# Preliminary Calculations

## The Operating Environment

The environment in which the aircraft is expected to operate plays a very important role in many of the conceptual design calculations to follow. The conditions corresponding to the current design brief are computed as follows:

In [42]: SeaLevelDens_kgm3 = ISA.alt2density(0, alt_units='ft',

density_units='kg/m**3') print 'ISA density at Sea level elevation: {:0.3f} kg/m^3'

.format(SeaLevelDens_kgm3)

ISA density at Sea level elevation: 1.225 kg/mA3

In [43]: TakeOffDens_kgm3 = ISA.alt2density(TakeOffElevation_feet

, alt_units=,ft,/ density_units='kg/m**3') print 'ISA density at take-off elevation: {:0.3f} kg/mA3'

.format(TakeOffDens_kgm3)

ISA density at take-off elevation: 1.225 kg/mA3

In [44]: ClimbAltDens_kgm3 = ISA.alt2density(ROCAlt_feet, alt_units='ft',

density_units='kg/m**3')

print 'ISA density at the climb constraint altitude: {:0.3f} kg/mA3' .format(ClimbAltDens_kgm3)

ISA density at the climb constraint altitude: 1.225 kg/mA3

In [45]: CruisingAltDens_kgm3 = ISA.alt2density(CruisingAlt_feet,

alt_units='ft', density_units='kg/m**3') print 'ISA density at cruising altitude: {:0.3f} kg/mA3'

.format(CruisingAltDens_kgm3)

ISA density at cruising altitude: 1.211 kg/mA3

In [46]: TopOfFinalAppDens_kgm3 = ISA.alt2density(TopOfFinalApp_feet,

alt_units=,ft,/ density_units='kg/m**3') print 'ISA density at the top of the final approach: (:0.3f}kg/mA3' .format(TopOfFinalAppDens_kgm3)

ISA density at the top of the final approach: 1.221 kg/mA3