Data Types

There are currently eight data types defined for AirEd. Further types are defined using conversions. Note that the ranges given are for the raw data type only, as stored in the AIR file. Indidvidual entries may have further limitations on the numbers. For example, the dry weight of an aircraft would not be a negative number, even though you could put one in.

Raw Data Types:

These are the types as stored in the AIR file. There are no conversions applied.

This means that the type of data is unknown. This can appear for entire records when nothing about the record is known, or for isolated areas of records where there are knowlege gaps.
The editor used is a Hex editor, since the type of the data items is unknown.

This denotes a record for which has multiple data members and at least some of the members are known. Clicking on this will expand the tree to show the data members in the record.

This means a Boolean one or zero. I have found that BOOL types in AIR files are all 4 bytes, just as the ones in M$ C compilers. All of those extra bits are unused. Just click on the entry to change it.

An 8-bit signed integer. This is the same as a C language "char". It can range from -128 to 128. There are no decimal capabilities to integer types.

A 16-bit signed integer. Ranges from -32768 up to 32768.

A 32-bit signed integer. Ranges from  -2147483648 all the way up to 2147483647.

A 64-bit signed value that can contain a decimal place. This is the only raw data member yet found in an AIR file that has a decimal place.

The record contains text only. Note that the text entered here has no effect on the flight or visual models. It is for information only.
 
 
 

Converted Data Types:

FS98s origins go back to when our computers' processors didn't have floating point coprocessors. Floating point decimal numbers were possible, but they took a LOT of processor time and therefore slowed programs down dramatically. The original FS authors avoided the slowdowns by using integer (whole number) representations of the data, and these remain in the sim (and the AIR files) to this day for many of the entries. Each new version of the AIR file, however, contains more and more floating point numbers.

The following types use conversions to the data so that they can be displayed in real world numbers. Conversions are used in AirEd only when they are proven to be accurate. Decimal rounding to integers are treated properly. The values to the right of the decimal place are not just dropped.

Piston Engine Governed RPM. The raw data is stored as 1/4 RPM per unit, and the amount is the number over 1400. In other words, a zero in the raw data will give 1400 in the sim, while 2400 raw data works out to 2000 actual RPM (1400 plus 1/4 of 2400). A rather strange way of doing things! Once converted, the number presented in AirEd is the actual RPM, and valid numbers are from 1400 to 9591.

A 16 bit integer representation of an angle. The raw data is an int16, with 182 units=1 degree. The data is presented as degrees from -180.0 to 180.0.

Internally, the sim represents this data as a 16 bit unsigned (positive only) integer. In the AIR file, an int32 is used, with only the low 16 bits valid. The data is presented by AirEd as the real world mach number, which is found by dividing the raw data by 20,480. Since the raw data has a maximum of 65,535, the converted number has a maximum of 3.1999. Used in Mmo.

This is a simple conversion. 128 raw data units per knot of airspeed. This gives a maximum of 511.992 knots. Used in Vmo.

This type is stored in the AIR files as 256ths of a meter. For consistancy I convert the data so that it is shown in inches.

Another simple conversion. 16383=100%.

This one is somewhat an educated guess. It was found by converting FSFS aircraft with easy values(100 and 10,000), and also by looking at many other planes with known good engine performance. The conversion factor used is 13.671. Others have tried to round this to the nearest houndred lbs thrust. I didn't, the data presented is direct from the conversion.
 

Tables:

An air file contains numerous tables. I have found out the purpose of just a few of these. To make them most understandable for editing, I present them in their own window as a graph. So far I have found two types of tables.

This presents a graph of all the data in the record. The data is treated as a series of int16 table entries.
Each entry has a vertical grey line. The entry being edited is highlighted by a blue line. The entry values are connected by straight red lines.
Editing is accomplished via the numpad and arrow keys. Be sure that your Num Lock is on!

The bar at the bottom shows the actual value of the entry being edited on the left, and the Num Lock status on the right.
The Enter key saves the changes and closes the window.
The Escape key closes the window without saving.
An alternate way to view this type is to first highlight the record, then press Alt-T. This allows checking if the record is a 16 bit table before editing the ini file.

This presents a two dimensional graph of the data. This is a special type of table that contains pairs of data. Each pair contains an X extent and a Y extent. These are graphed in the window and shown as text at the bottom. Editing is similar as the TBL16 type above.

This is a three dimensional data record, introduced in FS2k. Trying to represent this as a graph might prove confusing, so it is instead done similar to a spreadsheet table. This makes editing more familiar for most, and appears to be the way the data is stored in the record. Note that the numbers of x and y cells (with the same record identifier number) can vary by aircraft, so if you are putting one of these records into a file to make a true FS2k file, you may have to experiment to see which size one is correct for your aircraft.