Re: [Flightgear-devel] AI Carrier with Aircraft, and the last JSBSim version

[Bill Galbraith]

 


> With Catapult it is less a  problem, with answering time 
> delay, i mean it should work.
> Catapults features need only to know the "starting position" 
> with a more or less value precision: a carrier with 20 km 
> speed does 5.6 meter per second => 0.50 1/10 sec => 0.05 1/100 sec
> 
> The heading won't be  a difficulty,  the  heading of the 
> carrier  is not quickly moving.
> 

I haven't done much with FG or JSBSim lately, but thought I'd add my $0.02
worth, since I'm working on this stuff on a 'real' simulator.

Not all carriers shoot off at the carrier's heading. Some US carriers
(sorry, I can't name names) are left of carrier heading, up to 8 degrees.
Some secondary cats (cats 3 and 4) are off even more. (I think they even
show some of that in Top Gun).

Plus, the force applied is in carrier axes (with the aforementioned offset),
not in aircraft body axes. The force must be translated into body axis so
that it tracks down the cat track. That way, if you are lined up poorly on
the cat, it straightens you out. 

The carrier is most likely not going to be changing heading or speed during
a launch, but it should be accounted for. With a high-seas condition, the
boat is rock, roll, and heave a lot. Traps are REALLY difficult when the
seas are rough. They probably have to time a shot off a cat to coincide with
an up motion, so that you don't get shot into a wave.

Bill


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Re: [Flightgear-devel] 350 Mb movie

[Bill Galbraith]

Schweet. Details?  Are those dedicated instruemtns, or a FG monitor behind a
mask?
 
Bill


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Friday, February 29, 2008 8:17 PM
To: FlightGear developers discussions
Subject: [Flightgear-devel] 350 Mb movie


I just posted a movie of one of the things I've been working on this week.
It's a light-twin flight simulator with full cockpit and 7 visual channels
(LCD displays).  This movie shows an approach into 6WA8 (Ranger Creek) along
with the touch down.  This movie is straight off my camera without any
editing or compression so it weighs in at a whopping 345Mb.  But if you have
the bandwidth to burn I think it's pretty cool.  The 7 visual channels
combined with terrain, tree cover, full instrument panel, and cockpit
enclosure really give you an immersive feel.

http://baron.flightgear.org/~curt/tmp/MVI_0250.AVI

Curt.
-- 
Curtis Olson: http://baron.flightgear.org/~curt/ 

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Re: [Flightgear-devel] Request for modeling: Diamond Katana DA-20

[Bill Galbraith]

There is someone in the DATCOM world working on an aero model  DA-40. This
is what it looks like. Is it close to what you are doing?  If so, I'll hook
you up with him.

 

Bill





> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On
> Behalf Of Tatsuhiro Nishioka
> Sent: Tuesday, January 29, 2008 3:01 PM
> To: FlightGear developers discussions
> Subject: [Flightgear-devel] Request for modeling: Diamond Katana DA-20
>
> Hi,
>
> Does anyone have or is making DA-20 for FlightGear?
> If not, does anyone get interested in making one?
>
> A FlightGear user on Mac asked me if there is a model for DA-20.
> He is a real pilot of DA-20 and has its POH.
>
> Though I'm willing to make it, I am a bit busy making two
> aircraft and improving GUI for Mac.
> Please let me know if any of you guys want to make it. I
> think you can borrow a copy of POH from him.
>
> See more info on DA-20 from:
> http://en.wikipedia.org/wiki/Diamond_DA20
>
> Best,
>
> Tat
>
>
> --
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Re: [Flightgear-devel] an important growing trend now in softwareapplications to make them" portable" in the sense that thecomplete installation resides in it's one directory.

[Bill Galbraith]

 



  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Thursday, December 20, 2007 10:43 AM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] an important growing trend now in
softwareapplications to make them" portable" in the sense that thecomplete
installation resides in it's one directory.


On Dec 20, 2007 1:20 AM, GWMobile <> wrote:


There is an important growing trend now in software applications to make 
them" portable" in the sense that the complete installation resides in
it's one directory.


 

I was able to burn this onto a CD, and run it from that, so I don't know
what the problem is.
 
Bill
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Re: [Flightgear-devel] FlightGear Prerelease 0.9.11 some testresults

[Bill Galbraith]

 



  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Lee
Duke
Sent: Friday, November 30, 2007 8:14 AM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] FlightGear Prerelease 0.9.11 some
testresults


How about 0.x.y where x and y can be variables and everyone can just choose
their favorite or preferred numbers rather than filling my in box with
discussions of which number comes after z.

Lee



 

Okay, then I'm calling my version 0.3.14, because who doesn't love Pi?
Bill
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Re: [Flightgear-devel] FlightGear Prerelease 0.9.11 some testresults

[Bill Galbraith]

 



  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Friday, November 30, 2007 7:52 AM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] FlightGear Prerelease 0.9.11 some
testresults


I'm just a little surpised that the version number is such a contentious
issue.  It seems like there are more important battles to fight.  How about
we at least agree to skip 0.9.11 out of sensitivity to a very large group of
people.

 

Okay, so are we going to 0.10.1 ???
 
Geeze, it's just a number.
 
Bill 
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Re: [Flightgear-devel] [Fwd: Re: [Flightgear-cvslogs] CVS: data/Aircraft/R22/Models R22.xml, 1.3, 1.4 paint1.rgb, 1.1, 1.2 r22.ac, 1.3, 1.4]

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Syd&Sandy
> Sent: Monday, November 05, 2007 3:04 PM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] [Fwd: Re: 
> [Flightgear-cvslogs] CVS: data/Aircraft/R22/Models R22.xml, 
> 1.3, 1.4 paint1.rgb, 1.1, 1.2 r22.ac, 1.3, 1.4]
> 
> On Mon, 05 Nov 2007 20:57:04 +0100
> Maik Justus <[EMAIL PROTECTED]> wrote:
> 
> > Hi Heiko,
> > yes, thats the only source for drag/lift curves I found 
> about the R22 
> > rotor airfoil (NACA 63-015). I am not using the X-Plane 
> parameters; I 
> > just tried to get a similar shape of the drag/lift curves 
> as X-Plane 
> > is using, but to limitations of the airfoil models there are 
> > differences (esp. if the blade is stalled).
> > 
> > I sent some modifications of the R22 FDM to Syd. I think I 
> need to add 
> > some damage model to simulate mast bumping to the R22 (if 
> Syd agrees).
> > 
> > Maik
> > 
> > Heiko Schulz schrieb am 05.11.2007 14:45:
> > > Hi,
> > >
> > > for airfoil you could check X-Plane- They have a R-22, 
> and you can 
> > > easiliy see the airfoils in their demo.
> > > Problem could be the licence...
> > >
> > > Greetings
> > > HHS
> > > --- Syd&Sandy <[EMAIL PROTECTED]> schrieb:
> > >
> 


I sent Maik a scan of the NACA airfoil characteristics from the "Theory of
Wing Sections". If anyone else is interested in it, please contact me
off-list.

Bill
Bill (at) holycows.net


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Re: [Flightgear-devel] The Big Monitor show at FSWeekend,

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Durk Talsma
> Sent: Saturday, November 03, 2007 5:30 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: [Flightgear-devel] The Big Monitor show at FSWeekend,
> 
> Hi Everybody,
> 
> One thing that probably stands out at this year's FlightGear 
> booth is that we had 6 more monitors than presenters, and 
> that the monitor to presenter ratio at the booth is 3:1. This 
> leaves the question as to how many presenters were at the 
> booth, given that this number is a prime.
> 
> Torsten, Durk, and one developer who again wishes to remain 
> anonymous, had a pretty good show today, with a bit of a slow 
> start. Initially, we had some performance issues on the 
> windows machine, and some minor bugs to solve, but these 
> problems were gradually resolved during the day.
> 
> Many people asked how we could compete with big companies 
> like microsoft, or were wondering about our motivation to 
> start this program. Upon explaining, most people were 
> actually quite impressed by the fact that "just a bunch" of 
> volunteers were able to accomplish such a big feat. 
> 
> We did get the occasional comment that our (scenery) graphics 
> were a bit simple. We'll be back tomorrow for another day of 
> fun and flying. In the mean time, here's a quick impression. 
> More to follow later.
> 
> http://www.t3r.de/fsweekend.jpg
> 
> Cheers,
> Torsten, Durk, Martin
> 


What was the intent behind displaying at the show? I'm sure it wasn't free
for a booth, was it?  I've given the same idea some thought, but it's hard
to make money off of something that is free.

Bill


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Re: [Flightgear-devel] Consistent aircraft states

[Bill Galbraith]

 

> > I am clearly one that prefers to  start with the brakes set and all 
> > switches off as that is the way every real flight  starts.
> 
> (An aside: In my experience, it's rare that the parking brake 
> is on when a real light plane is parked, because line staff 
> wouldn't be able to move it around without gaining inside 
> access -- in fact, when I get out of the plane at a remote 
> airport, the first question from line staff is usually not 
> "do you need fuel?" but "is the brake off?".
> Normally, a plane on an apron is chocked, while a plane in 
> longer-term parking is tied down.)
> 


Also, if the brakes were applied for long periods of time, they might fuse
to the discs, requiring replacement of both.

(just my $0.05 worth, with inflation and tax)

Bill


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Re: [Flightgear-devel] tunnel for glide slope visualization

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Melchior FRANZ
> Sent: Tuesday, October 02, 2007 4:57 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: Re: [Flightgear-devel] tunnel for glide slope visualization
> 
> * Bill Galbraith -- Tuesday 02 October 2007:
> > Can you send a screen shot or two?
> 
>   http://members.aon.at/mfranz/gstunnel.png  [159.7 kB]  
> 
> Needed to use png, as jpg made the lines look really ugly. :-)
> 
> m.


Okay, that looks really good.

Now, let's make it more challenging. Let's see circles to get me back to the
squares in a reasonable amount of time ;-}

Bill


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Re: [Flightgear-devel] tunnel for glide slope visualization

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Melchior FRANZ
> Sent: Tuesday, October 02, 2007 4:24 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: [Flightgear-devel] tunnel for glide slope visualization
> 
> Here's a first stab at a glide slope tunnel visualization utility.
> It's a rather short Nasal script which uses the new 
> airportinfo() function. It requires a *very* up-to-date 
> FlightGear. To try it out just put it into ~/.fgfs/Nasal/ or 
> $FG_ROOT/Nasal/.
> 
>   http://members.aon.at/mfranz/gstunnel.nas  [2.4 kB]
> 
> The script checks in 5 second intervals for the nearest 
> airport, selects a "decent" runway and draws a glide slope 
> tunnel for it consisting of red squares.
> 
> There's much that can be improved. One could draw only the 
> next three or four squares instead of the whole tunnel, 
> remove the upper line (for better runway view), consider wind 
> direction etc.
> Also, one might prefer to be able to select a particular 
> airport, and have the tunnel drawn on the runway told by ATC, 
> or one might want a circuit tunnel for tutorials, etc. All 
> doable.  :-)
> 
> There are also problems:
> - as the airportinfo() function also returns heliports as nearest
>   airports, the glide slope is often drawn much too late. It's
>   therefore better to fly in not so crowded areas. (This needs
>   to be fixed in simple.cxx.)
> 
> - the tunnel isn't aligned at a few runways. This could be a bug
>   in terragear, which could also be responsible for wrong ILS
>   behavior (see, for example, KOAK/9R).
> 
> m.


This sounds interesting. Can you send a screen shot or two?

Bill


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Re: [Flightgear-devel] Glass cockpit and external gauges.

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Phil Panelli
> Sent: Monday, October 01, 2007 9:02 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: [Flightgear-devel] Glass cockpit and external gauges.
> 
> Hi ,
> 
> Is there anyone working on external gauge and/or panel 
> projects that are current ?
> 
> 
> If there are I may be able to help.  If not , let's talk about it. I 
> have a few ideas
> and some interesting hardware lying around. If there are other 
> priorities that need
> attention first I may be able to help with those as well.
> 
> 
> Thanks,
> 
> Phil
> 


"Interesting hardware"?  Might it be an 20"x8" screen?

Bill


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Re: [Flightgear-devel] Compiling SimGear on Cygwin

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Romeo Ahohe
> Sent: Thursday, August 09, 2007 2:38 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: [Flightgear-devel] Compiling SimGear on Cygwin
> 
> Hi,
> 
> I was able to compile and install plib and openal using Cygwin.
> However, the configure script for SimGear is unable to find 
> the openal installation. The following error message is 
> produced when i run that
> script:
> 
> checking for library containing alGenBuffers... no checking 
> for library containing alutInit... no
> 
> You *must* have the openal library installed on your system 
> to build SimGear!
> 
> Please see README.OpenAL for more details.
> 
> configure aborted
> 
> There was another problem too: there is no README.OpenAL in 
> the directory. Instead, I only see README, README.MSVC, and 
> README.zlib
> 
> Any help will be greatly appreciated.
> 
> Thanks,
> 
> Romeo


Let us know if you solve this. I'm interested in compiling the latest code
myself, I just don't have the time to work through all of the little
'opportunities to learn'. I'd love to see a complete, current set of
instructions.

Bill


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> Indeed, I was talking about two  2-D tables, "wrongly" 
> guessing that JSBSim would interpolate the data in case, 
> let's say, the current slat position is not any of the 
> specific slat for which the tables are defined. Such an 
> interpolation would be quite accurate, being better the more 
> 2-D tables we define. This would be a very useful feature, 
> and although I am not a programmer, I guess (hopefully right this
> time...) that it wouldn't be hard to implement (Jon?).

We could probably use the existing code to do that interpolation between two
or more tables. It would just be really ugly. In the case of DATOM+ output,
I'd have to generate that ugly code automatically.



> What is needed is just the 
> thrust effect, without having to worry about flaps or slats. 

I don't think that we can do that. Think about the twin-prop aircraft, flaps
down versus flaps up, idle power versus full power. Prop blast (and epsilon)
on the tail is going to be different for those case.

Bill


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> On the topic of calculating downwash at the tail, and the 
> effects thereof, rather than make a four dimensional table it 
> might be better to think outside the box and consider 
> alternative ways to do what you need. 

I agree. That's why I brought it up in the first place, to see if anyone had
any great ideas, or at least to spark a healthy discussion. Sometimes when
you have to explain something, you understand it better yourself because it
makes you organize your thoughts.


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> Quoting Fabian Grodek

> Now, regarding the 737 sample case, it should be checked 
> which flaps-slats combinations are normally possible; it may 
> be the case where let's say flaps 20 cannot come with 
> retracted slats (if there is a problem with the slats 
> deployment you are allowed to use only flaps 0).

Well, they sometimes use simulators to play "What if" scenarios after a
crash. Sure, there is logic built into the flap controller to not allow
flaps 20 with retracted slats, as in your example, but what if that logic is
flawed, or a sensor or linkage is broken, and it is achieved even though it
shouldn't be. Asymetric flap deflection shouldn't be allowed, but if the
sensor is on the jackscrew and the control horn on the flap for the
jackscrew breaks, the jackscrew might go to the 40 degree position, but the
flap retracts. I want DATCOM+ to be able to crank out all of this data,
because Datcom will allow us to.
 
> Regarding the tables with infinite numbers of dimensions; I 
> do not understand why this should be needed. The buildup 
> concept used in JSBSim lets you specify delta of each 
> coefficient for every aerodynamic surface (flaps, elevator, 
> stabilizer, etc.) independently; JSBSim adds all that 
> together. For the downwash, DATCOM could be executed first 
> for the clean configuration, obtain Epsilon vs. alpha, then 
> for certain airfoil representing one slat-flap combination, 
> obtain the new Epsilon vs. alpha, and finally we can build a 
> 2D table for deltaEpsilon vs. alpha vs. flaps. If the slat is 
> another input, then 3D tables (with tableData breakpoints) 
> are already applicable in JSBSim. We can then have one 2D 
> table for slats 0, then another for slats 20, etc. The 
> elevator sweeps could be done with flaps up, and then, this 
> elevator effects included as another contribution in the aero buildup.
> One important issue in generating the independent 
> contribution of each aero surface is that sometimes there are 
> interferences between them; this can be significant for 
> example between flaps and airbrakes.

I understand what you are trying to say here, but there are several issues
that you point out. Let me see if I can straighten out a couple of these
issues:

1. Unfortunately for us, Datcom doesn't provide downwash angles with
defelcted surfaces (flaps, etc.). It provides it for a wing only. That is
why I thought that I might have to figure out the airfoil section with the
flap deflected, and input that. Of course, I was going to let DATCOM spit
out the airfoil section with the flap deflected for me, and feed that back
into Datcom to obtain the downwash angles at the tail. The data should be
there, I just have to figure out how to get it out of there and feed it back
into itself (kinda like a self-eating watermelon)

2. I think what you are saying is:

epsilon = f( alpha, flap, slat )  

I don't think that you were advocating using two 2-D table

epsilon(slat=0)  = f ( alpha, flap )
epsilon(slat=20) = f ( alpha, flap )

If you were, there would have to be an interpolation done between these two
tables in order to get the effects during transitions. Yes, that is
important, because the dynamics of the aircraft during a surface change like
that is examined by the FAA during qualification. I'm just guessing that we
could cobble something together in the existing JSBSim structure to do an
interpolation between these two tables.

Now, if you add in thrust effects, you end up with:

epsilon = f( alpha, flap, slat, thrust )

We are now at a 4-D table. I guess my use of the term 'inifinate dimensions'
might have been a poor choice, but as soon as the code for 4-D tables is
finished, we'll find that we need 5 or 6 dimensions. As Jon pointed out, the
code isn't the important part, but the specification of poly-dimensional
tables in the XML file is.

Datcom cranks out data in 1-D and 2-D tables for a particular case. I am
trying to pack multiple cases together in one file, maybe varying several
parameters to get the overall picture. Those parameters include TE and LE
flaps, thrust coefficients, even height abouve ground for ground efects
(although I was able to factor this one out). Each new parameter adds
another dimension to our tables.


> One important issue in generating the independent 
> contribution of each aero surface is that sometimes there are 
> interferences between them; this can be significant for 
> example between flaps and airbrakes.

Again, unfortunately, Datcom doesn't provide interference effects between
various components. You are allowed to deflect one surface at a time only.
This is where building up the airfoil section based on flap deflection plays
in.

One other issue that I have to attack, which shouldn't really cause anyone
headache (famous last words) is that Datcom only allows one thrust
coefficient to be defined. I was going to change the PREDAT code to allow an
array of thrust coefficients instead of the 

Re: [Flightgear-devel] Asymetric flaps ?

[Bill Galbraith]

 
> I saw that ans it is a bit disturbing. If I understand well 
> you take the output from datcom and assign half of those 
> numbers to each flap. Except that we suddenly have negative 
> flap angles in the datcom.xml (they are positive in datcom.out).


ZOIKS!  You are correct. It was caused by some errant code that was supposed
to negate the delections for ground and air spoilers, but didn't do that
correctly. There are twelve different types of symetric surface deflections
possible, and I write them out for left and right surfaces, and a couple of
them are a little 'different'. This has been fixed, and will be included in
the next release. I might go to intermittant releases, to cover little
problems like these when they are found. 

Thanks,
Bill


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> Jon Replies:
> 
> I've been thinking about these issues for some time. I've 
> actually considered just guessing. :-)  I wonder how much 
> data is too much data? It would be great to have this level 
> of fidelity modeled.
> 
> Jon
>  


Don't know if anyone noticed, but the flaps are already split left and
right. I did this for the asymetric flap deflection issue. I wondered if the
737 that crashed in Pittsburgh in ...hmmm.. 1987(?) could have been caused
by a flap jack screw attachment point breaking, thereby allowing the flap to
blow up. In the post-crash investigation, it might look like the flap was
down because the jack screw was fully extended, but if it's not attached to
anything  That crash was blamed on a rudder failure, with a subsequent
redesign of the rudder servo, but it made me wonder what would happen if
I had never seen anything like asymetric flap deflection on a sim before,
but didn't see any reason Datcom couldn't do it. It's not like you can
collect that data any other way. I never did experiment with a 737 to see
what would happen, though

Bill


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Jon S. Berndt
> Sent: Saturday, July 21, 2007 2:49 PM
> To: 'FlightGear developers discussions'
> Subject: Re: [Flightgear-devel] Epsilon,alpha_tail and 
> independent tail contributions
> 
> > > We might actually be able to effectively do that, since we could 
> > > have multiple tables defined that create multipliers that 
> could be 
> > > used later.
> > >
> > > Jon
> > 
> > Well, that was going to be my initial approach, but it's a 
> real pain 
> > to remove one dimension like that out of a 4-D table to make it two 
> > 3-D tables (if I remember how that works). I haven't looked at your 
> > LFI implementation, but one that I did years ago I think used 
> > recursion, and therefore it was possible to have 'inifinty' 
> number of 
> > dimension.. Or maybe I was just working on that and never going it 
> > working. I don't know. I've spelt since then.
> > 
> > Bill
> 
> In my mind, the problem is not so much the 
> programmatic/algorithmic aspect, but how do you arrange the 
> data in our XML format in files? I've got a few ideas, but it 
> seems like it could be convoluted.
> 
> Jon
> 
> 

This is how I do 3-D data in my free-format method. Another dimension might
just be 2 entries on the "0.0" and "5000.0" lines, and there would have to
be another 2 tables, if the 4th dimension only has two values.


CP_ALTITUDE_CORRECTION_TABLE_TRAINING
   NON_DIMENSIONAL_TRUE_AIRSPEED
   SS_THRUST_COEFFICIENT
   DENSITY_ALTITUDE

   0.0

 6.377530E-03  6.799520E-03  7.671665E-03  8.155430E-03
8.714625E-03

  0.000   0.0   0.0   0.0   0.0   0.0

  0.075  -7.08702E-06  -7.46443E-06  -3.33640E-06   0.0   0.0

  0.095  -3.13841E-06  -2.70910E-06  -6.89935E-07   0.0   0.0

  0.115   9.80799E-09   2.24440E-06   3.75856E-06   0.0   0.0

  0.135   1.64757E-06   5.51617E-06   6.02906E-06   0.0   0.0

  0.155   3.16493E-06   8.90633E-06   9.08185E-06   0.0   0.0

  0.175   4.73170E-06   1.27943E-05   1.29269E-05   0.0   0.0

  0.195   6.08803E-06   1.72407E-05   1.61440E-05   0.0   0.0

  0.215   7.20410E-06   1.86653E-05   1.64733E-05   0.0   0.0

  0.235   9.13959E-06   2.25281E-05   1.90848E-05   0.0   0.0

  0.255   1.11248E-05   2.56991E-05   2.07885E-05   0.0   0.0

  0.275   1.48693E-05   3.54481E-05   2.81742E-05   0.0   0.0

  0.295   1.96035E-05   4.86056E-05   3.89821E-05   0.0   0.0

  0.315   2.43772E-05   5.99209E-05   4.68421E-05   0.0   0.0

  0.335   2.60403E-05   5.76844E-05   4.35042E-05   0.0   0.0

  0.355   3.45229E-05   6.20062E-05   4.31986E-05   0.0   0.0


   5000.0

 6.377530E-03  6.799520E-03  7.671665E-03  8.155430E-03
8.714625E-03

  0.000   0.0   0.0   0.0   0.0   0.0

  0.075  -5.82699E-06  -7.74447E-06  -3.98641E-06  -4.12238E-06
-2.16311E-06
  0.095  -2.94845E-06  -4.71913E-06  -2.63005E-06  -3.49648E-06
-2.35165E-06
  0.115  -1.14023E-06  -1.42562E-06   2.58558E-07   5.97211E-08
1.97976E-06
  0.135  -8.32457E-07   1.66066E-07   1.02905E-06   1.69658E-06
4.06150E-06
  0.155  -6.55098E-07   1.42632E-06   1.91189E-06   3.04350E-06
5.77344E-06
  0.175  -1.36832E-06   2.06431E-06   2.86690E-06   5.00068E-06
9.04538E-06
  0.195  -2.87194E-06   2.66073E-06   2.91396E-06   6.18843E-06
1.22274E-05
  0.215  -1.00594E-06   3.82526E-06   3.67334E-06   6.54650E-06
1.32896E-05
  0.235  -5.70348E-07   4.86814E-06   4.36482E-06   7.76484E-06
1.46019E-05
  0.255   9.14792E-07   5.92906E-06   4.92844E-06   9.11357E-06
1.53244E-05
  0.275  -9.10659E-07   8.20810E-06   6.30418E-06   1.05824E-05
1.77469E-05
  0.295  -4.84660E-06   9.83535E-06   7.65215E-06   1.42617E-05
2.20197E-05
  0.315  -5.64283E-06   1.19309E-05   8.17212E-06   1.69514E-05
2.69024E-05
  0.335   1.35030E-06   1.46345E-05   9.07423E-06   1.68110E-05
2.66753E-05
  0.355   1.51130E-05   2.15764E-05   1.23685E-05   1.73016E-05
2.39984E-05



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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> > Any chance JSBSim could be expanded to do infinity number of 
> > dimensions of tables (if it doesn't do it already)?
> > 
> > Bill
> 
> We might actually be able to effectively do that, since we 
> could have multiple tables defined that create multipliers 
> that could be used later.
> 
> Jon

Well, that was going to be my initial approach, but it's a real pain to
remove one dimension like that out of a 4-D table to make it two 3-D tables
(if I remember how that works). I haven't looked at your LFI implementation,
but one that I did years ago I think used recursion, and therefore it was
possible to have 'inifinty' number of dimension.. Or maybe I was just
working on that and never going it working. I don't know. I've spelt since
then.

I'll try to quantify how many dimensions that I need out of DATCOM data.

Bill


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 

> 
> Jon Replies:
> 
> I've been thinking about these issues for some time. I've 
> actually considered just guessing. :-)  I wonder how much 
> data is too much data? It would be great to have this level 
> of fidelity modeled.
> 
> Jon
>  
>  


Any chance JSBSim could be expanded to do infinity number of dimensions of
tables (if it doesn't do it already)?

Bill


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Re: [Flightgear-devel] Epsilon, alpha_tail and independent tail contributions

[Bill Galbraith]

 


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jon S.
Berndt
Sent: Saturday, July 21, 2007 12:48 PM
To: 'FlightGear developers discussions'
Subject: Re: [Flightgear-devel] Epsilon,alpha_tail and independent tail
contributions



Fabian wrote:

Currently , as far as I understand, JSBSim does not support the
buildup of the aerodynamic characteristics by taking the wing-body alone and
adding the tail contribution. This is essential for example in investigating
an aircraft behaviour during ice contaminated tailplane stall, a "hot"
subject nowadays.



For example, the total pitching moment would be: CM_wing-body +
CLtail * tail_volume.



Actually, JSBSim supports exactly that kind of thing. [You might want to
move this part of the discussion to the JSBSim list.] In JSBSim we use the
coefficient build-up method to define the forces and moments about each of
the axes. There is also the possibility of creating functions that calculate
whatever you want, which can then be applied to the coefficients as needed.
For example, multipliers into tables or other functions. You could use
DATCOM+ to calculate the wing/body effects, then add other effects as
needed, unless you already have data. For information on DATCOM+, see
 www.holycows.net/datcom. 



Of course, the aero model should then need to include the downwash
(Epsilon) at the tail (as a function of alpha, flaps, etc.) and CLtail vs.
alpha_tail.

 

My questions therefore are:

1. Is it possible to introduce Epsilon tables in the aircraft
properties file?



To my knowledge, nobody has tried this, yet. However, it is certainly
possible.



2. Is it possible to have an option to evaluate alpha_tail
(alpha_aircraft + horizontal_stab - Epsilon + dynamic components) whenever
an Epsilon table is present in the properties file? This would be essential
to calculate the tail lift and its contribution to the overall pitching
moment. 



 Yes. That's one of the reasons that we created the function capability. One
of our newsletters (see   www.jsbsim.org) has
information about defining functions in the aerodynamics section of a JSBSim
aircraft config file. Also, there is this (somewhat formal) definition of
JSBSim-ML: 



 
http://jsbsim.sourceforge.net/JSBSim/JSBSim.xsd.html

Some information on the function definition can be found here:

 

http://jsbsim.sourceforge.net/wiki/index.php/User%27s_Manual#Configuration_F
iles

For more information, as on the JSBSim list!

Jon

 

A couple problems that I've been addressing lately is that Datcom doesn't
produce downwash angles when you drop flaps. Also, the elevator sweeps are a
function of free-stream angle of attack (i.e., AOA at the wing, not the
elevator). Another important omission from Datcom is that you can't drop
flaps then do elevator sweeps. 

To me, these are important factors, since most of the crashes happen near
the ground, when you have flaps and gear down. The FAA testing is heavy on
near-ground performance, because that is where you get into the most
trouble, such as losing an engine during take-off or landing.

One approach that I've been considering is to calculate what the airfoil
looks like when you lower the flaps, and input THAT as the airfoil, then do
all of the normal calculations. For something like a 737 where you have
leading and trailing edge flaps, you could easily get into 20 cases, with
each case generating all of the coefficient tables (Cd, CL, CM, etc.). For a
twin-prop aircraft, you just have trailing edge flaps, but you really need
to run power effects at each flap setting, and you really should split the
aircraft in half, since you could be flying on one engine. Engine thrust
should be run at several settings, such as off, idle, cruise, and max, as a
minimum. Interpolation between those power settings should be fairly
accurate.

Let me give you a good example. Twin engine prop aircraft, drop the flaps
fully, you lose the right  engine, and push the left one to max in order to
climb. On the right side, you just have freestream airflow over the right
wing, flap, rudder and elevator. On the left side, you have a prop blast
hitting the wing, part of the flap, left side of the rudder, and most of the
elevator. Ignoring the engine torque issue, you are going to experience
different lift (higher on the left side) which creates a rolling moment. You
will also experience different elevator control effectiveness right versus
left. Rudder dynamic pressure might actually be different left versus right,
creating a yawing moment, which is in addition to the thrust different left
versus right.

Now, is this a little overkill? Maybe, since most trainers that I've seen
don't go into such details. It is possible to ge

Re: [Flightgear-devel] List message format

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Jon S. Berndt
> Sent: Saturday, July 21, 2007 12:51 PM
> To: Flightgear-Devel
> Subject: [Flightgear-devel] List message format
> 
> Is there a convention we should follow for formatting 
> messages here (besides trying not to top post - which I admit 
> I am guilty of)?
> 
> It's not easy to reply to messages formatted in HTML. I'd 
> personally like to see that format banned from the list.
> 
> Jon


I tried side-posting, but that just isn't practical. I don't see a problem
with top posting, or bottom posting, as long as you stay consistent. If you
are following a discussion, it's nice to see the reply at the top, so that
you don't have to scroll through a lot of stuff, just to see "okay, I'll try
that."

You can always change your reply from HTML to simple text.

Bill


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[Flightgear-devel] Pre-11 distribution for Windoze?

[Bill Galbraith]

Is there a recently compiled distribution package of the Flight Gear
0.9.pre11 package available, say something built within the last month?
 
I want to do some model development without having to build the pre11
release myself.
 
...and, as long as I have you on the line, with the 0.9.11 release include
the newest JSBSim code?
 
Thanks,
Bill
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Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of AnMaster
> Sent: Thursday, July 12, 2007 11:48 AM


> Why couldn't Datcom be installed in the user's home directory 
> like most programs? Or does datcom not support --prefix to 
> ./configure? (Note I have never used Datcom but I can't see 
> why one would need to be root to install
> it.) Oh and another question: Does Datcom work on non-x86 systems?

Well, I guess I hadn't thought of it. I am the only one on my Linux system,
so I naturally just install it there. My past experience having multiple
users on a system has me installing it in /usr/local/bin, so that everyone
could use it, since I was the system adminitrator. I guess I was hoping that
those people would be smart enough to install it somewhere in their path if
they didn't have root access. If you untar the executables with

   tar xvpzf datcom_bin.tz

You end up with a directory tree of /usr/local/bin under your current
directory, and then you can copy those files to whereever you need to to be
able to see them.

I'll consider changing it for the next release. Thanks.

Datcom and related programs are compiled only for x86 systems, sorry!

Bill




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Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Torsten Dreyer
> Sent: Thursday, July 12, 2007 9:52 AM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement
> 
> Hi Bill,
> 
> thanks for this great improvement. I just downloaded the 
> linux package and it ran without problems over the provided 
> examples on my OpenSuse 10.2 System.
> 
> Torsten


That is really great to hear. I wasn't sure if it was going to be compatible
across Linux systems. The biggest problem that the Linux guys are going to
have are probably having the password to the root account, and making sure
all of the required libraries are present, such as GL, GLU, glut, and
boost_program_options, and that gnuplot is present. The Linux guys are
generally a little more computer savy.  

For the Windows guys, it had to be completely push-button easy, because
there are more and more students using this package in their courses. It's
tough for them to learn how to use Cygwin AND Datcom, what with Datcom being
hard enough itself.

Now, if I could just figure out how to make money giving away free
software  ;-}

Bill



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Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement

[Bill Galbraith]

 


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Pablo
Rogina
Sent: Thursday, July 12, 2007 9:18 AM
To: flightgear-devel@lists.sourceforge.net
Subject: Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement



> 'helping', but he complained about stuff that I just wasn't seeing. There
> are some differences in the Windows XP installation ('Program Files'
becomes
> 'Programmes'). Turns out that his system was minorally hosed, and I 

Have you tried some installation builder to create the installation packege
for Windows? 
Most of them provide predefined variables (i.e. $PROGRAMFILES) to deal with
the different values
depending on language of each Windows installation. 

My company uses NSIS (http://nsis.sourceforge.net) with success

Regards, 

Pablo Rogina 
 

Thanks. That's what I was using. The problem is actually located in the NW
United States.  Some files need to be opened with Wordpad instead of Notepad
due to formatting. The registry is really different for Wordpad than it is
for Notepad, and I couldn't reverse engineer it, at least not in a couple
hours.
 
Anyone have any experience in NSIS setting Wordpad as a default editor
instead of Notepad?
 
Bill
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Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement

[Bill Galbraith]

Try downloading it, installing it, go out to the Datcom directory (folder on
your desktop), find the Examples directory, double-clickon Citation.dcm,
then when that process finishes, double click on Citation.ac and
citation.lfi. 5 minutes tops. It is SO easy now on Windows. Now, building
your own model, that's another story ;-}
 
That Windows installed damn near killed me. I was working 12-14 hours a day,
restoring Ghost images of WIndows XP or Vista, occassionally having to
rebuild my disk from scratch. I have WIndows XP with and without Notepad++
installed, Vista with and without Notepad, and Debian, all able to be
loaded. I really check ed this system out. I had a guy in Germany that was
'helping', but he complained about stuff that I just wasn't seeing. There
are some differences in the Windows XP installation ('Program Files' becomes
'Programmes'). Turns out that his system was minorally hosed, and I wasted
about 12 hours finxing something that wasn't a problem.
 
ANyway, give it a try.
 
B


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Wednesday, July 11, 2007 4:05 PM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] Datcom+ 2.1 Release annoucement


Dang, I really need to try this package out.  I'm going to need to take a
couple of vacation days or something though.  Getting hammered this entire
summer from all sides.

Made some progress with my UAV altitude hold controller this morning before
work.  I have a plot and a movie of the flightgear replay under today's
entry at this url: 

http://baron.flightgear.org/~curt/UAV/MicroGear1/

Full res movie (so you can read the gauges) is here:

http://baron.flightgear.org/~curt/tmp/mnav-alt-hold.mpeg

Regards,

Curt.


On 7/11/07, Bill Galbraith <  <mailto:[EMAIL PROTECTED]>
[EMAIL PROTECTED]> wrote: 

I am happy to annouce the release of of Datcom+ 2.1. This has been a LOT of
work packaging these tools into nice installation packages, for Windows XP
and Windows Vista for point and click people, Cygwin under Windows XP and
Vista for the smells-like-Linux group, and Linux (compiled under Debian).
 
For those of you that don't know what Datcom is, it is an United States Air
Force program that predicts aircraft performance characteristics based on
the geometric shape. There are three visualization tools associated with the
Datcom+ package, two for plotting coefficients and one for plotting the
three dimensional model.
 
The download packages and installation instructions can be found at
http://holycows.net/datcom/
 
This will be the LAST Datcom-related broadcast message on FlightGear and
JSBSim. There is a Yahoo group for Digital_Datcom at
http://tech.groups.yahoo.com/group/digital_datcom/. There are only 11
members right now, but I encourage you to join the group if you are
interested in Datcom. Email traffic is almost non-existant.
 
Bill

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Curtis Olson - University of Minnesota - FlightGear Project
http://baron.flightgear.org/~curt/  http://www.humanfirst.umn.edu/
http://www.flightgear.org
Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d 

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[Flightgear-devel] Datcom+ 2.1 Release annoucement

[Bill Galbraith]

I am happy to annouce the release of of Datcom+ 2.1. This has been a LOT of
work packaging these tools into nice installation packages, for Windows XP
and Windows Vista for point and click people, Cygwin under Windows XP and
Vista for the smells-like-Linux group, and Linux (compiled under Debian).
 
For those of you that don't know what Datcom is, it is an United States Air
Force program that predicts aircraft performance characteristics based on
the geometric shape. There are three visualization tools associated with the
Datcom+ package, two for plotting coefficients and one for plotting the
three dimensional model.
 
The download packages and installation instructions can be found at
http://holycows.net/datcom/
 
This will be the LAST Datcom-related broadcast message on FlightGear and
JSBSim. There is a Yahoo group for Digital_Datcom at
http://tech.groups.yahoo.com/group/digital_datcom/. There are only 11
members right now, but I encourage you to join the group if you are
interested in Datcom. Email traffic is almost non-existant.
 
Bill
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Re: [Flightgear-devel] Aircraft design idea: Cirrus Jet

[Bill Galbraith]

and.
 
(Usually when people send me this stuff, they want a DATCOM model and a
FlightGear package).
 
Thanks for not asking ;-}


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Friday, June 29, 2007 1:57 PM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] Aircraft design idea: Cirrus Jet




On 6/29/07, Curtis Olson <[EMAIL PROTECTED]> wrote: 

I had a rare chance on wednesday to go up to Cirrus Design and get a tour of
their facilty and see how their aircraft get put together.  This was an
extremely fascinating trip.  In addition, they just happened to be unveiling
the mockup of their new "personal jet" design to the media on Thursday
(yesterday.)  I got to see it a day earlier, even before the folks that have
plunked down $100k to get on the waiting list got to see it ... but all the
employees got to see it before me.  The Star Tribune ran a story with an
actual picture of the mockup: 

http://www.startribune.com/535/story/1275392.html


Here's another source of pictures, including a side shot and a front shot:

http://www.aero-news.net/index.cfm?ContentBlockID=5431e833-dbf8-48c8-870d-20
5481f2c09f#d
 

Curt.
-- 
Curtis Olson - University of Minnesota - FlightGear Project
http://baron.flightgear.org/~curt/
http://www.humanfirst.umn.edu/  http://www.flightgear.org
Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d 

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Re: [Flightgear-devel] new pseudo FDM for vehicles (osg branch)

[Bill Galbraith]

 

> 
> > I also have doubts that a single fdm can accurately 
> reproduce ship and 
> > car characteristics - [...]

A true Ship FDM would require sea state simulation, as a carrier is going to
rock in a heavy sea. Landing on a carrier in calm water in the daylight is
easy. It's that Sea State 5, with driving rain, at night, that is "like
having sex in a car wreck".



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Re: [Flightgear-devel] BlackBird SR-71

[Bill Galbraith]

Okay, now someone needs to refuel behind it. I understand the tanker is
firewalled, and the SR-71 is on the verge of stalling.

Bill



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Re: [Flightgear-devel] Fwd: Flight Gear being sold on ebay

[Bill Galbraith]

 



  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Thursday, June 14, 2007 10:02 AM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] Fwd: Flight Gear being sold on ebay


On 6/14/07, Bill Galbraith <[EMAIL PROTECTED]> wrote: 

DId you report this to EBay?  They are usually pretty good about resolving
issues like this.


I reported it myself, but i think if everyone on this list took a minute and
also reported it, ebay couldn't simply discount me as some lunatic
disgruntled customer with a petty grudge to settle. 

This is a legitimate GPL abuse that we can unite against.



I agree that his actions are slimy, but is this action actually an allowable
form of packaging this software. I am not an expert on this matter, by any
stretch of the imagination, but if I put FG and all of the available aicraft
on a CD and sold the CD for the costs involved in producing and distributing
the CD, isn't this allowed?  He can claim that his $^.99 or $4.99 is the
cost of packaging the pieces together, plus his labor.
 
I reported him anyway.
 
Bill
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Re: [Flightgear-devel] Fwd: Flight Gear being sold on ebay

[Bill Galbraith]

DId you report this to EBay?  They are usually pretty good about resolving
issues like this.


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Curtis
Olson
Sent: Thursday, June 14, 2007 9:50 AM
To: FlightGear developers discussions
Subject: [Flightgear-devel] Fwd: Flight Gear being sold on ebay


See attached forwarded message.  Someone is selling FlightGear on ebay.
This time there is no mention of our project name, they have changed the
name and are calling it "Pro Aircraft Flight Simulator".  In addition, they
are using the same sleazy tactics of selling a digital download, not actual
media ... for all I know, they tell their suckers/customers to go download
it from our own server after the buyer pays the money. 

I don't know if we can keep the grass clear of all the weeds here, but I
wonder if we have a large volume of people report this fraudulent ad to
ebay, if they might do something.  Ebay is heavily slanted towards sellers
rights, so I think we would need a pretty big ground swell here to get their
attention. 

Perhaps a little "question for the seller" message wouldn't hurt either ...
but I would caution that we need to be professional, honest, and fair in our
dealings here.  We can't stoop down to this persons level, we can't make
unfounded claims, we can't make stupid threats, or it just turns into a WWF
match and no one can win. 

Curt.


-- Forwarded message --
Date: Jun 14, 2007 8:30 AM
Subject: Flight Gear being sold on ebay

Curt, 


Noticed someone selling what sure looks like Flight Gear on Ebay - not
calling it Flight Gear of course.thought you'd be interested, hopefully you
can shut the clown down. Here's a link to one of the auctions:

http://cgi.ebay.com/PRO-Aircraft-Flight-Sim-Simulator-Bonus-Planes_W0QQitemZ
300120813715QQihZ020QQcategoryZ80336QQtcZphotoQQcmdZViewItem


If that link doesn't work, it's item# 300120813715

 


-- 
Curtis Olson - University of Minnesota - FlightGear Project
http://baron.flightgear.org/~curt/  http://www.humanfirst.umn.edu/
http://www.flightgear.org
Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d 

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Re: [Flightgear-devel] First Flight!

[Bill Galbraith]

 





This message is getting long and probably 99% of you have clicked
delete/next by now, but let me brag on FlightGear now a minute. 
 
 

First off, let me say CONGRATULATIONS. Not only did you have a successful
first flight, in that you proved that you could engage and override the
autopilot, but you got the aileron control correct. There are two ways to
wire it, which means youhav e 90% chance of wiring it wrong. And yes, I read
every word. Fascinating stuff, ever at 7 am on a Saturday.
 
Great to hear that FG is living up to it's potential. You know, you might
have more time to play with FG if you wrote shorter emails  ;-}
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Re: [Flightgear-devel] More ideas on dogfighting

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Ralf Gerlich
> Sent: Monday, May 14, 2007 10:23 AM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] More ideas on dogfighting
> 
> Hi,
> 
> Gene Buckle wrote:
> >>> Martin, the 300ms figure is really only applicable to a Level A 
> >>> simulator which is basically equivalent to a cockpit procedures 
> >>> trainer with no visuals.
> >> Ok - that one makes sense. On the other hand, any type of 'tricky' 
> >> VFR flight with 300 ms delay, I'd expect even with 150 ms 
> would ruin 
> >> every pilot's nerves   :-)
> >>
> > 150ms is the maximum allowed for a Level D certification.  I don't 
> > know of any that were that slow.  Even the 
> Conductron-Missouri 737-200 
> > simulator I
> 
> Hm, this sounds to me as if these _maximum_ numbers are 
> already unreasonably high and therefore obviously not a good 
> reference for discussing response times _acceptable to 
> users_, are they?
> 
> Currently, due to problems which might be related to an OSG 
> update, FlightGear is running on my system with 10fps in some 
> areas, where I used to get 25fps and more, and I would say 
> that this is essentially unbearable. So I'd be saying that we 
> should be talking about a maximum delay which is well below 100ms.
> 
> I won't enter this discussion, but just let me state for the 
> record that I'm clearly in favor of keeping the FDM with the client.
> 


If I remember correctly, the human eye can detect something less than about
15-20 fps.

Bill


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Re: [Flightgear-devel] More ideas on dogfighting

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Martin Spott
> Sent: Sunday, May 13, 2007 5:01 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: Re: [Flightgear-devel] More ideas on dogfighting
> 
> Hi Bill,
> 
> "Bill Galbraith" wrote:
> 
> > "Relative responses of the motion system, visual system, 
> and cockpit 
> > instruments shall be coupled closely to provide integrated sensory 
> > cues 6 These systems shall respond to abrupt pitch, roll and yaw 
> > inputs at the pilot's position within 150/300 milliseconds of the 
> > time, but not before the time, when the airplane would 
> respond under 
> > the same conditions. [...]"
> 
> Uh, 300 ms response time looks pretty bad to me at a first 
> glance. They already include the time which the 'real' 
> aircraft would need to respond aerodynamically - right ?
> 
> Personally I'd go crazy in the real Cessna if it would take 
> me one third of a second until the beast starts !! responding 
> to a control movement - this would turn almost every landing 
> at gusty crosswind into a really difficult situation 
> 

Sorry. I wasn't specific enough (and figured SOMEONE would question what I
wrote). That delay is not counting the aircraft aerodynamic delay. In the
simulation world, we set up special code for this testing, so that it takes
the same path through normal code, it just bypasses the aerodynamic effects
and recognizes the step control input, and generates a step output on the
three output systems (instruments, visual, motion).

Typically, one would also do a throughput analysis, if you have separate
computers for various functions (you do on real sims). You look at the
control input happened at t=0, but ooo, it just missed a data transfer from
the control loading computer to the host, so you have to wait for the next
one to come along. The host recognizes the input and generates the output,
and sends the signal out to the I/O, visual, and motion computers. Those
transfers are usually initiated by the host at the end of a frame, but if
they aren't you have to play the game of ooo, I just missed that data
transfer, I have to wait for the next one to happen, all the time adding up
the delays. If the theorical delay is too great, you don't have a good
architecure for something (data transfer, host execution, whatever) and may
have to make some changes. Your theorical value should be less than the 150
or 300 msec, since this is the worst that it's allowed to be. You won't
always hit the theorical number that you calculate, but hopefully you are
less some of the time.

Bill


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Re: [Flightgear-devel] More ideas on dogfighting

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Martin Spott
> Sent: Sunday, May 13, 2007 4:17 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: Re: [Flightgear-devel] More ideas on dogfighting
> 
> Maik Justus wrote:
> 
> > Does anyone know, which latency between control input and visible 
> > reaction is acceptable (== unnoticeable)?
> 
> I'm unable to cite a qualified source from the top of my 
> head. Yet I remember different people talking and/or writing 
> about not to exceed a delay of approx. 50 ms. As a rough 
> guess think of which FlightGear frame rate you consider as 
> 'flyable' - I'd say 20 fps is the absolute minimum of what 
> people call 'smooth',
> 

Measuring between a control input and the first response to instruments,
visual, or motion base.

FAA Advisory Circular AC 120-40B, for Aiplane Simulator Qualification says:

"Relative responses of the motion system,
visual system, and cockpit instruments shall be
coupled closely to provide integrated sensory
cues 6 These systems shall respond to abrupt
pitch, roll and yaw inputs at the pilot's position
within 150/300 milliseconds of the time, but not
before the time, when the airplane would respond
under the same conditions. Visual scene changes
from steady state disturbance shall occur within
the system dynamic response limit of
150/300 milliseconds but not before the resultant
motion onset. 

[Note: 300 msec for Level A and B, 150 msec for level C and D]

FAA AC 120-45A, for Flight Training Devices, requires 150 msec for level 7,
and 300 for levels 1 through 6.

Military standards are usually 150 msec, sometimes lowered to 100 msec.

There is also a requirement that the three outputs be within 50 msecs of
each other, and visual can't respond before the motion. 

Bill


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Re: [Flightgear-devel] More ideas on dogfighting

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Stefan Seifert
> Sent: Saturday, May 12, 2007 10:38 PM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] More ideas on dogfighting
> 
> -BEGIN PGP SIGNED MESSAGE-
> Hash: SHA1
> 
> James Palmer wrote:
> 
> > In your experience, Harald, what has been the approximate 
> ratio of FDM 
> > vs Graphics vs remainder code on CPU time?  Has anyone done work on 
> > clocking the various subroutines in FG to determine this?  
> (Perhaps I 
> > underestimate the CPU time required of the FDM?)
> 
> You could simply run stand-alone JSBSim 
> (http://www.jsbsim.org) to see, how much CPU a FDM needs. I'd 
> guess that Yasim lies in the same range.
> 
> Nine


I think that was investigated a few months ago. JSBSim FDM took only a
couple percent of the CPU, or course depending on your hardware and what you
were drawing. I don't think it's anything that you need to worry about.

BIll


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Re: [Flightgear-devel] More ideas on dogfighting

[Bill Galbraith]

 



  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of James
Palmer
Sent: Friday, May 11, 2007 8:06 AM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] More ideas on dogfighting


Thanks to all for the input... the collaboration of many is what makes FG so
great in my opinion.

I still plan to eventually add some sort of dogfighting capability,
HOWEVER,... I plan to start in the area detailed by this document
 . (thanks to Lorne McIntosh) I believe the changes detailed in the
architecture will benefit all participants of FG by taking advantage of
multi-core systems and future developments in parallelism.  It also brings
me a bit closer to my own goal of dogfighting by giving me the FDM server/
client separation that I need. 
For those concerned with non-dogfighting, please rest assured that I will
code a "turn off dogfighting" option that will make all weapons invisible
and they will have no effect on the player.  (you would still see the
dogfighting planes circling each other, just nothing else).  This option
would be turned off by default.  If you want to participate in a dogfight,
it will take an action on the part of the user to enable that feature. 

I encourage more discussion on this topic.  I enjoy and benefit from reading
the opinions and information others have to offer.
If anyone in the FG community has begun work on the architecture changes in
the document above (or would like to) please contact me. 

Regards
James
 

Okay, I'll be flying the heavily armoured Cessna F-172, so beware   ;-}
 
The Black Ace 
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Re: [Flightgear-devel] More ideas on dogfighting

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Martin Spott
> Sent: Thursday, May 10, 2007 6:04 PM
> To: flightgear-devel@lists.sourceforge.net
> Subject: Re: [Flightgear-devel] More ideas on dogfighting
> 
> James,
> 
> "James Palmer" wrote:
> 
> > Dogfight On/Off Option:  (Thanks to Vivian) -I will include 
> an option 
> > for turning off dogfighting and still allowing multi player.  As 
> > someone pointed out we don't want some kid shooting down 
> everyone over 
> > San Fransisco while everyone else is doing serious flying.
> 
> I'm not certain if it's really the kids we have to fear. I 
> guess some grown-ups that are going wild are much worse  !
> In total I don't think such effort is for the benefit of the 
> FlightGear simulator - well, the regulars on this list will 
> remember that we already had such discussion several times.
> 
> Putting dogfight and shooting/destroying capabilities into 
> FlightGear will attract a dubious clientele that no serious 
> 'pilot' wants to get molested by in their simulated 
> environment. Certainly some of those people will find enough 
> different ways to annoy the serious pilot even if he can 
> block them from shooting him.
> 
> As a consequence I'd propose considering to let this stuff 
> run in an isolated environment, say a 'sandbox', where it 
> can't do harm to the rest of us.
> 
> Regards,
>   Martin.
> --


Wasn't FlightGear designed with the idea of NOT doing dogfighting?  I think
there is someone else out there that does a dogfighting simulation, but the
name escapes me right now. Maybe you could search around looking for them,
as they already have the ability to dogfight over the net.

Bill


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Re: [Flightgear-devel] Phidot not zero.. And bank angle constant...

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Jon S. Berndt
> Sent: Friday, March 23, 2007 10:29 PM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] Phidot not zero.. And bank 
> angle constant...
> 
> > Hi,
> >
> > I'm sorry but its sounding a little anomalous to me.
> >
> > >From the kinematic relationships;
> >
> > p = phidot - psidot sin(theta)
> >
> > q = thetadot cos(phi) + psidot cos(theta) sin(phi)
> >
> > r = psidot cos(theta) cos(phi) - thetadot sin(phi)
> >
> > now for a steady turn, theta can be approximated close to 
> zero and for 
> > the thetadot is also close to zero and negligible.  So we are left 
> > with roughly;
> >
> > p = phidot
> >
> > q = psidot sin(phi)
> >
> > r  = psidot cos(phi)
> >
> > If we p q and r were to be measured in the body axis, I guess they 
> > would be zero.  But in the inertial frame;
> >
> > p = phidot = 0 since its in a level turn the bank angle would
> > be constant
> >
> > q = psidot sin(phi) = non zero since phi has a value and in the 
> > inertial frame the heading is changing
> >
> > r =  psidot cos(phi) = non zero again
> >
> > Therefore q and r should have values and so should psidot, but 
> > thetadot and phidot should be zero or close to zero.
> >
> > Am I missing something?  Please do let me know.
> 
> Sorry. I confused myself. I may have been thinking of body 
> accelerations, not rates. Or something.
> 
> Your equations look good.
> 
> I ran a test script with the JSBSim c172. In a constant turn 
> I saw this at steady state:
> 
> P = ~0
> Q = ~3.5 deg/sec
> R = ~6 deg/sec
> 
> Pdot = ~0
> Qdot = ~0
> Rdot = ~0
> 
> phi   = ~30 deg
> theta =  ~4 deg
> psi   = from 200 deg to 20 deg
> 
> phidot   = ~0.0
> thetadot = ~0.0
> psidot   = ~6 deg/sec
> 
> I think this works out about right. So, at least JSBSim is 
> working correctly.
> 
> Jon
> 


Yeah, what he said ;-}

Bill 


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Re: [Flightgear-devel] Phidot not zero.. And bank angle constant...

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Nicol Carstens
> Sent: Friday, March 23, 2007 5:51 AM
> To: flightgear-devel@lists.sourceforge.net; [EMAIL PROTECTED]; 
> [EMAIL PROTECTED]
> Subject: [Flightgear-devel] Phidot not zero.. And bank angle 
> constant...
> 
> 
> Hi guys.
> 
> First of all (before I start "complaining") let me start off 
> by saying: 
> thanks for sharing your work publicly! MUCH appreciated. If 
> you don't mind, and have some time to spare me, I need to ask 
> a question...
> 
> About myself and my project: I am qualified as an electronic 
> engineer (did a masters in control of a model RC helicopter), 
> and have about 6 years simulation experience in the Aerospace 
> industry. I am trying to use FlightGear for autopilot/AHRS 
> development work... I am looking at the data as received from 
> the Native-FDM UDP packet (at 20-40Hz). Maybe I am missing 
> something (not at all impossible)... but I think something 
> might be wrong... 
> I am using FlightGear Version 0.9.10.
> 
> My question:
> If I put the aircraft (Cub or 172) into a constant bank and 
> pitch angle turn ("trimmed"), I expect phidot and thetadot to 
> be near zero, and psidot non-zero... Yet, I see thetadot near 
> zero, and phidot and psidot non-zero (as a matter of fact: 
> phidot is almost as "large" as psidot). Surely this can't be 
> right? According to the FlightGear (and MathsWorks / Matlab) 
> documentation, this is not p,q,r but Euler/Gimbal angular 
> rates in rads/sec... not body rates...
> 
> I know that the pitch and roll angles are constant because I 
> can see it visually in the sim, and confirmed looking at the 
> UDP data (roll, pitch, yaw)...
> 
> My goal: I want to derive p,q,r (simulate rate gyroscope 
> sensors) and calculate the horizon... Building an AHRS. But 
> if I use the current data, the angles are drifting even 
> faster than using the real hardware!!
> 
> Am I missing something, or is there a bug??
> 
> Kind Regards,
> Nicol.


Sorry, but I don't have ANY time to respond to this, but keep in mind that
you are looking at BODY-AXIS rates and accelerations. If you are in a turn,
the pitch and roll are going to show values.

Bill


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Re: [Flightgear-devel] An2 problems

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Yurik V. Nikiforoff
> Sent: Friday, March 23, 2007 6:44 AM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] An2 problems
> 
> В сообщении от 23 Март 2007 15:53 AJ MacLeod написал(a):
> > > Some screenshots of new An-2 3d cocpit you can see here:
> > > http://www.avsim.ru/forum/index.php?showtopic=34552
> >
> > Or we could if we were registered users, I'm guessing :-\
> 
> Ooops! Whey change policy for anonymous login... sorry...
> 
> Look here:
> ftp://ftp.megasignal.com/pub/FlightGear/shots/3dcockpit/


I was just expecting some normal looking cockpit, but WOW. Great job.

Bill


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Re: [Flightgear-devel] FlightGear presentation

[Bill Galbraith]

There were some tanker chase videos that were pretty decent. I think they
were Curt's. I have them, if you'd like me to send them to you.


  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Berndt,
Jon S
Sent: Monday, March 12, 2007 10:20 AM
To: flightgear-devel@lists.sourceforge.net
Subject: [Flightgear-devel] FlightGear presentation



I'll be presenting an overview of FlightGear and JSBSim on Wednesday. I have
some good screen shots, but if someone can point me towards some more good
"eye candy" and movies of FlightGear in action, that would be appreciated.
Note that requested screen shots are not limited to showing JSBSim aircraft
in action - the FlightGear portion of the presentation will encompass -
albeit briefly - all aspects of FlightGear).

Jon 

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Re: [Flightgear-devel] An2 problems

[Bill Galbraith]

 

> To me , the last JSBSim FG CVS update is right, I can start 
> and fly every propeller Aircraft,  but the An2 which does not 
> take off (not enough power to take off) , it can fly only if 
> we launch it from altitude  (enough power to fly).

Do the props have pitch to them? Do you have to set condition levers?

Bill


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Re: [Flightgear-devel] An2 problems

[Bill Galbraith]

 

> -Original Message-
> From: [EMAIL PROTECTED] 
> [mailto:[EMAIL PROTECTED] On 
> Behalf Of Ron Jensen
> Sent: Thursday, March 08, 2007 12:43 AM
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] An2 problems
> 
> On Wed, 2007-03-07 at 21:54 -0600, Jon S. Berndt wrote:
> > > As a side note, the engine claims a displacement of 250 
> cubic inches and
> > > an output of 1300 horsepower!   I suspect something isn't right.
> > > Aeromatic suggests a 1300 hp piston engine should 
> displace ~2080 cubes.
> > > 
> > > Ron
> > 
> > 
> > One figure I saw online says the displacement is about 1800 in3.
> > 
> > Did this aircraft work at one time?
> > 
> > Jon
> 
> The chatter on IRC said it used to fly.
> 
> My web research agrees 1823 in3, most references to the 
> ASH-62 say 1000 hp, but it seems to be a variant of the 
> Wright Cyclone R1820 which I've found rated between 900 and 
> 2000 hp, so perhaps the 1300 hp in the definition file isn't 
> beyond belief.
> 
> I found a type certificate for the engine here:
> http://home.hiwaay.net/~jlwebs/engine.html
> 
> and much data on the airframe here:
> http://an2flyers.com/
> 


Jane's All the World Aircraft, 1991-1992, lists the following for the PZL
Mielec AN-2P powerplant:

One 746 kW (1000hp) PZL Kalisz Asz-621R nine-cylinder radial aircooled
engine, driving an AW-2 four-bladed variable-pitch metal propeller.

Hope this helps,
Bill


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Re: [Flightgear-devel] Better audio for FG

[Bill Galbraith]

 



  _  

From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Tom
Betka
Sent: Saturday, February 17, 2007 8:48 AM
To: flightgear-devel@lists.sourceforge.net
Subject: [Flightgear-devel] Better audio for FG


Hello all, 
 
I am new to FG and to the developer list. I sent an earlier e-mail around to
this effect but am not certain that it actually made it to the list, so I
will try it again.
In a recent developer's e-mail thread, the need for improved audio was
briefly discussed. I may be able to help in this regards. 
 
In addition to being a budding programmer and long-time flight sim fan, I am
a 25+ year pilot and have been a CFII/A&P for 20 years. I also own a 1967
Piper Aztec. In addition I have what amounts to a PC-based home recording
studio with several mid/high quality condenser mics and some of the latest
in sound gear, including Sonar software. It would not be at all difficult to
obtain audio samples of both reciprocating and turbine engine starts &
shut-downs, at the very least. 
 
I suppose what we need is a list of audio products needed. If I knew the
kinds of things you guys think the FG project needs, I would be able to tell
you how I could contribute to the project. Incidentally, I also have access
to the cockpits of various types of aircraft for panel pictures. Once
again--all I need to know is the types of things that are needed.
 
One last thing--I work as a physician, so sometimes my schedule can be a bit
hectic. But as our Wisconsin weather warms over the next couple of months,
there is no reason that I can't get several new audio samples.
 
Tom Betka
Green Bay, WI
 
 

Having been involved slightly in the audio portion of a Level C flight
simulator, one of the hardest parts of recording aircraft sounds is that you
need isolated sounds. These isolated sounds are then combined as events
happen to generate the entire spectrum of noise in the cockpit.
 
For example, It's not any fun trying to get the sound of the gear operating
if the engines are running and you have air rush. The solution for that
particular problem is that you need to have the aircraft on jackstands in a
hanger where there is nothing going on. For this not-for-profit, volunteer
effort, it's not practical for you to pay to have your aircraft placed on
jackstand and cycle the gear. However, if you have something schedule that
involves jackstands, or you are wandering through a hanger and there is
someone working on an aircraft in such a situation, grab your recorder. 
 
Some of the other items of value are sounds such as stall warnings, various
avionics noises, espcially such as the autopilot would make when a taret
altitude is reached. These can't always be isolated, but oft-times they are
generated tones of a certain frequency and cycle time. Recording them allows
someone later to determine the frequency and cycle time and then artifically
generate these sounds.
 
Microphone placement is another important issue. Placing it near the pilot's
ear is a good place, hanging rather than lying on a surface.
 
Hope this helps.
 
Bill
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