Just Flight 747 Classic, More Previews + Systems Overview

Just Flight has posted some new WIP images and a detailed systems overview in regards to the upcoming Boeing 747 Classic for FSX and Prepar3D.

First off, the screenshots highlight ongoing modelling and texture work with respect to the interior and exterior of the aircraft. Moreover, PBR and wing flex is currently under development – the first previews are expected in a couple of weeks.

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Next, please see below for a complete systems overview.



The Flight Engineer’s panel with nearly all normal operations is modelled. The systems respond accurately to both correct and incorrect configurations.

  • APU – fully simulated
  • Electrical system – fully simulated, including simulation of all TRs (transformer-rectifiers), buses, and relays
  • Pneumatic system – fully simulated. Responds to various configurations.
  • Air system (including packs) – fully simulated, including temperature zone simulation. The various zone temperatures are modelled, as are air mixing and auto/manual modes of operation.
  • Pressurisation system:
    • Fully simulated. The system uses a physics-based approach to modelling cabin pressure and responds to the external environment.
    • The system also responds to various configurations, such as whether or not the toilet fan is operating, which affects air out-flow
    • Both positive and negative pressure-relief valves are modelled, in addition to auto/manual modes of operation
  • Hydraulic system and brake systems:
    • All systems are modelled, with accurate engine and air-driven hydraulic pump simulation
    • System uses hydraulic pressure, and the braking systems are both modelled and draw hydraulic pressure accordingly from the primary systems when pressurised
    • The reserve braking system and accumulators are modelled in the braking systems, as is the Number 4 electric pump with correct operational limits. The braking system in use can be selected from the switch on the Captain’s side main panel.
  • Fuel system:
    • Fully simulated, including accurate fuel temperature modelling, icing, and fuel heaters (requiring bleed air to be present for operation)
    • Jet A fuel is modelled, with a freezing temperature of -40 degrees C. The system also simulates fuel waxing and detection of ice crystals in the fuel at ca. -35 degress C with the associated ICING lights. Engines will be starved of fuel if the fuel temperature reaches or exceeds -40 degrees C.
    • All crossfeed and boost pump operations are modelled, and engines can be gravity fed, fed from their respective tank, or fed from the crossfeed, depending on system configuration
    • Fuel is accurately and correctly taken from whichever tanks are supplying fuel at pressure
    • Fuel scavenge pump is modelled, with associated limitations
  • Fuel dump system – fully simulated
  • Fire systems – fully simulated, not only test capability but also operational
  • Anti-skid system – fully simulated
  • Gear system and steering – fully simulated
  • Flight controls – fully simulated, including the ability to isolate systems with a corresponding reduction in the effectiveness of controls
  • Flight instruments:
    • Air-data driven instruments including airspeed, altimeter, VSI are fully simulated using a physics-based system
    • System correctly models the pitot and static systems, and full ice modelling of one or both (pitot and/or static) systems, with correct effects upon the affected instruments
  • Captain, F/O and auxiliary systems are modelled (four in total) and drive their associated instruments, with complete instrument source switching
  • Additional effects due to aerodynamics are modelled, including differential pressures around the static ports due to AoA (angle of attack) and Beta (sideslip) affecting most notably the standby altimeter, but also the other ADC-driven instruments to a lesser effect (due to compensation built into the ADC). Altimeters and ASIs are subject to temperature (density) error.
  • Air data simulation – complete and independent simulation of the atmosphere is present, to include humidity and air density. Systems are affected by air density where appropriate, and not air pressure as is (incorrectly) the case elsewhere.
  • Engines
    • A custom thrust model is implemented, allowing accurate engine performance modelling and engine instrumentation. This translates to accurate aircraft performance and allows the aircraft to be flown ‘by the book’ regarding fuel flows and expected speeds (many FS aircraft don’t settle at a certain speed or settle at an incorrect speed). The custom model allows accurate performance across a very wide range of the flight envelope, from sea level to FL450.
    • Accurate engine performance also means accurate fuel consumption, and optimum/long-range cruise Mach number (M 0.83 for the -100/-200) now means something. Fly faster or slower than this optimum, and maximum range will not be achieved due to the increased fuel burns required.
    • Water injection is also accurately modelled, offering increased thrust at take-off. Usage of the system requires correct configuration and the availability of water. The mass of this water is also not insignificant – full water quantity is also accounted for in the flight model.
    • Engine start-up and shutdown are accurately modelled, including max. motoring RPM being linked to bleed air pressure
    • Advanced engine behaviours typical of non-FADEC (Full Authority Digital Engine Control) control. The fuel flow metering system is modelled, meaning that if large thrust changes are made quickly, especially from low RPM, the engines can be overheated or even catch fire.
    • Engine start procedures must be followed correctly, otherwise hot-starts/fires can occur, combined with failure of the engine to accelerate to idle thrust
    • EPR is accurately modelled and correctly reflects the thrust output of the engine in response to thrust setting and density altitude
  • CoG computer – the CoG is accurately computed for the aircraft, both on the ground and in flight. As fuel is burned, the CoG shifts and this is reflected in the handling (most notably, trim changes)
  • Gyro instruments – the gyro instruments are faithfully replicated including all drift and acceleration errors, as well as procession errors, ‘apparent’ and ‘real’ wander, ‘transport rate’ corrections etc.
  • Navigation:
    • The Delco INS is replicated and includes full functionality of all navigation functions and modes. System errors and position drift are also modelled.
    • VOR and ADF receivers are fully simulated, including advanced behaviours
    • ILS is custom-coded in order to avoid the many problems associated with the FS ILS system.
  • Auto-flight:
    • Thrust computer – the thrust-rating computer is fully functional and the EPR mode of automatic thrust is modelled, in addition to Speed and Mach hold functions
    • Dual autopilots with autoland capability are modelled, together with accurate system limitations and source selection
    • The flight director system is fully simulated, with source switching and accurate behaviours.


To view the original preview images and accompanying description, see the source post via Facebook. For more information about the Just Flight 747 Classic (including the systems overview), visit the project development page via Just Flight.

The project was last previewed back in March,

*Images courtesy of Just Flight.

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