>> I think it's grossly unfair to mix these issues: Spaceflight requires >> to essentially write a space simulator. One of my first statements in >> the >> forum was: >> >> "Orbital flights opens a whole new can of worms besides the need for >> different rendering - completely different physics, completely different >> numerical stability issues,... basically you want to write a new orbital >> simulator, because the amount of stuff you can really use from a flight >> simulator is pretty small." > > At one time I thought this to be true, but it is not necessarily. We have > been working on JSBSim very hard over the past years (thanks to the > efforts > of Fröhlich, Coconnier, myself, and others) to make sure that JSBSim can > handle orbital dynamics properly - because if orbital dynamic are handled > properly, it's a good indicator that aircraft dynamics are, as well. We > can > now do a high altitude, high inclination, high-eccentricity, orbit (with > the > spacecraft rotating) and after one simulated day end up a few hundred > feet > from the spot in space where a well-regarded software tool (AGI's "STK" > product) says we should be. The dynamics of flight are not really > different > at all. Stability is not a problem. I would disagree with your statements > above and in fact my experience has been almost the opposite, except for > the > rendering problem, which I have no experience with. I have been > approached > to help with testing JSBSim with Outerra, however, and obviously they are > doing rendering very well from space to ground.
To provide the context: I wrote the above in response to pictures of Mars (from Celestia) being posted and talk about Apollo missions, i.e. having interplanetary missions in mind. (Jon actually knows that, because I explained it later in the thread :-) ) - something which my wording 'orbital flight' actually doesn't reflect. I will be convinced that stability is not an issue here if someone demonstrates to me that a 4 month fast-forward running the simulation at a factor 1.000.000 time acceleration gets you a few 100.000.000 km later precisely where you're supposed to be. Gravitational slingshots require an incredible precision - you can't be 100 km off at target. Cheers, * Thorsten ------------------------------------------------------------------------------ Got Input? Slashdot Needs You. Take our quick survey online. Come on, we don't ask for help often. Plus, you'll get a chance to win $100 to spend on ThinkGeek. http://p.sf.net/sfu/slashdot-survey _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
