Implementing VNAV support in FlightGear: Difference between revisions

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Implementing VNAV support in FlightGear (view source)

Revision as of 23:00, 5 December 2013

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* VNAV automatically selects altitude targets and speed targets according to pilot MCP entries and the altitude and speed constraints in the FMS flightplan.
* VNAV automatically selects altitude targets and speed targets according to pilot MCP entries and the altitude and speed constraints in the FMS flightplan.
* VNAV automatically selects pitch and thrust control modes to fly to the targets. For example during descent, VNAV chooses between a FLCH descent, a vertical speed (fixed rate-of descent), and an FMS path descent. In the case where VNAV selects vertical speed control mode, VNAV also selects the vertical speed target.
* for the descent and approach, VNAV automatically provides an optimum path that is used as the reference for all automated altitude/speed target and control mode selections.


* VNAV automatically selects pitch and thrust control modes to fly to the targets. For example during descent, VNAV chooses between a FLCH descent, a vertical speed (fixed rate-of descent), and an FMS path descent. In the case where VNAV selects vertical speed control mode, VNAV also selects the vertical speed target.
FMS VNAV Rules:
* VNAV does not function until all PERFORMANCE INIT information has been programmed into the CDU
* VNAV is available for all phases of flight
* VNAV never passes through the altitude pre-selector
* VNAV keeps the aircraft as high as possible for as long as possible
* VPATH angles are from 1 to 6 degrees


* for the descent and approach, VNAV automatically provides an optimum path that is used as the reference for all automated altitude/speed target and control mode selections.


In a study of the software of contemporary VNAV functions, Sherry & Polson (1999), found that the typical VNAV function automatically chooses the active altitude target from a possible list of sixteen, and chooses the active speed target from a possible list of twenty-six.  
The typical VNAV function automatically chooses the active altitude target from a possible list of sixteen, and chooses the active speed target from a possible list of twenty-six.  


For more info, see:
For more info, see:
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* http://www.b737.org.uk/fmc.htm
* http://www.b737.org.uk/fmc.htm
* http://code7700.com/g450_vnav.html
* http://code7700.com/g450_vnav.html
* http://human-factors.arc.nasa.gov/ihi/research_groups/air-ground-integration/MACSassistant/MCP.htm
* h
 
{{Appendix|all|
* {{cite web |url=http://human-factors.arc.nasa.gov/publications/20051025130903_VNAVCogEngJournal1TM.pdf |title=Why VNAV in Descent is Difficult to Use }}
* {{cite web |url=http://www.smartcockpit.com/download.php%3Fpath%3Ddocs/%26file%3DGetting_To_Grips_With_Perfomance_Monitoring.pdf|title=getting to grips with aircraft performance monitoring (p.96 ff)}}
* {{cite web |url=http://www.google.com/patents/US20060200279 |title=Method of determining a comparison of an aircraft's performance capabilities with performance requirements }}
* {{cite web |url=http://www.google.com/patents/US20110118908 |title=Methods and systems for management of airplane speed profile }}
 
}}


== The Performance Database ==
== The Performance Database ==
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