units = speed_units, wheel_pants = wheel_pants)
power_req = tas_guess_fts * drag / 550.
error = power_avail - power_req
return error, tas_guess
def p(tas, dalt, wt, rpm, mp, prop):
"""
test function for RV-8A drag, to compare against CAFE foundation level
flt data.
prop is a prop_map.Prop instance.
"""
eas = A.tas2eas(tas, dalt, speed_units='mph')
# tas = A.cas2tas(cas, dalt, speed_units = 'mph')
tas_fts = U.speed_conv(tas, from_units='mph', to_units='ft/s')
drag = FT.eas2drag(eas, wt, 110, rv='8a', speed_units='mph')
drag_power = drag * tas_fts / 550.
power = IO.pwr(rpm, mp, dalt)
prop_eff = PM.prop_eff(prop, power, rpm, tas, dalt, speed_units='mph')
thrust_power = power * prop_eff
excess_power = thrust_power - drag_power
return excess_power
def advance_ratio(tas, rpm, dia, speed_units='kt', dia_units='in'):
"""
Returns the propeller advance ratio, J, given the
revolutions per minute (rpm), true airspeed (tas), temperature and
propeller diameter.
The advance ratio is the forward distance that the propeller advances
during one revolution, divided by the diameter of the propeller.
The diameter units may be specified as "in", "ft", or "m", but default
to inches if not specified.
"""
tas = U.speed_conv(tas, from_units=speed_units, to_units='m/s')
dia = U.length_conv(dia, from_units=dia_units, to_units='m')
advance_ratio = tas * 60. / (rpm * dia)
return advance_ratio
def p(tas, dalt, wt, rpm, mp, prop):
"""
test function for RV-8A drag, to compare against CAFE foundation level
flt data.
prop is a prop_map.Prop instance.
"""
eas = A.tas2eas(tas, dalt, speed_units = 'mph')
# tas = A.cas2tas(cas, dalt, speed_units = 'mph')
tas_fts = U.speed_conv(tas, from_units = 'mph', to_units = 'ft/s')
drag = FT.eas2drag(eas, wt, 110, rv = '8a', speed_units = 'mph')
drag_power = drag * tas_fts / 550.
power = IO.pwr(rpm, mp, dalt)
prop_eff = PM.prop_eff(prop, power, rpm, tas, dalt, speed_units = 'mph')
thrust_power = power * prop_eff
excess_power = thrust_power - drag_power
return excess_power
def roc(altitude, eas, weight, power, rpm, temp = 'std', temp_units = 'C', \
rv = 'F1', wing_area = 102, speed_units = 'kt', flap = 0, \
prop_eff = 0.7, load_factor = 1):
"""
Returns the rate of climb or descent.
"""
# PM.read_data_files_csv(base_name = prop)
tas = A.eas2tas(eas, altitude, temp=temp, speed_units=speed_units)
tas_fts = U.speed_conv(tas, from_units=speed_units, to_units='ft/s')
# prop_eff = PM.prop_eff(power, rpm, tas, altitude, temp = temp, \
# temp_units = 'C', speed_units = speed_units)
power_avail = power * prop_eff
drag = F.eas2drag(eas, weight, wing_area, rv = rv, flap = flap, \
speed_units = speed_units, load_factor = load_factor)
power_req = tas_fts * drag / 550.
excess_power = power_avail - power_req
roc = excess_power * 33000 / weight
return roc
def roc(prop, altitude, eas, weight, power, rpm, temp = 'std', temp_units = 'C', \
rv = '8', wing_area = 110, speed_units = 'kt', flap = 0, \
load_factor = 1, wheel_pants = 1, prop_factor=1):
"""
Returns the rate of climb or descent.
"""
# PM.read_data_files_csv(base_name = prop)
tas = A.eas2tas(eas, altitude, temp = temp, speed_units = speed_units)
tas_fts = U.speed_conv(tas, from_units = speed_units, to_units = 'ft/s')
prop_eff = PM.prop_eff(prop, power, rpm, tas, altitude, temp = temp, \
temp_units = 'C', speed_units = speed_units) * prop_factor
power_avail = power * prop_eff
drag = FT.eas2drag(eas, weight, wing_area, rv = rv, flap = flap, \
speed_units = speed_units, load_factor = load_factor, wheel_pants = wheel_pants)
power_req = tas_fts * drag / 550.
excess_power = power_avail - power_req
roc = excess_power * 33000 / weight
return roc
def alt2FP_speed(engine, prop, blade_angle, alt, weight = 1800, temp = 'std', \
temp_units = 'C', rv = '8', wing_area = 110, alt_units='ft', speed_units = 'kt' , \
MP_loss = 1.322, ram = 0.5, pwr_factor=1, mixture='pwr', MP='WOT', wheel_pants=1):
"""
Returns the predicted speed at full throttle for aircraft with fixed pitch prop.
The MP_loss is the MP lost in the induction tract at full throttle at 2700
rpm at MSL. The default value is from the Lycoming power charts.
The ram is the percentage of available ram recovery pressure that is
achieved in the MP.
"""
tas_low = 80
tas_high = 250
pwr_tolerance = .1
while 1:
tas_guess = (tas_low + tas_high) / 2.
tas_guess_fts = U.speed_conv(tas_guess, from_units = speed_units, to_units = 'ft/s')
rpm = tas2rpm(tas_guess, engine, prop, blade_angle, alt, temp=temp, alt_units=alt_units, temp_units=temp_units, speed_units=speed_units, MP=MP)
if MP == 'WOT':
MP = MP_pred(tas_guess, alt, rpm, rpm_base = 2700., MP_loss = MP_loss, ram = ram, temp=temp)
bhp = engine.pwr(rpm, MP, alt, temp=temp, alt_units=alt_units, temp_units=temp_units)
prop_eff = PM.prop_eff(prop, bhp, rpm, tas_guess, alt, temp = temp, temp_units = temp_units, speed_units = speed_units)
power_avail = bhp * prop_eff
eas_guess = A.tas2eas(tas_guess, alt, temp)
drag = FT.eas2drag(eas_guess, weight, wing_area, rv = rv, flap = 0, speed_units = speed_units, wheel_pants = wheel_pants)
power_req = tas_guess_fts * drag / 550.
if M.fabs(power_avail - power_req) < pwr_tolerance:
# print "MP = %.3f" % MP
# print "Pwr = %.2f"% bhp
# print "Prop Efficiency = %.3f, and power available = %.1f thp" % (prop_eff, power_avail)
return tas_guess, rpm, bhp
if power_req > power_avail:
tas_high = tas_guess
else:
tas_low = tas_guess
def Re(
V,
L,
KV,
speed_units=default_speed_units,
length_units=default_length_units,
#kinematic_viscosity_units=default_kinematic_viscosity_units
):
"""
Return Reynold's number, given velocity, characteristic length and kinematic viscosity'
V = velocity
L = characteristic length
KV = kinematic viscosity
"""
V = U.speed_conv(V, speed_units, 'm/s')
L = U.length_conv(L, length_units, 'm')
# KV = U.kinematic_viscosity_conv(KV, kinematic_viscosity_units, '??')
Re = V * L / KV
return Re
def cl2tas(
Cl,
altitude,
weight,
wing_area,
temperature='std',
load_factor=1,
speed_units=default_speed_units,
alt_units=default_alt_units,
weight_units=default_weight_units,
area_units=default_area_units,
temp_units=default_temp_units,
):
"""
Returns the true airspeed, given coefficient of lift, altitude, weight,
and wing area.
Temperature and load factor are optional inputs. The temperature, if
not provided, defaults to the standard temperature for the altitude.
The load factor, if not provided, defaults to 1.
"""
weight = U.wt_conv(weight, from_units=weight_units, to_units='kg')
wing_area = U.area_conv(wing_area, from_units=area_units,
to_units='m**2')
eas = ((((2. * weight) * g) * load_factor) / ((Rho0 * wing_area)
* Cl)) ** 0.5
eas = U.speed_conv(eas, from_units='m/s', to_units=speed_units)
tas = A.eas2tas(
eas,
altitude,
temperature,
speed_units,
alt_units,
temp_units=temp_units,
)
return tas
def eas2cl(
eas,
weight,
wing_area,
load_factor=1,
speed_units=default_speed_units,
weight_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the coefficient of lift, given equivalent airspeed, weight, and
wing area.
Load factor is an optional input. The load factor, if not provided,
defaults to 1.
Example:
if the wing area is 110 square feet,
and the weight is 1800 lb,
and the eas is 55 kt,
in straight and level flight (so the load factor = 1),
then:
>>> S = 110
>>> W = 1800
>>> EAS = 55
>>> eas2cl(EAS, W, S, speed_units='kt', weight_units='lb', area_units='ft**2')
1.597820083228606
"""
eas = U.speed_conv(eas, from_units=speed_units, to_units='m/s')
weight = U.wt_conv(weight, from_units=weight_units, to_units='kg')
wing_area = U.area_conv(wing_area, from_units=area_units,
to_units='m**2')
Cl = (((2. * weight) * g) * load_factor) / ((Rho0 * wing_area) * eas
** 2.)
return Cl
def cl2tas(
Cl,
altitude,
weight,
wing_area,
temperature='std',
load_factor=1,
speed_units=default_speed_units,
alt_units=default_alt_units,
weight_units=default_weight_units,
area_units=default_area_units,
temp_units=default_temp_units,
):
"""
Returns the true airspeed, given coefficient of lift, altitude, weight,
and wing area.
Temperature and load factor are optional inputs. The temperature, if
not provided, defaults to the standard temperature for the altitude.
The load factor, if not provided, defaults to 1.
"""
weight = U.wt_conv(weight, from_units=weight_units, to_units='kg')
wing_area = U.area_conv(wing_area, from_units=area_units, to_units='m**2')
eas = ((((2. * weight) * g) * load_factor) /
((Rho0 * wing_area) * Cl))**0.5
eas = U.speed_conv(eas, from_units='m/s', to_units=speed_units)
tas = A.eas2tas(
eas,
altitude,
temperature,
speed_units,
alt_units,
temp_units=temp_units,
)
return tas
def eas2cl(
eas,
weight,
wing_area,
load_factor=1,
speed_units=default_speed_units,
weight_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the coefficient of lift, given equivalent airspeed, weight, and
wing area.
Load factor is an optional input. The load factor, if not provided,
defaults to 1.
Example:
if the wing area is 110 square feet,
and the weight is 1800 lb,
and the eas is 55 kt,
in straight and level flight (so the load factor = 1),
then:
>>> S = 110
>>> W = 1800
>>> EAS = 55
>>> eas2cl(EAS, W, S, speed_units='kt', weight_units='lb', area_units='ft**2')
1.597820083228606
"""
eas = U.speed_conv(eas, from_units=speed_units, to_units='m/s')
weight = U.wt_conv(weight, from_units=weight_units, to_units='kg')
wing_area = U.area_conv(wing_area, from_units=area_units, to_units='m**2')
Cl = (((2. * weight) * g) * load_factor) / ((Rho0 * wing_area) * eas**2.)
return Cl
def tip_mach(tas, rpm, temperature, dia, speed_units="kt", temp_units="C", dia_units="in"):
"""
Returns the mach number of the propeller blade tip, given the
true airspeed (tas), revolutions per minute (rpm), temperature and
propeller diameter.
The speed units may be specified as "kt", "mph", "km/h" or "ft/s", but
default to "kt" if not specified.
The temperature units may be specified as "C", "F", "K" or "R", but
default to deg C if not specified.
The diameter units may be specified as "in", "ft", or "m", but default
to inches if not specified.
"""
dia = U.length_conv(dia, from_units=dia_units, to_units="m")
tas = U.speed_conv(tas, from_units=speed_units, to_units="m/s")
speed_of_sound = SA.temp2speed_of_sound(temperature, temp_units=temp_units, speed_units="m/s")
rotation_speed = dia * rpm * M.pi / 60
tip_speed = M.sqrt(tas ** 2 + rotation_speed ** 2)
tip_mach = tip_speed / speed_of_sound
return tip_mach
def run_tests(cd0=0.0221, e=0.825):
"""
Run all test cases to compare drag polar model against CAFE results.
"""
sum_sq = 0
wt_value_tot = 0
wing_area = 110
prop = PM.Prop('7666-4RV')
for n, test in enumerate(level_test_cases):
tas = test[0]
dalt = test[1]
wt = test[2]
rpm = test[3]
mp = test[4]
wt_value = test[5]
eas = A.tas2eas(tas, dalt, speed_units='mph')
tas_fts = U.speed_conv(tas, from_units='mph', to_units='ft/s')
cl = FT.eas2cl(eas, wt, wing_area, speed_units='mph')
cd = FT.cl2cd_test(cl, cd0, e, flap=0)
drag = FT.cd2drag(cd, eas, wing_area, speed_units='mph')
drag_power = drag * tas_fts / 550.
power = IO.pwr(rpm, mp, dalt)
prop_eff = PM.prop_eff(prop, power, rpm, tas, dalt, speed_units='mph')
thrust_power = power * prop_eff
excess_power = thrust_power - drag_power
print('Case', n, 'Altitude =', dalt, 'TAS =', tas, 'EAS =', eas,
'Excess power =', excess_power)
sum_sq += wt_value * excess_power**2
wt_value_tot += wt_value
print('Average sum of squares of excess power =', \
(sum_sq / wt_value_tot) ** 0.5)
def cl2lift(
Cl,
eas,
wing_area,
speed_units=default_speed_units,
lift_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the lift, given coefficient of lift, equivalent airspeed, and wing
area.
"""
eas = U.speed_conv(eas, from_units=speed_units, to_units='m/s')
wing_area = U.area_conv(wing_area, from_units=area_units, to_units='m**2')
lift = (((0.5 * Rho0) * eas**2.) * wing_area) * Cl
if lift_units == 'kg':
lift = U.force_conv(lift, 'N', 'lb')
lift = U.mass_conv(lift, 'lb', 'kg')
else:
lift = U.force_conv(lift, 'N', lift_units)
return lift
def descent_data(prop, weight=1600., alt_max=20000., fuel_units='USG', \
alt_interval=500., isa_dev=0, temp_units='C', rv='8', wing_area=110., \
tas=180., ROD=-500., angle='', speed_units='kt', rpm=2100., sfc=0.45, output='raw'):
"""
Returns a table of descent performance vs altitude.
The items in each row of the table are altitude, time, fuel burned and distance.
Time is in units of minutes, rounded to the nearest half minute.
Fuel units are selectable, with a default of USG.
Distances are in nm.
The output may be specified as raw, latex (a LaTeX table for the POH), or array.
tas is the TAS in descent (overridden by the angle, if the angle is provided).
angle is the flight path angle in degrees.
"""
tas_fts = U.speed_conv(tas, speed_units, 'ft/s')
if angle:
ROD = tas_fts * 60 * M.sin(angle * M.pi / 180)
rod_fts = ROD / 60
tas = U.speed_conv(tas, speed_units, 'kt')
alt = alt_max + alt_interval
temp = SA.isa2temp(isa_dev, alt, temp_units=temp_units)
time = 0
fuel_used = 0
dist = 0
if output == 'raw':
print S.center('Altitude', 10),
print S.center('ROD', 10),
print S.center('Time', 10),
print S.center('Fuel Used', 10),
print S.center('Dist', 10),
print S.center('Speed', 10)
print S.center('(ft)', 10),
print S.center('(ft/mn)', 10),
print S.center('(mn)', 10),
f_units = '(' + fuel_units + ')'
print S.center(f_units, 10),
print S.center('(nm)', 10),
print S.center('(KCAS)', 10)
# # data for max altitude
# print S.rjust(locale.format('%.0f', alt_max, True), 7),
# print S.rjust(locale.format('%.0f', round(ROD / 10.) * 10, True), 10),
# print S.rjust('%.1f' % (0), 10),
# print S.rjust('%.1f' % (fuel_used), 10),
# print S.rjust('%.1f' % (dist), 10),
# print S.rjust('%3d' % (A.tas2cas(tas, alt_max, temp, temp_units=temp_units)), 10)
# elif output == 'latex':
# # temp = 15 + isa_dev
# MSL_line = []
# MSL_line.append(str(locale.format('%.0f', weight, True)))
# MSL_line.append('0')
# MSL_line.append(str(locale.format('%.0f', temp)))
# MSL_line.append(str(locale.format('%.0f', A.tas2cas(tas, alt, temp, temp_units=temp_units))))
# MSL_line.append(str(locale.format('%.0f', round(ROD / 10.) * 10, True)))
# MSL_line.append('0')
# MSL_line.append(str(fuel_used))
# MSL_line.append(str(dist))
#
# print '&'.join(MSL_line) + '\\\\'
# print '\\hline'
# elif output == 'array':
# # no header rows, but make blank array
# array = [[alt_max,0,0,0]]
alts = []
RODs = []
times_temp = []
CASs = []
dists_temp = []
fuel_useds_temp = []
temps = []
calc_alt = alt_max - alt_interval / 2.
while alt > 0:
temp = SA.isa2temp(isa_dev, alt, temp_units = temp_units)
eas = A.tas2eas(tas, alt)
drag = FT.eas2drag(eas, weight)
pwr_level_flt = tas_fts * drag / 550
thrust_power = pwr_level_flt + FT.Pexcess_vs_roc(weight, ROD)
prop_eff = PM.prop_eff(prop, thrust_power, rpm, tas, alt, temp, temp_units=temp_units)
calc_pwr = thrust_power / prop_eff
#fuel_flow = IO.pwr2ff(calc_pwr, rpm, ff_units = 'lb/hr')
fuel_flow = calc_pwr * sfc
# print "Level flt pwr = %.1f, thrust power = %.1f, prop eff = %.3f, fuel flow = %.3f" % (pwr_level_flt, thrust_power, prop_eff, fuel_flow)
slice_time = alt_interval / rod_fts * -1.
slice_dist = tas_fts * slice_time
slice_fuel = fuel_flow * slice_time / 3600
fuel_used += slice_fuel
fuel_out = (U.avgas_conv(fuel_used, from_units = 'lb', \
to_units = fuel_units))
weight -= slice_fuel
alt -= alt_interval
cas_out = A.tas2cas(tas, alt, temp, temp_units=temp_units)
temp_out = SA.isa2temp(isa_dev, alt)
time += slice_time / 60.
dist += slice_dist / 6076.115
alts.append(alt)
CASs.append(cas_out)
RODs.append(ROD)
times_temp.append(time)
fuel_useds_temp.append(fuel_out)
dists_temp.append(dist)
temps.append(temp_out)
calc_alt += alt_interval
alts.reverse()
CASs.reverse()
RODs.reverse()
temps.reverse()
times = []
fuel_useds = []
dists = []
for n, time in enumerate(times_temp):
times.append(times_temp[-1] - time)
fuel_useds.append(fuel_useds_temp[-1] - fuel_useds_temp[n])
dists.append(dists_temp[-1] - dists_temp[n])
times.reverse()
fuel_useds.reverse()
dists.reverse()
if output == 'raw':
for n, alt in enumerate(alts):
print S.rjust(locale.format('%.0f', alt, True), 7),
# calculate ROC at the displayed altitude
print S.rjust(locale.format('%.0f', RODs[n], True), 10),
print S.rjust('%.1f' % (times[n]), 10),
print S.rjust('%.1f' % (fuel_useds[n]), 10),
print S.rjust('%.1f' % (dists[n]), 10),
print S.rjust('%3d' % (int(CASs[n])), 10)
elif output == 'latex':
for n, alt in enumerate(alts):
line = []
line.append(str(locale.format('%.0f', alt, True)))
line.append(str(locale.format('%.0f', round(temps[n]))))
line.append(str(locale.format('%.0f', CASs[n])))
line.append(str(locale.format('%.0f', round(RODs[n] / 10.) * 10, True)))
line.append(str(locale.format('%.0f', times[n])))
line.append(str(locale.format('%.1f', fuel_useds[n])))
line.append(str(locale.format('%.0f', dists[n])))
print '&' + '&'.join(line) + '\\\\'
print '\\hline'
elif output == 'array':
array = []
for n, alt in enumerate(alts):
array.append([alt, times[n], fuel_useds[n], dists[n]])
return array
def tas2ssec2(tas, ind_alt, oat, ias, std_alt = 0, speed_units=default_speed_units, alt_units=default_alt_units, temp_units=default_temp_units, press_units = default_press_units):
"""
Return static source position error as speed error, pressure error and
altitude error at sea level using speed course method.
Returns delta_Vpc, delta_Ps and delta_Hpc
tas = true airspeed determined by speed course method, or GPS
ind_alt = pressure altitude, corrected for instrument error
oat = outside air temperature, corrected for instrument error and ram temperature rise
ias = indicated airspeed, corrected for instrument error
std_alt = altitude to provide delta_Hpc for
delta_Vpc = error in airspeed = calibrated airspeed - indicated airspeed
corrected for instrument error
delta_Ps = error in the pressure sensed by the static system = pressure
sensed in the static system - ambient pressure
delta_Hpc = altitude error at std_alt = actual altitude - altitude
sensed by the static system
Uses analysis method from USAF Test Pilot School. Unlike some other
methods (e.g.. that in FAA AC 23-8B, or NTPS GPS_PEC.xls), this method
provides an exact conversion from TAS to CAS (some other methods assume
CAS = EAS), and it accounts for the effect of position error of altitude
on the conversion from TAS to CAS (some other methods assume pressure
altitude = indicated pressure altitude).
"""
tas = U.speed_conv(tas, speed_units, 'kt')
ind_alt = U.length_conv(ind_alt, alt_units, 'ft')
oat = U.temp_conv(oat, temp_units, 'C')
M = A.tas2mach(tas, oat, temp_units='C', speed_units='kt')
if M > 1:
raise ValueError, 'This method only works for Mach < 1'
delta_ic = SA.alt2press_ratio(ind_alt, alt_units='ft')
qcic_over_Psl = A.cas2dp(ias, speed_units='kt', press_units=press_units) / U.press_conv(constants.P0, 'pa', to_units=press_units)
qcic_over_Ps = qcic_over_Psl / delta_ic
Mic = A.dp_over_p2mach(qcic_over_Ps)
delta_mach_pc = M - Mic
if Mic > 1:
raise ValueError, 'This method only works for Mach < 1'
deltaPp_over_Ps = (1.4 * delta_mach_pc * (Mic + delta_mach_pc / 2)) / (1 + 0.2 * (Mic + delta_mach_pc / 2 )**2)
deltaPp_over_qcic = deltaPp_over_Ps / qcic_over_Ps
delta_Hpc = SA.alt2temp_ratio(std_alt, alt_units='ft') * deltaPp_over_Ps / 3.61382e-5
# experimental - alternate way to calculate delta_Hpc that gives same answer
Ps = SA.alt2press(ind_alt, alt_units='ft', press_units=press_units)
delta_Ps = deltaPp_over_Ps * Ps
P_std = SA.alt2press(std_alt, alt_units='ft', press_units=press_units)
deltaPs_std = deltaPp_over_Ps * P_std
delta_Hpc2 = SA.press2alt(P_std - deltaPs_std, press_units = press_units) - std_alt
delta_std_alt = SA.alt2press_ratio(std_alt, alt_units='ft')
asl = U.speed_conv(constants.A0, 'm/s', 'kt')
delta_Vpc_std_alt = deltaPp_over_Ps * delta_std_alt * asl**2 / (1.4 * ias * (1 + 0.2 * (ias / asl)**2)**2.5)
actual_alt = SA.press2alt(Ps + delta_Ps, press_units = press_units, alt_units = 'ft')
cas = A.tas2cas(tas, actual_alt, oat, speed_units='kt', alt_units='ft', temp_units='C')
return delta_Vpc, delta_Ps, delta_Hpc, cas
def test_04(self):
Value = U.speed_conv(1, from_units='m/s', to_units='ft/s')
Truth = 1 / 0.3048
self.assertTrue(RE(Value, Truth) <= 1e-8)
def tas2ssec2(tas,
ind_alt,
oat,
ias,
std_alt=0,
speed_units=default_speed_units,
alt_units=default_alt_units,
temp_units=default_temp_units,
press_units=default_press_units):
"""
Return static source position error as speed error, pressure error and
altitude error at sea level using speed course method.
Returns delta_Vpc, delta_Ps and delta_Hpc
tas = true airspeed determined by speed course method, or GPS
ind_alt = pressure altitude, corrected for instrument error
oat = outside air temperature, corrected for instrument error and ram temperature rise
ias = indicated airspeed, corrected for instrument error
std_alt = altitude to provide delta_Hpc for
delta_Vpc = error in airspeed = calibrated airspeed - indicated airspeed
corrected for instrument error
delta_Ps = error in the pressure sensed by the static system = pressure
sensed in the static system - ambient pressure
delta_Hpc = altitude error at std_alt = actual altitude - altitude
sensed by the static system
Uses analysis method from USAF Test Pilot School. Unlike some other
methods (e.g.. that in FAA AC 23-8B, or NTPS GPS_PEC.xls), this method
provides an exact conversion from TAS to CAS (some other methods assume
CAS = EAS), and it accounts for the effect of position error of altitude
on the conversion from TAS to CAS (some other methods assume pressure
altitude = indicated pressure altitude).
"""
tas = U.speed_conv(tas, speed_units, 'kt')
ind_alt = U.length_conv(ind_alt, alt_units, 'ft')
oat = U.temp_conv(oat, temp_units, 'C')
M = A.tas2mach(tas, oat, temp_units='C', speed_units='kt')
if M > 1:
raise ValueError('This method only works for Mach < 1')
delta_ic = SA.alt2press_ratio(ind_alt, alt_units='ft')
qcic_over_Psl = A.cas2dp(ias, speed_units='kt',
press_units=press_units) / U.press_conv(
constants.P0, 'pa', to_units=press_units)
qcic_over_Ps = qcic_over_Psl / delta_ic
Mic = A.dp_over_p2mach(qcic_over_Ps)
delta_mach_pc = M - Mic
if Mic > 1:
raise ValueError('This method only works for Mach < 1')
deltaPp_over_Ps = (1.4 * delta_mach_pc * (Mic + delta_mach_pc / 2)) / (
1 + 0.2 * (Mic + delta_mach_pc / 2)**2)
deltaPp_over_qcic = deltaPp_over_Ps / qcic_over_Ps
delta_Hpc = SA.alt2temp_ratio(
std_alt, alt_units='ft') * deltaPp_over_Ps / 3.61382e-5
# experimental - alternate way to calculate delta_Hpc that gives same answer
Ps = SA.alt2press(ind_alt, alt_units='ft', press_units=press_units)
delta_Ps = deltaPp_over_Ps * Ps
P_std = SA.alt2press(std_alt, alt_units='ft', press_units=press_units)
deltaPs_std = deltaPp_over_Ps * P_std
delta_Hpc2 = SA.press2alt(P_std - deltaPs_std,
press_units=press_units) - std_alt
delta_std_alt = SA.alt2press_ratio(std_alt, alt_units='ft')
asl = U.speed_conv(constants.A0, 'm/s', 'kt')
delta_Vpc_std_alt = deltaPp_over_Ps * delta_std_alt * asl**2 / (
1.4 * ias * (1 + 0.2 * (ias / asl)**2)**2.5)
actual_alt = SA.press2alt(Ps + delta_Ps,
press_units=press_units,
alt_units='ft')
cas = A.tas2cas(tas,
actual_alt,
oat,
speed_units='kt',
alt_units='ft',
temp_units='C')
return delta_Vpc, delta_Ps, delta_Hpc, cas
def test_03(self):
Value = U.speed_conv(1, from_units='km/h', to_units='m/s')
Truth = 1000 / 3600.
self.failUnless(RE(Value, Truth) <= 1e-8)
def test_05(self):
Value = U.speed_conv(1, from_units='ft/s', to_units='kt')
Truth = 3600. / (1852. / 0.3048)
self.failUnless(RE(Value, Truth) <= 1e-8)
def test_03(self):
Value = U.speed_conv(1, from_units='km/h', to_units='m/s')
Truth = 1000 / 3600.
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_04(self):
Value = U.speed_conv(1, from_units='m/s', to_units='ft/s')
Truth = 1 / 0.3048
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_01(self):
Value = U.speed_conv(1, from_units='kt', to_units='mph')
Truth = (1852. / 0.3048) / 5280
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_02(self):
Value = U.speed_conv(1, from_units='mph', to_units='km/h')
Truth = (5280 * 0.3048) / 1000
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_02(self):
Value = U.speed_conv(1, from_units='mph', to_units='km/h')
Truth = (5280 * 0.3048) / 1000
self.assertTrue(RE(Value, Truth) <= 1e-8)
def test_03(self):
Value = U.speed_conv(1, from_units='km/h', to_units='m/s')
Truth = 1000 / 3600.
self.assertTrue(RE(Value, Truth) <= 1e-8)
def descent_data(prop, weight=1600., alt_max=20000., fuel_units='USG', \
alt_interval=500., isa_dev=0, temp_units='C', rv='8', wing_area=110., \
tas=180., ROD=-500., angle='', speed_units='kt', rpm=2100., sfc=0.45, output='raw'):
"""
Returns a table of descent performance vs altitude.
The items in each row of the table are altitude, time, fuel burned and distance.
Time is in units of minutes, rounded to the nearest half minute.
Fuel units are selectable, with a default of USG.
Distances are in nm.
The output may be specified as raw, latex (a LaTeX table for the POH), or array.
tas is the TAS in descent (overridden by the angle, if the angle is provided).
angle is the flight path angle in degrees.
"""
tas_fts = U.speed_conv(tas, speed_units, 'ft/s')
if angle:
ROD = tas_fts * 60 * M.sin(angle * M.pi / 180)
rod_fts = ROD / 60
tas = U.speed_conv(tas, speed_units, 'kt')
alt = alt_max + alt_interval
temp = SA.isa2temp(isa_dev, alt, temp_units=temp_units)
time = 0
fuel_used = 0
dist = 0
if output == 'raw':
print(S.center('Altitude', 10), end=' ')
print(S.center('ROD', 10), end=' ')
print(S.center('Time', 10), end=' ')
print(S.center('Fuel Used', 10), end=' ')
print(S.center('Dist', 10), end=' ')
print(S.center('Speed', 10))
print(S.center('(ft)', 10), end=' ')
print(S.center('(ft/mn)', 10), end=' ')
print(S.center('(mn)', 10), end=' ')
f_units = '(' + fuel_units + ')'
print(S.center(f_units, 10), end=' ')
print(S.center('(nm)', 10), end=' ')
print(S.center('(KCAS)', 10))
# # data for max altitude
# print S.rjust(locale.format('%.0f', alt_max, True), 7),
# print S.rjust(locale.format('%.0f', round(ROD / 10.) * 10, True), 10),
# print S.rjust('%.1f' % (0), 10),
# print S.rjust('%.1f' % (fuel_used), 10),
# print S.rjust('%.1f' % (dist), 10),
# print S.rjust('%3d' % (A.tas2cas(tas, alt_max, temp, temp_units=temp_units)), 10)
# elif output == 'latex':
# # temp = 15 + isa_dev
# MSL_line = []
# MSL_line.append(str(locale.format('%.0f', weight, True)))
# MSL_line.append('0')
# MSL_line.append(str(locale.format('%.0f', temp)))
# MSL_line.append(str(locale.format('%.0f', A.tas2cas(tas, alt, temp, temp_units=temp_units))))
# MSL_line.append(str(locale.format('%.0f', round(ROD / 10.) * 10, True)))
# MSL_line.append('0')
# MSL_line.append(str(fuel_used))
# MSL_line.append(str(dist))
#
# print '&'.join(MSL_line) + '\\\\'
# print '\\hline'
# elif output == 'array':
# # no header rows, but make blank array
# array = [[alt_max,0,0,0]]
alts = []
RODs = []
times_temp = []
CASs = []
dists_temp = []
fuel_useds_temp = []
temps = []
calc_alt = alt_max - alt_interval / 2.
while alt > 0:
temp = SA.isa2temp(isa_dev, alt, temp_units=temp_units)
eas = A.tas2eas(tas, alt)
drag = FT.eas2drag(eas, weight)
pwr_level_flt = tas_fts * drag / 550
thrust_power = pwr_level_flt + FT.Pexcess_vs_roc(weight, ROD)
prop_eff = PM.prop_eff(prop,
thrust_power,
rpm,
tas,
alt,
temp,
temp_units=temp_units)
calc_pwr = thrust_power / prop_eff
#fuel_flow = IO.pwr2ff(calc_pwr, rpm, ff_units = 'lb/hr')
fuel_flow = calc_pwr * sfc
# print "Level flt pwr = %.1f, thrust power = %.1f, prop eff = %.3f, fuel flow = %.3f" % (pwr_level_flt, thrust_power, prop_eff, fuel_flow)
slice_time = alt_interval / rod_fts * -1.
slice_dist = tas_fts * slice_time
slice_fuel = fuel_flow * slice_time / 3600
fuel_used += slice_fuel
fuel_out = (U.avgas_conv(fuel_used, from_units = 'lb', \
to_units = fuel_units))
weight -= slice_fuel
alt -= alt_interval
cas_out = A.tas2cas(tas, alt, temp, temp_units=temp_units)
temp_out = SA.isa2temp(isa_dev, alt)
time += slice_time / 60.
dist += slice_dist / 6076.115
alts.append(alt)
CASs.append(cas_out)
RODs.append(ROD)
times_temp.append(time)
fuel_useds_temp.append(fuel_out)
dists_temp.append(dist)
temps.append(temp_out)
calc_alt += alt_interval
alts.reverse()
CASs.reverse()
RODs.reverse()
temps.reverse()
times = []
fuel_useds = []
dists = []
for n, time in enumerate(times_temp):
times.append(times_temp[-1] - time)
fuel_useds.append(fuel_useds_temp[-1] - fuel_useds_temp[n])
dists.append(dists_temp[-1] - dists_temp[n])
times.reverse()
fuel_useds.reverse()
dists.reverse()
if output == 'raw':
for n, alt in enumerate(alts):
print(S.rjust(locale.format('%.0f', alt, True), 7), end=' ')
# calculate ROC at the displayed altitude
print(S.rjust(locale.format('%.0f', RODs[n], True), 10), end=' ')
print(S.rjust('%.1f' % (times[n]), 10), end=' ')
print(S.rjust('%.1f' % (fuel_useds[n]), 10), end=' ')
print(S.rjust('%.1f' % (dists[n]), 10), end=' ')
print(S.rjust('%3d' % (int(CASs[n])), 10))
elif output == 'latex':
for n, alt in enumerate(alts):
line = []
line.append(str(locale.format('%.0f', alt, True)))
line.append(str(locale.format('%.0f', round(temps[n]))))
line.append(str(locale.format('%.0f', CASs[n])))
line.append(
str(locale.format('%.0f',
round(RODs[n] / 10.) * 10, True)))
line.append(str(locale.format('%.0f', times[n])))
line.append(str(locale.format('%.1f', fuel_useds[n])))
line.append(str(locale.format('%.0f', dists[n])))
print('&' + '&'.join(line) + '\\\\')
print('\\hline')
elif output == 'array':
array = []
for n, alt in enumerate(alts):
array.append([alt, times[n], fuel_useds[n], dists[n]])
return array
def test_01(self):
Value = U.speed_conv(1, from_units='kt', to_units='mph')
Truth = (1852. / 0.3048) / 5280
self.failUnless(RE(Value, Truth) <= 1e-8)
def test_05(self):
Value = U.speed_conv(1, from_units='ft/s', to_units='kt')
Truth = 3600. / (1852. / 0.3048)
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_02(self):
Value = U.speed_conv(1, from_units='mph', to_units='km/h')
Truth = (5280 * 0.3048) / 1000
self.failUnless(RE(Value, Truth) <= 1e-8)
def test_01(self):
Value = U.speed_conv(1, from_units='kt', to_units='mph')
Truth = (1852. / 0.3048) / 5280
self.assertTrue(RE(Value, Truth) <= 1e-8)
def test_04(self):
Value = U.speed_conv(1, from_units='m/s', to_units='ft/s')
Truth = 1 / 0.3048
self.failUnless(RE(Value, Truth) <= 1e-8)
def climb_data(prop, weight = 1800., alt_max = 20000., TO_fuel = 0, TO_dist = 0, \
fuel_units = 'USG', alt_interval = 500., isa_dev = 0, temp_units = 'C', \
rv = '8', wing_area = 110., pwr = 'max', pwr_factor=1.0, \
climb_speed = 'max', output = 'raw'):
"""
Returns a table of climb performance vs altitude.
The items in each row of the table are altitude, time, fuel burned and distance.
Time is in units of minutes, rounded to the nearest half minute.
Fuel units are selectable, with a default of USG.
Distances are in nm.
The output may be specified as raw, latex (a LaTeX table for the POH), or array.
pwr may be 'max', 'cc' (cruise climb = 2500 rpm and 25") or 2500 (2500 rpm and full throttle)
climb_speed may be 'max' (Vy), 'cc' (120 kt to 10,000 ft, then reducing by 4 kt/1000 ft) or
'norm' (100 kt to 10,000 ft, then reducing by 2 kt/1000 ft)
Note: compared cruise range for all climb speed and power. The predicted results are all
within 1.5 nm of range. Thus there is no advantage to using anything but Vy and max
power.
"""
def _alt2ROC(prop, alt):
"""
calculate ROC for an altitude
"""
temp = SA.isa2temp(isa_dev, alt)
calc_pwr = alt2pwr(alt, rpm=rpm, MP_max=MP_max, temp=temp) * pwr_factor
cas = alt2roc_speed(alt, climb_speed=climb_speed)
eas = A.cas2eas(cas, alt)
ROC = roc(prop, alt, eas, weight, calc_pwr, rpm, rv = rv, \
wing_area = wing_area)
return ROC
alt = 0
time = 0
fuel_used = U.avgas_conv(TO_fuel, from_units=fuel_units, to_units='lb')
weight = weight - fuel_used
dist = TO_dist
if pwr == 'max':
# rpm = 2700
rpm = 2650
MP_max = 30
elif pwr == 'cc':
rpm = 2500
MP_max = 25
elif pwr == 2500:
rpm = 2500
MP_max = 30
else:
raise ValueError("pwr must be one of 'max', 'cc', or 2500")
if output == 'raw':
print(S.center('Altitude', 10), end=' ')
print(S.center('ROC', 10), end=' ')
print(S.center('Time', 10), end=' ')
print(S.center('Fuel Used', 10), end=' ')
print(S.center('Dist', 10), end=' ')
print(S.center('Speed', 10))
print(S.center('(ft)', 10), end=' ')
print(S.center('(ft/mn)', 10), end=' ')
print(S.center('(mn)', 10), end=' ')
f_units = '(' + fuel_units + ')'
print(S.center(f_units, 10), end=' ')
print(S.center('(nm)', 10), end=' ')
print(S.center('(KCAS)', 10))
# data for MSL
print(S.rjust(locale.format('%.0f', 0, True), 7), end=' ')
# calculate ROC at MSL
print(S.rjust(locale.format('%.0f', round(_alt2ROC(prop, 0) / 10.) * 10, \
True), 10), end=' ')
print(S.rjust('%.1f' % (0), 10), end=' ')
print(S.rjust('%.1f' % (TO_fuel), 10), end=' ')
print(S.rjust('%.1f' % (TO_dist), 10), end=' ')
print(S.rjust('%3d' % (alt2roc_speed(0, climb_speed=climb_speed)), 10))
elif output == 'latex':
temp = 15 + isa_dev
MSL_line = []
MSL_line.append(str(locale.format('%.0f', weight, True)))
MSL_line.append('0')
MSL_line.append(str(locale.format('%.0f', temp)))
MSL_line.append(str(locale.format('%.0f', alt2roc_speed(0, \
climb_speed = climb_speed))))
MSL_line.append(str(locale.format('%.0f', round(_alt2ROC(prop, 0) / 10.)\
* 10, True)))
MSL_line.append('0')
MSL_line.append(str(TO_fuel))
MSL_line.append(str(TO_dist))
print('&'.join(MSL_line) + '\\\\')
print('\\hline')
elif output == 'array':
# no header rows, but make blank array
array = [[0, 0, TO_fuel, 0]]
calc_alt = alt_interval / 2.
while calc_alt < alt_max:
temp = SA.isa2temp(isa_dev, calc_alt)
pwr = alt2pwr(calc_alt, rpm=rpm, MP_max=MP_max, temp=temp)
calc_pwr = pwr * pwr_factor
cas = alt2roc_speed(calc_alt, climb_speed=climb_speed)
eas = A.cas2eas(cas, calc_alt)
tas = A.cas2tas(cas, calc_alt, temp=temp, temp_units=temp_units)
tas_fts = U.speed_conv(tas, from_units='kt', to_units='ft/s')
ROC = roc(prop, calc_alt, eas, weight, calc_pwr, rpm, rv = rv, \
wing_area = wing_area)
roc_fts = ROC / 60
fuel_flow = IO.pwr2ff(pwr, rpm, ff_units='lb/hr')
slice_time = alt_interval / roc_fts
slice_dist = tas_fts * slice_time
slice_fuel = fuel_flow * slice_time / 3600
fuel_used += slice_fuel
fuel_out = (U.avgas_conv(fuel_used, from_units = 'lb', \
to_units = fuel_units))
weight -= slice_fuel
alt += alt_interval
cas_out = alt2roc_speed(alt, climb_speed=climb_speed)
temp_out = SA.isa2temp(isa_dev, alt)
ROC = _alt2ROC(prop, alt)
time += slice_time / 60
dist += slice_dist / 6076.115
if output == 'raw':
print(S.rjust(locale.format('%.0f', alt, True), 7), end=' ')
# calculate ROC at the displayed altitude
print(S.rjust(locale.format('%.0f', ROC, True), 10), end=' ')
print(S.rjust('%.1f' % (time), 10), end=' ')
print(S.rjust('%.1f' % (fuel_out), 10), end=' ')
print(S.rjust('%.1f' % (dist), 10), end=' ')
print(S.rjust('%3d' % (int(cas_out)), 10))
elif output == 'latex':
line = []
line.append(str(locale.format('%.0f', alt, True)))
line.append(str(locale.format('%.0f', round(temp_out))))
line.append(str(locale.format('%.0f', cas_out)))
line.append(str(locale.format('%.0f',
round(ROC / 10.) * 10, True)))
line.append(str(locale.format('%.0f', time)))
line.append(str(locale.format('%.1f', fuel_out)))
line.append(str(locale.format('%.0f', dist)))
print('&' + '&'.join(line) + '\\\\')
print('\\hline')
elif output == 'array':
array.append([alt, time, fuel_out, dist])
calc_alt += alt_interval
if output == 'array':
return array
def climb_data(prop, weight = 1800., alt_max = 20000., TO_fuel = 0, TO_dist = 0, \
fuel_units = 'USG', alt_interval = 500., isa_dev = 0, temp_units = 'C', \
rv = '8', wing_area = 110., pwr = 'max', pwr_factor=1.0, \
climb_speed = 'max', output = 'raw'):
"""
Returns a table of climb performance vs altitude.
The items in each row of the table are altitude, time, fuel burned and distance.
Time is in units of minutes, rounded to the nearest half minute.
Fuel units are selectable, with a default of USG.
Distances are in nm.
The output may be specified as raw, latex (a LaTeX table for the POH), or array.
pwr may be 'max', 'cc' (cruise climb = 2500 rpm and 25") or 2500 (2500 rpm and full throttle)
climb_speed may be 'max' (Vy), 'cc' (120 kt to 10,000 ft, then reducing by 4 kt/1000 ft) or
'norm' (100 kt to 10,000 ft, then reducing by 2 kt/1000 ft)
Note: compared cruise range for all climb speed and power. The predicted results are all
within 1.5 nm of range. Thus there is no advantage to using anything but Vy and max
power.
"""
def _alt2ROC(prop, alt):
"""
calculate ROC for an altitude
"""
temp = SA.isa2temp(isa_dev, alt)
calc_pwr = alt2pwr(alt, rpm = rpm, MP_max = MP_max, temp = temp) * pwr_factor
cas = alt2roc_speed(alt, climb_speed = climb_speed)
eas = A.cas2eas(cas, alt)
ROC = roc(prop, alt, eas, weight, calc_pwr, rpm, rv = rv, \
wing_area = wing_area)
return ROC
alt = 0
time = 0
fuel_used = U.avgas_conv(TO_fuel, from_units = fuel_units, to_units = 'lb')
weight = weight - fuel_used
dist = TO_dist
if pwr == 'max':
# rpm = 2700
rpm = 2650
MP_max = 30
elif pwr == 'cc':
rpm = 2500
MP_max = 25
elif pwr == 2500:
rpm = 2500
MP_max = 30
else:
raise ValueError, "pwr must be one of 'max', 'cc', or 2500"
if output == 'raw':
print S.center('Altitude', 10),
print S.center('ROC', 10),
print S.center('Time', 10),
print S.center('Fuel Used', 10),
print S.center('Dist', 10),
print S.center('Speed', 10)
print S.center('(ft)', 10),
print S.center('(ft/mn)', 10),
print S.center('(mn)', 10),
f_units = '(' + fuel_units + ')'
print S.center(f_units, 10),
print S.center('(nm)', 10),
print S.center('(KCAS)', 10)
# data for MSL
print S.rjust(locale.format('%.0f', 0, True), 7),
# calculate ROC at MSL
print S.rjust(locale.format('%.0f', round(_alt2ROC(prop, 0) / 10.) * 10, \
True), 10),
print S.rjust('%.1f' % (0), 10),
print S.rjust('%.1f' % (TO_fuel), 10),
print S.rjust('%.1f' % (TO_dist), 10),
print S.rjust('%3d' % (alt2roc_speed(0, climb_speed = climb_speed)), 10)
elif output == 'latex':
temp = 15 + isa_dev
MSL_line = []
MSL_line.append(str(locale.format('%.0f', weight, True)))
MSL_line.append('0')
MSL_line.append(str(locale.format('%.0f', temp)))
MSL_line.append(str(locale.format('%.0f', alt2roc_speed(0, \
climb_speed = climb_speed))))
MSL_line.append(str(locale.format('%.0f', round(_alt2ROC(prop, 0) / 10.)\
* 10, True)))
MSL_line.append('0')
MSL_line.append(str(TO_fuel))
MSL_line.append(str(TO_dist))
print '&'.join(MSL_line) + '\\\\'
print '\\hline'
elif output == 'array':
# no header rows, but make blank array
array = [[0,0,TO_fuel,0]]
calc_alt = alt_interval / 2.
while calc_alt < alt_max:
temp = SA.isa2temp(isa_dev, calc_alt)
pwr = alt2pwr(calc_alt, rpm = rpm, MP_max = MP_max, temp = temp)
calc_pwr = pwr * pwr_factor
cas = alt2roc_speed(calc_alt, climb_speed = climb_speed)
eas = A.cas2eas(cas, calc_alt)
tas = A.cas2tas(cas, calc_alt, temp = temp, temp_units = temp_units)
tas_fts = U.speed_conv(tas, from_units = 'kt', to_units = 'ft/s')
ROC = roc(prop, calc_alt, eas, weight, calc_pwr, rpm, rv = rv, \
wing_area = wing_area)
roc_fts = ROC / 60
fuel_flow = IO.pwr2ff(pwr, rpm, ff_units = 'lb/hr')
slice_time = alt_interval / roc_fts
slice_dist = tas_fts * slice_time
slice_fuel = fuel_flow * slice_time / 3600
fuel_used += slice_fuel
fuel_out = (U.avgas_conv(fuel_used, from_units = 'lb', \
to_units = fuel_units))
weight -= slice_fuel
alt += alt_interval
cas_out = alt2roc_speed(alt, climb_speed = climb_speed)
temp_out = SA.isa2temp(isa_dev, alt)
ROC = _alt2ROC(prop, alt)
time += slice_time / 60
dist += slice_dist / 6076.115
if output == 'raw':
print S.rjust(locale.format('%.0f', alt, True), 7),
# calculate ROC at the displayed altitude
print S.rjust(locale.format('%.0f', ROC, True), 10),
print S.rjust('%.1f' % (time), 10),
print S.rjust('%.1f' % (fuel_out), 10),
print S.rjust('%.1f' % (dist), 10),
print S.rjust('%3d' % (int(cas_out)), 10)
elif output == 'latex':
line = []
line.append(str(locale.format('%.0f', alt, True)))
line.append(str(locale.format('%.0f', round(temp_out))))
line.append(str(locale.format('%.0f', cas_out)))
line.append(str(locale.format('%.0f', round(ROC / 10.) * 10, True)))
line.append(str(locale.format('%.0f', time)))
line.append(str(locale.format('%.1f', fuel_out)))
line.append(str(locale.format('%.0f', dist)))
print '&' + '&'.join(line) + '\\\\'
print '\\hline'
elif output == 'array':
array.append([alt, time, fuel_out, dist])
calc_alt += alt_interval
if output == 'array':
return array
def test_05(self):
Value = U.speed_conv(1, from_units='ft/s', to_units='kt')
Truth = 3600. / (1852. / 0.3048)
self.assertTrue(RE(Value, Truth) <= 1e-8)