generates a data file of aerodynamic lift and drag (and L/D) against
AoA at a specified speed and altitude through a full circle. Wrote it
to track down the YF-23 superthrust issue, but it wasn't any help.
All the forces look fine.
state. The only really obvious problem was a giant negative engine
RPM, which happened because of a lack of clamping in the engine code
combined with the YF-23's ability to actually reach speeds near the
engines _vMax value. It's not clear to me that this will fix the
superthrust issue at high AoA's, but it's an obvious bug nonetheless.
+ The wing compilation step was accidentally omitting regions that lie
between the tips and the first/last control object. That's a real
problem for wings that contain no controls, and a significant issue
for those that contain only a few. I'm stunned that this went
undetected for so long.
+ The Surface::flapLift() function was oddly returning 1.0 Newtons as
a minimum, instead of zero.
calculations. We run the FDM at 120hz and compute how many loops can fit into each FG loop.
Floating point rounding could lead to a situation where we could end up running
1, 3, 1, 3, 1, 3... loops of the FDM when in fact we want to run 2, 2, 2, 2, 2...
If we artificially inflate ml above by a tiny amount to get the
closest integer, then subtract the integer from the original
slightly smaller value, we can get a negative remainder.
Logically this should never happen, and we definitely don't want
to carry a negative remainder over to the next iteration, so
never let the remainder go below zero.
src/AIModel/AIAircraft.cxx src/ATC/AILocalTraffic.cxx
src/FDM/flight.cxx src/FDM/flight.hxx src/FDM/groundcache.cxx
src/FDM/groundcache.hxx src/Main/fg_init.cxx src/Main/main.cxx
src/Scenery/hitlist.cxx src/Scenery/hitlist.hxx
src/Scenery/scenery.cxx src/Scenery/scenery.hxx
Make use of the attached SGMaterial reference userdata on scenegraph
leafs. Make the SGMaterial pointer available to the ground query
routines.
SGPropertyNode to guarded ones. This is also done for JSBSim/JSBSim.hxx,
for which JSB had given explicit permission a while ago. I postponed that
back then, but now is the time.
I had inadvertently terminated a data line when reaching a tab character after
initial data was supplied. I tested the lightning file and it now appears to
read in correctly.
bunch of memory leaks that had accumulated over the years. FlightGear
doesn't currently bother to destroy and recreate a YASim context, but
at least it can do so now without worry.
groundcache addition -- the ground callback doesn't do anything at
solution time, so the ground plane was unset. Valgrind was whining
about this; it's not clear that it was actually causing a problem.
and in the calculation of the launchbar angle (by Vivian).
It also calculates the holdback angle, and sets a Boolean value which
can be used to initiate the release of the catapult strop submodel at
the appropriate moment (new code by Vivian).
control to piston engines that allows external scripts to control the
turbo/supercharger boost programatically by setting this axis to
values in the range [0:1]. It also adds a "turbo-lag" attribute (a
time in seconds) to engines implementing turbocharger spooling delays.
This isn't terribly well tested, but doesn't seem to have broken
anything.
propeller pitch stops for constant speed propellers. The default
values are the same as the previous hard-coded values. The new
attributes, "fine-stop" and "coarse-stop", are documented in the base
package, Docs/README.yasim.
This patch makes use of the vectors now available in simgear with that past
patch. And using that it simplyfies the carrier code somehow.
- Small additional factory's to the quaternion code are done in the simgear
part. Also more explicit unit names in the factory functions.
- The flightgear part makes use of them and simplyfies some computations
especially in the carrier code.
- The data part fixes the coordinate frames I used for the park positions in
the carrier to match the usual ones. I believed that I had done so, but it
was definitly different. Also there are more parking positions avaliable now.
Jon Stockill wrote:
> I've just discovered that when using the null fdm I'm not getting
> updates to /position/ground-elev-m any more. So I can't actually
> retrieve the terrain elevation. Is there somewhere else in the property
> tree I could read this from?
The attached patch fixes this problem.
Erik Hofman:
This patch contains an update to net_ctrls.hxx that adds an extra 100 bytes
(or an equivalent of 25 (u)int32_t types) of reserved space. This could be
used to make the protocol forward and backward compatibel within a certain
scope. Be sure to read the instructions at the begining of the header file
when addinf new variables.
remove a hack and do it properly: if the requested elevation is for some
reason below the surface and the intersection test fails (as it appears
to be the case in EGLL), try again from 10000m ASL
mf: typos
are sharp, as intended. These were are never seen in practice; I
found the problem while looking at 360 degree lift curve graphs
looking for discontinuities.
"jitter" when the aircraft was stopped. This is a fundamental
characteristic of the gear model, and can't be fixed without major
surgery (and not a small amount of blinding insight). But we can at
least clamp it so the value can't change unless the wheel is moving
with a nontrivial velocity (5cm/sec in this case).
there was the situation where four directories contained jst two files,
of which three directories were aircraft related, and one directory contained
test code from Curt that might be better of in SimGear anyhow.
This is just a patch to move a bunch of files to new locations. In case of
local changes to any of them you can do the following:
move replay.[ch]xx from src/Replay to src/Aircraft
move control.[ch]xx from src/Control to src/Aircraft
move ssgEntityArray.[ch]xx from src/Objects to simgear/screen
In addition it has been decided only to use .[ch]xx files in all directories
unless it's contained within an FDM specific directory, in which case the
author is free to do whatever (s)he wants.
In this repspect the following files have been renamed in src/Multiplayer:
tiny_xdr.[ch]pp has become tiny_xdr.[ch]xx
multiplaymgr.[ch]pp has become multiplaymgr.[ch]xx
CygWin/gcc-3.4.4 updates.
I replaced my cygwin compiler with 3.4.4, did a make clean of plib, simgear,
and flightgear, then did a make install of all three. With the included changes,
everything builds fine, and runs fine.
Attached is a patch to add oil temperature to the YASim piston engine
model. This brings to life one of the pa28-161's otherwise 'dead'
guages. It's a pretty simple 'model' based on temperatures and warmup
times I've observed in the labs on auto engines and run through my
dodgy-memory filter. It does the job of populating the guage with
something plausible though.
Using new gcc 4.0 I have some serios warnings about uninitialized
variables, that are used. I created a patch, but I have no idea if it
is possible to do it my way. Can you check this out please?
Erik: I've modified the patch slightly based on the contents of an older
version of hitlist.cxx. I think this is correct now.
it for the B-29). The gear model itself has supported this always,
but there was no interface from the XML file. Should be backwards
compatible. I don't think I broke anything...
I stumbled across two memory errors with two wrong const references to
std::string.
As I fixed that, I also moved aircraft_dir which is only used from UIUC into
UIUC. With that uiuc_aircraftdir.h is empty and can be removed.
I believe I have found the agl hud problems as well as the 'hole' in the
carrier's deck. I spent half the day to reproduce that problem, it did not
occure when you start on the carrier not does it occure with JSBSim and my
really often used testaircraft. So I really need to improove my helicopter
flying qualities.
I was under the impression that *all* FDM's call
FGInterface::updateGeo*Position(..)
so set the new position in the FDM interface. Therefore I had added at the
some code that updates the scenery elevation below the aircraft to *those*
functions.
Ok, not all FDM's do so :/
The attached patch factors out a function computing the scenery altitude at
the current FDM's position. This function is also used in those FDM's which
need to update this value themselves.
Also this patch restores the nearplane setting and uses the current views
altitude instead of the current aircrafts. I think that this should further
be changed to the eypoint's agl in the future.
The agl is again ok in YASim's hud.
Some quite extensive changes to the AIModel code:
1. Mathias has made major changes to the AICarrier code to provide better
alignment of an aircraft on deck with the carrier - this feature is a major
improvement on the existing, but has a bug which might cause it to fail when
the computer carries out other tasks - changing window size is a known
example. This bug is outwith this code.
2. I have made significant changes to the AIShip code to enable a ship the
turn and roll smoothly.
3. I have added some simple AI which enables the carrier to remain within,
or return to, an operating box.
4. An automated turn into wind for flying operations.
5. A simplistic implementation of TACAN within AICarrier. I am in the course
of implementing this as a generic instrument, but this is some time off
completion.
I have prepared a patch that:
- Introduces a FGTileMgr::scenery_available method which asks the tilemanager
if scenery for a given range around a lat/lon pair is already loaded and make
use of that method at some -9999 meter checks.
- Introduces a FGScenery::get_elevation_m method which queries the altitude at
a given position. In constrast to the groundcache functions this is the best
choice if you ask for one *single* altitude value. Make use of that thing in
AI/ATC classes and for the current views ground level. At the current views
part the groundcache is reused if possible.
- The computation of the 'current groundlevel' is no longer done on the
tilemanagers update since the required functions are now better seperated.
Alltogether it eliminates somehow redundant terrain level computations which
are now superseeded by that more finegrained functions and the existence of
the groundcache. Additionally it introduces an api to commonly required
functions which was very complex to do prevously.
Turns out to be a bad interaction between jsbsims crash detection and my
past initialization changes.
The attached patch fixes this by moving crash detection out of the
initialization phase of jsbsim.
I have traced that reset on carrier problem down to several problems. One of
them is the fact that on reset the carrier is updated while the aircraft is
not. That made the aircraft drop down an elevator sometimes. Depending on the
passed realtime while loading some parts of the scenery.
I have introduced the posibility to start directly on the carrier.
With that patch you will have a --carrrier=id argument where id can either be
the pennant number configured in the nimitz scenario or the carriers name
also configured in the carriers scenario.
Additionaly you can use --parkpos=id to select different positions on the
carrier. They are also configured in the scenario file.
That includes the switch of the whole FGInterface class to make use of the
groundcache.
That means that an aircraft no longer uses the current elevation value from
the scenery class. It rather has its own local cache of the aircrafts
environment which is setup in the common_init method of FGInterface and
updated either manually by calling
FGInterface::get_groundlevel_m(lat, lon, alt_m);
or implicitly by calling the above method in the
FGInterface::_updateGeo*Position(lat, lon, alt);
methods.
A call get_groundlevel_m rebuilds the groundcache if the request is outside
the range of the cache.
Note that for the real usage of the groundcache including the correct
information about the movement of objects and the velocity information, you
still need to set up the groundcache in the usual way like YASim and JSBSim
currently does.
If you use the native interface, you will get only static objects correctly.
But for FDM's only using one single ground level for a whole step this is IMO
sufficient.
The AIManager gets a way to return the location of a object which is placed
wrt an AI Object. At the moment it only honours AICarriers for that.
That method is a static one, which loads the scenario file for that reason and
throws it away afterwards. This looked like the aprioriate way, because the
AIManager is initialized much later in flightgears bootstrap, and I did not
find an easy way to reorder that for my needs. Since this additional load is
very small and does only happen if such a relative location is required, I
think that this is ok.
Note that moving on the carrier will only work correctly for JSBSim and YASim,
but you should now be able to start and move on every not itself moving
object with any FDM.
on RPM via a model developed by Vivian Meazza. Add a "boost" output
to the property tree. Fix a bug where MP would be reported "before"
the wastegate clamping.
this is basically the past patch I sent to the list and which should now
really (...!?!?) fix the no ground below aircraft problem.
Reasons:
I understood my remaining thinko I introduced with the prevous patch, and the
same thinko I made in my test cases.
The feedback from the list told me that it should help.
2.
I made YASim query the the ground cache at the wrong place. This one fixed
this, one can now land the bo105 on top of the oracle buildings :)
3.
Is a followup of the scenery center update code: Register the scenery center
transform at the time it is put into the scene graph not at creation time.
4.
I held that part back from the past hitlist patch, because I hoped that it
will be sufficient (and the last one was in fact the biggest part) without.
As some test cases from Melchior showed me, it is not. We have additionally
to the wrong computed transform from the prevous patch some roundoff
problems. This patch adds some small tolerance to for the point in triangle
test.
... may be one even needs to increase the eps value further if starting at
some tile boundaries still fails.
5.
That is a big chunk.
Tested now for two days while hunting the second patch :) .
That is a partial rewrite of the groundcache to use its own datastructures for
that flat scenegraph in the cache. The basic advantage is, what Erik
suggested, to precompute some often used values of these triangles. Also
allmost all computations are now in double precision which should decrease
(hopefully fix), together with a similar tolerance for some point in triangle
tests, the problems with 'no ground below aircraft'.
I am playing with octrees for the groundcache, that will finally solve the
performance problem when high triangular count models end up in the
groundcache. This patch is also some prework for those octrees ...
I have done a patch to eliminate the jitter of 3D-objects near the viewpoint
(for example 3D cockpit objects).
The problem is the roundoff accuracy of the float values used in the
scenegraph together with the transforms of the eyepoint relative to the
scenery center.
The solution will be to move the scenery center near the view point.
This way floats relative accuracy is enough to show a stable picture.
To get that right I have introduced a transform node for the scenegraph which
is responsible for that shift and uses double values as long as possible.
The scenery subsystem now has a list of all those transforms required to place
objects in the world and will tell all those transforms that the scenery
center has changed when the set_scenery_center() of the scenery subsystem is
called.
The problem was not solvable by SGModelPlacement and SGLocation, since not all
objects, especially the scenery, are placed using these classes.
The first approach was to have the scenery center exactly at the eyepoint.
This works well for the cockpit.
But then the ground jitters a bit below the aircraft. With our default views
you can't see that, but that F-18 has a camera view below the left engine
intake with the nose gear and the ground in its field of view, here I could
see that.
Having the scenery center constant will still have this roundoff problems, but
like it is now too, the roundoff error here is exactly the same in each
frame, so you will not notice any jitter.
The real solution is now to keep the scenery center constant as long as it is
in a ball of 30m radius around the view point. If the scenery center is
outside this ball, just put it at the view point.
As a sideeffect of now beeing able to switch the scenery center in the whole
scenegraph with one function call, I was able to remove a one half of a
problem when switching views, where the scenery center was far off for one or
two frames past switching from one view to the next. Also included is a fix
to the other half of this problem, where the view position was not yet copied
into a view when it is switched (at least under glut). This was responsible
for the 'Error: ...' messages of the cloud subsystem when views were
switched.
I have some small updates to the ground cache.
- Remove the usage of dynamic_cast where it is known that the result will be
non null.
- Renormalize the surface normal in double precision.
- Place the groundcaches center at the point it was requested not at the
scenery center. This fixes the problems with JSBSim's trimming together with
the ground cache. Now I am ready to commit JSBSim's ground cache usage.
have a "property" mode as well as the original "binary" mode. The property mode
will allow the remote module to request any set of properties, and it will send
those properties each frame. The remote module can reply with a list of arbitrary
property name/value pairs to update on the FlightGear side.
This is a first stab, so it's not the cleanest, most well concieved code, but it
allows an external module (communicating via a pipe) to have a huge amount of
flexibility in the data in can access and update.
popping up and crashing when the B-29 model is in use. This isn't the
right solution; we should fine the NaN condition. But it's harmless
and allows development with the B-29 to continue.
back, but forgot to put the same fix into the runtime code. Also
added some comments so I don't get confused again the next time I come
through here. :)
I still work on getting the YASim models see the detailed environment
especially the carrier.
I have *forgotten* to initialize and to destruct the ground cache object!
Oooopppss!
currently just returns a lagged normalized value in the range of 0-1 that
is proportional to N1. It's up to the engine gauge to scale to the right
range. This is for lack of a real model of these items so we can have
something to drive the engine gauges.
I have now split out the ground cache functions into src/FDM/groundcache.[ch]xx
Attached are the two files and the patch to integrate that cache into
FGInterface.
The code is nowhere used at the moment, the fdm's need to be updated to use
that ground cache. The JSBSim-dropin.tar.gz from Martins ftp server does this
for example.
The carrier's scenegraph is not yet processed to be visible for ground
intersection testing. So the only benefit up to now is that the api is set
up. Using this I can put the changes to make JSBSim work with that into
JSBSim's cvs. Also I aim to provide Andy a patch to make use of that with
YASim.
I've added two new debug log types for the instrumentation and systems. They
used to use the autopilot debug log, because I couldn't figure out how to
make new log types. Well, now I have figured it out. ;-)
As I had reported on 2004/8/4 00:02:56 ("yasim + bo105 + vrp + @#%$#@ == argh!")
there must be a bug somewhere in YASim, which is responsible for the Bo105
turning around the FDM origin (nose tip) rather than the CG. Some people assumed
that I was just another victim of the "view offset" illusion, but this wasn't
and isn't the case.
Maik Justus (the rotor man) has now supposedly found the bug in YASim[1].
Look at this code in FDM/YASim/Integrator.cpp:35--66:
Stub in hooks for Propeller feathering controls and the turbo prop "condition"
lever.
I added a line in FGFDM.cpp to force control properties to exist if they
don't already. This way you can specify anything you want and find them
in the property browser, otherwise no one else may create them and you are
stuck.
In PropEngine::solve() the code original sets _running = true at the
beginning and then sets running = false at the end. I changed this to
save the current value at the start, set to true, solve(), and then
restore the original value at the end. That way if we start off with
_running = true, we don't have to hack up the calc() routine which wasn't
using the value anyway.
Finally I added some very initial support to shut down a turbine engine
(_running = false) when the condition lever goes to zero.
I have 3 issues that are fixed by this set of patches.
1. In extensions.cxx
#else if !defined( WIN32 ) must be changed by
#elif !defined( WIN32 ) because the text after #else
seems to be ignored
2. banner is not available on windows, only cygwin
3. ANSI escape sequences are not interpreted on the
windows console. We just have garbage that is hard
to read.
the 30 seconds that Maik had originally intended, according to the comment.
This is important for the pending sound and rotor disc changes (and of course
for realism).
"slow/windmilling propeller" regime. I'm happy with the foundations
of the solution, but this hasn't been complete tested yet. The
solution behavior seems fine on the planes I tried.
PistonEngine class has grown an "Engine" superclass. Some other stuff
moved around too, and I cleaned up some property naming while I was in
there. This hasn't been tested very thorougly, hopefully I didn't
break anything.
configure and compile out-of-the-box on a MinGW target:
Use -lSDL instead of -lglut32 on windows builds when --enable-sdl
is set.
Link against alut.dll in addition to openal32.dll.
Replace BSD bcopy() with ANSI C memmove() in a few places. This is
simpler than trying to abstract it out as a platform dependency in a
header file; bcopy() has never been standard.
The ENABLE_THREADS handling has changed to be set to 0 when threads
are not in use. This breaks expressions like #ifdef ENABLE_THREADS.
Replace with a slightly more complicated expression. It might have
been better to fix the configure.ac script, but I didn't know how and
this whole setting is likely to go away soon anyway.
The MinGW C runtime actually does include snprintf, so only MSVC
builds (and not all WIN32 ones) need _snprintf in JSBSim/FGState.cpp
Building on a platform with no glut at all exposed some spots where
plib/pu.h was being included without a toolkit setting (it defaults to
glut). Include fg_os.hxx first.
And when still using glut, glut.h has a bizarre dependency on a
_WCHAR_T_DEFINED symbol. It it's not defined, it tries to redefine
(!!) wchar_t to disasterous effect.
This update contains a change to not overwrite the altitude-ft preset during
"onground" start. The change also prevents a ground trim issue with the
JSBSim fdm when a "reset" is done by FlightGear.
work on the pa28 idle and without creating ridiculous side effects
(like being able to fly the aircraft with the starter motor, heh).
This one looks pretty good for now, pending work on the propeller to
get its low speed drag in line with reality.
reads the /consumables tree for input to determine weights, but
places output only in /engines/engine[n]/fuel-consumed-lbs where
it gets picked up by the Nasal code.
This is a fix for my earlier "Remove some hardcoded dependencies between fdm,
viewer and acmodel" patch. The problem was discovered when testing the
wrightFlyer.
deriving a class and the base class used this type.) Return to using
const char and hope people compiling against earlier versions of plib
have compilers that think typedef const char cchar; char *abc; is equivalent
to const char *abd;
controls in the cockpit vs. which wheels they apply to. FlightGear now
sets /controls/gear/brake-left, /controls/gear/brake-right, and
/controls/gear/brake-parking. It should be up to the FDM to sort out
which wheels under which circumstances are affected by these controls
and ultimately what happens to the physical motion of the aircraft.
places now use sgCartToGeod() instead of rolling their own
approximation. And YASim is now using exactly the same 3D coordinate
system as the rest of FlightGear is.
the core YASim stuff. Mostly cosmetic: whitespace adjustment, dead
code & meaningless comment removal, a little code motion to better
partition the helicopter handling from the original code (no more
giant if() { ... } around the solver). Added a warning to the parser
to try to eliminate the string booleans that crept in.
There should be NO behavioral changes with this checkin.
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.
now read the config file out of the individual aircraft directory rather
than the collective Aircraft-yasim/ directory (which is now obsolete.)
This requires a corresponding update of the base package cvs.
The Propeller class ignored negative RPM but still returned a torque
value, which ratcheted up a higher and higher negative RPM until drag
overwhelmed the aircraft.
In reality, the propeller should windmill at a reasonable postive RPM,
introducing a constant drag on the aircraft -- the propeller should
*not* stop unless the plane is flying very slowly. That's a future
project.
I have added a fledgling replay system that records flight data and control
positions during the flight.
I have added an internal command called "replay" which will trigger a replay
of the entire saved flight data set. This could be bound to a keyboard or
menu command, in fact this entire module is screaming for someone to build
a gui to control playback speed, amount of playback, etc.
This is the initial version so there are kinks that still need to be worked
out, please be patient.
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
> > Here's a patch to add manual-pitch control to the propeller in YASim. A new
> > control axis "PROPPITCH" is added. Requires "manual-pitch" boolean property
> > in the "propeller" tag.
> >
> > Tags and Properties to add in order to enable:
> >
> > manual-pitch="true"
> >
> > <control-input axis="/controls/engines/engine[0]/propeller-pitch"
> > control="PROPPITCH" src0="0" src1="1" dst0="0.40" dst1="0.80"/>
> >
> > Note that for the time being, excessively low RPM or excessively high RPM is
> > brought undercontrol by a scaling range defined in the control-input tag
> > (see "dst0" and "dst1" properties).
I have attached some revisions for the UIUCModel and some LaRCsim.
The only thing you should need to check is LaRCsim.cxx. The file
I attached is a revised version of 1.5 and the latest is 1.7. Also,
uiuc_getwind.c and uiuc_getwind.h are no longer in the LaRCsim
directory. They have been moved over to UIUCModel.
I split the FGModelPlacement code out into it's own set of source files.
I created two versions of the fgLoad3DModel() routine. One that is
unecumbered by a panelnode dependency and one that is. acmodel.cxx is
the only place that needs to load an aircraft with instrument panels.
model.[ch]xx are now pretty much free to move over into simgear.
loader.[ch]xx should be able to follow closely behind.
This will be a big step towards being able to move the material management
code over into simgear.
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.
that after a reset or reposition, several FDM variable were not unbound
correctly and left dangling pointing to unallocated memory. This wasn't
a crash type bug, but those properties then had bogus values. This
specifically prevented the turn coordinator gyro modeling from working after
a reset or reposition.
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.
FGExternalPipe is destructed.) This leaves the name pipe hanging around
even after flightgear exits, but assuming we put the files in /tmp that
shouldn't be a big deal.
ExternalNet interface:
- allows a much more closely coupled execution. A remote network FDM will run
at it's own rate, and maybe a particular data packets will come, maybe it
won't. This makes it very hard to control timing and keep the animation
smooth. There are also cpu scheduling issues with running multiple
processes on a single machine. The linux scheduler by default runs at
100hz. If an FDM process uses a sleep/alarm system to avoid wasting
CPU, it will be forced to run at 100hz, 50hz, 25hz, 20hz, etc. This
makes it *impossible* to serve a display system running at 60hz without
dropping frames.
- the downside is that the FDM process must now run on the same machine as
the master flightgear process.
- NED and UVW are working correctly
- knots is giving true airspeed instead of calibrated airspeed
- mach is not working at all
This desperately needs a trimming routine.
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.
really useful unless we simultaneously change the per-iteration deltas
to be smaller. Add another pseudo-tunable to control the speed with
which we change values across iterations. As it turns out, this is
much more effective than the threshold tunable. It does come at the
cost of lower solution performance, however.
Link the standalone executable against the source files explicitly rather
than libYASim, as the Irix linker can't handle the unneeded dependance on
other parts of FlightGear.
isn't well-constrained by the solution process is the drag-vs-aoa curve.
The default value that YASim picked was very steep, and resulted in most
of the jets flying their approaches *way* behind the power curve. This
changes the default to be more forgiving, and adds an "idrag" tunable
to the configuration file for tweakers.
Also, change the default gear springiness to be less stiff.
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.
A bug lurked into our uiuc code.
There are two changes:
[1] Comment out the chunk of code as shown (compare w/ the old)
[2] Put back in the function call, and in that code change AlphaTail to Alpha.
speedups to uiuc_menu.cpp.
(Note these were originally submitted before the cutoff date for new
features, but something was corrupted in the transfer so I granted a bit
of leeway in the schedule.)
- Removed some old cruft.
- Removed some support for older versions of automake which technically was
correct, but caused the newer automakes to squawk warnings during an
initial sanity check (which isn't done very intelligently.)
NOTE: this fix is technically not correct for older version of automake.
These older version use the variable "INCLUDES" internally and could have
them already set to an important value. That is why we were appending
our values to them. However, newer versions of automake don't set this
value themselves so it is an error to append to a non-existant variable.
We seem to "get away" with overwriting the value on older versions of
automake, but if you have problems, consider upgrading to at least
automake-1.5.
instrument. This needs to move somewhere permanent.
Also, remove a bogus fuel consumption setting that (1) was off by a factor
of 3600 (hours, not seconds) and (2) collided with identical code in FGFDM.
the amount of drag that the produced lift *would* have produced given an
unflapped air surface. A nifty trick involving the assumption that AoA is
small works for this, and produces plausible results in the high AoA case
as well.
Also, trim for approach using the elevator-trim control, not elevator.
Just cosmetic for current planes, but future ones might have differing
implementations of trim.
(and not the throttle setting), but the recalculation left in a degeneracy
when the target/throttle setting was exactly zero. Zero times a big number
is still zero. Fixed to use real math, not theoretical math.
Fetch all pending remote fdm network packets so there is not chance of
getting behind.
Add support for driving control panel lights.
Working on better modeling KX 155 tuning behavior.
won't apply the right gross weight due to fuel differences.
When solving for zero force, do so in the global frame, not the
aircraft's. In principle, this shouldn't matter (zero is zero in all
frames), but in practice this should help to avoid oscillations.
Calculating lift as force perpendicular to the ground (and not the
wing plane) is clearly the Right Thing, anyway.
Also added support for a /yasim/gross-weight-lbs property, which
should be generically useful.
when the lift/drag are really solid. And defer the approach trim until
the all four of the other variables are perfect. I believe this should
fix the solution failures under gcc 2.95.2.
implicitly in PropEngine by disallowing negative torques, but that was
removed at some point. We really need the explosion protection here
at the source.
This is a new improved patch for the previous tile manager fixes.
Rather than building dependencies between FGlocation or the viewer or fdm with
tilemgr what I ended up doing was linking the pieces together in the Mainloop
in main.cxx. You'll see what I mean...it's been commented fairly well. More
than likely we should move that chunk somewhere...just not sure where yet.
The changes seem clean now. As I get more ideas there could be some further
improvement in organizing the update in tilemgr. You'll note that I left an
override in there for the tilemgr::update() function to preserve earlier
functionality if someone needs it (e.g. usage independent of an fdm or
viewer), not to mention there are a few places in flightgear that call it
directly that have not been changed to the new interface (and may not need to be).
The code has been optimized to avoid duplicate traversals and seems to run
generally quite well. Note that there can be a short delay reloading tiles
that have been dropped from static views. We could call the tile scheduler on
a view switch, but it's not a big deal and at the moment I'd like to get this
in so people can try it and comment on it as it is.
Everything has been resycned with CVS tonight and I've included the
description submitted earlier (below).
Best,
Jim
Changes synced with CVS approx 20:30EDT 2002-05-09 (after this evenings updates).
Files:
http://www.spiderbark.com/fgfs/viewer-update-20020516.tar.gz
or
http://www.spiderbark.com/fgfs/viewer-update-20020516.diffs.gz
Description:
In a nutshell, these patches begin to take what was one value for ground
elevation and calculate ground elevation values seperately for the FDM and the
viewer (eye position). Several outstanding view related bugs have been fixed.
With the introduction of the new viewer code a lot of that Flight Gear code
broke related to use of a global variable called "scenery.cur_elev".
Therefore the ground_elevation and other associated items (like the current
tile bucket) is maintained per FDM instance and per View. Each of these has a
"point" or location that can be identified. See changes to FGLocation class
and main.cxx.
Most of the problems related to the new viewer in terms of sky, ground and
runway lights, and tower views are fixed.
There are four minor problems remaining. 1) The sun/moon spins when you pan
the "lookat" tower view only (view #3). 2) Under stress (esp. magic carpet
full speed with max visibility), there is a memory leak in the tile caching
that was not introduced with these changes. 3) I have not tested these
changes or made corrections to the ADA or External FDM interfaces. 4) The
change view function doesn't call the time/light update (not a problem unless
a tower is very far away).
Details:
FDM/flight.cxx, flight.hxx - FGInterface ties to FGAircraftModel so that it's
location data can be accessed for runway (ground elevation under aircraft)
elevation.
FDM/larsim.cxx, larcsim.hxx - gets runway elevation from FGInterface now.
Commented out function that is causing a namespace conflict, hasn't been
called with recent code anyway.
FDM/JSBSim/JSBSim.cxx, YASim/YASim.cxx - gets runway elevation from
FGInterface now.
Scenery/newcache.cxx, newcache.hxx - changed caching scheme to time based
(oldest tiles discard).
Scenery/tileentry.cxx, tileentry.hxx - added place to record time, changed
rendering to reference viewer altitude in order to fix a problem with ground
and runway lights.
Scenery/tilemgr.cxx, tilemgr.hxx - Modified update() to accept values for
multiple locations. Refresh function added in order to periodically make
the tiles current for a non-moving view (like a tower).
Main/fg_init.cxx - register event for making tiles current in a non-moving
view (like a tower).
Main/location.hxx - added support for current ground elevation data.
Main/main.cxx - added second tilemgr call for fdm, fixed places where viewer
position data was required for correct sky rendering.
Main/options.cxx - fixed segfault reported by Curtis when using --view-offset
command line parameter.
Main/viewer.cxx, viewer.hxx - removed fudging of view position. Fixed numerous
bugs that were causing eye and target values to get mixed up.
the wrong place. The Atmosphere::getStd*() calls are used by the
solver, and thus really need to return values for a "standard"
atmosphere. Otherwise, an aircraft started up in Moscow will behave
differently than one initialized in Cairo. :)
The place where environmental pressure and temperature get inspected
at runtime is in YASim.cxx. The changes there, happily, end up being
even smaller than the ones to Atmosphere. This ends up replacing code
only, and removing some comments.
set_Density; since JSBSim doesn't override the get_* methods from
FGInterface as well, the wrong values are always set anyway.
Take the static temperature, static pressure, and density values from
an external source if requested by the
/environment/params/control-fdm-atmosphere property. This isn't
working properly yet for JSBSim because of interactions with the
trimming routine.
Removed configuration option --with-new-environment and
FG_NEW_ENVIRONMENT macro.
Added configuration option --with-weathercm and FG_WEATHERCM macro.
FGEnvironment is now the default; use --with-weathercm to get the old
weather.
- changed FGSubsystem::update(int) to
FGSubsystem::update(delta_time_sec); the argument is now delta time
in seconds rather than milliseconds
- added FGSubsystem::suspend(), FGSubsystem::suspend(bool),
FGSubsystem::resume(), and FGSubsystem::is_suspended(), all with
default implementations; is_suspended takes account of the master
freeze as well as the subsystem's individual suspended state
- the FDMs now use the delta time argument the same as the rest of
FlightGear; formerly, main.cxx made a special case and passed a
multiloop argument
- FDMs now calculate multiloop internally instead of relying on
main.cxx
There are probably some problems -- I've done basic testing with the
major FDMs and subsystems, but we'll probably need a few weeks to
sniff out bugs.
Due to jumpy joystick read-outs the UFO jitters a lot in turns.
This patch implements simple damping for aileron/elevator/throttle.
Furthermore it lets the UFO fly backwards if brake[0] is active
(by default associated with the joystick's fire button). After all,
everyone knows that UFO's can fly backwards!
It's cumbersome to use the MagicCarpet as 3D cursor, because everytime
you shoot over the target you have first to turn by 180 degrees and to
fly back.
This patch lets the magic carpet fly backwards if brake[0] is active,
which is by default associated with the joystick's fire button.
> I have attached some new additions to the UIUC code. Most of the
> changes allow for the addition of apparent mass. This is very
> useful with light aircraft and gliders.
I have finished working the bugs out of my "Enhanced" version of the Magic
Carpet FDM. The UFO FDM works the same as the Magic Carpet with the
following exceptions:
The aircraft's pitch is determined by the Elevator setting (with a pitch
rate of 45 degrees per second).
Climb is forward velocity * sin(pitch)
Speed is forward velocity * soc(pitch)
Roll is tied to the aileron (again, with a roll rate of 45 degrees per
second)
Turn rate is sin(roll) * 45 degrees.
Yes, this does mean that turning is quite a bit more sluggish than
climbing.
If you are wondering why a UFO FDM, it is because it's best that I not
replace the existing magic carpet and this FDM does behave like a UFO (it
hovers, can spin and pitch while hovering, and does not obey the laws of
physics ;)
- Throttle control position
- Mixture control position
- Magneto/starter control position
Added support for receiving:
- Engine state (off, cranking, running)
- RPM
- Fuel Flow
- EGT
- Oil Temp
- Oil Pressure
- Fuel tank quantity
- Weight on wheels
Changed the steering gain from +/-0.1 to +/-1.0, so that the steering
angle for the nosewheel (when present) is the same as the rudder
deflection angle. That's probably not exactly right, but it's much
better than we had before -- you can now steer the plane on the ground
reasonably during taxiing.
ability to run a nonlinear model with flaps. The files ls_model.c and
uiuc_aero.c were changed since we had some functions with the same
name. The name changes doesn't affect the code, it just makes it a
little easier to read. There are changes in LaRCsim.cxx so UIUC
models have engine sound. Could you send me an email when you receive
this and/or when the changes make it to the CVS? Thanks.
Also I noticed you have some outdated files that are no longer used in
the UIUCModel directory. They are uiuc_initializemaps1.cpp,
uiuc_initializemaps2.cpp, uiuc_initializemaps3.cpp, and
uiuc_initializemaps4.cpp
Rob
for fuselage Surface objects. If the fuselage wasn't aligned perpendicular
to the Y axis, the matrix wouldn't be orthonormal. Since all of, perhaps,
three aircraft have ever been built this way, it's doubtful I would have
found this as a bug report. :)
interface instead of string. This will result in a lot more
efficiency later, once I add in a simple hash table for caching
lookups, since it will avoid creating a lot of temporary string
objects. The major considerations for users will be that they cannot
use
node->getName() == "foo";
any more, and will have to use c_str() when setting a string value
from a C++ string.
inclueded in some of the files. Irix doesn't have cout in the std class,
so I changed it to "cout" and included SG_USING_NAMESPACE(std) at the
beginning of the files.
And some minor warning cleanups.
separate header file. This change will help integrate properties into
JSBSim.
Also, I (David Megginson) removed most of the SimGear include
statements from globals.hxx, reducing the amount of recompilation
every time SimGear changes. This required making minor changes to a
lot of files that were depending on the side-effects of the inclusions
in globals.hxx.
is a work in progress and needs severe enhancement before it will be
useful. It provides a UDP data channel that goes both ways between
flightgear and the fdm. It also provides a TCP 'command' channel so
flightgear can 'reliably' send commands to the remote fdm (such as set
starting position, reset on ground, etc.)
and scaling of control values to properties. Also added a time interpolation
feature that replaces the hacked-in "retract-time" feature for the gear in
a more general way (applicable to flaps, too!). Incompatibly breaks
the XML syntax; get new files!
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.
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.
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.
Added fuel-flow and total fuel to the LaRCSim model. Its still a bit
rough for now but it works, except the engine dosn't stop when fuel runs
out at the moment since there's no refuelling capability in the sim just
now. It takes about 4 gallons use before you see the fuel guages begin
to drop since there's 28 gal per tank but the guages go to 26.
Basically I've rewritten the prop model along similar lines to how
Jon has done his - using published efficiency and coefficient of
power data. It works *much* better - try pulling the throttle back
to idle and putting the plane into a dive before and after updating
and you'll see what I mean. It doesn't require a fudge factor either
:-)
FGOptions is history, and the modules are (starting) to use the property
manager directly. Let me know if I left any files out.
Inevitably, there will be some problems with broken options, etc.,
that I haven't found in my tests, but I'll try to fix them quickly.
We also need to stress that the property names currently in use are
not stable -- we need to reorganize them a bit for clarity.
bring EGT down to a more reasonable range. EGT is now returned in
deg Fahrenheit (yuk!!) by the accessor function since that is what
the guage is calibrated in, and the absolute max value that can be
output (max power mixture at max power) is about 750 deg F. Dave, I
suggest that you set the guage to run from 450 - 750 deg F between
the four big marker ticks. What do the offset and scale actually
refer to in the .xml config file BTW?
Fuel flow, better handling of manifold pressure wrt engine speed, and
proper consideration of altitude effects next, hopefully.
temperature. The cylinder head is assumed to be at uniform
temperature. Obviously this is incorrect, but it simplifies things a
lot, and we're just looking for the behaviour of CHT to be correct.
Energy transfer to the cylinder head is assumed to be one third of the
energy released by combustion at all conditions. This is a reasonable
estimate, although obviously in real life it varies with different
conditions and possibly with CHT itself. I've split energy transfer
from the cylinder head into 2 terms - free convection - ie convection
to stationary air, and forced convection, ie convection into flowing
air. The basic free convection equation is: dqdt = -hAdT Since we
don't know A and are going to set h quite arbitarily anyway I've
knocked A out and just wrapped it up in h - the only real significance
is that the units of h will be different but that dosn't really matter
to us anyway. In addition, we have the problem that the prop model
I'm currently using dosn't model the backwash from the prop which will
add to the velocity of the cooling air when the prop is turning, so
I've added an extra term to try and cope with this.
In real life, forced convection equations are genarally empirically
derived, and are quite complicated and generally contain such things
as the Reynolds and Nusselt numbers to various powers. The best
course of action would probably to find an empirical correlation from
the literature for a similar situation and try and get it to fit well.
However, for now I am using my own made up very simple correlation
for the energy transfer from the cylinder head:
dqdt = -(h1.dT) -(h2.m_dot.dT) -(h3.rpm.dT)
where dT is the temperature different between the cylinder head and
the surrounding air, m_dot is the mass flow rate of cooling air
through an arbitary volume, rpm is the engine speed in rpm (this is
the backwash term), and h1, h2, h3 are co-efficients which we can play
with to attempt to get the CHT behaviour to match real life.
In order to change the values of CHT that the engine settles down at
at various conditions, have a play with h1, h2 and h3. In order to
change the rate of heating/cooling without affecting equilibrium
values alter the cylinder head mass, which is really quite arbitary.
Bear in mind that altering h1, h2 and h3 will also alter the rate of
heating or cooling as well as equilibrium values, but altering the
cylinder head mass will only alter the rate. It would I suppose be
better to read the values from file to avoid the necessity for
re-compilation every time I change them.
LaRCsim c172 on-ground and in-air starts, reset: all work
UIUC Cessna172 on-ground and in-air starts work as expected, reset
results in an aircraft that is upside down but does not crash FG. I
don't know what it was like before, so it may well be no change.
JSBSim c172 and X15 in-air starts work fine, resets now work (and are
trimmed), on-ground starts do not -- the c172 ends up on its back. I
suspect this is no worse than before.
I did not test:
Balloon (the weather code returns nan's for the atmosphere data --this
is in the weather module and apparently is a linux only bug)
ADA (don't know how)
MagicCarpet (needs work yet)
External (don't know how)
known to be broken:
LaRCsim c172 on-ground starts with a negative terrain altitude (this
happens at KPAO when the scenery is not present). The FDM inits to
about 50 feet AGL and the model falls to the ground. It does stay
upright, however, and seems to be fine once it settles out, FWIW.
To do:
--implement set_Model on the bus
--bring Christian's weather data into JSBSim
-- add default method to bus for updating things like the sin and cos of
latitude (for Balloon, MagicCarpet)
-- lots of cleanup
The files:
src/FDM/flight.cxx
src/FDM/flight.hxx
-- all data members now declared protected instead of private.
-- eliminated all but a small set of 'setters', no change to getters.
-- that small set is declared virtual, the default implementation
provided preserves the old behavior
-- all of the vector data members are now initialized.
-- added busdump() method -- FG_LOG's all the bus data when called,
useful for diagnostics.
src/FDM/ADA.cxx
-- bus data members now directly assigned to
src/FDM/Balloon.cxx
-- bus data members now directly assigned to
-- changed V_equiv_kts to V_calibrated_kts
src/FDM/JSBSim.cxx
src/FDM/JSBSim.hxx
-- bus data members now directly assigned to
-- implemented the FGInterface virtual setters with JSBSim specific
logic
-- changed the static FDMExec to a dynamic fdmex (needed so that the
JSBSim object can be deleted when a model change is called for)
-- implemented constructor and destructor, moved some of the logic
formerly in init() to constructor
-- added logic to bring up FGEngInterface objects and set the RPM and
throttle values.
src/FDM/LaRCsim.cxx
src/FDM/LaRCsim.hxx
-- bus data members now directly assigned to
-- implemented the FGInterface virtual setters with LaRCsim specific
logic, uses LaRCsimIC
-- implemented constructor and destructor, moved some of the logic
formerly in init() to constructor
-- moved default inertias to here from fg_init.cxx
-- eliminated the climb rate calculation. The equivalent, climb_rate =
-1*vdown, is now in copy_from_LaRCsim().
src/FDM/LaRCsimIC.cxx
src/FDM/LaRCsimIC.hxx
-- similar to FGInitialCondition, this class has all the logic needed to
turn data like Vc and Mach into the more fundamental quantities LaRCsim
needs to initialize.
-- put it in src/FDM since it is a class
src/FDM/MagicCarpet.cxx
-- bus data members now directly assigned to
src/FDM/Makefile.am
-- adds LaRCsimIC.hxx and cxx
src/FDM/JSBSim/FGAtmosphere.h
src/FDM/JSBSim/FGDefs.h
src/FDM/JSBSim/FGInitialCondition.cpp
src/FDM/JSBSim/FGInitialCondition.h
src/FDM/JSBSim/JSBSim.cpp
-- changes to accomodate the new bus
src/FDM/LaRCsim/atmos_62.h
src/FDM/LaRCsim/ls_geodesy.h
-- surrounded prototypes with #ifdef __cplusplus ... #endif , functions
here are needed in LaRCsimIC
src/FDM/LaRCsim/c172_main.c
src/FDM/LaRCsim/cherokee_aero.c
src/FDM/LaRCsim/ls_aux.c
src/FDM/LaRCsim/ls_constants.h
src/FDM/LaRCsim/ls_geodesy.c
src/FDM/LaRCsim/ls_geodesy.h
src/FDM/LaRCsim/ls_step.c
src/FDM/UIUCModel/uiuc_betaprobe.cpp
-- changed PI to LS_PI, eliminates preprocessor naming conflict with
weather module
src/FDM/LaRCsim/ls_interface.c
src/FDM/LaRCsim/ls_interface.h
-- added function ls_set_model_dt()
src/Main/bfi.cxx
-- eliminated calls that set the NED speeds to body components. They
are no longer needed and confuse the new bus.
src/Main/fg_init.cxx
-- eliminated calls that just brought the bus data up-to-date (e.g.
set_sin_cos_latitude). or set default values. The bus now handles the
defaults and updates itself when the setters are called (for LaRCsim and
JSBSim). A default method for doing this needs to be added to the bus.
-- added fgVelocityInit() to set the speed the user asked for. Both
JSBSim and LaRCsim can now be initialized using any of:
vc,mach, NED components, UVW components.
src/Main/main.cxx
--eliminated call to fgFDMSetGroundElevation, this data is now 'pulled'
onto the bus every update()
src/Main/options.cxx
src/Main/options.hxx
-- added enum to keep track of the speed requested by the user
-- eliminated calls to set NED velocity properties to body speeds, they
are no longer needed.
-- added options for the NED components.
src/Network/garmin.cxx
src/Network/nmea.cxx
--eliminated calls that just brought the bus data up-to-date (e.g.
set_sin_cos_latitude). The bus now updates itself when the setters are
called (for LaRCsim and JSBSim). A default method for doing this needs
to be added to the bus.
-- changed set_V_equiv_kts to set_V_calibrated_kts. set_V_equiv_kts no
longer exists ( get_V_equiv_kts still does, though)
src/WeatherCM/FGLocalWeatherDatabase.cpp
-- commented out the code to put the weather data on the bus, a
different scheme for this is needed.
ing features:
a) ADA Flight model - ADA.cxx, ADA.hxx, flight.hxx
b) Fighter a/c HUD - flight.hxx, hud.hxx, hud.cxx, cockpit.cxx, hud_ladr.c
xx, hud_card.cxx
c) 3-window display - options.hxx, options.cxx, viewer.cxx
d) Moving objects (ship) - main.cxx
e) Patches - main.cxx
ADA.cxx, ADA.hxx
--------------------------
Interface to the external ADA flight dynamics package.
flight.hxx
----------
Included prototypes for accepting additional data fron the External flight
model for fighter aircraft HUD
Hud.hxx
-------
Included prototypes for accepting additional data for fighter HUD from Exernal F
light model.
Defined FIGHTER_HUD pre-processor directive to enable compilation of fighter hud
code.
hud.cxx, cockpit.cxx, hud_ladr.cxx, hud_card.cxx
---------------------------------------
Included code to initialise additional reticles/text for fighter HUD which is co
nditionally
compiled if FIGHTER_HUD is defined.
options.hxx
-----------
Added window_offset, and function to retrieve its value for 3 windows
options.cxx
-----------
Changed few options to suit ADA/CEF projection system/screens and checks for win
dow offset.
views.cxx
---------
Added code to retrieve view offset for window.
Main.cxx
--------
Added code to load and move an aircraft carrier.
Patch to enable clouds from command line until Curtis fixes it. By default cloud
s are disabled.
I have a scrollable panel working (it didn't take long in the end). A
panel can now be much wider or higher than the available area, and the
user can scroll around using [Shift]F5, [Shift]F6, [Shift]F7, and
[Shift]F8. The user can also scroll the panel down to get a bigger
external view. Mouse clicks seem still to be working correctly.
To set the panel's (virtual) height and width, use the panel file's /w
and /h properties in a panel XML file; to set the initial x- and y-
offsets (untested), use the panel file's /x-offset and /y-offset
properties; to set the initial height of the external view (untested
and optional), use the panel file's /view-height property. Note that
none of these show up in the regular FGFS property manager.
Unfortunately, these patches will not affect your initialization
problems with the property manager -- I'm having a hard time tracking
them down because I cannot reproduce them.
I have also made some patches to main.cxx and views.cxx to do two
things:
1. Expand or shrink the external view as the panel moves up and down.
2. Set the window ratio correctly, so that we don't get an oval sun
and flat clouds when the panel is visible (the problem before was
integer division, so I added casts).
Unfortunately, the window ratio is not set properly at start-up --
there are too many dependencies, and I haven't figured that part out
yet. As soon as you hide and redisplay the panel or move it
vertically (i.e. force fgReshape to be called), you'll see the correct
ratio.
- /engines/engine0/rpm changed to read-only
- /engines/engine0/egt added (read-only)
- /controls/mixture added
- /controls/propellor-pitch added (not used for C172)
BFI:
- getEGT() added
- getMixture() and setMixture() added
- getPropAdvance() and setPropAdvance() added (= pitch)
- cleaned up reinit function a bit
- force reinit only when values are actually changed; for example,
setting the flight model to the current flight model will not cause
a reinit
LaRCSim:
- hook up mixture and pitch to FGControls (they were hard-coded
before)
- /engines/engine0/rpm changed to read-only
- /engines/engine0/egt added (read-only)
- /controls/mixture added
- /controls/propellor-pitch added (not used for C172)
BFI:
- getEGT() added
- getMixture() and setMixture() added
- getPropAdvance() and setPropAdvance() added (= pitch)
- cleaned up reinit function a bit
- force reinit only when values are actually changed; for example,
setting the flight model to the current flight model will not cause
a reinit
LaRCSim:
- hook up mixture and pitch to FGControls (they were hard-coded
before)
and prop inertia and passed the timestep from LaRCsim in order to have
the engine rpm behaving according to the applied torque and the laws of
physics.
