Attached is a fix to add a short period of cranking time required
before the engine fires. I've also added a little hack to limit the
torque applied by the starter motor when the rpm is less than 10 in
order to avoid the rpm overshooting idle in the first time step when
the prop is producing very little resistance due to the low rpm.
I've attached 3 diffs against files in FlightGear to fix some printf
format strings. The changes are pretty straight forward. Let me know
if you have any questions. (BTW, I'm using gcc 2.95.4)
/sim/freeze/master (implimented)
/sim/freeze/fuel (implimented)
/sim/freeze/position (not implimented)
/sim/freeze/time-of-day (not implimented)
/sim/freeze/master is bound to the 'p' key via keyboard.xml, however,
/sim/freeze/fuel is not bound to anything at the moment so you must
change it via the external property interface, or specify an initial
value on the command line.
otherwise, the logic in FGEngine::ConsumeFuel breaks down and the
engine is starved when *any* feed tank is empty, rather than when all
feed tanks are empty.
FDM people. FlightGear now supports an unlimited number of fuel
tanks. Also added correct fuel-flow reporting for piston engines, and
tracked new features in SimGear property support.
Changed _set_Accels_Pilot_Body to use FGAuxiliary::GetNpilot instead
of FGAuxiliary::GetPilotAccel. It looks like a similar change was
started but never finished, and there are artifacts still lingering.
With this change, the slip/skid ball now works reasonably on the C172
when in motion, but not at rest (that will have to wait for fixes to
the gear code).
- automake-1.4 sets default values for INCLUDES which we can't
overwrite.
- automake-1.5 renames this to DEFAULT_INCLUDES and leaves INCLUDES
open for the developer to use.
Thus for automake-1.4 we are forced to 'append' to INCLUDES and in
automake-1.5 we can just set the value to whatever we like.
Unfortunately, the behaviors of the two versions are mutually
incompatible.
The solution I am committing now works for both versions but
automake-1.5 generates a lot of spurious warning messages that are
annoying, but not fatal.
(i.e. multiloop). Most subsystems currently ignore the parameter, but
eventually, it will allow all subsystems to update by time rather than
by framerate.
FGInterface::_updateGeocentricPosition() for clarity. Also added an
FGInterface::_updateGeodeticPosition() since it is useful.
A few clean ups to native_fdm.cxx and raw_fdm.hxx.
Here's an unusual patch for FlightGear -- I've created .cvsignore
files for every source directory, to make CVS output more informative.
This is especially nice when using cvs-examine from (X)Emacs to look
for changes.
Note there is still a problem when doing a 'reset' after doing
a 'goto'. Curt says: I also see that doing two subsequent reset's on a
JSBSim model results in a segfault in a deconstructor deep inside JSBSim.
Dynamics (Sim)ulator. Basically, this is a rough, first cut of a "different
take" on FDM design. It's intended to be very simple to use,
producing reasonable results for aircraft of all sorts and sizes,
while maintaining simulation plausibility even in odd flight
conditions like spins and aerobatics. It's at the point now where one
can actually fly the planes around.
- delete table in destructor
** src/FDM/flight.cxx
- bind engine properties in FGInterface::bind, and publish properties
for all engines rather than just engine 0
** src/Main/fg_props.cxx
- removed all engine properties; now bound in FGInterface::bind
** src/Sounds/fg_fx.cxx
- support multiple engine and cranking sounds
** src/Sounds/fg_fx.hxx
- support multiple engine and cranking sounds
fix startup sequence problems where we initialize the FDM before we know
the desired starting altitude.
These changes delay fdm initialization until the local tile has been loaded
and we can do a real intersection and find the true ground elevation.
In order to do this, I depend more on the property manager as glue, rather
than the FGInterface.
There are some glitches still when switching to a new airport or reseting
the sim. I will work on addressing these, but I need to commit the changes
so far to keep in sync with other developers.
through the controls interface and the running and cranking flags through
the engine interface. This has no current effect on LaRCsim (other than
to make the code neater) but is necessary to add engine startup to JSBSim
which is now underway. I've also put in main.cxx which escaped getting
committed in the previous round of changes - adding this will add
the cranking sound to LaRCsim during engine startup.
one I sent yesterday. I have re-zipped all four files so you can
neglect the last lot but only io360.cxx has changed if you've
already committed. It's untested since I can't start the engine until
John has committed his update with separate properties. Should
work fine though.
that overrides in JSBSim will work (i.e. properties can be set)
- modified set_(u|v|w)Body to use set_Velocities_Wind_Body, so
that overrides in JSBSim will work (i.e. properties can be set)
He writes:
Here are the final changes to add threads to the tile loading. All the
thread related code is in the new FGTileLoader class.
./configure.in
./acconfig.h
Added --with-threads option and corresponding ENABLE_THREADS
definition. The default is no threads.
./src/Scenery/tilemgr
Removed load_queue and associated references. This has been replaced by
a new class FGTileLoader in FGNewCache.
Made the global variable global_tile_cache a member.
schedule_needed(): removed global_tile_cache.exists() tests since
sched_tile() effectively repeats the test.
initialize_queue(): removed code that loads tiles since this is now
performed by FGTileLoader.
update(): ditto
./src/Scenery/newcache
Added new class FGTileLoader to manage tile queuing and loading.
tile_map typedefs are private.
exists() is a const member function.
fill_in(): deleted
load_tile(): added.
./src/Scenery/FGTileLoader
The new threaded tile loader. Maintains a queue of tiles waiting to be
loaded and an array of one or more threads to load the tiles. Currently
only a single thread is created. The queue is guarded by a mutex to
synchronize access. A condition variable signals the thread when the
queue is non-empty.
CLO: I made a few tweaks to address a couple issues, hopefully what we
have is solid, but now we kick it out to the general public to see. :-)
The files in the attached tarball make the following changes to
FlightGear:
- rename the existing FGInterface::init() method to
FGInterface::_setup to get it out of the way
- move *all* FDM initialization code out of src/Main/fg_init.cxx and
into FGInterface::init(), and clean up fg_init.cxx a little
(especially by removing the zillions of attempts to place the plane on
the ground at various locations in the code)
- modify FGInterface::bind() so that no values are picked up
automatically at bind time (they are set previously by init() instead)
- modify the init() methods of the classes derived from FGInterface
(i.e. larcsim, jsbsim, balloon, magic, and ada) to invoke
FGInterface::init() explicitly before doing their own setup
I don't claim that the code in FGInterface::init() is optimal (or even
correct), but it seems to work for on-ground starts with both LaRCSim
and JSBSim on runways pointing various directions from near sea level
to about 700' ASL (the range I happened to test). I expect that Jon
and Tony will want to look at the code and refactor and correct it now
that they can see what's going on in one place.
Here's a quick outline of what is invoked:
cur_fdm_state = new <whatever>(dt);
cur_fdm_state->init();
cur_fdm_state->bind();
The constructor allocates memory and sets default values only (with
the help of the FGInterface::_setup() method). The init() method pull
any required properties out of the property tree and sets up the
initial state of the FDM. The bind() method takes ownership of
FDM-related properties so that the FDM can publish them to the rest of
the sim.
Note that bind() and init() are virtual, so any implementation in a
subclass will hide the implementation in FGInterface; that's why
subclass implementations of init() and bind() have to invoke
FGInterface::init() and FGInterface::bind() explicitly, probably at
the start, so that they get the basic initialization.
hope, with earlier versions as well)
- support for the new LONG value type
- gear support for UIUC (updated for the newly renamed SG_* stuff;
otherwise identical to what I sent you before)
- fixed reported MSVC problem in src/FDM/flight.cxx
I have created a set of patches to provide configurable landing gear
for the UIUC models. The patches (including four new files) are
available at
http://megginson.com/private/fgfs/uiuc-20010309.tar.gz
A modified UIUC configuration file for the Twin Otter (DHC-6) is
available at
http://megginson.com/private/fgfs/aircraft.dat
It should be possible to configure appropriate gear for all of the
UIUC models now. As a bonus, the models also support braking, both
absolute and differential, as well as nose-wheel steering (all of
which are currently missing from the UIUC models) -- when you land,
you don't have to keep rolling off the end of the runway anymore, and
you don't have to bank to steer in a taxi.
My sample configuration file contains absolutely bizarre, wild
guesses, and many places that I didn't even bother to guess properly.
The only actual data I had was the wing-span of the DHC-6 (65ft),
which I used for positioning the wing tips. The wing-tips for this
model actually work now -- I hit the aileron hard while accelerating
for take-off, and the wingtip noticeably strikes the ground and
bounces up (quite dramatic in external view using the DHC-6 model from
Wolfram's site).
Details
-------
The UIUC models now support up to 16 gear points each where a gear
point is anything in the aircraft that can come in contact with the
ground, including the tail and wing-tips. I have added the following
new fields to the UIUC configuration files, where <index> is an
integer between 0 and 15, and <value> is a real number:
gear <index> Dx_gear <value> # x offset from CG [ft]
gear <index> Dy_gear <value> # y offset from CG [ft]
gear <index> Dz_gear <value> # z offset from CG [ft]
gear <index> cgear <value> # spring damping [lbs/ft/sec]
gear <index> kgear <value> # springiness [lbs/ft]
gear <index> muGear <value> # rolling coefficient
gear <index> strutLength <value> # gear travel [ft] (not yet used)
Most of these names were already pencilled into the UIUC documentation
(as TODO items), but I had to make up Dx_gear, Dy_gear, and Dz_gear --
if those are inappropriate, I'd appreciate suggestions for better
names.
It will be necessary to modify the other UIUC configuration files to
include some kind of gear support as well, or the planes will sink
nose-first into the ground down to their CG's (it's actually quite
funny to watch with an external view).
Background
----------
As I frequently remind everyone here, I have no math background worth
spitting at, so I will not even pretend to have done the hard stuff.
The UIUC code uses a copy of a very old version of the LaRCsim
c172_gear.c -- I wanted to update it with Tony Peden's excellent newer
version, which includes differential braking among other goodies (the
UIUC models don't support brakes, period).
I copied the newer code into uiuc_aero.c, and it compiled and ran, but
all of the planes ended up sitting on their tails with their noses in
the air. Since Tony made his gear code nicely parameterized, I
experimented with different values, and found that it wasn't too hard
to balance the Twin Otter by moving the gear back a bit. At first, I
used properties to set different values, but then I decided to
integrate the whole thing properly into the UIUC configuration
framework. Thanks to Tony Peden, who did the real modelling work -- I
can take credit only for two or three hours of integration. It turns
out that Tony's code is generalized enough to deal with a wide range
of different gear structures -- I suspect that it will even work for
the 747, when I get around to trying some values.
