individual aircraft to have different sounds (and cleaning up my code
a fair bit). The most important user-visible change is the renaming
of the /sim/sound property to /sim/sound/audible.
(other than "none") is "spin", which must be tied to a property giving
a value in RPM. This gets the DC-3 propellers turning. The next type
will be "rotation", which will allow the flaps, elevators, ailerons,
and rudders to move (and even gear, eventually). Later, I'll add
"shift" for sliding things around, and will figure something out for
blinking lights.
the XML file, including the path to the 3D file.
This change obsoletes the existing /sim/model/*-offset-deg and
/sim/model/*-offset-m properties in the main property tree, and
replaces them with /offsets/*-deg and /offsets/*-m in the model
property file. The /path property in the model XML file is relative
to the XML file's location rather than FG_ROOT.
Added two new properties:
/environment/temperature-sea-level-degc
/environment/pressure-sea-level-inhg
These are now supported in FGEnvironment as well, though they always
have the same value for now. They need to be hooked up to the FDMs.
different locations, and hitched it into FGGlobals. FGEnvironmentMgr
has taken over as the subsystem, while FGEnvironment is simple the
information that it returns. I've removed current_environment
completely -- everything now uses properties or goes through
FGGlobals. FGGlobals itself has a couple of useful methods:
const FGEnvironment * get_environment ();
const FGEnvironment * get_environment (double lat, double lon, double alt);
The first one returns the environment data for the plane's current
position, while the second returns the environment data for any
arbitrary location. Currently, they both return the same information,
but that will change soon.
properties have been renamed from wind-(north|east|down)-fps to
wind-from-(north|east|down)-fps, and the FDMs modified appropriately.
No other changes should be visible unless FG_OLD_WEATHER is defined.
Attached are patches for adding the command line options to set initial
glideslope and climb rate. This was really easy to do as all the pieces
were in place. It works well with JSBSim because the trimming routine
finds the right throttle and elevator settings. It should work with
LaRCsim as well, but it has no trimming routine so there will be some
dynamics at startup. I don't know what YASim will do.
the panel controls for the autopilot. The heading dialog would only show the
last setting you did through it, even if it was later tweaked with the bug on
the hsi. The altitude dialog did a similar thing. Now the values default to
the same that show on the panel displays.
via the command line (--enable-clock-freeze / --disable-clock-freeze)
and can be toggled during a run. However this property is not currently
bound to any menu or keystroke so you have to do it via the gui property
interface or externally via the web property browser or a script.
are being driven from an external data source.)
Akso found and fixed a bug in the simgear that caused the time to go goofy
temporarily while scenery was being loaded.
as well as visibility.
This means that if you are using this protocal to exchange data with a
visual channel, you should be able to change time and visibility on the master
and all the slaved visual channels will match it.
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.
- remove buffer with class scope
- remove variable 'length' (isn't used anywhere)
- make process_command private (it isn't used anywhere outside, and it
shouldn't be)
- define buffers where they are needed (two places)
- comment out stale debug message (it doesn't buy anything, because the
contents are output two lines below, anyway)
- let every error message begin with "ERR ". This makes error messages
less beautiful, but easier to recognize for scripts. Every internet
protocol that outputs text, has such a tag for distinguishing regular
output from error messages. (pop3 uses "-ERR ", smtp uses error codes,
etc.)
- fix html bug (<form> was closed by another <form>, instead of </form>)
- remove useless <br>
- fix a bug, that would have truncated an argument containing a '&'
- extend the comment for urlEncode: cite the concerned RFC
max(width, height) by default (easily changeable) rather than just width.
(src/GUI/gui.cxx, src/Main/main.cxx, src/Main/viewer.cxx, src/Main/viewer.hxx)
This works on a CygWin build, and probably works on non-Cygwin builds
as well.
2. Enable FG to start even if audio is not available. (soundmgr.cxx)
Avoids the FGSoundMgr constructor crashing; the rest of FG then runs
OK without sound.
1. Enable auto-configure on more versions of auto tools. (configure.in)
2. Warnings from auto-configure tools. (src/Time/Makefile.am)
3. Typo: "the it's" -> "its". (docs-mini/README.Joystick)
4. Remove definition of FGViewer::update() that now is (or can be) pure
virtual\
. (src/Main/viewer.cxx)
5. Preferred form of function name according to comments in plib:
"not_working"\
-> "notWorking". (src/Sound/soundmgr.hxx)
format before reading/writing data from/to remote machine. This allows
different endian machines to talk to each other. Also added support for
passing time and time offset (warp) in the data packet.
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.
properties /sim/view/view-tilt-deg and /sim/view/goal-view-tilt-deg
control the tilt. There are (temporarily) keyboard bindings in the
base package for experimentation: Ctrl-O to tilt the view down, and
Ctrl-P to tilt the view up.
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.
other -- it is now possible to set properties at startup (such as an
autopilot altitude). The only user-visible change, other than the
fact that the properties work as they are supposed to, is that the
heading bug no longer starts at a random value.
function to allow property files as non-option parameters after the
options have finished (and added "--" to terminate options). It's now
possible to do something like
fgfs denver-am.fgd
or even
fgfs at-lax.fgd in-c310.fgd around-sunset.fgd
This works the same way as the --config option, but will be friendlier
for GUIs, where start-up situation files can now be associated easily
with FlightGear.
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).
material-specific logic is now removed from the material library and
encapsulated in the material class itself, and materials are loaded
from $FG_ROOT/materials.xml rather than $FG_ROOT/materials. This also
removes a nasty bug in the old material-loading code that caused a
floating-point exception.
- 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.
beginning of main() for the exceptions that can be enabled (only
divide-by-zero is enabled by default, but you can uncomment any ones
you want); eventually, FlightGear should run cleanly with all FPEs
enabled.
(i.e. multiloop). Most subsystems currently ignore the parameter, but
eventually, it will allow all subsystems to update by time rather than
by framerate.
has absolutely no bearing on actual wheel performance and has nothing to do
with the fdm. It is just a simplistic wheel spin velocity model used to
avoid subsequent squealing when a tire is bouncing, or touches down right after lifting off. If at some point tire spin is modeled by an FDM we could
transition to using real data.
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.
These will log trace messages whenever a specific property value is
read or written through the property manager. They do not cause
FlightGear to poll bound values, so if a class variable that is bound
is changed directly, no trace message will be displayed.
These options are also useful in conjunction with a debugger.
--trace-read will cause the private SimGear SGPropertyNode::trace_read
method to be invoked, and --trace-write will cause the private SimGear
SGPropertyNode::trace_write method to be invoked; in a debugger
session, a user can set breakpoints on these methods then get a
backtrace to see what specific points in the code are reading or
writing properties.
works like this:
1. Parse preferences.xml, which will usually specify a default
aircraft using the /sim/aircraft property.
2. If /sim/aircraft is specified and not empty, parse the properties
in $FG_ROOT/Aircraft/{/sim/aircraft}-set.xml to set up a default
aircraft.
3. During command-line parsing, whenever the --aircraft option appears
set /sim/aircraft appropriately and parse the properties in
$FG_ROOT/Aircraft/{/sim/aircraft}-set.xml. Any --config, --prop, or
--aircraft options afterwards will take precedence.
more intuitive. We switch to an include in the preferences.xml to include
the default model, and then if the user specifies --aircraft=, that is
expanded immediately so portions can be overwritten by subsequent command
line options.
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.
a top level aircraft def file (c172-set.xml)
preferences.xml or --aircraft= or any other property setting mechanism can
be used to set the property "/sim/aircraft". After all options and config
files are parsed, the contents of /sim/aircraft is expanded into a *-set.xml
file and loaded.
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.
- changed all sound file properties to end in /path for pathname, and
added /sound and /pitch (with current values as defaults)
- don't activate the stall horn if CAS is less than 30kt (this needs
to be refined somehow)
- declarations to support changes to cxx file
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
to control logging
- /sim/logging/classes takes a value like "terrain|astro", where the
names are the macros from simgear/debug/debug_types.h with the
initial "SG_" removed and converted to lower case; for none, use
"none"
- /sim/logging/priority takes a single name like "warn", where the
name is a macro from simgear/debug/debug_types.h with the initial
"SG_" removed and converted to lower case
(the global temperature property returns that at the aircrafts altitude) and
adding "information" to the airport name to avoid having to store it
in the default.atis file 1200 odd times.
Heres an update to the ATIS stuff. In brief:
The possible buffer overflow in the display with wind should
hopefully be fixed.
Temperature is taken from the global temperature property instead
of being hardwired.
The display class now includes an implementation of the member
function to change the repeating message.
The message callsign is no longer hardwired. The first message
from each station is generated with a random callsign.
Subsequent messages from the same station have the callsign
incremented every hour. A map of airport-id vs. last callsign and
transmission time is kept for each station that has transmitted for
the duration of the FlightGear session. The logic might be flaky if
FlightGear is run for more than 24 hours at a stretch between
visiting the same ATIS station though! (ie I don't check the day.)
This map is kept in the atislist class. This might not be the best
long-term place for it (in an ATC class of some sort might be
better), but it works for now.
What was happening was that we screwed up and scheduled tiles for
(lon,lon) rather than (lon,lat) ... note the typo. This generated
bogus tile id's which the system happily accepted, put into the tile
cache system, and attempted to load. The problem was that these bogus
tile id's were negative where as all valid tile id's should be >= 0.
These negative tile id's up the logic used to remove tiles from the
cache. When identifying tiles for removal, we look for the furthest
tile away from us by starting out the furthest id at -1 and if we find
something further, we update the furthest tile id. Then at the end we
check if the furthest tile id >= 0 to see if we found anything we
could remove. However, the furthest tile id was these bogus tiles
with negative tile id's so the system always assumed there was nothing
appropriate for removal. This made it impossible to ever remove a
tile from the cache meaning it quickly filled up and no more tiles
could be loaded.
I fixed the one instance of scheduling tiles for a bogus location, and
added a sanity check so if it ever happens again we'll bomb with an
appropriate error message.
ends of the same runway share the same frequency. This is probably the best
we can do until we impliment some sort of operator interface to manually set
which end is active (like is done in real life.)
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.
meaning of "win_ratio". I've removed win_ratio and added fov_ratio and
aspect_ratio, as it seems both are needed.
n.b. The multi-line changes in fgReshape comprise:
extracting common code,
removing an apparently arbitrary "+1" on the view height,
changing "set_win_ratio" to "set_aspect_ratio".
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.
- use guiErrorMessage
- added new properties /sim/view/pilot/x-offset-m,
/sim/view/pilot/y-offset-m, and /sim/view/pilot/z-offset-m to
control pilot-position offset from CG
but no entries qualify for removal. It will keep trying to schedule the
tile(s) until an entry frees up. Entries in the cache do not qualify for
removal if they are in the process of being loaded.
I've updated the WeatherDatabase to be able to use only the n closest
stations. This can speed up the initalization dramatically.
To take a benefit from that you need:
- http://129.13.102.67/out/flight/current.txt.gz in
FG_ROOT/weather/current.txt.gz
- --prop:/environment/weather/working-type=internet
- --prop:/environment/weather/max-stations=what_ever_you_want
The WeatherCM stuff now publishes its data in the property system.
/environment/weather/wind-north-mps
/environment/weather/wind-east-mps
/environment/weather/wind-up-mps
/environment/weather/temperature-K
/environment/weather/air-pressure-Pa
/environment/weather/vapor-pressure-Pa
/environment/weather/air-density
are the new properties.
have multiple ptrs to individual entries (aliases) but the destructor was
trying to delete every ptr so it would delete already freed memory for aliases.
I implimented a simple ref counting scheme (similar to the plib mechanism) to
track references to material lib entries and only "delete" them when the last
reference is removed.
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)
can bind a single input to multiple properties)
Made the following properties archivable:
- /controls/aileron
- /controls/elevator
- /controls/elevator-trim
- /controls/rudder
- /controls/flaps
- /controls/throttle[*]
- /controls/mixture[*]
- /controls/propellor-pitch[*]
- /controls/brakes[*]
in init)
- free data structures in destructor
- ensure that interpolation tables are allocated before any searching
is done; otherwise, starting at some locations (such as CYYZ) causes
a segfault
node, and to modify that directly for scaling events: that will make
handling joystick axes much more efficient
- modified FGBinding to work with the new command state, so that
commands can save their state (i.e. compiled arguments) from the last
pass
- removed FGBinding::_fire implementation
- implemented FGBinding copy constructor
pointing to a non-existant material name. (This has been fixed.)
The alias code didn't check to see if this condition would occur so it
was putting a 'NULL' entry in the material library which was causing
the crash. It now checks for and skips bad aliases and prints a
warning message.
- moved shift-F3 (reload panel) bindings to XML
- moved shift-F4 (reload prefs) bindings to XML
- moved shift-F5, shift-F6, shift-F7, and shift-F8 (scroll panel) to
XML
- no longer includes Main/bfi.hxx
- added implementations of GLUTkey, GLUTkeyup, GLUTspecialkey, and
GLUTspecialkeyup
- include Input/input.hxx
- register GLUTkeyup and GLUTspecialkeyup with glut
- comment out call to fgJoystickRead
- comment out call to fgJoystickInit
- add call to FGInput::update to replace fgJoystickRead
this way, keyboard buttons can work the same way as joystick buttons
- added declaration for FGBinding::fire(double); this adds a setting
property to the arguments passed to the command, so that it can use
the current axis position as part of its calculations
- added data structures from joystick.cxx
- go back to using index as key code (otherwise, we'll get nasty
surprises when users try to override bindings)
- XML config file now nests bindings inside modifiers
- allow user to specify whether key is repeatable
- removed hard-coded bindings for 'b', ',', and '.'
- added code from joystick.cxx, with the following major changes:
- changed from js0, axis0, button0 to js[0], axis[0], button[0], etc.
- removed factor, offset, etc. since they will be args to command in
binding
- allow multiple bindings, as with key mappings
- allow access to keyboard modifier keys for bindings
- include infrastructure for modifiers (only FG_MOD_UP is used so far)
- removed unused 'saturation' property
- temporarily removed capture property and trim code; it will have to
be rewritten to be more generic
- allow modifiers for joystick buttons
want binding/property rather than binding/control
- removed hard-coded bindings for F3 (screenshot), Ctrl-S
(autothrottle), v (cycle view) and all of the keypad view-direction
keys; these are now defined in $FG_ROOT/keyboard.xml
- removed unused action method
a crash when relocating to a new airport. Pending work from the old
area is now just completed as normal, rather than trying to empty the various
queues in their various stages when can lead to many problems in a threaded
environment.
with different modifiers (the format of the key bindings has changed
again slightly, adding a <code>..</code> element; see keyboard.xml for
details).
2. Modified FGInput to try default modifiers for ctrl, shift, and alt
when the initial bindings fail (i.e. you don't have to specify
mod-shift explicitly for upper-case 'P' any more).
3. Fixed problems with properties and panel reloading reported by
Martin Dressler and John Check.
4. Updated preferences.xml to get rid of obsolete references to
/controls/brakes/left and /controls/brakes/right (as reported by John
Check).
There were also two non-bugs reported by John Check:
(a) Differential braking doesn't work (John was using the obsolete
properties from #4 above).
(b) Duplicates show up in the property tree using the telnet interface
(the property tree doesn't show indices, and John was seeing separate
entries for each possible engine, etc.).
Fixed a few glitches in the autopilot keys
Added a #define to be able to make a compile time decision to revert to
older GPS like autopiolt behavior this define SHOULD become a property
so that it is run time switchable.
(src/Input). So far, FGInput replaces most of src/Main/keyboard.cxx
(I've left a tiny stub); in the very near future, it will also take
over control of the joystick, mouse (Norm permitting), and panel
instrument interactions, so that there is a single mechanism for
configuring all input devices.
The new format should be (close to) self-explanatory by looking at the
new base-package file keyboard.xml, which is now included by
preferences.xml (I'll do the same thing for the joystick when I have a
chance). I have not managed to move all keybindings into this file
yet, but I've made a good start. I'm including Tony in the recipient
list so that he can see how bindings can use an external XML file.
This patch also adds support for multiple bindings for a single key,
special keys (i.e. keypad and function keys), and key modifiers
(shift/alt/ctrl); special keys use the PUI convention of adding 256 to
the Glut key code.
Unfortunately, everything comes with a price; in this case, I have not
yet found a general mechanism for the old (hard-coded) modal bindings,
which behaved differently depending on the autopilot state (i.e. left
rudder or move AP heading left); with my patches, this functionality
disappears, but you can still adjust the autopilot using the panel or
the GUI input dialogs.
to have attached an ssg loaded object to this branch, then plib will remove
it and all it's states (and textures) which will call opengl api commands
which will crash the program if run from a separate thread from the main render
thread.
- model loading deferred to primary thread
- tile removal deferred to paging thread
- other tweaks and rearrangments.
Airport signs
- first stab at some support for adding taxiway and runway signs. This
is non-optimal, but I'm under the gun for a demo.
a newly loaded tile to the scene graph. Instead it puts it in a queue
for the tile manager. I've used your counter_hack to check the loaded
queue and add any tiles to the scene graph. I was playing around with
the counter_hack so there might be some commented out code, etc. I also
changed some SG_DEBUGs to SG_INFOs so I could track the tile loading.
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. :-)
tile has been loaded. Since this flag can be set by another thread I've
declared it "volatile bool".
Also cleaned up delete vs delete[] usage. Gcc is happy with delete[],
which is the correct usage.
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.
implicitly correcting for that yet. The plane now makes it to 11000ft on
autopilot *slowly*. I think I'll have to look at the prop parameters
next - altering the diameter and blade angle just slightly can have
quite an effect. If you want to play then try changing the values
prop_diameter and blade_angle in FGNewEngine::init. Keep blade
angle between 20 and 25 (since those are the only values for which
I've entered data and I interpolate between them) and ignore
FGProp1_Blade_Angle since that's an old variable that isn't used. I
really ought to read all the engine and prop parameters from file to
avoid recompilation when tweaking !
the actual air pressure and temperature from the LaRCSim model
instead of assuming that it is at sea level as before. This has
reduced the ceiling from over 60000 ft to about 9000 ft. This is a bit
low (should be around 13 - 14000 ft I think) but I still have some
stuff to do with the engine power correlation and its ignoring the
temperature at the moment so I'm not panicking yet :-)
I've also changed the mixture-power correlation to one from a
published paper since the curve from the IO360 manual seemed to
be a load of rubbish, and didn't have any numbers on the mixture
axis anyway.
I've also knocked the full rich mixture down a touch in line with
Riley Rainey's recommendation, and cleaned up the code a bit.
a) I was compairing feet vs. meter (making the range 3x too. big)
b) I was using the diameter in place of the radius (making the range an
additional 2x too big.)
c) Updated the equation for calculating range to model the weak transmitter
not being picked up at upper altitudes.
We still might need some additional tweaking, but I think we are starting to
get in the right ball park.
is 9 not 8.) Note that the initial altitude setting was placing us way below
the ground, but as it doesn't seem to have caused us problems, it's probably
redundant!
When you tune into a station start at a "random" point in the sequence.
Sped up the words per minute to 13 to which means one sequence per about 4 secs.
This means we get through the whole sequence in about 20 seconds leaving 10
seconds of silence.
joystick input, and then will ignore the actual position of that input
until the user places it in the proper position to match the trimmed position.
At that point the joystick input captures control over the value and the
value will match the joystick position from then on. This is primarily set
up so that the FDM can trim in an initial throttle position.
