Re: [Flightgear-devel] heading: magnetic or not?
Major A [EMAIL PROTECTED] said: How about the HSI on the A4 panel? It appears to be fixed at true heading, and it doesn't seem to be adjustable (it's supposed to be a gyro, so it should be). Do you mean the AI or the HSI? The AI isn't adjustable because when I set it up there wasn't a way to recieve clicks in a 3D cockpit. It's on my list. All the other instruments are just standards (for the c172 mostly) from the Aircraft/Instruments directory and not unique to the A4 at all (well maybe the AoA and ASI are unique). Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] heading: magnetic or not?
Just another question: I noticed that the different places in which heading plays a role (the different indicators as well as the autopilot) use magnetic and geographic heading at will. Are there any plans to unify them and/or come up with a convention of what heading is magnetic and what isn't? Andras === Major Andras e-mail: [EMAIL PROTECTED] www:http://andras.webhop.org/ === ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
re: [Flightgear-devel] heading: magnetic or not?
Major A writes: Just another question: I noticed that the different places in which heading plays a role (the different indicators as well as the autopilot) use magnetic and geographic heading at will. Are there any plans to unify them and/or come up with a convention of what heading is magnetic and what isn't? Are you sure? Here's what you should find in the 172: - The magnetic compass displays magnetic heading, but it is strongly affected by acceleration and turning errors: it will be accurate only in straight-and-level steady flight (or sitting flat on the ground). - The directional gyro is purely relative and doesn't care what it displays: you can set it to true, magnetic, or anything in-between. It will drift during flight, however, so you have to reset it from time to time. Its starting point is fairly arbitrary -- make sure you adjust it to what you want before you take off. - The autopilot in the 172 tries to keep the orange heading bug at the top of the directional gyro, period. If you set the DG to the true heading (as you would in the Arctic), then the autopilot uses true heading; if the DG has drifted, the AP will be off by the amount of the drift. Bigger planes have more sophisticated flight-management systems, but we're not modelling those properly yet. - The ADF needle simply points to the ADF station (in real life, +/-10 degrees -- it's not all that accurate). - The VOR indicators show (roughly) what radial the plane is on. That's not necessarily the direction you're flying, or even exactly the direction to the VOR. The only place you can get the true heading directly is the HUD, which isn't really meant to simulate anything you'll find in a small plane -- it's just a (useful) developer's tool or a user's toy. Usually it should be turned off. All the best, David -- David Megginson, [EMAIL PROTECTED], http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
- The autopilot in the 172 tries to keep the orange heading bug at the top of the directional gyro, period. If you set the DG to the true heading (as you would in the Arctic), then the autopilot uses true Ever flown a (real) 172 across the North Pole? :-) The only place you can get the true heading directly is the HUD, which isn't really meant to simulate anything you'll find in a small plane -- it's just a (useful) developer's tool or a user's toy. Usually it should be turned off. Oh. I used the HUD quite a bit in the past because it gives me information I really want given the limits of the input devices I have (mouse and keyboard...). How about the HSI on the A4 panel? It appears to be fixed at true heading, and it doesn't seem to be adjustable (it's supposed to be a gyro, so it should be). Andras === Major Andras e-mail: [EMAIL PROTECTED] www:http://andras.webhop.org/ === ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
David Megginson writes: The only place you can get the true heading directly is the HUD, which isn't really meant to simulate anything you'll find in a small plane -- it's just a (useful) developer's tool or a user's toy. Note David is talking from a 'small plane' C172 perspective. There are much more sophisticated platforms modeled in FGFS where the HUD is quite appplicable Best Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
Major A writes: - The autopilot in the 172 tries to keep the orange heading bug at the top of the directional gyro, period. If you set the DG to the true heading (as you would in the Arctic), then the autopilot uses true Ever flown a (real) 172 across the North Pole? :-) No, but the Arctic starts a long way from the North Pole. Many people in Canada fly 172's in Northern Domestic Airspace (roughly north of 60, but it zigzags a lot), where you use true rather than magentic headings. The same may apply to parts of Alaska. How about the HSI on the A4 panel? It appears to be fixed at true heading, and it doesn't seem to be adjustable (it's supposed to be a gyro, so it should be). I don't use the A4, so I haven't noticed. It should probably be showing magnetic heading. Usually, an HSI is slaved to a separate magnetic sensor that keeps it aligned, so that you don't have to adjust it manually (it's also very expensive, at least for a small plane). All the best, David -- David Megginson, [EMAIL PROTECTED], http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
Norman Vine writes: The only place you can get the true heading directly is the HUD, which isn't really meant to simulate anything you'll find in a small plane -- it's just a (useful) developer's tool or a user's toy. Note David is talking from a 'small plane' C172 perspective. Yes, as I noted. This would also include all but the most sophisticated transport planes. For fighter jets, a HUD is sometimes appropriate, but I don't think we're modelling any specific real-word HUD's right now. It's a *great* development and debugging tool, though. All the best, David -- David Megginson, [EMAIL PROTECTED], http://www.megginson.com/ ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
David Megginson wrote: Major A writes: - The autopilot in the 172 tries to keep the orange heading bug at the top of the directional gyro, period. If you set the DG to the true heading (as you would in the Arctic), then the autopilot uses true Ever flown a (real) 172 across the North Pole? :-) No, but the Arctic starts a long way from the North Pole. Many people in Canada fly 172's in Northern Domestic Airspace (roughly north of 60, but it zigzags a lot), where you use true rather than magentic headings. The same may apply to parts of Alaska. It's worth pointing out that a DG will work fine in the polar regions. Other than precession (which has a 24 hour period -- hardly a huge source of error), there's no way for it to know that it's over the pole. It will even work fine on the pole itself, in the sense that it will always point toward the same meridian. It won't tumble or do anything silly. Only floating point euler angle computations have trouble at the poles; real hardware is a little more robust. :) Andy -- Andrew J. RossNextBus Information Systems Senior Software Engineer Emeryville, CA [EMAIL PROTECTED] http://www.nextbus.com Men go crazy in conflagrations. They only get better one by one. - Sting (misquoted) ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
David Megginson writes: Major A writes: - The autopilot in the 172 tries to keep the orange heading bug at the top of the directional gyro, period. If you set the DG to the true heading (as you would in the Arctic), then the autopilot uses true Ever flown a (real) 172 across the North Pole? :-) No, but the Arctic starts a long way from the North Pole. Many people in Canada fly 172's in Northern Domestic Airspace (roughly north of 60, but it zigzags a lot), where you use true rather than magentic headings. FYI This page demonstrates why a magnetic compass is not the necessarily very useful near the pole http://www.geolab.nrcan.gc.ca/geomag/e_nmpole.html Cheers Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] heading: magnetic or not?
Andy Ross writes: It's worth pointing out that a DG will work fine in the polar regions. Other than precession (which has a 24 hour period -- hardly a huge source of error), there's no way for it to know that it's over the pole. It will even work fine on the pole itself, in the sense that it will always point toward the same meridian. It won't tumble or do anything silly. Only floating point euler angle computations have trouble at the poles; real hardware is a little more robust. :) FWIW I would be interested in test cases where FGFS has a 'pole' problem Best Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
