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• Ranges & Mission Performance

Detailed mission performance and range evaluations are derived from first principles, based on the current aerodynamics, mass, and engine characteristics. It is possible to examine any design mission (starting at MTOW) or off-design missions corresponding to specific takeoff weights or required block distances.

Climb, cruise and descent segments of a mission are analysed through rigorous step-by-step techniques. Diversion, hold, and contingency reserves and allowances can be specified in any combination (e.g. international reserves of 5% of block fuel + 45 mins. hold + 200 n.m. diversion, or 10% of flight time, etc).

Typically, operational climbs use airspeed schedules consisting of a constant calibrated airspeed (CAS) segment followed by a constant Mach number. Schedules can be calculated or specified by the user. Acceleration corrections are included, and a standard 250 kts ATC limitation is applied below 10,000 ft.

The cruise phase can be flown at a constant altitude or over a sequence of altitudes (a 'step-up' profile), or using a variable optimal altitude ('drift-up'). Step-up segment calculations are based on standard westbound-eastbound rules or user-input Flight Levels. The cruise Mach number can be set to match nominal conditions (e.g. high-speed, maximum Specific Air Range or 99% of max SAR), or input by the user.

Descents can be at made at idle conditions or using partial power to satisfy cabin re-pressurisation constraints.

Operating ceilings and ICAC (Initial Cruise Altitude Capability) can be determined at various combinations of engine rating and residual Rate of Climb with all engines operating. Engine-out cases are evaluated to match a residual gradient.

The following is a sample range report summary:

  RANGE REPORT  {design}

  {TOW 73500.kg./ OEW 41310.kg./ Fuel 18540.kg./ Payload 13650.kg.}

  Range mode: 99% max.SAR, step-up cruise 

  Climb schedule: 250./ 278.kcas/ mach 0.732 above 29683.feet

  Cruise at Mach = 0.781  {FL 350 390}

  ICA 35000.feet, 450.ktas, 265.kcas, CL=0.62, 4550.lbf./eng=MCR-18% 
  FCA 39000.feet, 448.ktas, 241.kcas, CL=0.61, 3782.lbf./eng=MCR-19% 

                Distance        Time      Fuelburn
                (n.miles)      (min.)      (kg.)
                _________      ______     _______
  Climb            140.          23.        1696.   {S.L to ICA}
  Cruise          2628.         352.       13087.   {ICA to ICA}
  Descent          102.          18.         156.   {ICA to S.L}
                _________      ______     _______
  Trip  total     2870.         393.       14939.
  Block total   =========       409.       15389.

  Emissions: taxi,t/o  climb   cruise  descent  app,taxi   total
  (kg.NOx)      2.6     20.2     78.7      0.5      1.3    103.3
  (kg.HC)      0.12     0.07     1.56     0.25     0.13     2.13
  (kg.CO)       2.0      3.6     51.4      3.7      2.1     62.8

  Manoeuvre allowances:
  taxi-out      92. kg. {extra to t/o mass}     7.5 min.
  takeoff      125. kg.                         1.0 min.
  approach     172. kg.                         3.0 min.
  taxi-in       61. kg. {taken from reserves}   5.0 min.

  Reserves {at landing mass 58264.kg.}:

  Diversion distance          200. n.miles
  Diversion mach            0.566
  Diversion altitude        21413. feet
  Diversion fuel             1391. kg.

  Holding time                 30. minutes
  Holding mach              0.300
  Holding altitude           5000. feet
  Holding fuel               1151. kg.

  Contingency fuel            762. kg. {5.% of mission fuel}

  Total Reserve fuel         3304. kg.

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