> Jon S. Berndt wrote: > > I haven't been following this thread very closely. Can someone > > concisely recap what is wanted, here? It's most likely a very simple > > addition for us if it's something we don't now model. > > Actually, YASim uses a Nasal-based fuel system that was designed to be > FDM-independent. It doesn't handle the stuff internally at all. > > Instead, each engine sets an /engine/engines[n]/fuel-consumed-lbs > property. Each iteration, it adds its newly consumed fuel (that is, > just flow rate * timestep) to this property. The Nasal script then > comes around in a polling loop, sucks this stuff out and subtracts it > from the tanks according to the fuel selector properties. > > YASim then just uses each tanks level-lbs property as a pure input > property to set weights on the tank objects.
This is good for YASim. However, the Nasal approach won't apply for other applications which use JSBSim, and JSBSim also needs its own fuel management for batch runs (standalone operation) outside of FlightGear. The downside to that requirement is that somehow we have to all learn to play nice together in a sensible way. This has been kind of an irritatant to me, that there are probably going to be items in our (JSBSim) configuration spec which are ignored or overwritten by FlightGear, which leads to user confusion and debugging headaches (I'm referring to fuel quantities and weight and balance issues). > FWIW, another cool thing this dialog gets you is automatic weight > management. You can assign "named" weight objects in your -set.xml > file and use sliders to control their sizes at runtime. Not many of > the YASim aircraft are doing this yet (I did the pa28-161 and a4, I > know). It's a much cleaner interface than having separate FDM > configurations for each aircraft loadout. This points out a headache for FlightGear, too: how to manage different capabilities in different FDMs and not leave users scratching their heads: "why can I do this with this aircraft and not that one?" Some of the features can be added to the various FDMs without much trouble, I'm guessing, and made more "common" through the FGInterface class. With JSBSim, though, we have to be careful and make sure new features don't break other people's apps and continue to work with standalone operation. Anyhow, we support specification of named mass objects in the configuration file. There are static once defined. We might consider writing up a list of common features that we'd like to see supported by all FDMs, so the user has a more homogenous experience with the various aircraft. Innis has written that all that is really needed from us it to provide a "total fuel" property. That's very simple to do. Jon _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
