RE: [Flightgear-devel] YASim turbo/supercharger issues
Andy Ross wrote Drew wrote: IMHO, it's best to use interpolation tables rather than equations if you're trying to curve fit empirical data. Not in this context. The data here isn't being used to model a specific engine, but to provide sane parameters for all (super/turbochared) engines. The performance and code size advantages of an equation here are significant. At the moment we are looking at gear driven centrifugal compressors. Although I haven't researched it in any detail, the output of turbo-driven centrifugal compressors do not have a direct relationship with rpm (turbo lag), and the situation is complicated by the wastegate which operates on the turbo rather than the compressor. I suspect that this is another black art! Gear driven is easy in comparison. When someone comes up with a turbo we may have to have separate models. Regards, Vivian ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ..any estimates on SW rendering?, was: World Wind as moving map display
On Mon, 2005-04-18 at 23:17 +0200, Arnt Karlsen wrote: ..not yet, I'm scheeming a renderfarm stunt; some new 2'nd hand HW shop here says they got 200 Celeron 850's handy, so that got me thinking about picking this: http://tldp.org/HOWTO/BogoMips/x29.html#AEN54 sweet spot for a wee while. ;o) ..now this 200 node farm would need about 40, 50 to 60kWe, which I would like to feed off a genset or 2 burning gas which I would make off pelletized sewer sludge in my trusty old thermochemical gasifier. ;o) ..now, a 320,000 BogoMips rig running on poo for half a day, oughtta be able to do flyable software rendering for FlightGear at 1600x1200? ;o) ..what else can I do with this stunt rig, make our new global scenery? I guess it's time to do that ray-traced FGFS after all. But you don't have enough bandwidth for that. Perhaps 5 years out someone will have one of those new 16 processor/32 core AMD boxes laying around. That might do the job. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] realistic scenery
On Wed, 2005-04-20 at 08:16 -0700, Andy Ross wrote: Oliver C. wrote: How does X-Plane 8.1 solve that? It's not that terribly hard: store the texture mesh (2D, from the land use data) and polygon mesh (3D, from the elevation data) separately and do an intersection test when generating them (or even at load time). If the textures are allowed to overlap, you'll need to do multipass stuff or use a multitexture renderer, obviously. Another (somewhat lossy) option is to just create new texture maps from the originals. Take 2 scenery triangles (that share an edge) of roughly the same size and create a square/rectangular texture to cover them with whatever resolution you need. Then fill this texture by sampling the originals. Not all your samples will come from the same texture in the original, but when you're done, FG won't have the added complexity. There are lots of ways to do the sampling, but simply grabbing the nearest texel would be the simplest first attempt and will likely be necessary for more complex methods. It's a little lossy but keeps the complexity in the scenery generation rather than the renderer. If you've got higher resolution imagery than you want in your textures, it starts to become the perfect solution because the losses vanish as this ratio increases. -Paul ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ..any estimates on SW rendering?, was: World Wind as moving map display
On Sat, 23 Apr 2005 11:27:01 -0400, Paul wrote in message [EMAIL PROTECTED]: On Mon, 2005-04-18 at 23:17 +0200, Arnt Karlsen wrote: ..not yet, I'm scheeming a renderfarm stunt; some new 2'nd hand HW shop here says they got 200 Celeron 850's handy, so that got me thinking about picking this: http://tldp.org/HOWTO/BogoMips/x29.html#AEN54 sweet spot for a wee while. ;o) ..now this 200 node farm would need about 40, 50 to 60kWe, which I would like to feed off a genset or 2 burning gas which I would make off pelletized sewer sludge in my trusty old thermochemical gasifier. ;o) ..now, a 320,000 BogoMips rig running on poo for half a day, oughtta be able to do flyable software rendering for FlightGear at 1600x1200? ;o) ..what else can I do with this stunt rig, make our new global scenery? I guess it's time to do that ray-traced FGFS after all. ..tell me more. But you don't have enough bandwidth for that. .. how much do I need? Perhaps 5 years out someone will have one of those new 16 processor/32 core AMD boxes laying around. That might do the job. -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] YASim turbo/supercharger issues
On Sat, 23 Apr 2005 10:15:31 +0100, Vivian wrote in message [EMAIL PROTECTED]: Andy Ross wrote Drew wrote: IMHO, it's best to use interpolation tables rather than equations if you're trying to curve fit empirical data. Not in this context. The data here isn't being used to model a specific engine, but to provide sane parameters for all (super/turbochared) engines. The performance and code size advantages of an equation here are significant. At the moment we are looking at gear driven centrifugal compressors. Although I haven't researched it in any detail, the output of turbo-driven centrifugal compressors do not have a direct relationship with rpm (turbo lag), and the situation is complicated by the wastegate which operates on the turbo rather than the compressor. I suspect that this is another black art! Gear driven is easy in comparison. When someone comes up with a turbo we may have to have separate models. ..if your supercharger code takes shaft input (shaft speed, torque or power), then it can be re-used in the turbocharger's compressor code. ..the turbocharger's compressor or turbo-compound engine's crankshaft then only needs a turbine derivering shaft outnput (shaft speed, torque or power) to the compressor or gear box. -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Another fgfs enabled rating!
On Fri, 22 Apr 2005 21:24:25 +0200, Thomas wrote in message [EMAIL PROTECTED]: Am Freitag 22 April 2005 05:07 schrieb Dave Perry: I passed my instrument rating oral and practical (check ride) this afternoon. Five hours including the oral and ride. Congratulations Dave. Thanks to the entire FlightGear team for a great simulator with real world applicability! I really second this. I started flight school after FlightGear gave me the confidence that I could do it. The result is, that I had my first solo today (after just a bit more than 7 hours, think I'll need lots of alcohol to sleep tonight). ..how about re-doing your solo with --jgp-factory running, and make a movie? ;o) Nothing spectacular, after three patterns my FI suddenly decided to leave the plane and I did 2 more patterns, while he was collecting flowers for the photo... :-) So also from Germany a big THANK YOU for the FlightGear team. .. ;o) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Another fgfs enabled rating!
On Fri, 22 Apr 2005 21:09:34 +0200, Thomas wrote in message [EMAIL PROTECTED]: Am Freitag 22 April 2005 18:33 schrieb Martin Spott: Adam Dershowitz wrote: Martin: Yes, in the US it is often done in single engine airplanes. There is a lot of single engine IFR flying here, so the rating is very useful on its own, rather than as a step to other ratings. It really increases the utility of a airplane greatly when a few clouds don't ground you. Oh yes, I understand the intention, as long as it's really focused on IFR flying - and I'd wish to do it as well. Unfortunately in Germany, probably in most of Europe, we have to face major and in large parts unnecessary hindrance which probably will make the IFR rating unreachable for me :-( As far as I know, you do not have to have a multiengine rating for the IFR one in Germany. Both ratings are independent of each other. So nothing hinders you to go straight through... :-) Nevertheless we have way too much restrictions here in Germany, with new ones developed at an increasing rate after 9/11 (I'm currently filling a Request for a security check of my very own person :-( ) ..huh??? This is so you can walk to 'n from your plane and preflight etc it at your local and other airports? To be honest, I believe experienced people actually _do_ fly IFR if they have an aircraft that is equipped accordingly - even without having the proper license :-) No they do not, at least not for long time. On our way back from Friedrichshafen (Aero, Europes biggest GA trade show) we properly descended from FL 95 to FL 55, even at the cost of 10 extra minutes, because ATC didn't let us cross Nuremburgs D airspace. The point is, as proper IFR traffic you can expect separation from ATC. Don't expect that as VFR in IMC. ..I and David Magginson discussed this here a year or so back, post-9/11 GA sounds quite as paranoid as Cold War time GA up north in Norway (Finnmark), it _was_ over the hill paranoid, file flight plan 1hour in advance, always, alway, always carry max fuel so you could get as far away from the Red Army as possible if they move in, and if you can, carry your own radar and hide in terrain or clouds while running away to some useable or ditchable field, we expected our northern airports and ATC either taken, nuked, or in the queue in a couple of hours, in case of a Soviet invasion. ..the idiot war in Iraq is GWB's own doing, but I really have a problem forgiving those _assholes_ who lured the Russians into that idiot war in Chechenya. -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ..any estimates on SW rendering?, was: World Wind as moving map display
Arnt Karlsen wrote: On Sat, 23 Apr 2005 11:27:01 -0400, Paul wrote in message [EMAIL PROTECTED]: I guess it's time to do that ray-traced FGFS after all. ..tell me more. But you don't have enough bandwidth for that. .. how much do I need? One 1024x768x24 image is what? 2.25MB Even at a slow 15fps that's 33 MB per second or 266Mbps plus overhead. Besides, there's no way something like that could be integrated in the time available before your stunt. I just like to think out loud sometimes. Sorry. -Paul ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Fun with Nasal (II)
On Fri, 22 Apr 2005 15:21:46 -0700, Andy wrote in message [EMAIL PROTECTED]: Anyway, have fun with it. I just kinda wanted to show it off. :) ..show-off, shouldn't there be a 622'nd here? ;o) http://99-bottles-of-beer.net/n.html -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] YASim turbo/supercharger issues
Arnt Karlsen wrote: Andy Ross wrote Drew wrote: IMHO, it's best to use interpolation tables rather than equations if you're trying to curve fit empirical data. Not in this context. The data here isn't being used to model a specific engine, but to provide sane parameters for all (super/turbochared) engines. The performance and code size advantages of an equation here are significant. At the moment we are looking at gear driven centrifugal compressors. Although I haven't researched it in any detail, the output of turbo-driven centrifugal compressors do not have a direct relationship with rpm (turbo lag), and the situation is complicated by the wastegate which operates on the turbo rather than the compressor. I suspect that this is another black art! Gear driven is easy in comparison. When someone comes up with a turbo we may have to have separate models. ..if your supercharger code takes shaft input (shaft speed, torque or power), then it can be re-used in the turbocharger's compressor code. It doesn't because a gear driven compressor has a fixed relationship to engine rpm, and I deal with 2 speed superchargers separately, but you are right: a centrifugal compressor neither knows nor cares if it is gear- or turbo-driven. ..the turbocharger's compressor or turbo-compound engine's crankshaft then only needs a turbine derivering shaft outnput (shaft speed, torque or power) to the compressor or gear box. Now, if we knew what the turbo rpm was for a given engine rpm, and I think we need throttle opening ... any guidance welcome. Otherwise ... it's going to have to be magic mushrooms. Regards, Vivian ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] ..any estimates on SW rendering?, was: World Wind as moving map display
On Sat, 23 Apr 2005 14:48:21 -0400, Paul wrote in message [EMAIL PROTECTED]: Arnt Karlsen wrote: On Sat, 23 Apr 2005 11:27:01 -0400, Paul wrote in message [EMAIL PROTECTED]: I guess it's time to do that ray-traced FGFS after all. ..tell me more. But you don't have enough bandwidth for that. .. how much do I need? One 1024x768x24 image is what? ..what size image is used on rendering commercial movies? 2.25MB Even at a slow 15fps that's 33 MB per second or 266Mbps plus overhead. ..some of these leased box batches are getting new enough to have a coupla usb2 holes, that's 480Mbps per hole. So I shoot for movie theater framerates. ;o) Besides, there's no way something like that could be integrated in the time available before your stunt. ..that's why everything will be run off scripts. ;o) I just like to think out loud sometimes. Sorry. ..so make up for it by telling me more truths. ;o) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] YASim turbo/supercharger issues
On Sat, 23 Apr 2005 20:02:48 +0100, Vivian wrote in message [EMAIL PROTECTED]: Arnt Karlsen wrote: Andy Ross wrote Drew wrote: IMHO, it's best to use interpolation tables rather than equations if you're trying to curve fit empirical data. Not in this context. The data here isn't being used to model a specific engine, but to provide sane parameters for all (super/turbochared) engines. The performance and code size advantages of an equation here are significant. At the moment we are looking at gear driven centrifugal compressors. Although I haven't researched it in any detail, the output of turbo-driven centrifugal compressors do not have a direct relationship with rpm (turbo lag), and the situation is complicated by the wastegate which operates on the turbo rather than the compressor. I suspect that this is another black art! Gear driven is easy in comparison. When someone comes up with a turbo we may have to have separate models. ..if your supercharger code takes shaft input (shaft speed, torque or power), then it can be re-used in the turbocharger's compressor code. It doesn't because a gear driven compressor has a fixed relationship to engine rpm, and I deal with 2 speed superchargers separately, but you are right: a centrifugal compressor neither knows nor cares if it is gear- or turbo-driven. ..the turbocharger's compressor or turbo-compound engine's crankshaft then only needs a turbine derivering shaft outnput (shaft speed, torque or power) to the compressor or gear box. Now, if we knew what the turbo rpm was for a given engine rpm, .._not_ gonna happen. Turbo rpm will always, always, always be a function of the exhaust gas pressures piped in and out, and, the turbines own shaft loads, temperature, mass, and time. ..just think of any water wheel, or power turbine, to do the power turbine code part of the turbo. Then you can saw the gear box off the supercharger shaft and weld that stub onto the power turbine to make a turbocharger. ;o) and I think we need throttle opening ... any guidance welcome. ..just like in the supercharger code. Now, keep in mind, the power turbine _only_ sees exhaust gas pressures and temperatures piped in and out and its own mass and inertia, time and the shaft and bearing and lube film loads. ..the compressor on the _other_ end of that turbo shaft, will see the _same_ as the supercharger, except for the power turbine replacing the gear box. ..exhaust gas pressures and temperatures vary, think pulses, spikes, waste gates and even exhaust throttles, if you wanna model a new fancy way of blowing up a model engine in that spectacular way I read about in some model magazine some 20 years back. ;o) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] YASim turbo/supercharger issues
-Original Message- From: [EMAIL PROTECTED] [mailto:flightgear-devel- [EMAIL PROTECTED] On Behalf Of Arnt Karlsen Sent: 23 April 2005 22:02 To: FlightGear developers discussions Subject: Re: [Flightgear-devel] YASim turbo/supercharger issues On Sat, 23 Apr 2005 20:02:48 +0100, Vivian wrote in message [EMAIL PROTECTED]: Arnt Karlsen wrote: Andy Ross wrote Drew wrote: IMHO, it's best to use interpolation tables rather than equations if you're trying to curve fit empirical data. Not in this context. The data here isn't being used to model a specific engine, but to provide sane parameters for all (super/turbochared) engines. The performance and code size advantages of an equation here are significant. At the moment we are looking at gear driven centrifugal compressors. Although I haven't researched it in any detail, the output of turbo-driven centrifugal compressors do not have a direct relationship with rpm (turbo lag), and the situation is complicated by the wastegate which operates on the turbo rather than the compressor. I suspect that this is another black art! Gear driven is easy in comparison. When someone comes up with a turbo we may have to have separate models. ..if your supercharger code takes shaft input (shaft speed, torque or power), then it can be re-used in the turbocharger's compressor code. It doesn't because a gear driven compressor has a fixed relationship to engine rpm, and I deal with 2 speed superchargers separately, but you are right: a centrifugal compressor neither knows nor cares if it is gear- or turbo-driven. ..the turbocharger's compressor or turbo-compound engine's crankshaft then only needs a turbine derivering shaft outnput (shaft speed, torque or power) to the compressor or gear box. Now, if we knew what the turbo rpm was for a given engine rpm, .._not_ gonna happen. Turbo rpm will always, always, always be a function of the exhaust gas pressures piped in and out, and, the turbines own shaft loads, temperature, mass, and time. ..just think of any water wheel, or power turbine, to do the power turbine code part of the turbo. Then you can saw the gear box off the supercharger shaft and weld that stub onto the power turbine to make a turbocharger. ;o) and I think we need throttle opening ... any guidance welcome. ..just like in the supercharger code. Now, keep in mind, the power turbine _only_ sees exhaust gas pressures and temperatures piped in and out and its own mass and inertia, time and the shaft and bearing and lube film loads. ..the compressor on the _other_ end of that turbo shaft, will see the _same_ as the supercharger, except for the power turbine replacing the gear box. ..exhaust gas pressures and temperatures vary, think pulses, spikes, waste gates and even exhaust throttles, if you wanna model a new fancy way of blowing up a model engine in that spectacular way I read about in some model magazine some 20 years back. ;o) Or TFD - I'll think about it later (much later :-). Regards, Vivian ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
