Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-17 Thread Rex
The textbook solution for straight wings is that 1 degree of positive dihedral adds approximately .0002 to Cl, the rolling moment coefficient .   This would be added to the Clb coefficient in the input file, since it is sideslip that generates the effect.  I use an old copy of Perkins and H

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-17 Thread Steve Hosgood
Dave Culp wrote: But it doesn't. Seems like an oversight to me. I'm trying to model a 'plane with almost no dihedral AFAICS and I'm not sure what to twiddle in the .xml file to get that effect. My advice is don't worry about it. Is there something about the way the Colditz

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-16 Thread Dave Culp
On Tuesday 16 May 2006 11:40 am, Steve Hosgood wrote: > Trouble is, most aircraft modellers would struggle to work out what > those effects are. So we might expect that Aeromatic (which is the > "compiler" if you like) actually takes in a value for dihedral and works > out the magic numbers for th

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-16 Thread Steve Hosgood
Dave Culp wrote: Well, wing incidence *is* one of the configuration items that can go into a JSBSim configuration file. As for dihedral, I think you're still not getting the methodology of JSBSim. In JSBSim you don't specify the dihedral, you specify the *effect* of dihedral. What I'm

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-16 Thread Dave Culp
On Friday 12 May 2006 08:21 am, Steve Hosgood wrote: > What I meant was, regardless that most of the physical measurements are > missing from jsbsim's .xml files, **Aeromatic** should have a way of > specifying them so that it can produce the right "magic" coefficients. > > Yet it doesn't. Aeromati

RE: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-16 Thread Jon S. Berndt
I'm working on a thorough document now, but I still only hav e alittle psare time in which to write it. :-(   Jon -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Steve HosgoodSent: Friday, May 12, 2006 8:22 AMTo: flightgear-devel@lists.sou

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-16 Thread Steve Hosgood
Dave Culp wrote: On Thursday 11 May 2006 11:08 am, Steve Hosgood wrote: Deriving the parameters like "yaw moment due to beta" and other such magic numbers from physical parameters is going to be pretty non-trivial. You can use "common numbers" from some hard to find sour

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Dave Culp
On Thursday 11 May 2006 11:08 am, Steve Hosgood wrote: > Things are becoming a bit more transparent. Trouble is, an aircraft > modeller usually starts by knowing just physical parameters (location of > wings and things, location of tail, rudder etc along with amount of > dihedral, angle of inciden

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Steve Hosgood
Dave Culp wrote: On Thursday 11 May 2006 04:56 am, Steve Hosgood wrote One thing I've noticed about the aircraft.xml file (both the new version and the old) is that the "metrics" section (describing the physical layout of the plane) is rather "lightweight" compared with the vast

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Dave Culp
On Thursday 11 May 2006 04:56 am, Steve Hosgood wrote: > Do you confirm that the "AERORP" is the point from which the "tail arm" > and "rudder arm" are referenced? Since it doesn't seem possible to > specify a "wing arm", do I assume that the "AERORP" must be sited at the > 0.25 chord point of the

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Jim Wilson
> From: Erik Hofman > > Steve Hosgood wrote: > > I just *know* I'm going to get totally flamed for this, but can someone > > please tell me how the CG, Eyepoint, AERORP and VRP are interconnected? > > Yeah, I know - RTFM. > > It basically comes down to this, *you* decide where (0,0,0) is > ref

RE: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Jon S. Berndt
Steve:   I'll have to get back to you in the next day or two or three on this. I'm unusually booked-up.   Gotta run!   Jon -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]On Behalf Of Steve HosgoodSent: Thursday, May 11, 2006 4:57 AMTo: flightgear-dev

RE: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Jon S. Berndt
> Steve Hosgood wrote: > > > Before I say anything, I'd like to commend you Jon, along with Dave Culp > > and Erik Hofman for your three replies to my original question. *None* > > of you flamed me or anyone else, and answered pretty much all my > > questions really neatly. > > > > You're not subsc

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Josh Babcock
Steve Hosgood wrote: > Before I say anything, I'd like to commend you Jon, along with Dave Culp > and Erik Hofman for your three replies to my original question. *None* > of you flamed me or anyone else, and answered pretty much all my > questions really neatly. > You're not subscribed to [EMAIL

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Steve Hosgood
Steve Hosgood wrote: There doesn't seem to be any way to specify the angle of the wing chord w.r.t the aircraft centerline, or the angle of the horizontal stabilizer chord w.r.t the aircraft centerline. This comes back to my original question about orientation of the X axis. I know it

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Steve Hosgood
Jon S. Berndt wrote: I just *know* I'm going to get totally flamed for this, but can someone please tell me how the CG, Eyepoint, AERORP and VRP are interconnected? Yeah, I know - RTFM. I'd say that, but there really isn't much of one, yet! :-( You won't get flamed. It's not

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-11 Thread Erik Hofman
Steve Hosgood wrote: I just *know* I'm going to get totally flamed for this, but can someone please tell me how the CG, Eyepoint, AERORP and VRP are interconnected? Yeah, I know - RTFM. It basically comes down to this, *you* decide where (0,0,0) is referenced and you will have to define all o

RE: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-10 Thread Jon S. Berndt
> I just *know* I'm going to get totally flamed for this, but can someone > please tell me how the CG, Eyepoint, AERORP and VRP are interconnected? > Yeah, I know - RTFM. I'd say that, but there really isn't much of one, yet! :-( You won't get flamed. It's not the easiest concept to figure out.

Re: [Flightgear-devel] Frames of Reference in jsbsim

2006-05-10 Thread Dave Culp
On Wednesday 10 May 2006 11:43 am, Steve Hosgood wrote: > Where is this "other point"? Just some arbitrary convenient point? yes > I think I know what the "eyepoint" is :-). It is specified with an > [X,Y,Z] too, but in what coordinate frame? same as above > Likewise the VRP. This is the loc

[Flightgear-devel] Frames of Reference in jsbsim

2006-05-10 Thread Steve Hosgood
I just *know* I'm going to get totally flamed for this, but can someone please tell me how the CG, Eyepoint, AERORP and VRP are interconnected? Yeah, I know - RTFM. Trouble is, I think I did R the FM (there was an article by Jon S. Berndt himself in Issue 1, Vol1 of the Quarterly Newsletter) b