def pwr2ff(pwr, rpm, mixture='pwr', ff_units='gph'):
"""
Returns fuel flow. Defaults to mixture for best power ("pwr"), but may
also be used with mixture for best economy ("econ"). Fuel flow units
default to USG/hr, but pounds per hour ("lb/hr") and litres per hour
("l/hr") may also be selected.
"""
if mixture == 'pwr':
if rpm >= 2600:
rpm1 = 2600
rpm2 = 2700
elif rpm >= 2400:
rpm1 = 2400
rpm2 = 2600
elif rpm >= 2200:
rpm1 = 2200
rpm2 = 2400
else:
rpm1 = 2000
rpm2 = 2200
ff1 = _pwr_ff_best_power(rpm1, pwr)
ff2 = _pwr_ff_best_power(rpm2, pwr)
elif mixture == 'econ':
if rpm >= 2600:
rpm1 = 2600
rpm2 = 2700
elif rpm >= 2400:
rpm1 = 2400
rpm2 = 2600
elif rpm >= 2200:
rpm1 = 2200
rpm2 = 2400
elif rpm >= 2000:
rpm1 = 2000
rpm2 = 2200
else:
rpm1 = 1800
rpm2 = 2000
ff1 = _pwr_ff_econ(rpm1, pwr)
ff2 = _pwr_ff_econ(rpm2, pwr)
else:
raise ValueError('mixture must be one of "econ" or "pwr"')
# else:
# raise ValueError, 'Invalid value for mixture.'
ff = ff1 + (ff2 - ff1) * (rpm - rpm1) / (rpm2 - rpm1)
if ff_units == 'lb/hr':
pass
elif ff_units == 'gph':
ff = U.avgas_conv(ff, to_units='USG')
elif ff_units == 'l/hr':
ff = U.avgas_conv(ff, to_units='l')
else:
raise ValueError('Invalid fuel flow units')
return ff
def pwr2ff(pwr, rpm, mixture = 'pwr', ff_units = 'gph'):
"""
Returns fuel flow. Defaults to mixture for best power ("pwr"), but may
also be used with mixture for best economy ("econ"). Fuel flow units
default to USG/hr, but pounds per hour ("lb/hr") and litres per hour
("l/hr") may also be selected.
"""
if mixture == 'pwr':
if rpm >= 2600:
rpm1 = 2600
rpm2 = 2700
elif rpm >= 2400:
rpm1 = 2400
rpm2 = 2600
elif rpm >= 2200:
rpm1 = 2200
rpm2 = 2400
else:
rpm1 = 2000
rpm2 = 2200
ff1 = _pwr_ff_best_power(rpm1, pwr)
ff2 = _pwr_ff_best_power(rpm2, pwr)
elif mixture == 'econ':
if rpm >= 2600:
rpm1 = 2600
rpm2 = 2700
elif rpm >= 2400:
rpm1 = 2400
rpm2 = 2600
elif rpm >= 2200:
rpm1 = 2200
rpm2 = 2400
elif rpm >= 2000:
rpm1 = 2000
rpm2 = 2200
else:
rpm1 = 1800
rpm2 = 2000
ff1 = _pwr_ff_econ(rpm1, pwr)
ff2 = _pwr_ff_econ(rpm2, pwr)
else:
raise ValueError, 'mixture must be one of "econ" or "pwr"'
# else:
# raise ValueError, 'Invalid value for mixture.'
ff = ff1 + (ff2 - ff1) * (rpm - rpm1) / (rpm2 - rpm1)
if ff_units == 'lb/hr':
pass
elif ff_units == 'gph':
ff = U.avgas_conv(ff, to_units = 'USG')
elif ff_units == 'l/hr':
ff = U.avgas_conv(ff, to_units = 'l')
else:
raise ValueError, 'Invalid fuel flow units'
return ff
def power(ff, ff_at_pk_EGT, rpm, CR=8.7, displacement=360, ff_units='USG/h', fric_power_factor=1):
"""
Returns engine power, based on fuel flow data. Based on an internal
Lycoming document, apparently for use during flight test programs.
ff = fuel flow
ff_at_pk_EGT = fuel flow at peak EGT
rpm = engine speed
CR = compression ratio. Allowable values are 6.75, 7, 7.2,
7.3, 8, 8.5, 8.7 or 9 (10 to be implemented later).
displacement = engine displacement in cubic inches. Allowable values are
235, 320, 360, 480, 480S, 540, 540S, 541 or 720.
The suffix S denotes GSO or IGSO engines.
# type = type of fuel delivery system. Allowable values are
# 'port_injection', 'carb', and 'single_point' (i.e fuel
# injected at a single point, prior to the intake tubes).
# This input is not yet implemented, as it is only needed
# for an alternate method, for high power conditions where
# it is not safe to lean to peak EGT.
ff_units = fuel flow units. Allowable values are 'USG/h', 'ImpGal/h',
'l/h', 'lb/h', and 'kg/h'
"""
ff_units = ff_units[:-2]
ff = U.avgas_conv(ff, from_units=ff_units, to_units='lb')
ff_at_pk_EGT = U.avgas_conv(ff_at_pk_EGT, from_units=ff_units, to_units='lb')
ff_best_mixture = ff_at_pk_EGT / .849
SFC_best_mixture = iSFC(CR)
best_mixture_pwr = ff_best_mixture / SFC_best_mixture
ihp = best_mixture_pwr * pwr_ratio_vs_ff_ratio(ff / ff_best_mixture)
try:
imep = P.BMEP(best_mixture_pwr, rpm, displacement, power_units='hp', vol_units='in**3')
disp_numeric = displacement
except TypeError:
disp_numeric = int(displacement[:3])
imep = P.BMEP(best_mixture_pwr, rpm, disp_numeric, power_units='hp', vol_units='in**3')
if imep < 140:
imep_best_pwr = imep
for n in range(10):
SFC_best_mixture = iSFC(CR, imep_best_pwr)
best_mixture_pwr = ff_best_mixture / SFC_best_mixture
imep_best_pwr = P.BMEP(best_mixture_pwr, rpm, disp_numeric, power_units='hp', vol_units='in**3')
# print 'iSFC = %.4f' % SFC_best_mixture
ihp = best_mixture_pwr * pwr_ratio_vs_ff_ratio(ff / ff_best_mixture)
bhp = ihp - friction_hp(displacement, rpm) * fric_power_factor
return bhp
def test_02(self):
# 200 lb of nominal fuel at -40 deg C to USG
# truth value from Canada Flight Supplement
Value = U.avgas_conv(200., from_units='lb', to_units='USG', temp=-40)
Truth = 200. / 6.41
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_01(self):
# 10 USG of nominal fuel at nominal temperature to lbs
# truth value from Canada Flight Supplement
Value = U.avgas_conv(10, from_units='USG', to_units='lb')
Truth = 60.1
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_01(self):
# 10 USG of nominal fuel at nominal temperature to lbs
# truth value from Canada Flight Supplement
Value = U.avgas_conv(10, from_units='USG', to_units='lb')
Truth = 60.1
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_02(self):
# 200 lb of nominal fuel at -40 deg C to USG
# truth value from Canada Flight Supplement
Value = U.avgas_conv(200., from_units='lb', to_units='USG',
temp=-40)
Truth = 200. / 6.41
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_03(self):
# 200 lb of 100LL grade fuel at 15 deg C to Imperial Gallons
# truth value from Air BP Handbook of Products - 715 kg/m**3
Value = U.avgas_conv(200., from_units='lb', to_units='ImpGal',
grade='100LL')
Truth = (((200. / 2.204622622) / 715) * 1000) / 4.54609
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_03(self):
# 200 lb of 100LL grade fuel at 15 deg C to Imperial Gallons
# truth value from Air BP Handbook of Products - 715 kg/m**3
Value = U.avgas_conv(200.,
from_units='lb',
to_units='ImpGal',
grade='100LL')
Truth = (((200. / 2.204622622) / 715) * 1000) / 4.54609
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_05(self):
# 200 l of 80 grade fuel at -40 deg C to kg
# truth value from Air BP Handbook of Products - 690 kg/m**3 at 15 deg C
Value = U.avgas_conv(200., from_units='l', to_units='kg',
grade='80', temp=-40)
Truth = (200. / 1000) * 690
# correct for temperature, using ratio given in Canada Flight Supplement
Truth *= 6.41 / 6.01
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_04(self):
# 200 kg of 100 grade fuel at 30 deg C to l
# truth value from Air BP Handbook of Products - 695 kg/m**3 at 15 deg C
Value = U.avgas_conv(200., from_units='kg', to_units='l',
grade='100', temp=30)
Truth = (200. / 695) * 1000
# correct for temperature, using ratio given in Canada Flight Supplement
Truth *= 6.01 / 5.9
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_05(self):
# 200 l of 80 grade fuel at -40 deg C to kg
# truth value from Air BP Handbook of Products - 690 kg/m**3 at 15 deg C
Value = U.avgas_conv(200.,
from_units='l',
to_units='kg',
grade='80',
temp=-40)
Truth = (200. / 1000) * 690
# correct for temperature, using ratio given in Canada Flight Supplement
Truth *= 6.41 / 6.01
self.failUnless(RE(Value, Truth) <= 5e-4)
def test_04(self):
# 200 kg of 100 grade fuel at 30 deg C to l
# truth value from Air BP Handbook of Products - 695 kg/m**3 at 15 deg C
Value = U.avgas_conv(200.,
from_units='kg',
to_units='l',
grade='100',
temp=30)
Truth = (200. / 695) * 1000
# correct for temperature, using ratio given in Canada Flight Supplement
Truth *= 6.01 / 5.9
self.failUnless(RE(Value, Truth) <= 5e-4)
def power_lop(ff, n, ff_units='USG/h'):
"""
Alternate, very simplified and approximate method to determine power, for
lean of peak operations. Optimized for operations at 50 deg F lean of
peak on Lycoming IO-360A series engines. This was a trial, and initial
testing suggests this function is not adequately accurate.
"""
ff_units = ff_units[:-2]
ff = U.avgas_conv(ff, from_units=ff_units, to_units='USG')
a, b, c, d, e, f, g, h, i = [4.61824610e+00, -7.90382136e-01, -4.09623195e-03, 7.58928066e-04,
-3.51093492e-05, -1.87325980e-07, 8.64253036e-09, 3.65001722e-02,
1.02174312e-06]
sfc = a + b * ff + c * n + d * ff * n + e * ff**2 * n + f * ff * n**2 + g * ff**2 * n**2 + h * ff**2 + i * n**2
pwr = ff * 6.01 / sfc
return pwr
def power_lop(ff, n, ff_units='USG/h'):
"""
Alternate, very simplified and approximate method to determine power, for
lean of peak operations. Optimized for operations at 50 deg F lean of
peak on Lycoming IO-360A series engines. This was a trial, and initial
testing suggests this function is not adequately accurate.
"""
ff_units = ff_units[:-2]
ff = U.avgas_conv(ff, from_units=ff_units, to_units='USG')
a, b, c, d, e, f, g, h, i = [
4.61824610e+00, -7.90382136e-01, -4.09623195e-03, 7.58928066e-04,
-3.51093492e-05, -1.87325980e-07, 8.64253036e-09, 3.65001722e-02,
1.02174312e-06
]
sfc = a + b * ff + c * n + d * ff * n + e * ff**2 * n + f * ff * n**2 + g * ff**2 * n**2 + h * ff**2 + i * n**2
pwr = ff * 6.01 / sfc
return pwr
def test_01(self):
Value = U.avgas_conv(100, from_units='lb', to_units='kg')
Truth = 45.359
self.failUnless(RE(Value, Truth) <= 1e-5)
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 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 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 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 test_01(self):
Value = U.avgas_conv(100, from_units='lb', to_units='kg')
Truth = 45.359
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_03(self):
Value = U.avgas_conv(100, from_units='lb', to_units='lb')
Truth = 100
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_03(self):
Value = U.avgas_conv(100, from_units='lb', to_units='lb')
Truth = 100
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_02(self):
Value = U.avgas_conv(45.359, from_units='kg', to_units='lb')
Truth = 100
self.failUnless(RE(Value, Truth) <= 1e-5)
def test_02(self):
Value = U.avgas_conv(45.359, from_units='kg', to_units='lb')
Truth = 100
self.failUnless(RE(Value, Truth) <= 1e-5)
def power(ff,
ff_at_pk_EGT,
rpm,
CR=8.7,
displacement=360,
ff_units='USG/h',
fric_power_factor=1):
"""
Returns engine power, based on fuel flow data. Based on an internal
Lycoming document, apparently for use during flight test programs.
ff = fuel flow
ff_at_pk_EGT = fuel flow at peak EGT
rpm = engine speed
CR = compression ratio. Allowable values are 6.75, 7, 7.2,
7.3, 8, 8.5, 8.7 or 9 (10 to be implemented later).
displacement = engine displacement in cubic inches. Allowable values are
235, 320, 360, 480, 480S, 540, 540S, 541 or 720.
The suffix S denotes GSO or IGSO engines.
# type = type of fuel delivery system. Allowable values are
# 'port_injection', 'carb', and 'single_point' (i.e fuel
# injected at a single point, prior to the intake tubes).
# This input is not yet implemented, as it is only needed
# for an alternate method, for high power conditions where
# it is not safe to lean to peak EGT.
ff_units = fuel flow units. Allowable values are 'USG/h', 'ImpGal/h',
'l/h', 'lb/h', and 'kg/h'
"""
ff_units = ff_units[:-2]
ff = U.avgas_conv(ff, from_units=ff_units, to_units='lb')
ff_at_pk_EGT = U.avgas_conv(ff_at_pk_EGT,
from_units=ff_units,
to_units='lb')
ff_best_mixture = ff_at_pk_EGT / .849
SFC_best_mixture = iSFC(CR)
best_mixture_pwr = ff_best_mixture / SFC_best_mixture
ihp = best_mixture_pwr * pwr_ratio_vs_ff_ratio(ff / ff_best_mixture)
try:
imep = P.BMEP(best_mixture_pwr,
rpm,
displacement,
power_units='hp',
vol_units='in**3')
disp_numeric = displacement
except TypeError:
disp_numeric = int(displacement[:3])
imep = P.BMEP(best_mixture_pwr,
rpm,
disp_numeric,
power_units='hp',
vol_units='in**3')
if imep < 140:
imep_best_pwr = imep
for n in range(10):
SFC_best_mixture = iSFC(CR, imep_best_pwr)
best_mixture_pwr = ff_best_mixture / SFC_best_mixture
imep_best_pwr = P.BMEP(best_mixture_pwr,
rpm,
disp_numeric,
power_units='hp',
vol_units='in**3')
# print 'iSFC = %.4f' % SFC_best_mixture
ihp = best_mixture_pwr * pwr_ratio_vs_ff_ratio(ff / ff_best_mixture)
bhp = ihp - friction_hp(displacement, rpm) * fric_power_factor
return bhp
