Post by Tom Goodrick on Sept 8, 2008 22:39:58 GMT -5
Different Airfiles -- Various parameters
« on: Oct 31st, 2007, 3:39pm » Quote Modify Remove
--------------------------------------------------------------------------------
I've looked at various airfiles and found something I should have found out a long time ago. They don't contain the same entries! I wanted to get to the source of the engine parameters but it seems like comparing apples and oranges. Since all of these airfiles 'fly' they do contain what's required.
Elaborating on the above, some have an FS98 Engine section. This could mean that they're old. However, even FS2004 airfiles have entries that are listed as being disabled in FS9. Thus, they're carried over as relicts from FS7 or FS8 but don't effect anything anymore. From a designer point of view it may be prudent to start out with a recent airfile. This way we ensure that we're spending time on tweaking one that contains all of the current parameters.
Regarding the aircraft.cfg Tom has adviced me to dump other people's attempts and start from scratch. While I see the point in not being confused by erroneous entries there are at least a few sections that we don't have to do over. Provided the visual model sits nicely on the tarmac there's no reason to redo the the section on gear position, height and default angle. Moreover, there may be electrical parameters, the autopilot section and more that work as intended. Most mistakes are found in the MOI section, the primary aerodynamics section (wing length / area and so on) and in the engine perfomance section. Until we got Tom's power panel it was anyone's guess what performance we really got. I've tested a few aircraft that deviate considerably from the rated power specs. Some are payware aircraft that have been praised on all major flightsim sites for their outstanding adherence to realistic performance.
Anyway, this thread should mainly focus on the airfile. Since they seem to come in different flavors we should be concerned which sections a 'modern' airfile ought to contain to be worth any effort.
« Last Edit: Oct 31st, 2007, 3:41pm by Hans_Petter » 84.49.151.53
--------------------------------------------------------------------------------
best regards,
Hans Petter
Tom Goodrick
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Re: Different Airfiles -- Various parameters
« Reply #1 on: Oct 31st, 2007, 7:08pm » Quote Modify Remove
--------------------------------------------------------------------------------
The part of the FD we should concentrate on here, from what you have said, is the aircraft.cfg file. In all the areas you have mentioned, that is the only file that counts. The air file can be ignored in these areas.
You have no pure FS98 files flying in FS9.
They may have started out that way, but when you moved them up to each successive version, little conversion programs operated on them to bring the air file as up to date as was needed and bringing the aircraft.cfg files fully up to date.
One thing about the aircraft.cfg file is that its lines can be listed in any order and the file still works. You cannot take a line from one part and put it in another part. But you can move the parts around and move the lines around within each part.
Indeed there are parts that are completely ommitted. The main part like that is the [flight tuning] part. That is considered optional by Microsoft. Of course, they thought they got it completely right the first time! But it is often necessary to copy in a [flight tuning] part from another aircraft. Some parts will be automatically replaced if you erase them. For, example the brake part can be erased and will reappear when you next fly the plane and then look at the file.
The Aircraft Container SDK helps with this in that it shows all the possible parts and all the possible lines that can be in a part.
It is the responsibility of each of us to try to keep the order of the aircraft.cfg file relatively uniform and to be sure that all necessary lines are included.
One thing I have found out the hard way is that when a part is duplicated, the version nearest the end of the file is the only one that counts. I spent a lot of time adjusting some scalars once in the [Flight Tuning] section with absolutely no effect. Then I discovered the second section farther toward the end of the file, threw it away, and all was well.
216.180.4.187
BudsBud
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Posts: 131
Re: Different Airfiles -- Various parameters
« Reply #2 on: Nov 1st, 2007, 11:04am » Quote Modify Remove
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Different Airfiles -- Various parameters
As Hans said if it were not for Toms Power Panel I would not have had any idea
that my B-314 was so far out of specs. No wonder that the bird took off like a rocket. I am showing 2000+ hp @ 1500 Rpm 27” MP and at 85% throttle she
over speeds and over- stress the plane BAH! I think we should show 1600 hp
at 2700 Rpm with about 40+ “ MP
Can I find the B-314 power /prop specs for this bird. What other plane uses
The Wright GR2600 engine.
24.110.4.48
Tom Goodrick
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Re: Different Airfiles -- Various parameters
« Reply #3 on: Nov 1st, 2007, 8:01pm » Quote Modify Remove
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I found some data in Jane's Fighting Aircraft of WWII on the Wright Cyclone GR2600 series. The A model gave 1600 at military power, the B 1700 and the BB 1900.
There were 14 cylinders. They give a displacement of 2603 cu in but I don't know if that is total or per cylinder. the compression for the A was 6.3 to 6.85 for the models. The gear ratio was 0.5625. Try adjusting the inputs and see if you can get 1600hp. But it might fly better at 1900 and that would not be unreasonable.
I don't have prop specs.
216.180.4.163
Chris_Ross
Member
Never,ever give up!
Posts: 215
Re: Different Airfiles -- Various parameters
« Reply #4 on: Nov 2nd, 2007, 2:57pm » Quote Modify Remove
--------------------------------------------------------------------------------
Boeing 314
Brewster SB2A Buccaneer
Curtiss SB2C Helldiver
Douglas A-20
Douglas B-23 Dragon
Grumman TBF Avenger
Lioré et Olivier LeO 451
Martin Baltimore
Martin Mariner
Miles Monitor
North American B-25 Mitchell
Vultee A-31 Vengeance
The book I have says they added 1200 USG fuel to 5400 USG and increased the size of the propellors with the upgrade to 314A but it doesn't mention the sizes
« Last Edit: Nov 2nd, 2007, 3:09pm by Chris_Ross » 121.209.233.117
Ed_Burke
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It's fun that keeps us alive; not healthy living!
Posts: 434
Re: Different Airfiles -- Various parameters
« Reply #5 on: Nov 3rd, 2007, 4:28am » Quote Modify Remove
--------------------------------------------------------------------------------
If it was 2603 cubes per pot I want to be there when they light the fuse.
Ed
58.104.170.187
--------------------------------------------------------------------------------
ED B
Tom Goodrick
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Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #6 on: Nov 3rd, 2007, 10:26am » Quote Modify Remove
--------------------------------------------------------------------------------
I fixed up my Boeing 314 so it gives the right power. But with that low power setting (1900) it will not start moving in the water.
Water drag is far beyond our control.
If you have something that works, stay with it!
I had to boost power by 1.2 and thrust by 1.8 to get moving.
To get the right power, I put in:
cylinder displacement = 185.93
compression ratio = 6.3
number of cylinders = 14
gear reduction ratio 1.778 //recip of 0.5625
« Last Edit: Nov 3rd, 2007, 10:30am by Tom Goodrick » 216.180.4.223
Hans_Petter
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Posts: 424
Re: Different Airfiles -- Various parameters
« Reply #7 on: Nov 3rd, 2007, 3:56pm » Quote Modify Remove
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I just edited some useful engine parameters for the old prop aircraft that I've been playing with. The tables are 508, 509, 511 and 512. When these agree with the rpm and the beta range in the aircraft.cfg the power scalar is next to obsolete. We haven't been too focused on engine sounds versus rpm. However, when these tables are set to agree with the specs the engine sounds are more correct for the range of rpm. This indicates that the tables should be in the ballpark before we adjust the power with the power scalar.
For starters, check that the graphs in the airfile covers the entire range of rpm / beta for your aircraft. For instance, table 511 gives prop efficiency versus beta pitch. Some airfiles list the range from 15 -30 and some go to 35 or 40. If your aircraft comes with a beta max beyond 30 in the aircraft.cfg the table 511 ought to have a curve that covers the upper range. It may be possible to add entries to the tables 511 and 512 but I don't think AAM will do the job. The other tables can be altered to cover the upper rpm range in case your aircraft requires a higher maximum value.
84.49.151.53
--------------------------------------------------------------------------------
best regards,
Hans Petter
BudsBud
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Posts: 131
Re: Different Airfiles -- Various parameters
« Reply #8 on: Nov 3rd, 2007, 4:21pm » Quote Modify Remove
--------------------------------------------------------------------------------
ED
Boy that was a good one:>)
The specs that I found on the net indicate what Tom has:
Total Dispalcement 2603 Cu"
Cyl Displcment 185.9285
Comp Ratio 6.3:1
HP @ TO 1700 @ 2600 RPM
Looks good
24.110.4.48
Ed_Burke
Member
It's fun that keeps us alive; not healthy living!
Posts: 434
Re: Different Airfiles -- Various parameters
« Reply #9 on: Nov 4th, 2007, 4:55am » Quote Modify Remove
--------------------------------------------------------------------------------
We had a PBY-5A around the Aussie traps years ago doing magnatometer work with two of those babies making the noise. It had some mombo.
Ed
220.237.212.26
--------------------------------------------------------------------------------
ED B
Tom Goodrick
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Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #10 on: Nov 4th, 2007, 8:42am » Quote Modify Remove
--------------------------------------------------------------------------------
Hans, I don't think you should do anything with those tables you mention.
508 is torque coefficient vs RPM. It is flat at 0.49 in the range of flight RPM. The most you could do would be to extend it to cover your max RPM. But I don't think that will accomplish anything because the sim interpolates linearly between all points in tables and automatically extands the left-most point.
509 is Engine Turboprop Friction Torque vs RPM. The most you could do is extend RPM.
511 shows curve of prop efficiency vs Advance Ratio for several values of prop beta angle ranging from 15 to 40 degrees. You can't do anything to these curves. They are too complex. Advance ratio is 101.2*KTAS/RPM/Diam. All you can do is make sure you allow min beta below 15 and max beta at or above 40. I like to use 10 to 45. These are the limits set in the aircraft.cfg file. While flying several aircraft recently with the PowerPanel, I have watched prop beta. It starts at the lower limit and moves up to about 30 during takeoff and stays there during most of the flight. On a turboprop I saw it go up to 40 as I was cruising at 20,000 ft on 80% power. That is the highest I have seen it. (That was with a limit of 45 degrees.)
512 is power coefficient vs advance ratio for several values of beta. The same considerations apply as above. You certainly cannot mess with the y values of these. You can only make sure you allow a range of beta as wide or wider than the range shown.
All I can say is that the standard values seen in these tables do not screw anything up. The file for that souped up R4D you are working with has been badly screwed up. Do not use it as an indication of what should be done with air files in general.
When I am confronted with a screwed up air file (it has happened many times), I dump it and put in an air file for a similar aircraft that behaves well. When you do that, there are only a few things in the .air file that need adjustment. Everything else is handled in the aircraft.cfg file.
If you want to improve the sound, work on the sound.cfg file to emphasize certain .wav files. The SDK has some info about this file too.
« Last Edit: Nov 4th, 2007, 9:17am by Tom Goodrick » 216.180.4.44 216.180.4.105
Hans_Petter
Member
Posts: 424
Re: Different Airfiles -- Various parameters
« Reply #11 on: Nov 4th, 2007, 2:20pm » Quote Modify Remove
--------------------------------------------------------------------------------
I assume what I did was exactly to fix something that had been screwed up badly
I used an airfile that Tom G had edited for a standard DC-3 for reference. Some of the torque and power curves were very different before I tweaked them. Tom, if you never touched these curves I guess I replaced "mine" with standard FS curves. Then I extended anything pertaining to my higher max values to cover the extremes of "my" aircraft.
The proof of the pudding is that a power scalar of 1.1 is all that I need now. It used to be 0.62 to get the rated horsepowers and I suspect that the relations between power, rpm and prop advance (beta) were off. Hence, a power scalar may not produce a well-balanced power plant even though it gets the hp right. While the scalar is a nice tool for fine-tuning it should be viewed as an indication of underlying problems when it takes extreme scalar numbers to obtain rated specs.
« Last Edit: Nov 4th, 2007, 2:21pm by Hans_Petter » 84.49.151.53
--------------------------------------------------------------------------------
best regards,
Hans Petter
Tom Goodrick
Administrator
Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #12 on: Nov 4th, 2007, 7:44pm » Quote Modify Remove
--------------------------------------------------------------------------------
There are so many things in an .air file that we do not know much about that I consider it a waste of time to dig deeply into it. Prop advance ratio is not the same as beta. They are related but only in that they are both independent parameters against which prop performance is displayed. Prop advance is 101.2*V/RPM/Diam with V in knots, Diam in feet.
Perhaps removing the water boost had something to do with reducing the excessive power.
The original intent of this thread was to discuss why airplanes seem to fly similarly when they contain different settings in the FD files. In most cases the answer is that differences in the .air file are cancelled by corrections in the aircraft.cfg file. But in other cases the explanation is that we just don't see the differences.
Using a program like Bud has given us that puts flight data into Excel sheets is one way to show these differences. By conducting an experiement intended to highlight the differences and recording the data, we can have some charts to aid the discussion. Bud's lates version records any of the parameters listed in the Panel SDK which includes engine power and several engine performance indications as well as the control inputs and flight performance values associated with the experiment.
216.180.4.214
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« on: Oct 31st, 2007, 3:39pm » Quote Modify Remove
--------------------------------------------------------------------------------
I've looked at various airfiles and found something I should have found out a long time ago. They don't contain the same entries! I wanted to get to the source of the engine parameters but it seems like comparing apples and oranges. Since all of these airfiles 'fly' they do contain what's required.
Elaborating on the above, some have an FS98 Engine section. This could mean that they're old. However, even FS2004 airfiles have entries that are listed as being disabled in FS9. Thus, they're carried over as relicts from FS7 or FS8 but don't effect anything anymore. From a designer point of view it may be prudent to start out with a recent airfile. This way we ensure that we're spending time on tweaking one that contains all of the current parameters.
Regarding the aircraft.cfg Tom has adviced me to dump other people's attempts and start from scratch. While I see the point in not being confused by erroneous entries there are at least a few sections that we don't have to do over. Provided the visual model sits nicely on the tarmac there's no reason to redo the the section on gear position, height and default angle. Moreover, there may be electrical parameters, the autopilot section and more that work as intended. Most mistakes are found in the MOI section, the primary aerodynamics section (wing length / area and so on) and in the engine perfomance section. Until we got Tom's power panel it was anyone's guess what performance we really got. I've tested a few aircraft that deviate considerably from the rated power specs. Some are payware aircraft that have been praised on all major flightsim sites for their outstanding adherence to realistic performance.
Anyway, this thread should mainly focus on the airfile. Since they seem to come in different flavors we should be concerned which sections a 'modern' airfile ought to contain to be worth any effort.
« Last Edit: Oct 31st, 2007, 3:41pm by Hans_Petter » 84.49.151.53
--------------------------------------------------------------------------------
best regards,
Hans Petter
Tom Goodrick
Administrator
Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #1 on: Oct 31st, 2007, 7:08pm » Quote Modify Remove
--------------------------------------------------------------------------------
The part of the FD we should concentrate on here, from what you have said, is the aircraft.cfg file. In all the areas you have mentioned, that is the only file that counts. The air file can be ignored in these areas.
You have no pure FS98 files flying in FS9.
They may have started out that way, but when you moved them up to each successive version, little conversion programs operated on them to bring the air file as up to date as was needed and bringing the aircraft.cfg files fully up to date.
One thing about the aircraft.cfg file is that its lines can be listed in any order and the file still works. You cannot take a line from one part and put it in another part. But you can move the parts around and move the lines around within each part.
Indeed there are parts that are completely ommitted. The main part like that is the [flight tuning] part. That is considered optional by Microsoft. Of course, they thought they got it completely right the first time! But it is often necessary to copy in a [flight tuning] part from another aircraft. Some parts will be automatically replaced if you erase them. For, example the brake part can be erased and will reappear when you next fly the plane and then look at the file.
The Aircraft Container SDK helps with this in that it shows all the possible parts and all the possible lines that can be in a part.
It is the responsibility of each of us to try to keep the order of the aircraft.cfg file relatively uniform and to be sure that all necessary lines are included.
One thing I have found out the hard way is that when a part is duplicated, the version nearest the end of the file is the only one that counts. I spent a lot of time adjusting some scalars once in the [Flight Tuning] section with absolutely no effect. Then I discovered the second section farther toward the end of the file, threw it away, and all was well.
216.180.4.187
BudsBud
Member
Return To Pearl
Posts: 131
Re: Different Airfiles -- Various parameters
« Reply #2 on: Nov 1st, 2007, 11:04am » Quote Modify Remove
--------------------------------------------------------------------------------
Different Airfiles -- Various parameters
As Hans said if it were not for Toms Power Panel I would not have had any idea
that my B-314 was so far out of specs. No wonder that the bird took off like a rocket. I am showing 2000+ hp @ 1500 Rpm 27” MP and at 85% throttle she
over speeds and over- stress the plane BAH! I think we should show 1600 hp
at 2700 Rpm with about 40+ “ MP
Can I find the B-314 power /prop specs for this bird. What other plane uses
The Wright GR2600 engine.
24.110.4.48
Tom Goodrick
Administrator
Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #3 on: Nov 1st, 2007, 8:01pm » Quote Modify Remove
--------------------------------------------------------------------------------
I found some data in Jane's Fighting Aircraft of WWII on the Wright Cyclone GR2600 series. The A model gave 1600 at military power, the B 1700 and the BB 1900.
There were 14 cylinders. They give a displacement of 2603 cu in but I don't know if that is total or per cylinder. the compression for the A was 6.3 to 6.85 for the models. The gear ratio was 0.5625. Try adjusting the inputs and see if you can get 1600hp. But it might fly better at 1900 and that would not be unreasonable.
I don't have prop specs.
216.180.4.163
Chris_Ross
Member
Never,ever give up!
Posts: 215
Re: Different Airfiles -- Various parameters
« Reply #4 on: Nov 2nd, 2007, 2:57pm » Quote Modify Remove
--------------------------------------------------------------------------------
Boeing 314
Brewster SB2A Buccaneer
Curtiss SB2C Helldiver
Douglas A-20
Douglas B-23 Dragon
Grumman TBF Avenger
Lioré et Olivier LeO 451
Martin Baltimore
Martin Mariner
Miles Monitor
North American B-25 Mitchell
Vultee A-31 Vengeance
The book I have says they added 1200 USG fuel to 5400 USG and increased the size of the propellors with the upgrade to 314A but it doesn't mention the sizes
« Last Edit: Nov 2nd, 2007, 3:09pm by Chris_Ross » 121.209.233.117
Ed_Burke
Member
It's fun that keeps us alive; not healthy living!
Posts: 434
Re: Different Airfiles -- Various parameters
« Reply #5 on: Nov 3rd, 2007, 4:28am » Quote Modify Remove
--------------------------------------------------------------------------------
If it was 2603 cubes per pot I want to be there when they light the fuse.
Ed
58.104.170.187
--------------------------------------------------------------------------------
ED B
Tom Goodrick
Administrator
Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #6 on: Nov 3rd, 2007, 10:26am » Quote Modify Remove
--------------------------------------------------------------------------------
I fixed up my Boeing 314 so it gives the right power. But with that low power setting (1900) it will not start moving in the water.
Water drag is far beyond our control.
If you have something that works, stay with it!
I had to boost power by 1.2 and thrust by 1.8 to get moving.
To get the right power, I put in:
cylinder displacement = 185.93
compression ratio = 6.3
number of cylinders = 14
gear reduction ratio 1.778 //recip of 0.5625
« Last Edit: Nov 3rd, 2007, 10:30am by Tom Goodrick » 216.180.4.223
Hans_Petter
Member
Posts: 424
Re: Different Airfiles -- Various parameters
« Reply #7 on: Nov 3rd, 2007, 3:56pm » Quote Modify Remove
--------------------------------------------------------------------------------
I just edited some useful engine parameters for the old prop aircraft that I've been playing with. The tables are 508, 509, 511 and 512. When these agree with the rpm and the beta range in the aircraft.cfg the power scalar is next to obsolete. We haven't been too focused on engine sounds versus rpm. However, when these tables are set to agree with the specs the engine sounds are more correct for the range of rpm. This indicates that the tables should be in the ballpark before we adjust the power with the power scalar.
For starters, check that the graphs in the airfile covers the entire range of rpm / beta for your aircraft. For instance, table 511 gives prop efficiency versus beta pitch. Some airfiles list the range from 15 -30 and some go to 35 or 40. If your aircraft comes with a beta max beyond 30 in the aircraft.cfg the table 511 ought to have a curve that covers the upper range. It may be possible to add entries to the tables 511 and 512 but I don't think AAM will do the job. The other tables can be altered to cover the upper rpm range in case your aircraft requires a higher maximum value.
84.49.151.53
--------------------------------------------------------------------------------
best regards,
Hans Petter
BudsBud
Member
Return To Pearl
Posts: 131
Re: Different Airfiles -- Various parameters
« Reply #8 on: Nov 3rd, 2007, 4:21pm » Quote Modify Remove
--------------------------------------------------------------------------------
ED
Boy that was a good one:>)
The specs that I found on the net indicate what Tom has:
Total Dispalcement 2603 Cu"
Cyl Displcment 185.9285
Comp Ratio 6.3:1
HP @ TO 1700 @ 2600 RPM
Looks good
24.110.4.48
Ed_Burke
Member
It's fun that keeps us alive; not healthy living!
Posts: 434
Re: Different Airfiles -- Various parameters
« Reply #9 on: Nov 4th, 2007, 4:55am » Quote Modify Remove
--------------------------------------------------------------------------------
We had a PBY-5A around the Aussie traps years ago doing magnatometer work with two of those babies making the noise. It had some mombo.
Ed
220.237.212.26
--------------------------------------------------------------------------------
ED B
Tom Goodrick
Administrator
Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #10 on: Nov 4th, 2007, 8:42am » Quote Modify Remove
--------------------------------------------------------------------------------
Hans, I don't think you should do anything with those tables you mention.
508 is torque coefficient vs RPM. It is flat at 0.49 in the range of flight RPM. The most you could do would be to extend it to cover your max RPM. But I don't think that will accomplish anything because the sim interpolates linearly between all points in tables and automatically extands the left-most point.
509 is Engine Turboprop Friction Torque vs RPM. The most you could do is extend RPM.
511 shows curve of prop efficiency vs Advance Ratio for several values of prop beta angle ranging from 15 to 40 degrees. You can't do anything to these curves. They are too complex. Advance ratio is 101.2*KTAS/RPM/Diam. All you can do is make sure you allow min beta below 15 and max beta at or above 40. I like to use 10 to 45. These are the limits set in the aircraft.cfg file. While flying several aircraft recently with the PowerPanel, I have watched prop beta. It starts at the lower limit and moves up to about 30 during takeoff and stays there during most of the flight. On a turboprop I saw it go up to 40 as I was cruising at 20,000 ft on 80% power. That is the highest I have seen it. (That was with a limit of 45 degrees.)
512 is power coefficient vs advance ratio for several values of beta. The same considerations apply as above. You certainly cannot mess with the y values of these. You can only make sure you allow a range of beta as wide or wider than the range shown.
All I can say is that the standard values seen in these tables do not screw anything up. The file for that souped up R4D you are working with has been badly screwed up. Do not use it as an indication of what should be done with air files in general.
When I am confronted with a screwed up air file (it has happened many times), I dump it and put in an air file for a similar aircraft that behaves well. When you do that, there are only a few things in the .air file that need adjustment. Everything else is handled in the aircraft.cfg file.
If you want to improve the sound, work on the sound.cfg file to emphasize certain .wav files. The SDK has some info about this file too.
« Last Edit: Nov 4th, 2007, 9:17am by Tom Goodrick » 216.180.4.44 216.180.4.105
Hans_Petter
Member
Posts: 424
Re: Different Airfiles -- Various parameters
« Reply #11 on: Nov 4th, 2007, 2:20pm » Quote Modify Remove
--------------------------------------------------------------------------------
I assume what I did was exactly to fix something that had been screwed up badly
I used an airfile that Tom G had edited for a standard DC-3 for reference. Some of the torque and power curves were very different before I tweaked them. Tom, if you never touched these curves I guess I replaced "mine" with standard FS curves. Then I extended anything pertaining to my higher max values to cover the extremes of "my" aircraft.
The proof of the pudding is that a power scalar of 1.1 is all that I need now. It used to be 0.62 to get the rated horsepowers and I suspect that the relations between power, rpm and prop advance (beta) were off. Hence, a power scalar may not produce a well-balanced power plant even though it gets the hp right. While the scalar is a nice tool for fine-tuning it should be viewed as an indication of underlying problems when it takes extreme scalar numbers to obtain rated specs.
« Last Edit: Nov 4th, 2007, 2:21pm by Hans_Petter » 84.49.151.53
--------------------------------------------------------------------------------
best regards,
Hans Petter
Tom Goodrick
Administrator
Simaholic
Posts: 3589
Re: Different Airfiles -- Various parameters
« Reply #12 on: Nov 4th, 2007, 7:44pm » Quote Modify Remove
--------------------------------------------------------------------------------
There are so many things in an .air file that we do not know much about that I consider it a waste of time to dig deeply into it. Prop advance ratio is not the same as beta. They are related but only in that they are both independent parameters against which prop performance is displayed. Prop advance is 101.2*V/RPM/Diam with V in knots, Diam in feet.
Perhaps removing the water boost had something to do with reducing the excessive power.
The original intent of this thread was to discuss why airplanes seem to fly similarly when they contain different settings in the FD files. In most cases the answer is that differences in the .air file are cancelled by corrections in the aircraft.cfg file. But in other cases the explanation is that we just don't see the differences.
Using a program like Bud has given us that puts flight data into Excel sheets is one way to show these differences. By conducting an experiement intended to highlight the differences and recording the data, we can have some charts to aid the discussion. Bud's lates version records any of the parameters listed in the Panel SDK which includes engine power and several engine performance indications as well as the control inputs and flight performance values associated with the experiment.
216.180.4.214
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