Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
Am Dienstag, den 25.12.2007, 22:24 +0100 schrieb R. van Steenbergen: gerard robin schreef: With an aircraft which has gears retractable , the landing on sea can be done smoothly on the belly. TableData drag (and lift) can be given with the best values according to the water reaction. The values regarding landing on ground remains right. We have, only, to select the right TableData according to terrain type, which is easy to do. The possibility of belly landing an aircraft depends on the aircraft type -- an A/C with underwing mounted engines and a low wing is impossible to make a graceful belly-ditch (like the 737) since the engines would scoop up all the water and cause a huge amount of drag (and pitch the nose forward). In this case the pilot approaches the water with a slight bank, so only one engines hits the water. The drag will cause the aircraft to make a strong yaw-movement, thereby loosing speed and reducing the tendency to dive nose over. This is a standard procedure for emergency landing and has been successfully (without loss of lives) conducted in the past. IMO, the aircraft's fuselage, engines, and wings could also be considered contact points, albeit higher situated than an extended landing gear. For example, when you land a 737 or 747 over its recommended landing weight, you run the risk of either breaking the gear struts or causing enough gear compression to impact the engines on the runway. And of course, belly-landing an A/C on tarmac or grass is just as possible as ditching on water, but those methods could only be considered in an extreme emergency (like a jammed landing gear). Even MSFS can be fooled into doing it: I once bellied a Learjet 45 on the runway at Malaga in FS2004, only noticing that I made a fuselage landing when I tried to taxi off the runway and the aircraft didn't move (and I switched to external camera, realizing I forgot to lower the gear before landing. Next time: THREE GREENS! :)) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
GWMobile wrote: You are really missing the point. What I am saying is no one interested in reality is going to land on water in the first place so the people who would expect a crash indication won't be doing the landing anyway. Well, maybe so, then again... maybe not... http://ca.youtube.com/watch?v=01E_6oxvlQA -- Visit my Gallery at http://www.ascendant-online.net - Aviaton and other Art, Avation Stories, Philosophy, Flight Simulator News, and the occasional rant. AMD Phenom Quad Core Processor review http://www.ascendant-online.net/node/371 - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
On Tuesday 25 December 2007 13:57:10 GWMobile wrote: 1. Anyone who lands on water in a flight sim knows they are doing it. It is highly likely they WANT to do it - ie have a float plane or want to ditch. Setting a crash default is silly. It forces people to not be able to do what they want and it isn't realistic. Good idea. We could ditch those stupid complex FDMs that cause newbies to crash all the time too. After all, if they WANT to fly, why should they be forced to crash just because they did something that's impossible in real life? snip vast acreage of, IMHO, nonsense I'm sorry, but from your comments it seems clear that you have no idea how crash detection works in any FG FDM. It looks like you're writing about a different sim altogether to me? With YASim in particular we have excellent ground and water modelling (as Maik, who wrote it and therefore knows what he's talking about) very politely explained... you should perhaps take the time to investigate what we already have. Have fun practising much more realistic ditching ;-) Cheers, AJ - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
On Dec 26, 2007, at 1:00 AM, Shad Young wrote: GWMobile wrote: You are really missing the point. What I am saying is no one interested in reality is going to land on water in the first place so the people who would expect a crash indication won't be doing the landing anyway. Well, maybe so, then again... maybe not... http://ca.youtube.com/watch?v=01E_6oxvlQA They don't have much weight on the wheels. This guy puts more weight on the wheels: http://ca.youtube.com/watch?v=W7o--nT-Pt0 - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
Hi, Shad Young schrieb am 26.12.2007 10:00: GWMobile wrote: You are really missing the point. What I am saying is no one interested in reality is going to land on water in the first place so the people who would expect a crash indication won't be doing the landing anyway. Well, maybe so, then again... maybe not... http://ca.youtube.com/watch?v=01E_6oxvlQA This should be possible with all YASim aircrafts; but I am not sure, if we have such flat water in Flightgear. And this can be done, too: http://ca.youtube.com/watch?v=W7o--nT-Pt0feature=related (and we get realistic behavior even without simulating structural damages). Maik - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
The original post quoted below exemplifies why I beleive it is a mistake to ever have crash detection for water in a flight sim however let me lay it out simply. 1. Anyone who lands on water in a flight sim knows they are doing it. It is highly likely they WANT to do it - ie have a float plane or want to ditch. Setting a crash default is silly. It forces people to not be able to do what they want and it isn't realistic. 2. In reality all water is in fact landable even in a non float plane. It simply acts like extremely mushy ground. It should be treated like land and have a large drag component. In fact all ground should have a drag componenet so pavement, grass, snow, and muddy runways can be modeled - water should just have a very large drag component. This would more properly simulate takeoffs and landings on ground on water or snow or hard ground etc.. Water should be treated like land - period. Any crash detection should ONLY result from the speed of vertical decent during landing but frankly even that should be selectable because all planes have different undercarriage survivability (and again you will end up limiting people.) We should rememeber that water crashes were an error result caused by limited flight sims of the late 80's. Water Crashes in flight sims originated When BAO marketed by Microsoft added water crashes early on and it was an ENTERTAINMENT feature - it caused an exciting sound and forced a restart. IT WAS A BAD IDEA THEN AND HAS BEEN CARRIED FORWARD BY HABIT RATHER THAN REALISM ever since. It was a cheap stunt partially caused by limited contact feature routines (there was only one contact routine - crash!) in the EIGHTIES whether between buildings, other vehicles or water plus I suspect the desire of Microsoft (or BAO Bruce Artwick) to create excitement and a feature for amateur flyers. One should NEVER CRASH simply because one lands in water. One should be allowed to land in water anywhere. Anyone landing on water is chosing it. He either has a float plane or has decided he wants to put his cessna down ignoring all reality or simulating a ditching. The sim should on default allow it. One should ONLY crash when the rate of collision in the direction of contact (in landing that is vertical speed) exceeds any reasonable impact whether it be with a building, other aircraft, or in a landing. That should be modeled with seperate default factors for vertical side and frontal impacts - especially vertical- that an aircraft model file will carry modifiers for so different aircraft structures survivability can be slightly modeled without full structurally analysis. This way a jungle jumper or bush plane could have say a 3 in the vertical modifier key so the sim could calculate that the bush plane won't crash unless it's vertical touchdown (rate of descent in meters/sec) component is more than 3 times default. If you want to get even more accurate landing without structural analysis, crashes (unrecoverable landings) should be modeled by calculating the gross weight including remaining fuel times the vertical component at touchdown times the aircraft models factor modifier. Anything beyond that and you need to start introducing structural analysis in the sim which is a whole different ballgame. George On Mon, 24 Dec 2007 7:08 am, gerard robin wrote: On lun 24 décembre 2007, AnMaster wrote: Maik Justus wrote: Hi Gerard, gerard robin schrieb am 24.12.2007 01:14: BTW: i could not use the c172 because mine makes difference between water and solid Cheers Yes, all YASim aircrafts do. But while the default scenery looks like water it is marked as solid. Therfore you can land on water everywhere you have no scenery installed. That sounds strange, you would be unable to land with a float plane on sea tiles then? And when I started with A-6E once where I laked scenery, I was unable to take off, because the aircraft had crashed into the water. Regards, Arvid Norlander I am not sure that i have understood very well. My c172 is a JSBSim aircraft and it makes difference between water and solid. The seaplane can land and take off on that sea tile, when there is sea tile, the North Pole shows that there is NO tile, which explain that the Aircraft can't fly on it. Merry Christmas! -- Gérard http://pagesperso-orange.fr/GRTux/ - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
On mar 25 décembre 2007, GWMobile wrote: The original post quoted below exemplifies why I beleive it is a mistake to ever have crash detection for water in a flight sim however let me lay it out simply. 1. Anyone who lands on water in a flight sim knows they are doing it. It is highly likely they WANT to do it - ie have a float plane or want to ditch. Setting a crash default is silly. It forces people to not be able to do what they want and it isn't realistic. 2. In reality all water is in fact landable even in a non float plane. It simply acts like extremely mushy ground. It should be treated like land and have a large drag component. In fact all ground should have a drag componenet so pavement, grass, snow, and muddy runways can be modeled - water should just have a very large drag component. This would more properly simulate takeoffs and landings on ground on water or snow or hard ground etc.. Water should be treated like land - period. Any crash detection should ONLY result from the speed of vertical decent during landing but frankly even that should be selectable because all planes have different undercarriage survivability (and again you will end up limiting people.) We should rememeber that water crashes were an error result caused by limited flight sims of the late 80's. Water Crashes in flight sims originated When BAO marketed by Microsoft added water crashes early on and it was an ENTERTAINMENT feature - it caused an exciting sound and forced a restart. IT WAS A BAD IDEA THEN AND HAS BEEN CARRIED FORWARD BY HABIT RATHER THAN REALISM ever since. It was a cheap stunt partially caused by limited contact feature routines (there was only one contact routine - crash!) in the EIGHTIES whether between buildings, other vehicles or water plus I suspect the desire of Microsoft (or BAO Bruce Artwick) to create excitement and a feature for amateur flyers. One should NEVER CRASH simply because one lands in water. One should be allowed to land in water anywhere. Anyone landing on water is chosing it. He either has a float plane or has decided he wants to put his cessna down ignoring all reality or simulating a ditching. The sim should on default allow it. One should ONLY crash when the rate of collision in the direction of contact (in landing that is vertical speed) exceeds any reasonable impact whether it be with a building, other aircraft, or in a landing. That should be modeled with seperate default factors for vertical side and frontal impacts - especially vertical- that an aircraft model file will carry modifiers for so different aircraft structures survivability can be slightly modeled without full structurally analysis. This way a jungle jumper or bush plane could have say a 3 in the vertical modifier key so the sim could calculate that the bush plane won't crash unless it's vertical touchdown (rate of descent in meters/sec) component is more than 3 times default. If you want to get even more accurate landing without structural analysis, crashes (unrecoverable landings) should be modeled by calculating the gross weight including remaining fuel times the vertical component at touchdown times the aircraft models factor modifier. Anything beyond that and you need to start introducing structural analysis in the sim which is a whole different ballgame. George I don't know enough with YASim FDM, however i can answer with JSBSim. Yes we can do what you described, since we can detect which terrain is under the aircraft. Only as a first step i have introduced to c172p an update which makes it to be unable to land (and to take off) on sea, and it that case because the gears are not retractable (in reality) it crash the noise UP/DOWN to finish the course on the back ( we could tune a better simulation ). With an aircraft which has gears retractable , the landing on sea can be done smoothly on the belly. TableData drag (and lift) can be given with the best values according to the water reaction. The values regarding landing on ground remains right. We have, only, to select the right TableData according to terrain type, which is easy to do. Cheers -- Gérard http://pagesperso-orange.fr/GRTux/ - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
On mar 25 décembre 2007, gerard robin wrote: On mar 25 décembre 2007, GWMobile wrote: The original post quoted below exemplifies why I beleive it is a mistake to ever have crash detection for water in a flight sim however let me lay it out simply. 1. Anyone who lands on water in a flight sim knows they are doing it. It is highly likely they WANT to do it - ie have a float plane or want to ditch. Setting a crash default is silly. It forces people to not be able to do what they want and it isn't realistic. 2. In reality all water is in fact landable even in a non float plane. It simply acts like extremely mushy ground. It should be treated like land and have a large drag component. In fact all ground should have a drag componenet so pavement, grass, snow, and muddy runways can be modeled - water should just have a very large drag component. This would more properly simulate takeoffs and landings on ground on water or snow or hard ground etc.. Water should be treated like land - period. Any crash detection should ONLY result from the speed of vertical decent during landing but frankly even that should be selectable because all planes have different undercarriage survivability (and again you will end up limiting people.) We should rememeber that water crashes were an error result caused by limited flight sims of the late 80's. Water Crashes in flight sims originated When BAO marketed by Microsoft added water crashes early on and it was an ENTERTAINMENT feature - it caused an exciting sound and forced a restart. IT WAS A BAD IDEA THEN AND HAS BEEN CARRIED FORWARD BY HABIT RATHER THAN REALISM ever since. It was a cheap stunt partially caused by limited contact feature routines (there was only one contact routine - crash!) in the EIGHTIES whether between buildings, other vehicles or water plus I suspect the desire of Microsoft (or BAO Bruce Artwick) to create excitement and a feature for amateur flyers. One should NEVER CRASH simply because one lands in water. One should be allowed to land in water anywhere. Anyone landing on water is chosing it. He either has a float plane or has decided he wants to put his cessna down ignoring all reality or simulating a ditching. The sim should on default allow it. One should ONLY crash when the rate of collision in the direction of contact (in landing that is vertical speed) exceeds any reasonable impact whether it be with a building, other aircraft, or in a landing. That should be modeled with seperate default factors for vertical side and frontal impacts - especially vertical- that an aircraft model file will carry modifiers for so different aircraft structures survivability can be slightly modeled without full structurally analysis. This way a jungle jumper or bush plane could have say a 3 in the vertical modifier key so the sim could calculate that the bush plane won't crash unless it's vertical touchdown (rate of descent in meters/sec) component is more than 3 times default. If you want to get even more accurate landing without structural analysis, crashes (unrecoverable landings) should be modeled by calculating the gross weight including remaining fuel times the vertical component at touchdown times the aircraft models factor modifier. Anything beyond that and you need to start introducing structural analysis in the sim which is a whole different ballgame. George Ouups some ugly mistakes (the champagne explain it :) ) I don't know enough with YASim FDM, however i can answer with JSBSim. Yes we can do what you described, since we can detect which terrain is under the aircraft. Only as a first step i have introduced to c172p an update which makes it to be unable to land (and to take off) on sea In that case, because the gears are not retractable (in reality) it crash the NOSE UP/DOWN to end the course on the back ( we could tune a better simulation ). With an aircraft which has gears retractable , the landing on sea can be done smoothly on the belly. TableData drag (and lift) can be given with the best values according to the water reaction. The values regarding landing on ground remains right. We have, only, to select the right TableData according to terrain type, which is easy to do. Cheers -- Gérard http://pagesperso-orange.fr/GRTux/ - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
gerard robin schreef: With an aircraft which has gears retractable , the landing on sea can be done smoothly on the belly. TableData drag (and lift) can be given with the best values according to the water reaction. The values regarding landing on ground remains right. We have, only, to select the right TableData according to terrain type, which is easy to do. The possibility of belly landing an aircraft depends on the aircraft type -- an A/C with underwing mounted engines and a low wing is impossible to make a graceful belly-ditch (like the 737) since the engines would scoop up all the water and cause a huge amount of drag (and pitch the nose forward). IMO, the aircraft's fuselage, engines, and wings could also be considered contact points, albeit higher situated than an extended landing gear. For example, when you land a 737 or 747 over its recommended landing weight, you run the risk of either breaking the gear struts or causing enough gear compression to impact the engines on the runway. And of course, belly-landing an A/C on tarmac or grass is just as possible as ditching on water, but those methods could only be considered in an extreme emergency (like a jammed landing gear). Even MSFS can be fooled into doing it: I once bellied a Learjet 45 on the runway at Malaga in FS2004, only noticing that I made a fuselage landing when I tried to taxi off the runway and the aircraft didn't move (and I switched to external camera, realizing I forgot to lower the gear before landing. Next time: THREE GREENS! :)) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
Hi, GWMobile schrieb am 25.12.2007 14:57: The original post quoted below exemplifies why I beleive it is a mistake to ever have crash detection for water in a flight sim however let me lay it out simply. 1. Anyone who lands on water in a flight sim knows they are doing it. It is highly likely they WANT to do it - ie have a float plane or want to ditch. Setting a crash default is silly. It forces people to not be able to do what they want and it isn't realistic. Just to clarify: YASim does not crash, because you land with an airplane on water. With most aircrafts you will get a nose-roll-over (due to the high drag of the gear in the water) and the crash is the result of this nose-roll-over. If the parameters are unrealistic you can tune them. You can even describe the fuselage of an aircraft with retractable gear as a float to get emergency-water-landing-capability. And you can add additional gears to aircrafts with retractable gears defining the fuselage as a skid on ground. For an example try the dhc2F. You can land it on grass with retracted gear, but you should not try to land on water with extended gear. Therefore everything you are asking for is already there. The only question is, if the aircraft maintenancer is using all these features. Maik - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
Again just proving that sims can't do accurate landing crash detection without strutural analysis and therefore shouldn't fake it under any condition. No one benefits by the sim saying you crashed except a little kid who says to his friend hey watch this. That situation is best handled with a destruct button which can be triggered anytime. Now midair collison detection IS relevant because you want to know perhaps if you squeaked by the building or other aircraft but landing crash? Not unless you are going to do the math for the laods and the gear strentgh. On Tue, 25 Dec 2007 4:24 pm, R. van Steenbergen wrote: gerard robin schreef: With an aircraft which has gears retractable , the landing on sea can be done smoothly on the belly. TableData drag (and lift) can be given with the best values according to the water reaction. The values regarding landing on ground remains right. We have, only, to select the right TableData according to terrain type, which is easy to do. The possibility of belly landing an aircraft depends on the aircraft type -- an A/C with underwing mounted engines and a low wing is impossible to make a graceful belly-ditch (like the 737) since the engines would scoop up all the water and cause a huge amount of drag (and pitch the nose forward). IMO, the aircraft's fuselage, engines, and wings could also be considered contact points, albeit higher situated than an extended landing gear. For example, when you land a 737 or 747 over its recommended landing weight, you run the risk of either breaking the gear struts or causing enough gear compression to impact the engines on the runway. And of course, belly-landing an A/C on tarmac or grass is just as possible as ditching on water, but those methods could only be considered in an extreme emergency (like a jammed landing gear). Even MSFS can be fooled into doing it: I once bellied a Learjet 45 on the runway at Malaga in FS2004, only noticing that I made a fuselage landing when I tried to taxi off the runway and the aircraft didn't move (and I switched to external camera, realizing I forgot to lower the gear before landing. Next time: THREE GREENS! :)) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake images. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
All I say is the default for water for the sim regardless of aircraft without modifying anything should be allowed landing and even takeoff because if anyone is doing it in the sim they are doing it for a reason and have made a consious decision to defy reality. Therefore everything you are asking for is already there. The only question is, if the aircraft maintenancer is using all these features. www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake images. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
You are really missing the point. What I am saying is no one interested in reality is going to land on water in the first place so the people who would expect a crash indication won't be doing the landing anyway. But those who want to land on water because they aren't concerned about reality find the water crash limiting to them and this will be a large protion of newbies. Furthermore your argument that landing on water isn't realistic doesn't mean it is THEREFORE realistic to model a crash without doing the full structural analysis to determine whether a crash would have in fact occured. Therefore you aren't realistic either way but if you let people land on water you actually let people explore more possibilities in the sim. And just to make the case - lets say you land on a grass penisula at a lake. You are doing 5 mph when you hit the edge of the lake. Still think a crash is in order? You do an emergency landing on abeach. The sim can't do detailed coastlines so suddenly you are deteced as hitting the water with say the barest tip of your side wheel . The sim triggers a crash . Again really not correct. Crash detection on water is always an unsupportable result in any but the msot extreme case in a flight sim and never provides any feedback that is more than entertainment. By not modeling a water crash as a default you let a lot more possibilites be explored in a sim - possibilites that will be enjoyed by many - no of whom will think they can actually land on water in real life. It was a mistake for BAo to provide the entertainment water crash function. It is now so firmly engrained it takes some real reflection to accurately consider the issue but that is exactly what I am suggest flight gear do. I'm sorry but this just seems silly to me. You cannot land on water if you are not in an aircraft with a planing hull or floats. A transitional planing phase, where the hull or floats change from being _on_ the water to being _in_ the water, or visa-versa for takeoffs, is necessary both for takeoff and landing. You can't plane on water with wheels, at least not at any sort of speed that could be attained with fixed gear or with retractable gear extended, even if the water was perfectly flat and undisturbed. Also, water doesn't act just like mushy ground. Ditching a land-plane into water does a lot more damage to the aircraft than belly landing it on any sort of ground. Even if you hit the water at a low vertical descent rate you won't plane on the surface because the fuselage will not have been designed and built for the stresses, unlike the planing hulls and floats on a seaplane/floatplane. The outer non-structural fuselage panelling will be quickly torn away leaving just the structural frames and members and once these are exposed the drag will shoot through the roof. This, in turn, results in a much higher decceleration rate than you would get in a ground belly-landing. Just the decceleration forces on their own would cause severe stress and structural damage to the airframe, quite apart from the impact damage, but in addition to this water is forced in to every opening and vent, at very high 'pressure', causing even more 'internal' damage to the aircraft and it's systems. I'm afraid that I can't agree with all that you say about ground drag components either. While it's certainly true that paved, grass, snowy, icy or muddy runways will have different co-efficients of friction, this only really applies to objects that are sliding across the surface - not rolling upon it. Sure, a grass strip will have a greater rolling-resistance than a paved strip but the power levels in anything but the earliest aircraft are more than sufficient to compensate for it. In any event, I know that YASim allows you to specify both the dynamic and static friction for wheeled landing gear, so it is possible to simulate low or high pressure tyres, which is what really dictates what sort of surfaces you can operate from and the corresponding ground characteristics are implicit in that. I'm not familiar with JSBSim but I expect it has similar capabilities. I just can't see how you describe the default crash result from landing in the water in a land plane as unrealistic. Once you've ditched in a land plane you're certainly not going to be flying it anywhere else because it will no longer function as an aircraft and that, to all intents and purposes, is a crash. LeeE www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake images. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list
Re: [Flightgear-devel] RE water crashes or landing - a change in design principle and default is suggested
On Tue, 25 Dec 2007 22:24:07 -0500, GWMobile wrote in message [EMAIL PROTECTED]: Again just proving that sims can't do accurate landing crash detection without strutural analysis and therefore shouldn't fake it under any condition. ..agreed, however there are a few such programs out there on GPL licenses that _can_ be used as a starting point. Me, I like to see global sea water level rise modelled first. No one benefits by the sim saying you crashed except a little kid who says to his friend hey watch this. That situation is best handled with a destruct button which can be triggered anytime. Now midair collison detection IS relevant because you want to know perhaps if you squeaked by the building or other aircraft but landing crash? Not unless you are going to do the math for the laods and the gear strentgh. ..track the frontal area projections and call midair if 2 such tracks meet? -- ..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. - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
