def WOT_speed(altitude, weight = 2100, rpm = 2700, temp = 'std', \
temp_units = 'C', rv = 'F1', wing_area = 102, speed_units = 'kt', \
prop_eff = 0.78, MP_loss = 1.322, ram = 0.5, rated_power=275):
"""
Returns the predicted speed at full throttle.
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.
"""
press = SA.alt2press(altitude, press_units='in HG')
MP_loss = MP_loss * (rpm / 2700.)**2
cas_guess = 300
error = 1
while error > 0.0001:
dp = A.cas2dp(cas_guess, press_units='in HG')
# print 'dp =', dp
ram_press = ram * dp
# print 'Ram rise =', ram_press
MP = press - MP_loss + ram_press
pwr = O.pwr(rpm, MP, altitude, temp=temp,
temp_units=temp_units) * rated_power / 180
print('MP =', MP, 'Power =', pwr)
tas = speed(altitude, weight, pwr, rpm, temp = temp, \
temp_units = temp_units, rv = rv, wing_area = wing_area, \
speed_units = speed_units, prop_eff = prop_eff)
cas = A.tas2cas(tas, altitude, temp=temp, temp_units=temp_units)
error = M.fabs((cas - cas_guess) / cas)
cas_guess = cas
# print 'CAS =', cas, 'TAS =', tas
return tas
def WOT_speed(altitude, weight = 2100, rpm = 2700, temp = 'std', \
temp_units = 'C', rv = 'F1', wing_area = 102, speed_units = 'kt', \
prop_eff = 0.78, MP_loss = 1.322, ram = 0.5, rated_power=275):
"""
Returns the predicted speed at full throttle.
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.
"""
press = SA.alt2press(altitude, press_units = 'in HG')
MP_loss = MP_loss * (rpm / 2700.) ** 2
cas_guess = 300
error = 1
while error > 0.0001:
dp = A.cas2dp(cas_guess, press_units = 'in HG')
# print 'dp =', dp
ram_press = ram * dp
# print 'Ram rise =', ram_press
MP = press - MP_loss + ram_press
pwr = O.pwr(rpm, MP, altitude, temp = temp, temp_units = temp_units) * rated_power/180
print 'MP =', MP, 'Power =', pwr
tas = speed(altitude, weight, pwr, rpm, temp = temp, \
temp_units = temp_units, rv = rv, wing_area = wing_area, \
speed_units = speed_units, prop_eff = prop_eff)
cas = A.tas2cas(tas, altitude, temp = temp, temp_units = temp_units)
error = M.fabs((cas - cas_guess) / cas)
cas_guess = cas
# print 'CAS =', cas, 'TAS =', tas
return tas
def roca(altitude,
weight=2100,
press_drop=1.2,
temp='std',
temp_units='C',
prop_eff=0.7,
load_factor=1,
rated_power=275,
rpm=2700):
"""
Returns speed for best rate of climb and the rate of climb at that speed.
"""
MP = SA.alt2press(altitude) - press_drop
pwr = O.pwr(rpm, MP, altitude, temp=temp,
temp_units=temp_units) * rated_power / 180
roc_max = -100000
eass = range(60, 150, 1)
rocs = []
for eas in eass:
rocs.append((roc(altitude,
eas,
weight,
pwr,
2700,
temp=temp,
prop_eff=prop_eff,
load_factor=load_factor), eas))
mroc, meas = max(rocs)
return meas, mroc
def aoca(prop, altitude, weight = 1800, press_drop = 1.2, temp = 'std', \
climb = True):
"""
Returns speed for best climb or descent gradient and the gradient at
that speed.
"""
MP = SA.alt2press(altitude) - press_drop
pwr = IO.pwr(2700, MP, altitude, temp=temp)
if climb == True:
eass = list(range(550, 800, 1))
else:
eass = list(range(700, 1200, 1))
aocs = []
if climb == True:
for eas in eass:
aocs.append((aoc(prop,
altitude,
eas / 10.,
weight,
pwr,
2700,
temp=temp), eas))
else:
for eas in eass:
aocs.append((aoc(prop,
altitude,
eas / 10.,
weight,
0,
2700,
temp=temp), eas))
maoc, meas = max(aocs)
return meas / 10., maoc
def test_01(self):
# Truth values from NASA RP 1046
Value = SA.alt2press(5000)
Truth = 24.8959
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_01(self):
# Truth values from NASA RP 1046
Value = SA.alt2press(5000)
Truth = 24.8959
self.assertTrue(RE(Value, Truth) <= 1e-5)
def test_03(self):
# test pa and m
# Truth values from NASA RP 1046
Value = SA.alt2press(25000, alt_units='m', press_units='pa')
Truth = 2511.01
self.assertTrue(RE(Value, Truth) <= 1e-5)
def test_06(self):
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(65322, press_units='pa', alt_units='m')
Truth = 9.4609
self.assertTrue(RE(Value, Truth) <= 5e-5)
def test_02(self):
# test psf
# Truth values from NASA RP 1046
Value = SA.alt2press(49000, press_units='psf')
Truth = 254.139
self.assertTrue(RE(Value, Truth) <= 1e-5)
def test_03(self):
# test pa and m
# Truth values from NASA RP 1046
Value = SA.alt2press(25000, alt_units='m', press_units='pa')
Truth = 2511.01
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_06(self):
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(65322, press_units='pa', alt_units='m')
Truth = 9.4609
self.failUnless(RE(Value, Truth) <= 5e-5)
def test_02(self):
# test psf
# Truth values from NASA RP 1046
Value = SA.alt2press(49000, press_units='psf')
Truth = 254.139
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_05(self):
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(49610, press_units='pa', alt_units='m')
Truth = 79.779
self.failUnless(RE(Value, Truth) <= 3e-5)
def test_05(self):
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(49610, press_units="pa", alt_units="m")
Truth = 79.779
self.failUnless(RE(Value, Truth) <= 3e-5)
def test_07(self):
# test units in other order
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(80956, press_units='pa', alt_units='m')
Truth = 0.75009
self.assertTrue(RE(Value, Truth) <= 1e-4)
def test_07(self):
# test units in other order
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(80956, press_units='pa', alt_units='m')
Truth = 0.75009
self.failUnless(RE(Value, Truth) <= 1e-4)
def test_04(self):
# test units in other order
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(39750, press_units='pa', alt_units='m')
Truth = 287.14
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_04(self):
# test units in other order
# truth value calculated from program at:
# http://www.sworld.com.au/steven/space/atmosphere/
Value = SA.alt2press(39750, press_units="pa", alt_units="m")
Truth = 287.14
self.failUnless(RE(Value, Truth) <= 1e-5)
def MP_pred(tas, alt, rpm, rpm_base = 2700., MP_loss = 1.322, ram = 0.5, temp='std'):
press = SA.alt2press(alt, press_units = 'in HG')
if temp == 'std':
temp = SA.alt2temp(alt)
dp = A.tas2dp(tas, alt, temp, speed_units='kt', alt_units='ft', temp_units='C', press_units='in HG')
ram_press = ram * dp
MP_loss = MP_loss * (rpm / rpm_base) ** 1.85 # exponent from various online pressure drop calculators
# MP_loss = MP_loss * (rpm / rpm_base)
MP = press - MP_loss + ram_press
# print "MP = %.3f" % MP
return MP
def alt2pwr(alt, rpm = 2700, MP_max = 30, temp = 'std', alt_units = 'ft', \
temp_units = 'C'):
"""
Returns power at a given altitude. Default rpm is 2700.
The maximum MP may be specified, if for example, one
wanted to use 25 inches MP until full throttle was reached.
"""
# MP loss at full throttle at 2700 rpm at sea level.
# From Lycoming power chart
MP_loss_base = 29.9213 - 28.6
press = SA.alt2press(alt, alt_units = alt_units)
# assume pressure drop is proportional to square of velocity
MP_loss = MP_loss_base * (rpm / 2700.) ** 2
MP = min(press - MP_loss, MP_max)
# from climb testing, get MP of 0.5 above ambient
# get 2650 rpm during climb
MP = SA.alt2press(alt) + 0.5 * (2650./rpm) ** 2
pwr = IO.pwr(rpm, MP, alt, temp = temp, alt_units = alt_units, \
temp_units = temp_units)
# decrement power as a function of altitude to make predicted climb perf match flight test resutls
# this decrement is optimized for the MT prop
pwr = pwr * (0.8525 - 4.35E-10 * alt**2)
return pwr
def alt2pwr(alt, rpm = 2700, MP_max = 30, temp = 'std', alt_units = 'ft', \
temp_units = 'C'):
"""
Returns power at a given altitude. Default rpm is 2700.
The maximum MP may be specified, if for example, one
wanted to use 25 inches MP until full throttle was reached.
"""
# MP loss at full throttle at 2700 rpm at sea level.
# From Lycoming power chart
MP_loss_base = 29.9213 - 28.6
press = SA.alt2press(alt, alt_units=alt_units)
# assume pressure drop is proportional to square of velocity
MP_loss = MP_loss_base * (rpm / 2700.)**2
MP = min(press - MP_loss, MP_max)
# from climb testing, get MP of 0.5 above ambient
# get 2650 rpm during climb
MP = SA.alt2press(alt) + 0.5 * (2650. / rpm)**2
pwr = IO.pwr(rpm, MP, alt, temp = temp, alt_units = alt_units, \
temp_units = temp_units)
# decrement power as a function of altitude to make predicted climb perf match flight test resutls
# this decrement is optimized for the MT prop
pwr = pwr * (0.8525 - 4.35E-10 * alt**2)
return pwr
def roca(prop, altitude, weight = 1800, press_drop = 1.2, temp = 'std', \
load_factor =1, prop_factor=1):
"""
Returns speed for best rate of climb and the rate of climb at that speed.
"""
MP = SA.alt2press(altitude) - press_drop
pwr = IO.pwr(2700, MP, altitude, temp=temp)
roc_max = -100000
eass = list(range(600, 1500, 1))
rocs = []
for eas in eass:
rocs.append((roc(prop, altitude, eas/10., weight, pwr, 2700, temp = temp, \
load_factor = load_factor, prop_factor=prop_factor),eas/10.))
mroc, meas = max(rocs)
return meas, mroc
def roca(prop, altitude, weight = 1800, press_drop = 1.2, temp = 'std', \
load_factor =1, prop_factor=1):
"""
Returns speed for best rate of climb and the rate of climb at that speed.
"""
MP = SA.alt2press(altitude) - press_drop
pwr = IO.pwr(2700, MP, altitude, temp = temp)
roc_max = -100000
eass = range(600, 1500, 1)
rocs = []
for eas in eass:
rocs.append((roc(prop, altitude, eas/10., weight, pwr, 2700, temp = temp, \
load_factor = load_factor, prop_factor=prop_factor),eas/10.))
mroc, meas = max(rocs)
return meas, mroc
def roca(altitude, weight = 2100, press_drop = 1.2, temp = 'std', \
temp_units='C', prop_eff = 0.7, load_factor =1, rated_power=275, \
rpm=2700):
"""
Returns speed for best rate of climb and the rate of climb at that speed.
"""
MP = SA.alt2press(altitude) - press_drop
pwr = O.pwr(rpm, MP, altitude, temp = temp, temp_units = temp_units) * rated_power/180
roc_max = -100000
eass = range(60, 150, 1)
rocs = []
for eas in eass:
rocs.append((roc(altitude, eas, weight, pwr, 2700, temp = temp, \
prop_eff = prop_eff, load_factor = load_factor),eas))
mroc, meas = max(rocs)
return meas, mroc
def WOT_speed_orig(prop, altitude, weight = 1800, rpm = 2700, temp = 'std', \
temp_units = 'C', rv = '8', wing_area = 110, speed_units = 'kt' , \
MP_loss = 1.322, ram = 0.5, pwr_factor=1, mixture='pwr', \
wheel_pants=1):
"""
Returns the predicted speed at full throttle.
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.
"""
press = SA.alt2press(altitude, press_units='in HG')
MP_loss = MP_loss * (rpm / 2700.)**2
cas_guess = 300
error = 1
if mixture == 'econ':
pwr_factor *= .86 # average power ratio to max power when at 50 deg LOP mixture
elif mixture == 'pwr':
pass
else:
raise ValueError('mixture must be one of "pwr" or "econ"')
while error > 0.0001:
dp = A.cas2dp(cas_guess, press_units='in HG')
# print 'dp =', dp
ram_press = ram * dp
# print 'Ram rise =', ram_press
MP = press - MP_loss + ram_press
pwr = IO.pwr(rpm, MP, altitude, temp=temp,
temp_units=temp_units) * pwr_factor
# print 'MP =', MP, 'Power =', pwr
tas = speed(prop, altitude, weight, pwr, rpm, temp = temp, \
temp_units = temp_units, rv = rv, wing_area = wing_area, \
speed_units = speed_units, wheel_pants = wheel_pants)
cas = A.tas2cas(tas, altitude, temp=temp, temp_units=temp_units)
error = M.fabs((cas - cas_guess) / cas)
cas_guess = cas
# print 'CAS =', cas, 'TAS =', tas
# print "MP = %.3f" % MP
# print "Pwr = %.2f" % pwr
return tas
def MP_pred(tas, alt, rpm, rpm_base=2700., MP_loss=1.322, ram=0.5, temp='std'):
press = SA.alt2press(alt, press_units='in HG')
if temp == 'std':
temp = SA.alt2temp(alt)
dp = A.tas2dp(tas,
alt,
temp,
speed_units='kt',
alt_units='ft',
temp_units='C',
press_units='in HG')
ram_press = ram * dp
MP_loss = MP_loss * (
rpm / rpm_base
)**1.85 # exponent from various online pressure drop calculators
# MP_loss = MP_loss * (rpm / rpm_base)
MP = press - MP_loss + ram_press
# print "MP = %.3f" % MP
return MP
def WOT_speed_orig(prop, altitude, weight = 1800, rpm = 2700, temp = 'std', \
temp_units = 'C', rv = '8', wing_area = 110, speed_units = 'kt' , \
MP_loss = 1.322, ram = 0.5, pwr_factor=1, mixture='pwr', \
wheel_pants=1):
"""
Returns the predicted speed at full throttle.
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.
"""
press = SA.alt2press(altitude, press_units = 'in HG')
MP_loss = MP_loss * (rpm / 2700.) ** 2
cas_guess = 300
error = 1
if mixture == 'econ':
pwr_factor *= .86 # average power ratio to max power when at 50 deg LOP mixture
elif mixture == 'pwr':
pass
else:
raise ValueError, 'mixture must be one of "pwr" or "econ"'
while error > 0.0001:
dp = A.cas2dp(cas_guess, press_units = 'in HG')
# print 'dp =', dp
ram_press = ram * dp
# print 'Ram rise =', ram_press
MP = press - MP_loss + ram_press
pwr = IO.pwr(rpm, MP, altitude, temp = temp, temp_units = temp_units) * pwr_factor
# print 'MP =', MP, 'Power =', pwr
tas = speed(prop, altitude, weight, pwr, rpm, temp = temp, \
temp_units = temp_units, rv = rv, wing_area = wing_area, \
speed_units = speed_units, wheel_pants = wheel_pants)
cas = A.tas2cas(tas, altitude, temp = temp, temp_units = temp_units)
error = M.fabs((cas - cas_guess) / cas)
cas_guess = cas
# print 'CAS =', cas, 'TAS =', tas
# print "MP = %.3f" % MP
# print "Pwr = %.2f" % pwr
return tas
def mach2cl(
mach,
altitude,
weight,
wing_area,
load_factor=1,
alt_units=default_alt_units,
weight_units=default_weight_units,
area_units=default_area_units,
):
"""
Returns the coefficient of lift, given equivalent mach, altitude, 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,
altitude is 10,000 ft,
the weight is 1800 lb,
and the Mach number is 0.3 kt,
in straight and level flight (so the load factor = 1),
then:
>>> Hp = 10000
>>> S = 110
>>> W = 1800
>>> Mach = 0.3
>>> mach2cl(Mach, Hp, W, S, weight_units='lb', area_units='ft**2')
0.17847495222708878
"""
P = SA.alt2press(altitude, alt_units=alt_units, press_units="pa")
wing_area = U.area_conv(wing_area, from_units=area_units, to_units="m**2")
weight = U.wt_conv(weight, from_units=weight_units, to_units="kg")
Cl = (weight * g * load_factor) / (0.7 * P * wing_area * mach**2)
return Cl
def aoca(prop, altitude, weight = 1800, press_drop = 1.2, temp = 'std', \
climb = True):
"""
Returns speed for best climb or descent gradient and the gradient at
that speed.
"""
MP = SA.alt2press(altitude) - press_drop
pwr = IO.pwr(2700, MP, altitude, temp = temp)
if climb == True:
eass = range(550, 800, 1)
else:
eass = range(700, 1200, 1)
aocs = []
if climb == True:
for eas in eass:
aocs.append((aoc(prop, altitude, eas/10., weight, pwr, 2700, temp = temp),eas))
else:
for eas in eass:
aocs.append((aoc(prop, altitude, eas/10., weight, 0, 2700, temp = temp),eas))
maoc, meas = max(aocs)
return meas/10., maoc
def roc_vs_temp(prop, alt_max = 20000, alt_interval=2000, weight=1800, temps=[-20,0,20,40], pwr='max', \
pwr_factor=1.0, climb_speed='max', output='raw'):
"""
Returns the rates of climb at various temperatures
"""
if pwr == 'max':
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 on of 'max', 'cc', or 2500"
alt = 0
while alt<alt_max:
press = SA.alt2press(alt)
MP = press - (29.9213 - 28.6)
cas = alt2roc_speed(alt, climb_speed = climb_speed)
eas = A.cas2eas(cas, alt)
# for temp in temps:
# print temp, '\t\t\t',
# print '\n',
print '%.0f\t%.0f\t%.0f\t' % (weight, alt, cas),
for temp in temps:
# power = IO.pwr(rpm, MP, alt, temp) * pwr_factor
power = alt2pwr(alt, rpm = rpm, MP_max = MP_max, temp = temp)
ROC = roc(prop, alt, eas, weight, power, rpm, temp) /10
ROC = int('%.0f' % (ROC)) * 10
print '%.0f\t' % (ROC),
print '\n'
alt += alt_interval
def roc_vs_temp(prop, alt_max = 20000, alt_interval=2000, weight=1800, temps=[-20,0,20,40], pwr='max', \
pwr_factor=1.0, climb_speed='max', output='raw'):
"""
Returns the rates of climb at various temperatures
"""
if pwr == 'max':
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 on of 'max', 'cc', or 2500")
alt = 0
while alt < alt_max:
press = SA.alt2press(alt)
MP = press - (29.9213 - 28.6)
cas = alt2roc_speed(alt, climb_speed=climb_speed)
eas = A.cas2eas(cas, alt)
# for temp in temps:
# print temp, '\t\t\t',
# print '\n',
print('%.0f\t%.0f\t%.0f\t' % (weight, alt, cas), end=' ')
for temp in temps:
# power = IO.pwr(rpm, MP, alt, temp) * pwr_factor
power = alt2pwr(alt, rpm=rpm, MP_max=MP_max, temp=temp)
ROC = roc(prop, alt, eas, weight, power, rpm, temp) / 10
ROC = int('%.0f' % (ROC)) * 10
print('%.0f\t' % (ROC), end=' ')
print('\n')
alt += alt_interval
def pwr_vs_alt_temp(temps):
"""
Returns a series of powers at full throttle and 2700 rpm at various temps
0 ft
-20 0 20 40 ISA
213.4 205.4 198.3 191.9 200.0
2000 ft
-20 0 20 40 ISA
197.3 189.9 183.3 177.4 186.2
4000 ft
-20 0 20 40 ISA
182.4 175.6 169.5 164.0 173.4
6000 ft
-20 0 20 40 ISA
167.8 161.5 155.9 150.9 160.6
8000 ft
-20 0 20 40 ISA
154.1 148.3 143.2 138.6 148.6
10000 ft
-20 0 20 40 ISA
141.3 136.1 131.3 127.1 137.3
12000 ft
-20 0 20 40 ISA
129.3 124.5 120.2 116.3 126.6
14000 ft
-20 0 20 40 ISA
118.2 113.8 109.8 106.2 116.5
16000 ft
-20 0 20 40 ISA
107.4 103.4 99.8 96.6 106.7
18000 ft
-20 0 20 40 ISA
97.3 93.7 90.4 87.5 97.4
20000 ft
-20 0 20 40 ISA
87.7 84.4 81.5 78.9 88.5
"""
alts = list(range(0, 22000, 2000))
for alt in alts:
print(alt, 'ft')
for temp in temps:
print(temp, '\t', end=' ')
print('ISA')
for temp in temps:
power = alt2pwr(alt, temp=temp)
print('%.1f' % (power), '\t', end=' ')
press = SA.alt2press(alt)
MP = press - (29.9213 - 28.6)
isa_pwr = IO.pwr(2700, MP, alt)
print('%.1f' % (isa_pwr), '\n')
def pwr_vs_alt_temp(temps):
"""
Returns a series of powers at full throttle and 2700 rpm at various temps
0 ft
-20 0 20 40 ISA
213.4 205.4 198.3 191.9 200.0
2000 ft
-20 0 20 40 ISA
197.3 189.9 183.3 177.4 186.2
4000 ft
-20 0 20 40 ISA
182.4 175.6 169.5 164.0 173.4
6000 ft
-20 0 20 40 ISA
167.8 161.5 155.9 150.9 160.6
8000 ft
-20 0 20 40 ISA
154.1 148.3 143.2 138.6 148.6
10000 ft
-20 0 20 40 ISA
141.3 136.1 131.3 127.1 137.3
12000 ft
-20 0 20 40 ISA
129.3 124.5 120.2 116.3 126.6
14000 ft
-20 0 20 40 ISA
118.2 113.8 109.8 106.2 116.5
16000 ft
-20 0 20 40 ISA
107.4 103.4 99.8 96.6 106.7
18000 ft
-20 0 20 40 ISA
97.3 93.7 90.4 87.5 97.4
20000 ft
-20 0 20 40 ISA
87.7 84.4 81.5 78.9 88.5
"""
alts = range(0,22000, 2000)
for alt in alts:
print alt, 'ft'
for temp in temps:
print temp, '\t',
print 'ISA'
for temp in temps:
power = alt2pwr(alt, temp = temp)
print '%.1f' % (power), '\t',
press = SA.alt2press(alt)
MP = press - (29.9213 - 28.6)
isa_pwr = IO.pwr(2700, MP, alt)
print '%.1f' % (isa_pwr), '\n'
piece.append('2400'.center(cols))
piece.append('2200'.center(cols))
piece.append('2300'.center(cols))
piece.append('2400'.center(cols))
piece.append('2500'.center(cols))
full_line = '|'.join(piece)
print('|' + full_line + '|')
for alt in range(0, 16000, 1000):
piece = []
piece.append(str(alt).rjust(col1))
temp = SA.alt2temp(alt, temp_units='F')
temp = int(temp)
piece.append(str(temp).rjust(col2))
press = SA.alt2press(alt)
pwr = .55 * max_pwr
for rpm in range(2100, 2500, 100):
mp = float(O.pwr2mp(pwr, rpm, alt))
if press - mp < diff:
piece.append('FT'.center(col2))
else:
piece.append(str(round(mp, 1)).center(col2))
pwr = .65 * max_pwr
for rpm in range(2100, 2500, 100):
mp = float(O.pwr2mp(pwr, rpm, alt))
if press - mp < diff:
piece.append('FT'.center(col2))
else:
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 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
piece.append('2400'.center(cols))
piece.append('2200'.center(cols))
piece.append('2300'.center(cols))
piece.append('2400'.center(cols))
piece.append('2500'.center(cols))
full_line = '|'.join(piece)
print '|' + full_line + '|'
for alt in range(0, 16000, 1000):
piece = []
piece.append(str(alt).rjust(col1))
temp = SA.alt2temp(alt, temp_units = 'F')
temp = int(temp)
piece.append(str(temp).rjust(col2))
press = SA.alt2press(alt)
pwr = .55 * max_pwr
for rpm in range(2100, 2500, 100):
mp = float(O.pwr2mp(pwr, rpm, alt))
if press - mp < diff:
piece.append('FT'.center(col2))
else:
piece.append(str(round(mp,1)).center(col2))
pwr = .65 * max_pwr
for rpm in range(2100, 2500, 100):
mp = float(O.pwr2mp(pwr, rpm, alt))
if press - mp < diff:
piece.append('FT'.center(col2))
else:
