Engine Spool Times
- Thread starter capceo
- Start date
Here is the info I have from Ron Freimuth's aircraft.cfg document:
[TurbineEngineData]
fuel_flow_gain=0.004 << Affects spool up rate by changing fuel controller gain
inlet_area=9.80 << Set near or 10% above real turbine inlet area to
start. Higher values increase ram drag, less net thrust at high speeds
[TurbineEngineData]
fuel_flow_gain=0.004 << Affects spool up rate by changing fuel controller gain
inlet_area=9.80 << Set near or 10% above real turbine inlet area to
start. Higher values increase ram drag, less net thrust at high speeds
Greetings Joe,
The aircraft.cfg contains a series of single values which are either multipliers of whole curves. or whole 3D surfaces, encoded in the air file, else the values in the aircraft.cfg are the maximum, or the minimum values beyond which FS9 will not process data encoded in the curves and comples surfaces of the air file, (for a larger range of values).
To change the rate at which something happens within FS9 it is necessary to alter the slope of the relevant air file curve(s) or the shape of the air file multi dimensional surface which controls that rate of change. A rate of change is the same thing as the varying slope of a graph which depicts data in a software look up table (TBL). Within FS9 the software look up tables are in the air file. The engine variables in an aircraft.cfg may define the max and / or min of a slope but they do not define how it curves from one to the other. Varying any scalar in an aircraft.cfg alters min and max equally without altering slope (rate of change) from min to max.
Only the simplest events in the science of dynamics are of the type 'a versus b' or 'a mutiplied by b'. Many events are more complex and involve more variables.
(Rate of change of) corrected N2 (CN2) varies not only with throttle%, but also concurrently with both Mach and inverse air pressure (IAP).
The slopes which interpolate to create the multi dimensional surface across which Corrected N2 versus IAP versus Throttle % versus Mach move during flight simulation are encoded in look up Tables 1503 and 1504 of the air file. FS9.exe interpolates the data from the four curves (rates of change) in the two tables we encode. The varying slope of that complex interpolated surface is the rate of change of turbine rotation.
To control rate of change (spool up rate) from CN2(less) to CN2(more) we must edit the shape of the inperpolated surface between the relevant values of CN2 on the y axis of each TBL (which we can view as a graph using an air file editor). To create the 3D surface we must do that for Mach = 0 in TBL 1503 and for a Mach number higher than the aeroplane in question will ever achieve without structural failure during similation in TBL 1504 so that the slope (rate of change) between any CN2(less) to any CN2(more) is also correct for every intervening Mach number and every inverse air pressure that the simulation could ever encounter emanating from the FS9 real time atmosphere and weather model.
The (turbine rotation rate of change) surface is therefore plotted using four curves in two tables of the air file.
1) Throttle % v sea level (where IAP =1) & (Mach = 0)
2) Throttle % v FL700 (where IAP =22.57) & (Mach = 0)
3) Throttle % v sea level (where IAP =1) & (Mach > Mne)
4) Throttle % v FL700 (where IAP =22.57) & (Mach > Mne)
Air pressure at FL700 is 100/22.57 = 4.43% of sea level
To deliver realistic turbine spool rates within FS9 we need to copy those data into the relevant air file TBLs from the real engine manuals for the specific engine in question, else we have to be able to estimate the shape of each of those four curves from underlying scientific principles.
Turbine spool up rate in FS9 can be highly realistic or highly unrealistic, that just depnds on the accuracy of the four curves described above, but it is always the consequence of three interacting variibles, throttle %, Mach, and IAP. It is not possible to create a flight simultor in which control of turbine spool up rate is any simpler than encoding accurate shapes for the four curves in two software tables method used in FS9 and described above.
FSAviator.
The aircraft.cfg contains a series of single values which are either multipliers of whole curves. or whole 3D surfaces, encoded in the air file, else the values in the aircraft.cfg are the maximum, or the minimum values beyond which FS9 will not process data encoded in the curves and comples surfaces of the air file, (for a larger range of values).
To change the rate at which something happens within FS9 it is necessary to alter the slope of the relevant air file curve(s) or the shape of the air file multi dimensional surface which controls that rate of change. A rate of change is the same thing as the varying slope of a graph which depicts data in a software look up table (TBL). Within FS9 the software look up tables are in the air file. The engine variables in an aircraft.cfg may define the max and / or min of a slope but they do not define how it curves from one to the other. Varying any scalar in an aircraft.cfg alters min and max equally without altering slope (rate of change) from min to max.
Only the simplest events in the science of dynamics are of the type 'a versus b' or 'a mutiplied by b'. Many events are more complex and involve more variables.
(Rate of change of) corrected N2 (CN2) varies not only with throttle%, but also concurrently with both Mach and inverse air pressure (IAP).
The slopes which interpolate to create the multi dimensional surface across which Corrected N2 versus IAP versus Throttle % versus Mach move during flight simulation are encoded in look up Tables 1503 and 1504 of the air file. FS9.exe interpolates the data from the four curves (rates of change) in the two tables we encode. The varying slope of that complex interpolated surface is the rate of change of turbine rotation.
To control rate of change (spool up rate) from CN2(less) to CN2(more) we must edit the shape of the inperpolated surface between the relevant values of CN2 on the y axis of each TBL (which we can view as a graph using an air file editor). To create the 3D surface we must do that for Mach = 0 in TBL 1503 and for a Mach number higher than the aeroplane in question will ever achieve without structural failure during similation in TBL 1504 so that the slope (rate of change) between any CN2(less) to any CN2(more) is also correct for every intervening Mach number and every inverse air pressure that the simulation could ever encounter emanating from the FS9 real time atmosphere and weather model.
The (turbine rotation rate of change) surface is therefore plotted using four curves in two tables of the air file.
1) Throttle % v sea level (where IAP =1) & (Mach = 0)
2) Throttle % v FL700 (where IAP =22.57) & (Mach = 0)
3) Throttle % v sea level (where IAP =1) & (Mach > Mne)
4) Throttle % v FL700 (where IAP =22.57) & (Mach > Mne)
Air pressure at FL700 is 100/22.57 = 4.43% of sea level
To deliver realistic turbine spool rates within FS9 we need to copy those data into the relevant air file TBLs from the real engine manuals for the specific engine in question, else we have to be able to estimate the shape of each of those four curves from underlying scientific principles.
Turbine spool up rate in FS9 can be highly realistic or highly unrealistic, that just depnds on the accuracy of the four curves described above, but it is always the consequence of three interacting variibles, throttle %, Mach, and IAP. It is not possible to create a flight simultor in which control of turbine spool up rate is any simpler than encoding accurate shapes for the four curves in two software tables method used in FS9 and described above.
FSAviator.
I had heard that there is a Beta setting in the aircraft config file that you can tweak and it makes the 'spool up' of the turboprop 'less' tempermental. For instance, one gentleman that wasnt happy with the Epic LT spool up, had found that if he adjusted the Beta to 10 from a lower 'sum', it was much more manageable.
I have no idea which Beta setting that is though. There are several beta settings in the aircraft config.
PS; Per the Epic though, I didnt tame it as the factory said it was just like that in the real bird.
PS2; Beta refers to prop angle settings.
Bill
I have no idea which Beta setting that is though. There are several beta settings in the aircraft config.
PS; Per the Epic though, I didnt tame it as the factory said it was just like that in the real bird.
PS2; Beta refers to prop angle settings.
Bill