Hi Hubbabubba,
Let's take the example of the cockpit viewpoint. I am working on an airplane that has a POV that is 27.5 inches above the CoG. You have probably noticed that you often can't specify the exact number you want in either AIR file editor. The values will come close, but there is a quantum step you can't get below. It will hit only the closest step.
In this case,
FDE gives me 27.52830 inches
AirEd gives me 27.5279 inches
Remember that some time back we calculated that the formula for calculating SCASM offsets was:
Inches * 25.4 / 1000 * 512 = SCASM Offset
For FDE, we get 358.00003584 Units
For AirEd, we get 357.99483392 Units
It is pretty obvious what the value should be: 358 Units, but I know which one is closer.
This is from AirEd.INI (Courtesy of Jerry Beckwith) This is the best version I have found.
; Valid types are...
; record, BOOL, int8, int16, int32, double, text, thrust, 16pct,
; fwgt, m256 ang16, aspd, mach, prpm, tbl16, tbldb, tbl3d
; Binary conversion factors for data types:
; 16pct, fwgt, m256
; i16/16384 i16/256 i16/6.5025
; ang16, aspd, mach, prpm,
; i16/182, i32/128, i32/20480, i16*15/32
[301]
1=00,m256,*Cockpit View Right+/Left- CoG (inches)
1h=Pilots' view point from the center of the aircraft to one side.
2=02,m256,*Cockpit View Above+/Below- CoG (inches)
2h=Pilots' view point from the center of gravity up.
3=04,m256,*Cockpit View Fore+/Aft- CoG (inches)
3h=Pilots' view point from the center of gravity fore/aft.
4=06,int32,*CoG Height From Ground
4h=Height for initial loading|Gear Length * 1600 for Light AC - * 1800 for Heavy AC ?
5=0A,ang16,*Fuselage Angle
5h=Fuselage angle for initial loading|Neg angle for Pos pitch on ground
This is from FDECtrl.txt
301,,301 Fuselage,Header,1
301,0,Cockpit View Right+/Left- C of G (inches),Integer2,6.5024
301,2,Cockpit View Above+/Below- C of G (inches),Integer2,6.5024
301,4,Cockpit View Fore+/Aft- C of G (inches),Integer2,6.5024
301,6,C of G above Ground,Integer4,1
301,10,Fuselage Angle,Integer2,182
Now here is where life gets really interesting:
Note that SCASM offets are 1/512 meter. AIR File offsets are only 1/256 meter, so we only get even offsets in SCASM if we use AIR File values.
If we use the formula specified above for calculating SCASM Offsets, we get 13.0048 for 1/512 meter. For 1/256 meter in the AIR file, we get half that or 6.5024 which is the exact divisor we specified in FDECtrl.txt. For AirEd.INI, the internal conversion is apparently 6.5025, which is close, but not exact and we can't do a thing about it.
For this task, it isn't a very big problem. Now if I wanted to do things in Metric instead of inches, All I really need to do in FDE is to alter the conversion factor to something like 1/512 but for AirEd, I can't do a thing. Perhaps I want the value in Feet instead of Inches to match what I see in AF99. This is also trivial for FDE, but impossible for AirEd.....
;-)
- Ivan.
)!
.
