20,741
edits
Implementing VNAV support in FlightGear: Difference between revisions
Jump to navigation
Jump to search
Implementing VNAV support in FlightGear (view source)
Revision as of 18:47, 1 December 2013
, 1 December 2013→Background
| Line 41: | Line 41: | ||
|author=Zakalawe |date= Thu Oct 13, 2011 6:03 am}}</ref>|Zakalawe}} | |author=Zakalawe |date= Thu Oct 13, 2011 6:03 am}}</ref>|Zakalawe}} | ||
{{cquote|What you need is a simplified performance model of the aircraft or, rather, a set of simplified performance models as function of your | |||
relevant variables which in your case may only be c.g. position. Once you have such a model, predicting flight paths is not difficult. The | |||
problem is getting such a model. The only way I've ever done it was totake a full-envelope aerodynamic model, a full-envelope thrust model, | |||
trim the aircraft at lots of Mach-altitude points, and derive a simple model at each point. Generally, what you want is lift-coefficient as a | |||
function of angle of attack, a drag polar model, and some simple moment coefficients so you can predict rotational effects (such as turning and | |||
turn rate). Building a program to beat the crap out of a standard model is the only sane way to approach the issue of generating performance | |||
models. | |||
Good luck.<ref>{{cite web |url=http://sourceforge.net/p/jsbsim/mailman/message/12270464/ |title=JSBSim Issue#29: performance database/prediction | |||
|author=Lee Duke|date=2007-03-19 17:35:10}}</ref>|Lee Duke}} | |||
{{cquote|I've seen the use of simple simulation within a simulation, where performance data is being calculated. It was not within JSBSim, however. This is an interesting prospect. Nobody has ever done this, up to now. My initial reaction was pessimistic. However, the flight control components within JSBSim are fairly capable, and you are permitted to define arbitrary functions. So, my guess at this time is, yes, you should be able to set up JSBSim to calculate *some* performance data. It may be a lot of work, but it should be possible. <ref>{{cite web |url=http://sourceforge.net/p/jsbsim/feature-requests/29/?limit=10&page=1#8ce6 |title=JSBSim Issue#29: performance database/prediction | {{cquote|I've seen the use of simple simulation within a simulation, where performance data is being calculated. It was not within JSBSim, however. This is an interesting prospect. Nobody has ever done this, up to now. My initial reaction was pessimistic. However, the flight control components within JSBSim are fairly capable, and you are permitted to define arbitrary functions. So, my guess at this time is, yes, you should be able to set up JSBSim to calculate *some* performance data. It may be a lot of work, but it should be possible. <ref>{{cite web |url=http://sourceforge.net/p/jsbsim/feature-requests/29/?limit=10&page=1#8ce6 |title=JSBSim Issue#29: performance database/prediction | ||