Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On 3/23/04 at 11:55 PM Matthew Law wrote: On Tue, 23 Mar 2004 22:19:52 +, David Luff [EMAIL PROTECTED] wrote: eg one-zero-one-three-decimal-two You can probably drop the decimal point for millibars. This makes UK flying a lot more realistic now. Thanks :-) The following snippet is from http://www.schiratti.com/humour.html ATC: Pan Am 1, descend to 3,000 ft on QNH 1019. Pan AM 1: Could you give that to me in inches? ATC: Pan Am 1, descend to 36,000 inches on QNH 1019 Seemed kind of appropriate given the discussion ;-) Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
[Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
I just squeezed in one little item I thought would be useful for the release, since many aircraft do not have clickable panels. Ctrl-I now pops up an instrument-settings dialog (also available from the menu bar) to change the altimeter setting and adjust the heading indicator. For those of you flying with the live, METAR weather, you've probably noticed that the altimeter is often off by hundreds or sometimes thousands of feet. To fix that, as in real life, you need to do one of two things: 1. Get the altimeter setting from the ATIS and put it into your altimeter -- this is the normal thing to do when you're airborne. 2. Change the altimeter setting until the altimeter reads the correct altitude -- this is the normal thing to do on the ground (but you need to cross-check with the ATIS if available). A big part of flying cross-country in a real plane (below the flight levels) is adjusting the altimeter setting constantly throughout the trip. If you're IFR, ATC will tell you what altimeter setting to use at every handoff (it will be the one that everyone else in your sector is using, based on the largest airport in the sector); if you're VFR, it's up to you to call flight services or local UNICOMs as you fly to keep your altimeter setting up to date. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
David Megginson wrote: 1. Get the altimeter setting from the ATIS and put it into your altimeter -- this is the normal thing to do when you're airborne. 2. Change the altimeter setting until the altimeter reads the correct altitude -- this is the normal thing to do on the ground (but you need to cross-check with the ATIS if available). A big part of flying cross-country in a real plane (below the flight levels) is adjusting the altimeter setting constantly throughout the trip. If you're IFR, ATC will tell you what altimeter setting to use at every handoff (it will be the one that everyone else in your sector is using, based on the largest airport in the sector); if you're VFR, it's up to you to call flight services or local UNICOMs as you fly to keep your altimeter setting up to date. David, Your mentioning of this area reminds me of an issue with the altimeter setting. I am told that when you change the setting by 0.1 (i.e. from 29.92 to 30.02) that the altimeter reading should change by about 120 feet. Currently it only changes about 100 feet which is about 20' error per 0.1 inch of hg. A separate, but I think related observation is that if I start out at KDEN with the environment conditions set at 29.92 and the altimeter set at 29.92, the altimeter matches the HUD (true) altitude pretty close (between 5340 and 5350 MSL.) If I then set the environment conditions to 30.12 and set the altimeter also to 30.12, the altimeter reads closer to 5400 which is pretty close to that same 20' error per 0.1 change in pressure. I was showing FG to an FAA guy and a former Air Force instructor and this was one of the first things they spotted. During the demo, the air force instructor (female not that it matters) had an unfortunate complete loss of oil pressure on climb out in the c172, but flew an unpublished back course down to 100' minimums in screaming winds and dropped out of the clouds dead center over the runway right as the engine quit ... Regards, Curt. -- Curtis Olson Intelligent Vehicles Lab FlightGear Project Twin Cities[EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
David Megginson writes: I just squeezed in one little item I thought would be useful for the release, since many aircraft do not have clickable panels. Ctrl-I now pops up an instrument-settings dialog (also available from the menu bar) to change the altimeter setting and adjust the heading indicator. For those of you flying with the live, METAR weather, you've probably noticed that the altimeter is often off by hundreds or sometimes thousands of feet. To fix that, as in real life, you need to do one of two things: 1. Get the altimeter setting from the ATIS and put it into your altimeter -- this is the normal thing to do when you're airborne. Ack - ATIS isn't giving the altimeter at the moment - I took it out since it was hardwired to 29.92. Is there a property or a function that I can use to get the current value, it would be easy to put in. Also - millibars or inches? Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On Tue, 23 Mar 2004 20:57:20 +, David Luff [EMAIL PROTECTED] wrote: millibars or inches? Can FG be set up to use millibars/Hecto Pascals for the Altimeter pressure setting and imperial for the rest of the units as we use in the UK? All the best, Matt. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
David Luff wrote: Ack - ATIS isn't giving the altimeter at the moment - I took it out since it was hardwired to 29.92. Is there a property or a function that I can use to get the current value, it would be easy to put in. Also - millibars or inches? Inches of mercury for North America, please. The property /environment/pressure-sea-level-inhg contains the altimeter setting for the aircraft's current location -- that's not exactly what you want, but until we figure out the best way to interface with the METAR stuff, it will be a good start. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
Curtis L. Olson wrote: Your mentioning of this area reminds me of an issue with the altimeter setting. I am told that when you change the setting by 0.1 (i.e. from 29.92 to 30.02) that the altimeter reading should change by about 120 feet. Currently it only changes about 100 feet which is about 20' error per 0.1 inch of hg. All of the pilot training material says 100 ft for every tenth of an inch of Mercury -- I'll check on my altimeter next time I'm at the airport. Here's what the AIP Canada (the official Transport Canada pilot's manual) says: Whether a pilot inadvertently sets an incorrect pressure on the altimeter subscale or sets the correct pressure for one area and then, without altering the setting, flies to an area where the pressure differs, the result is the same -- the zero reference to the altimeter will not be where it should be but will be displaced by an amount proportional to 1000 feet indicated altitude per 1 inch of mercury tha the subscale setting is in error. Both the PPL and IFR written exams have a series of questions on different altimeter-setting scenarios, and both expect 1000 ft per inch of Mercury. The same applies to materials I've read from the U.S. That doesn't mean that they're all right, of course, but it does mean that it's what pilots expect. It is also possible that you might be thinking of density altitude: it changes by approximately 120 ft for every degree Celsius difference from the ISA. A separate, but I think related observation is that if I start out at KDEN with the environment conditions set at 29.92 and the altimeter set at 29.92, the altimeter matches the HUD (true) altitude pretty close (between 5340 and 5350 MSL.) If I then set the environment conditions to 30.12 and set the altimeter also to 30.12, the altimeter reads closer to 5400 which is pretty close to that same 20' error per 0.1 change in pressure. That might be a different problem: a barometric altimeter is sensitive to both pressure and temperature variations. On the ground, the temperature variation is neutralized, since the altimeter-reporting station is subject to the same errors; in the air, it can cause the altimeter to be off by hundreds or even thousands of feet. FlightGear currently assumes that all altimeter settings come from stations at sea level, so I wouldn't be surprised to see errors creep in for higher-elevation stations just from small differences in temperature calculations -- we'll have to find a way to deal with that. I was showing FG to an FAA guy and a former Air Force instructor and this was one of the first things they spotted. During the demo, the air force instructor (female not that it matters) had an unfortunate complete loss of oil pressure on climb out in the c172, but flew an unpublished back course down to 100' minimums in screaming winds and dropped out of the clouds dead center over the runway right as the engine quit ... Yes, I have unfortunately accidents like that a lot in FlightGear -- it's good practice. Note that a 50 ft error is (just) within legal tolerance anyway, even for IFR. Still, since it's not deliberate, we need to look into it. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
Matthew Law writes: On Tue, 23 Mar 2004 20:57:20 +, David Luff [EMAIL PROTECTED] wrote: millibars or inches? Can FG be set up to use millibars/Hecto Pascals for the Altimeter pressure setting and imperial for the rest of the units as we use in the UK? All the best, I'm sure it can, but maybe not for the next release! Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
Matthew Law wrote: Can FG be set up to use millibars/Hecto Pascals for the Altimeter pressure setting and imperial for the rest of the units as we use in the UK? It's a (relatively) simple matter to make instruments calibrated in millibars instead of inches of mercury; localizing dialog boxes will be a bit trickier, though. In general, I think that our policy should be to follow the nationality of the callsign or markings of each aircraft's 3D model: North American aircraft (like the default 172 and my Warrior model) should use inches of mercury; European aircraft should use millibars. If or when we model old Soviet aircraft, we might need to calibrate the airspeed indicators in kilometers per hour and the altimeters in meters as well (I'm not certain). Eventually, then, someone will need to do a repaint of some of the common aircraft with UK markings and a slightly different panel. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On Tue, 23 Mar 2004 18:07:34 -0500, David Megginson [EMAIL PROTECTED] wrote: It's a (relatively) simple matter to make instruments calibrated in millibars instead of inches of mercury; localizing dialog boxes will be a bit trickier, though. In general, I think that our policy should be to follow the nationality of the callsign or markings of each aircraft's 3D model: North American aircraft (like the default 172 and my Warrior model) should use inches of mercury; European aircraft should use millibars. If or when we model old Soviet aircraft, we might need to calibrate the airspeed indicators in kilometers per hour and the altimeters in meters as well (I'm not certain). Eventually, then, someone will need to do a repaint of some of the common aircraft with UK markings and a slightly different panel. All the best, David It would be nice to eventually be able to map the relevant instruments to any of these units. In the interests of internationalisation, you understand :-) Incidentally, I believe that Eastern block aircraft flown here have to have an altimeter in feet/millibars onboard. All the best, Matt. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
David Megginson writes: David Luff wrote: Ack - ATIS isn't giving the altimeter at the moment - I took it out since it was hardwired to 29.92. Is there a property or a function that I can use to get the current value, it would be easy to put in. Also - millibars or inches? Inches of mercury for North America, please. The property /environment/pressure-sea-level-inhg contains the altimeter setting for the aircraft's current location -- that's not exactly what you want, but until we figure out the best way to interface with the METAR stuff, it will be a good start. That'll do for now - I'll whack it in hopefully before the release. It will of course be pronounced al-tee-meter instead of the al-tim-iter that I imagine the US uses! Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
David Megginson said: I just squeezed in one little item I thought would be useful for the release, since many aircraft do not have clickable panels. Ctrl-I now pops up an instrument-settings dialog (also available from the menu bar) to change the altimeter setting and adjust the heading indicator. Did you notice that there are problems when a menu dialog is up already and you hit Ctrl-R (presumably Ctrl+I too)? It's like the buttons work on the wrong dialog. Best, Jim ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
Matthew Law writes: On Tue, 23 Mar 2004 20:57:20 +, David Luff wrote: millibars or inches? Can FG be set up to use millibars/Hecto Pascals for the Altimeter pressure setting and imperial for the rest of the units as we use in the UK? All the best, OK, by special request the ATIS now puts out millibars for the UK, and inches for the rest of the world. Millibars are to 1 decimal place and inches Hg to 2 eg one-zero-one-three-decimal-two and two-niner-decimal-niner-two Is this reasonable? Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On Tue, 23 Mar 2004 22:19:52 +, David Luff [EMAIL PROTECTED] wrote: eg one-zero-one-three-decimal-two You can probably drop the decimal point for millibars. This makes UK flying a lot more realistic now. Thanks :-) All the best, Matt ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
Matthew Law wrote: It would be nice to eventually be able to map the relevant instruments to any of these units. In the interests of internationalisation, you understand :-) The problem is that we have to make different textures for the faces, etc., so it will never be automatic. Once you've gone to all that trouble, it's no big deal to make a separate XML animation file. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
Matthew Law writes: On Tue, 23 Mar 2004 22:19:52 +, David Luff wrote: eg one-zero-one-three-decimal-two You can probably drop the decimal point for millibars. Done. This makes UK flying a lot more realistic now. Thanks :-) No problem. However, since the panel altimeter is always still in inches and I can't mentally divide by 33.864 in real time I've made it user settable and defaulted it to inches - you need to start flightgear with --prop:/sim/atc/use-millibars=true, or put it in your preferences.xml. Note that even when set true, you'll still only get millibars in the UK, and eventually other countries that use it, not N America. Once we've got a millibar altimeter for the UK I'll make it the default for the ATC here. Cheers - Dave ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On Tue, 23 Mar 2004, David Luff wrote: Ack - ATIS isn't giving the altimeter at the moment - I took it out since it was hardwired to 29.92. Is there a property or a function that I can use to get the current value, it would be easy to put in. Also - millibars or inches? I'd prefer it in millibars, but all the instruments seem to be calibrated in inches - any chance of alternate settings disks for the instruments? -- Jon Stockill [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On Tue, 23 Mar 2004, David Luff wrote: OK, by special request the ATIS now puts out millibars for the UK, and inches for the rest of the world. Millibars are to 1 decimal place and inches Hg to 2 eg one-zero-one-three-decimal-two and two-niner-decimal-niner-two Is this reasonable? Seems fine to me. -- Jon Stockill [EMAIL PROTECTED] ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Instrument Settings Dialog; Setting the Altimeter
On Tue, 23 Mar 2004 22:19:52 +, David Luff [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]: Matthew Law writes: On Tue, 23 Mar 2004 20:57:20 +, David Luff wrote: millibars or inches? Can FG be set up to use millibars/Hecto Pascals for the Altimeter pressure setting and imperial for the rest of the units as we use in the UK? All the best, OK, by special request the ATIS now puts out millibars for the UK, and inches for the rest of the world. Millibars are to 1 decimal place and inches Hg to 2 eg one-zero-one-three-decimal-two and two-niner-decimal-niner-two Is this reasonable? ..yes, for added sim realism, you may want to have all us non-US and non-UK etc in the metric ICAO world, use metric hPa's. ;-) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
