Es/FlightGear Newsletter December 2013: Difference between revisions

=== Implementing VNAV -a Brainstorming ===

[[File:Route-managed-with-fgscript-support.png|thumb|270px|route manager dialog with added support for exporting to JSBSim/FGScript XML files]]

We've recently had another discussion on the forums about implementing VNAV in FlightGear. In comparison with other flight simulators, FlightGear has been lacking support for simulating VNAV features found on many modern aircraft since day one.

So far, the general consensus has been that it simply isn't yet possible in FlightGear to properly implement VNAV because VNAV depends on having access to an aircraft-specific performance database to provide the proper pitch/thrust changes to make certain VNAV altitude/speed/time constraints,  which boils down to a lack of support by the FDMs (JSBsim/YaSim) actually.  

As an open source project, we do not have access to the corresponding  flight data or such a performance database, and even if we did, we probably couldn't easily use said data due to its proprietary nature.  

In addition, a real performance database would probably not serve us too well, because our FDM configurations are custom, too - i.e. the performance database would need to  match the performance of the simulated aircraft.

Thus, a performance DB would ideally be provided by the FDM itself. Either in a pre-created fashion, i.e. compiled during an offline "test flight", or preferably at runtime by running a simulation of the FDM inside the actual FDM.

We've now started gathering all information from past VNAV discussions to come up with a brainstorming and determine how to implement the building blocks required for supporting VNAV (vertical navigation) in FlightGear (YaSim/JSBSim). Any feedback is greatly appreciated.

Continue reading at [[Implementing VNAV support in FlightGear]]...