Re: [Flightgear-devel] Temperature and air pressure
On Fri 22. February 2002 23:41, you wrote: I've added two new properties tied to the FGEnvironment class (you'll see these only if you compile with --with-new-environment): /environment/temperature-sea-level-degc /environment/pressure-sea-level-inhg I'm sticking with sea-level-equivalent values for now, because I know that the FDM people are pretty possessive of their atmosphere models. Later I might add properties and methods for the values at current altitude as well. I'd very much like to figure out how to hook these up to the FDMs, so that we can have sluggish climb behaviour on hot, muggy days, etc. We might also need a relative-humidity property. What units should we use? Do the FDMs care about humidity? All the best, David Is Humidity important? Why not report just air density and viscosity. IMHO viscosity is importanat for count of Reynolds number. Maybe Re don't play big role in currents FDMs but is really important for RC modeling. OT: What are necessary values for FDM. air pressure air density viscosity temperature wind vector gravitation vector, Forgot I something? Reagrds, Madr -- Martin Dressler e-mail: [EMAIL PROTECTED] http://www.musicabona.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Temperature and air pressure
Martin Dressler wrote: Is Humidity important? Why not report just air density and viscosity. IMHO viscosity is importanat for count of Reynolds number. Maybe Re don't play big role in currents FDMs but is really important for RC modeling. OT: What are necessary values for FDM. air pressure air density viscosity temperature wind vector gravitation vector, Forgot I something? If you want to provide data you need it first. And there are no weather reports that give me viscosity AFAIK. So any weather system can only provide data that it has and that it can derivate (e.g. denisty from pressure and temperature). If you want viscosity and it's possible to derivate, that's fine. But to 'publish' that data it's important how expensive it's to compute (and to publish) and how many subsystems need it. So it *might* be better if that data isn't provided and the (yet-to-come) ModelSim FDM calculates it itself. CU, Christian -- The idea is to die young as late as possible.-- Ashley Montague Whoever that is/was; (c) by Douglas Adams would have been better... ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Temperature and air pressure
Arnt Karlsen wrote: I'm sticking with sea-level-equivalent values for now, because I know that the FDM people are pretty possessive of their atmosphere models. Later I might add properties and methods for the values at current altitude as well. Possesive? Heh, I hereby declare that I'd be extraordinarily happy to dump the YASim atmosphere model in favor of a standard one. The reason it's there at all is for the solver -- it's nice to be able to specify a cruise altitude instead of an air temperature and pressure, and there has to be some way to convert altitude to these values. ..for flight in other atmospheres (Mars, Venus, Jupiter, or in fluids like water), which atmosphere model is easier to work from? The air pressure model in WeatherCM (documentaion for it is in the same directory) should work easily with arbitrary atmospheres. The only limitation (but that'll be easy to fix) might be that I hardcoded an oxigen/nitrogen atmosphere. But the rest (i.e. the pressure curve) should be fairly right. CU, Christian -- The idea is to die young as late as possible.-- Ashley Montague Whoever that is/was; (c) by Douglas Adams would have been better... ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Temperature and air pressure
On Fri, 22 Feb 2002 15:29:18 -0800, Andy Ross [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]: David Megginson wrote: I've added two new properties tied to the FGEnvironment class (you'll see these only if you compile with --with-new-environment): /environment/temperature-sea-level-degc /environment/pressure-sea-level-inhg I'm sticking with sea-level-equivalent values for now, because I know that the FDM people are pretty possessive of their atmosphere models. Later I might add properties and methods for the values at current altitude as well. Possesive? Heh, I hereby declare that I'd be extraordinarily happy to dump the YASim atmosphere model in favor of a standard one. The reason it's there at all is for the solver -- it's nice to be able to specify a cruise altitude instead of an air temperature and pressure, and there has to be some way to convert altitude to these values. ..for flight in other atmospheres (Mars, Venus, Jupiter, or in fluids like water), which atmosphere model is easier to work from? -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Temperature and air pressure
..for flight in other atmospheres (Mars, Venus, Jupiter, or in fluids like water), which atmosphere model is easier to work from? -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) I started work some time ago on making JSBSim accept a different gravity model. This was specifically for flight over the surface of other planets. The atmosphere, of course, needs to be modeled differently. Right now we model a standard atmosphere within JSBSim, and perhaps soon a variable, weather-aware atmosphere. I would like (someday) to model other atmospheres. I do have a copy of an older Gramm model of the Mars atmosphere in Fortran. JSBSim will likely have (*if* we someday do model other planetary atmospheres) at least a rudimentary standard model for those planets we choose to model. This is not something we (or at least I) am currently spending any thought on, other than that it is something I'd like to do. Of course, the things one needs to keep in mind are the constituent gases, the specific heat ratio will differ from that of earth, etc. I am not sure how this would fit into JSBSim's FGAtmosphere, though. Perhaps as a table read-in? Jon ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
