David Megginson wrote:
> Andy Ross writes:
> > JSBSim and YASim do things pretty much the same way, using a
> > coefficient of friction for gear as they slide over the ground. This
> > integration works fine for a moving aircraft,
>
> Unfortunately, not -- when the JSBSim and YASim aircraft are ro
> Come to think about it, it's not averaging we need. The landing gear
> calculations are a vector from the midpoint between all wheels and as
> such should be added as a vector product to the calculations tot the
> separate wheels.
>
> Erik
?? Not sure I follow you.
Also, I've renamed the threa
Erik Hofman writes:
> So now you've got:
>
> 1. friction calculate every wheel separately.
> 2. add all frictions for the landing gear.
> 3. make the friction for every wheel dependent to wheel spin and use the
> result for moments and force calculations.
> 4. calculate the moments and fo
Erik Hofman wrote:
Thinking about it a bit more this makes sense.
Calculating every wheel separately isn't the whole story. In the end
there is the friction caused by the complete landing gear which isn't
wheel spin dependent.
So now you've got:
1. friction calculate every wheel separately.
2.
Erik Hofman wrote:
David Culp wrote:
I think the trick is to zero-out the speeds, forces and moments when
the airplane's forward speed approaches zero. But you then have to
allow the airplane to accelerate out of this "frozen" state to move
again. I didn't find an answer.
After thinking a b
David Megginson wrote:
Andy Ross writes:
> JSBSim and YASim do things pretty much the same way, using a
> coefficient of friction for gear as they slide over the ground. This
> integration works fine for a moving aircraft,
Unfortunately, not -- when the JSBSim and YASim aircraft are rolling,
t
David Culp wrote:
I think the trick is to zero-out the speeds, forces and moments when the
airplane's forward speed approaches zero. But you then have to allow the
airplane to accelerate out of this "frozen" state to move again. I didn't
find an answer.
After thinking a bit about this problem
Andy Ross writes:
> But this is only one problem of many. FWIW, I think most of the YASim
> planes sit quite well.
Unless there's any wind:
fgfs --aircraft=c172-yasim [EMAIL PROTECTED]
All the best,
David
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Flightgear-devel mailing list
[E
Andy Ross writes:
> JSBSim and YASim do things pretty much the same way, using a
> coefficient of friction for gear as they slide over the ground. This
> integration works fine for a moving aircraft,
Unfortunately, not -- when the JSBSim and YASim aircraft are rolling,
they are still far too
> > If there were no winds at all, that might help. Otherwise, it doesn't
> > work at all.
>
> Oh. Why is that?
I tried limiting the ground reactions and found that if you lower them enough
to stop the jitter, the airplane will get blown around by the wind. I
believe this is the relevant bit
> If there were no winds at all, that might help. Otherwise, it doesn't work
> at all.
>
> Jon
Let me expand on that. If you do come to a stop, and there are no winds at
the moment, then the winds come up after you have stopped, then having
reduced the forces as your velocity goes to zero, you won
Jon Berndt <[EMAIL PROTECTED]> said:
> > Might it be useful to have some arbitrary mulitplier that affects the way
> in
> > which forces or friction are scaled as zero velocity is approached? This
> > still should be added _after_ the aircraft pretty much just sits
> > there on it's own.
> >
> >
> Might it be useful to have some arbitrary mulitplier that affects the way
in
> which forces or friction are scaled as zero velocity is approached? This
> still should be added _after_ the aircraft pretty much just sits
> there on it's own.
>
> Best,
>
> Jim
If there were no winds at all, that
Andy Ross <[EMAIL PROTECTED]> said:
>
> Basically, this just won't work. Sorry. The idea of switching from a
> sliding friction model to a static spring at low speeds is probably as
> good as we're going to get. But quite honestly, it's been my
> experience that almost all of the YASim aircraf
Martin Spott wrote:
> Simulating friction on the ground should be quite easy as long as you
> know some parameters: You have to know about position as well as
> horizontal and vertical forces of _each_ wheel. Probably this is
> already there for a C172 (as mentioned above, I don't know), the rest
>
> Did I overlook something, do I miss some relevant information ?
>
> Thanks,
> Martin.
Hi, Martin:
I'm pretty busy at the moment doing some rewriting of the JSBSim propulsion
systems, but I will refer you at the moment to a set of notes I wrote for
our gear model. I have not revisited th
Andy Ross <[EMAIL PROTECTED]> wrote:
> David Megginson wrote:
>> Paul Surgeon writes:
>> > I don't know about everyone else's experience but I haven't found
>> > one aircraft in FG that wants to sit still on the ground even with
>> > the engine off.
> An ideal mechanism would keep track of how muc
bject: RE: [Flightgear-devel] Airport
vehicle (driving) sim
-Original Message-From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]On Behalf Of
NickSent: Saturday, November 15, 2003 2:39 PMTo:
FlightGear developers discussionsSubject: Re: [Flightgear-
"Jon Berndt" <[EMAIL PROTECTED]> wrote:
> Oh, God. Yes, I went through the mental gyrations for that one a year or
> two ago. It's a "story problem nightmare" when considering how to implement
> with multiple and variable numbers of gear bogeys. What if you run into ice
> on one gear?
You might
On Saturday 15 Nov 2003 9:24 pm, Paul Surgeon wrote:
> FlightGear would need several changes in various areas to support things
> like water landings.
>
> Firstly we would need to be able to specify various ground types.
>
> One way of doing this is to have a number attached to each polygon in the
> FlightGear would need several changes in various areas to support
> things like water landings.
Not really. The FDM would initially assume that you were going to land on
water. The "ground" reactions would be the same no matter what kind of
terrain you were on. This could prove interesting, lan
On Saturday, 15 November 2003 21:25, Jon Berndt wrote:
> I have some design docs for floatplanes such as the older 1940's era
> "Clipper" style of aircraft and I am wanting in the worst way to model one
> of those just for nostalgia - they were fascinating planes, and I believe a
> well modeled air
-Original Message-From:
[EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]On Behalf Of
NickSent: Saturday, November 15, 2003 2:39 PMTo:
FlightGear developers discussionsSubject: Re: [Flightgear-devel]
Airport vehicle (driving) sim
Good afternoon again.
I just remembered
Nick wrote:
> I just remembered another trick about zero-speed rolling models.
> Below a threshold speed (say 1 m/s) you make the force proportional to
> the velocity. That way you'll get zero force at zero speed. The
> other thing that can happen if you don't is that you'll oscillate
> about the
ny of those things are of interest let me
know and I'll pitch in to help.
Nickolas HeinMorgantown WV
- Original Message -
From:
Andy Ross
To: FlightGear developers
discussions
Sent: Saturday, November 15, 2003 12:25
PM
Subject: Re:
> I have some design docs for floatplanes such as the older 1940's era
> "Clipper" style of aircraft and I am wanting in the worst way to model one
> of those just for nostalgia - they were fascinating planes, and I
> believe a
> well modeled aircraft would add a lot to FlightGear. Imagine a nice f
> I like the idea of just having some sort of "overide FDM" when stationary.
> We can model surface conditions later including water landings
> for floatplanes and snow landings for aircraft with skis.
I have some design docs for floatplanes such as the older 1940's era
"Clipper" style of aircraft
Well I don't think we need to go to such extremes so soon unless someone has
some time on their hands. :)
It would be nice to at least get it to a point where people can park an
aircraft on the apron and come back 10 minutes later and find it where they
left it.
I like the idea of just having
> It's the ground reaction code. :)
>
> JSBSim and YASim do things pretty much the same way, using a
> coefficient of friction for gear as they slide over the ground. This
> integration works fine for a moving aircraft, but it's really not
> right for a stopped one. An aircraft with exactly zero
n to help.
Nickolas HeinMorgantown WV
- Original Message -
From:
Andy Ross
To: FlightGear developers
discussions
Sent: Saturday, November 15, 2003 12:25
PM
Subject: Re: [Flightgear-devel] Airport
vehicle (driving) sim
David Megginson wrote:> Paul Surgeon write
David Megginson wrote:
> Paul Surgeon writes:
> > I don't know about everyone else's experience but I haven't found
> > one aircraft in FG that wants to sit still on the ground even with
> > the engine off.
>
> It might be that the problem is not ground reactions but
> aerodynamics.
It's the groun
Paul Surgeon writes:
> I don't know about everyone else's experience but I haven't found
> one aircraft in FG that wants to sit still on the ground even with
> the engine off. I've never seen a stationary aircraft "weather
> vane" into a 10 knot wind in real life.
It might be that the proble
On Saturday, 15 November 2003 08:39, JD Fenech wrote:
> Stupid idea: Has anyone thought to make a simple FDM for ground
> vechicles? I admit it might get boring quickly, but in a multiplay
> situation, it might be intresting to allow someone to simply watch
> takeoffs from the ground, with a mobile
Stupid idea: Has anyone thought to make a simple FDM for ground
vechicles? I admit it might get boring quickly, but in a multiplay
situation, it might be intresting to allow someone to simply watch
takeoffs from the ground, with a mobile camera. It's half-assed, and
since I can barely get FG to
David Megginson writes:
> If they ever need a volunteer to taxi around a virtual plane, getting
> in the drivers' way, let me know.
They actually had a pretty neat scripting system. You could click a
starting point, ending point, and a midpoint. The system would figure
a reasonably optimal route
Curtis L. Olson writes:
> Today I had a chance to see a driving sim located at KMSP. They use
> it to train drivers for driving around on the airport grounds
> (taxiways, runways, service roads, tunnels, etc.) The really
> interesting thing about this sim is they had a beautifully done model
On Friday 14 November 2003 23:50, Curtis L. Olson wrote:
> Today I had a chance to see a driving sim located at KMSP. They use
> it to train drivers for driving around on the airport grounds
> (taxiways, runways, service roads, tunnels, etc.) The really
> interesting thing about this sim is they
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