BFF CL Software - Short User Guide


Previous    Contents     Next

Appendix E. Heavy Jet Mode 2 - Sim-Avionics.

Heavy Jet Mode 2 provides a heavy jet operating mode that integrates with the Sim Avionics flight deck software for B737 and B777. It is similar in operating principal to Heavy Jet Mode 1; however it integrates with the Sim-A auto pilot and generates A/P position following movement in elevator and aileron main axes.

In this mode the trim and A/P following behaviour of the controls differs from that for the default GA mode of operation - for a reminder of GA mode operation see the Heavy Jet Mode 1 page.

In Heavy Jet Mode 2 (Sim-A) the control axis behaviours are....

  • Elevator

    CL trim input is disabled. Instead elevator axis trim remains under the control of Sim-A. This disables the CL system elevator axis trim force adjustment. This causes the elevator axis to exhibit only one hands-off position - at mid position. In effect the trim input moves the aircraft stabiliser whilst allowing the elevator to be returned to its neutral plane at mid position; this replicates the native FSX elevator trim behaviour.

    When Sim-A A/P is engaged the elevator axis follows the control actions applied to the main elevator axis by the Sim-A auto pilot. In this mode the FSX/P3D native A/P is ignored.

    This A/P trim following behaviour requires that elevator axis trim buttons or switches are configured for normal Sim-A trim input.

    Whilst A/P is engaged the control loading on the elevator axis is replaced by PID position following, and position feed to Sim-A is suspended. You will see the elevator control move, and the elevator trim move to bring the elevator back towards mid under the command of the Sim-A A/P.

    If the feature is set, displacing the elevator position away from its set position will cause A/P to disengage.

  • Aileron

    The behaviour of the aileron axis remains similar to the default GA mode...

    CL system aileron trim is active (FSX / Sim-A aileron trim is disabled) - trimming causes the force balance on the aileron axis to change, which allows the aileron to be brought into force balance (hands-off condition) wherever the pilot is holding it. So non-mid hands-off positions can be trimmed.

    When Sim-A A/P is engaged the CL system moves the main aileron axis to simulate the bank control actions of Sim-A A/P. When this is happening the position feed to the Sim-A aileron control is disabled.

  • Rudder

    Trim operation is similar to the default GA mode -

    CL system rudder trim is active (FSX / Sim-A rudder trim is disabled) - trimming causes the force balance on the rudder axis to change, which allows the rudder to be brought into force balance (feet-off condition) where the pilot is holding it. So non-mid feet-off positions can be trimmed.

    However A/P behaviour is different from GA mode behaviour - when Sim-A A/P is engaged the rudder pedals will follow any movement induced in the main rudder axis by Sim-A A/P.

Additional Features

In addition to the above trim and A/P following behaviours other features are relevant with Heavy Jet mode (although they can also be used in the default GA mode). These parameters can be set using the Configuration Manager.

  1. (Force) Neutral position shift

    Parameter Tab 5 Item 9 Neutral_Pos_Offset_E can be set to define the neutral (or zero force) position shifted away from elevator axis mid range position. This can be helpful in some mechanical setups.

    Example, Neutral_Pos_Offset_E=20 will set the zero-force position at +20% of the column's half-range movement. This will then be the zero position at which the CL system will base its force calculations; it will be the natural hands-off position, assuming no fixed force components are configured which will cause a shift in position.

    Note that the position shift will NOT be visually apparent in the FSX virtual cockpit controls, but it will be present in the physical controls.

    Requires dsPIC firmware V41 or later.

    If you use this setting you may also want to use the Tab 4 Item 8 setting to set the mid-position for A/P position following.
  2. Rudder Position Scaler

    Parameter Tab 5 Item 15 Rudder_Pos_Scaler can be set to scale down the position input from the rudder axis to FSX.

    Example, setting Rudder_Pos_Scaler=0.75 will reduce the rudder position sent to FSX to 75% of the actual rudder pedal position.


Important Pre-requisites for using Heavy Jet Mode 2:

  1. CL_SPU_USB & BLDRV3 cards.
  2. CL software v2 and background process v2 (or later) are required.

Configuration Settings:

A heavy jet Sim-A default configuration file is available which has most settings already made. However they are detailed below for reference.

  1. Open the Configuration Manager and a "Heavy Sim-A" configuration file to start with. Go to Tab 5 and select Item 18b (Sim-A Mode), and then click Update_Mode.

    This will enable heavy jet mode 2 (Use_FSTrim=11), and make sure pot-less mode is set.

    This will also set the FSUIPC control position offsets in Items 12, 13 & 14 to those required by Sim-A for external position control (0x52F0, 52F2 & 52F4).

    It will also set Tab 4 Item 1 = 2 to enable A/P following and set the A/P status offset Item 25 = 0x5300 (default). This must be configured in your Sim-A FSUIPC I/O interface file - see next item.
  2. In your Sim-A FSUIPC I/O Interface file set a single byte offset to export the A/P status -

    [FSUIPC_OUTPUTS] section:

    // MCP Lights

    NB change "5300" to suit your chosen offset. If you change this you must also change Tab 4 Item 25 to suit.
  3. The CL software will issue A/P disengage commands via Sim-A MultiFunction offset 0x53DB. So make sure...

    MULTI_FUNCTION=53DB also set in your file.

    The CL software will issue the A/P disengage command if the pilot forces the elevator or aileron control is away from its set point by more than the trigger distances set in Tab 4 Items 13 & 14.

  4. If you wish to use the Neutral Position Shift feature set Tab 5 Item 9 Neutral_Pos_Offset_E to the required shift (as a %tage of the column 1/2 range movement). You may need to experiment to determine if a +ve or -ve shift is required on your set up.
  5. To use the Rudder Position Scaling feature set Tab 5 Item 15 Rudder_Pos_Scaler to the required scaling factor (range 0-1.0).
  6. Trim input to the CL software for the elevator axis is NOT required (it is left to Sim-A). However Sim-A trim inputs for aileron and rudder should be disabled, and trim inputs to the CL software set up for those axes.
  7. Tab 4 Item 13 (Line 44: Elev AP Disengage Trigger) can be set to control the amount of displacement of the elevator required to cause A/P disengage.
  8. Remember to SAVE your configuration settings.
  9. NOTE: Breakout settings on the elevator axis can be usefully employed in heavy jet mode to set a force detent at the hands-off position. See Tab1 Items 26 & 27.


If the above settings are not made correctly then the heavy jet mode 2 (Sim-A) may not engage properly.

If the CL software detects a problem with the settings it will display an error message. Check the log files for further details of the issue.




Previous    Contents     Next

Copyright 2018 BFF Design Ltd All Rights Reserved.