Here's a new FGSimTurbine module. Changes are:
1. Adds starting and stopping functionality
2. Calculate() now calls other functions, based on the engine's state, which gives more readable code.
Until now turbine engines were always running as long as fuel was available. With this new module the engine defaults to OFF. To start with the engine running, the variable FGEngine::Running must be set to true at sim startup. In FlightGear this is done with --prop:/engines/engine[n]/running=true.
To start the engine (on the ground), first set the starter to ON, i.e. FGEngine::Starter is set to true. In FlightGear this is done by toggling /controls/engines/engine[n]/starter to TRUE. Note that the current FlightGear key binding will not work, as it causes the starter to quit when the key is released. A new key binding is needed, without the mod-up.
When N2 reaches 15% or greater, place the fuel cutoff control to FALSE. This is FGEngine::Cutoff. In FlightGear this is done with /controls/engines/engine[n]/cutoff set to FALSE. The engine will then accelerate to idle. Upon reaching idle, the starter is automatically turned off, and the engine is running. There is presently no FlightGear key binding for the fuel cutoff switch.
To shut off the engine, place the fuel cutoff control to TRUE.
If you shut down the engine in flight it will windmill. To airstart you will need at least 15% N2, just as with a ground start. When you have enough N2, place the cutoff control to FALSE and the engine will restart. Note that if you can't get enough N2 by speeding up, you can get it by using the starter.
The reverser still works, and is controlled in FlightGear with /controls/engines/engine[n]/reverser. With the reverser control on (TRUE), the engine will produce negative thrust in proportion to throttle position, i.e. to get more reverse
thrust, increase throttle.
Here's a new FGSimTurbine module. Changes are:
1. Adds starting and stopping functionality
2. Calculate() now calls other functions, based on the engine's state, which gives more readable code.
Until now turbine engines were always running as long as fuel was available. With this new module the engine defaults to OFF. To start with the engine running, the variable FGEngine::Running must be set to true at sim startup. In FlightGear this is done with --prop:/engines/engine[n]/running=true.
To start the engine (on the ground), first set the starter to ON, i.e. FGEngine::Starter is set to true. In FlightGear this is done by toggling /controls/engines/engine[n]/starter to TRUE. Note that the current FlightGear key binding will not work, as it causes the starter to quit when the key is released. A new key binding is needed, without the mod-up.
When N2 reaches 15% or greater, place the fuel cutoff control to FALSE. This is FGEngine::Cutoff. In FlightGear this is done with /controls/engines/engine[n]/cutoff set to FALSE. The engine will then accelerate to idle. Upon reaching idle, the starter is automatically turned off, and the engine is running. There is presently no FlightGear key binding for the fuel cutoff switch.
To shut off the engine, place the fuel cutoff control to TRUE.
If you shut down the engine in flight it will windmill. To airstart you will need at least 15% N2, just as with a ground start. When you have enough N2, place the cutoff control to FALSE and the engine will restart. Note that if you can't get enough N2 by speeding up, you can get it by using the starter.
The reverser still works, and is controlled in FlightGear with /controls/engines/engine[n]/reverser. With the reverser control on (TRUE), the engine will produce negative thrust in proportion to throttle position, i.e. to get more reverse thrust, increase throttle.
Square the normalized direction acceleration for the y and z axes, so
that turbulence predominantly affects pitch.
Bind to the /environment/turbulence/magnitude-norm and
/environment/turbulence/rate-hz properties in FlightGear.
This version handles a zero fuel load better. I found that if you try to consume fuel from an empty tank, with zero fuel flow, the FGEngine::Starved flag alternates
scene management code and organizing it within simgear. My strategy is
to identify the code I want to move, and break it's direct flightgear
dependencies. Then it will be free to move over into the simgear package.
- Moved some property specific code into simgear/props/
- Split out the condition code from fgfs/src/Main/fg_props and put it
in it's own source file in simgear/props/
- Created a scene subdirectory for scenery, model, and material property
related code.
- Moved location.[ch]xx into simgear/scene/model/
- The location and condition code had dependencies on flightgear's global
state (all the globals-> stuff, the flightgear property tree, etc.) SimGear
code can't depend on it so that data has to be passed as parameters to the
functions/methods/constructors.
- This need to pass data as function parameters had a dramatic cascading
effect throughout the FlightGear code.
ttStandard is copied from ttBerndt, with the following modifications:
1. All turbulence is diminished within three wingspans of the ground.
2. The horizontal forces are used to calculate the moments, but then
zeroed out so that only the vertical force is actually applied to
the aircraft.
3. The yaw moment is not used.
In fact, the horizontal forces and the yaw moment should be allowed,
but they are extremely rare compared to the vertical force and the
pitch/roll moments. For now, simply zeroing them gives the most
accurate feel.
Some more cmall changes to the SimGear header files and removed the
SG_HAVE_NATIVE_SGI_COMPILERS dependancies from FlightGear.
I've added a seperate JSBSim patch for the JSBSim source tree.
Changed steering to use the rudder command rather than the rudder
position. During taxi, the rudder trim shouldn't affect the steering
in any serious way.
This should be configurable in the aircraft file, since not all
aircraft use the rudder pedals for ground steering.
[In FlightGear, this may make it easier to taxi straight.]
The general idea is to help clean up some aspects of the FDM init and be
able to provide startup conditions in a less ambiguous manner.
Previously, things like positions, orientations, and velocites were set on
"the bus". These had to be read by the FDMs which then were supposed to
initialized themselves to those values and turn write around and start
modifying those values. It was messy and cumbersome.
Now, all the initial fdm conditions are written to a sub-[property-]tree
under /sim/presets/
The values in /sim/presets/ always stay set to what the user has specified.
The user can change these at his/her liesure, and then request a "reset"
which will reset to the new conditions. I don't even want to say how this
worked before. :-)
Now, an script, or gui interface can stage a set of initial conditions while
the sim is running (without disrupting it), and then call "reset" to commit
the change.
People who should worry about all this are FDM writters, and a small few
others who care about over all program structure and flow.
