Wind correction for GC steering
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has anybody commented on whether wind correction for navigation will be implemented in the next update?
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No one?
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has anybody commented on whether wind correction for navigation will be implemented in the next update?
Sounds awesome, but I thought the GPS HSD already calculates wind drift when alining SP through navigational waypoints.
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Not properly, the plane flies offset for some reason. In a crosswind, on track to a steerpoint, the FPM should be offset from the STPT diamond, the GCSC should be lined up with the FPM, and the FPM should be at the same azimuth as the STPT diamond - i.e. your ground track is the same as the heading to the STPT.
In BMS last I looked, which was apparently a little over 12 months ago, lining up the GCSC with the FPM results in an arcing curve being flown to the STPT, with gradually increasing or decreasing heading as you get closer to the STPT.
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I never had any problem with wind in navigation everything seems natural to me in the system i never had to correct anything
system indates you the heading of steerpoint no wind involved
To take wind into account just align fpm and diamond
I think it is the way it is working in real. The GCSC does not take wind
Real pilot to confirm
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I would assume the GCSC would be placed on the desired ground track azimuth and it would be up to the pilot to place the nose wherever is necessary to put the FPM on the tadpole and Bob’s your uncle. In the case of drift C/O everything moves over so it’s still FPM on GCSC just shifted.
I’m failing to see what could be modeled wrong here.
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I never had any problem with wind in navigation everything seems natural to me in the system i never had to correct anything
system indates you the heading of steerpoint no wind involved
To take wind into account just align fpm and diamond
I think it is the way it is working in real. The GCSC does not take wind
Real pilot to confirm
I did post images from a manual a little over 12 months ago in another thread of the relevant parts of the GCSC implementation, Deejay commented but nothing specific. Ill try to find it for you and give you something less vague to work with, sorry its not very precise an explanation.
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right, and if the FPM was on the steerpoint, that would be alignment of TRACK. if the nose is on the STPT, that would be alignment of HEADING.
so the question was should the MMC use BEARING or TRACK?
and according to DJ, it uses BEARING.
1.11.4.2 Great Circle Steering Cue. The great circle steering cue (Figure 1-177) consists of a 12 mr line extending outward
from a 6 mr circle. The location on the HUD of the roll stabilized steering cue is relative in azimuth to the flightpath marker;
steering is accomplished by flying the flightpath marker to the steering cue. The orientation of the steering cue line on the HUD
indicates bearing to the steerpoint. At the 12 o’clock position relative to the horizon, the steering cue line indicates that bearing to
the steerpoint is zero degrees; at the 3 o’clock position, the steering cue line indicates that bearing to the steerpoint is 90 degrees
right.this geometry here shows true ground track being used to calculate G/C steering error… implying that it should correct for wind as long as the INU has a good status.
2.6.1.3 In the NAV modes, the MMC uses the great circle steering error computed by the INU to position a steering cue on the
HUD. The cue consists of a circle which is positioned at the same elevation as the FPM and a line extending outward from the
circle toward the steerpoint. The lateral displacement of the symbol with respect to the FPM represents steering error. The line
allows the pilot to anticipate that the aircraft is approaching the correct course while the circle is used for more precise steering.
The pilot should fly the FPM to the steering symbol. The MMC also computes distance to steerpoint in nautical miles and time
to steerpoint in minutes and seconds at current groundspeed and displays them along with steerpoint number in the lower right
corner of the HUD.The paragraph you copied, refers to the tail of the cue IMHO. It states that the cue consists of a circle and a line, and that the orientation of the line (=tail) relative to the horizon indicates the bearing to the steerpoint. So if it points straight up (12 'o clock) your bearing to the steerpoint is zero degrees. It does not say where the cue should be relative to the fpm.
Of course, if you combine this info with my assumption, you’d get steerpoint marker, tadpole, and fpm nicely aligned, but the tail of the tadpole wouldn’t point straight up, because you’d be flying crabbed because of the crosswind.
does that help? realistically, it would likely only be a few degrees difference from straight up, which will be not very noticeable on a 12 mr line… on the other hand, a few degrees is very noticeable on a 300nm line.
I do not have enough time to deeply study the above … but had a quick look … it shows the magnetic variation, but I didn’t seen anything about wind and drift … so try the same in flight without wind (wind 0kts) and see what happens. FPM, steering cue and diamond should be superposed (no mag var model in BMS).
right, and the steering in the HUD will be superimposed in the real jet too, in a winds calm condition.
the magnetic variation is used to calculate your G/C error, i.e. where the G/C cue should be placed in azimuth relative to the FPM.
Bit of a big post, but that is the information from the other thread way back when.
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The picture was enough. It doesn’t look right. What I said should be how it is but that picture shows otherwise. Diamond and tadpole should be directly above/below.
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Whenever I see discussions like this, I second-guess my intelligence and ability to get a private pilot license……
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Its easier than it looks Jinro, just go for it.
Freferf, the other thing is that if you have any wind, on a long leg flying ‘straight’ using the AP, your heading will graudually increase or decrease as you approach the STPT. This was what ticked me onto it originally.
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The picture was enough. It doesn’t look right. What I said should be how it is but that picture shows otherwise. Diamond and tadpole should be directly above/below.
sorry but i dont see anything wrong in that picture….
can someone explain to me ?
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Okay, the current setup in BMS is that aligning the FPM with the GCSC will cause the nose to be pointed directly at the STPT, rather than causing the FPM to be pointed at the STPT. i.e. in BMS, the GCSC points the aircraft to the correct BEARING, not the correct TRACK.
excerpts from the -34 above indicate that in at least one OFP, this is not correct behavior.
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sorry but i think there is a misunderstanding here.
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The DIAMOND marks the physical location where the AC shall fly over : DO YOU AGREE ?
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The FPM reprensents the velocity vector, in other words this is where the AC is flying to , taking into account wind and turbulence or even beta side slip : DO YOU AGREE ?
1 + 2 = to fly over the physical waypoint location , the FPM SHALL be aligned with the DIAMOND
the GCSC is the marker line on the heading tape, correct ? (i think it is , i am no specialist here with acronyms)
to me the GCSC shall indicat the heading where the noze shall be put in order that the FPM be align with diamond, simply because when there is a lot of drift , fpm can not be seen , so the only way to know is to indicate the pilot the heading relatively to the NOZE => GCSC
so in your picture the GCSC should be around 29 / 30 (i.e. on the right…) and pilot should align his noze to it
according to my memories , this is exactly what BMS does and i dont understand how it could work otherwise ?
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JP : the issue is that when you align the tadpole (“têtard”) inside the FPM, your FPM is not aligned with the waypoint, the nose is.
Edit : that is what you meant with GCSC, Blu3wolf, right ? Because I couldnt find this acronym in the Dash-1. For me it is always called the tadpole.
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JP : the issue is that when you align the tadpole (“têtard”) inside the FPM, your FPM is not aligned with the waypoint, the nose is.
Edit : that is what you meant with GCSC, Blu3wolf, right ? Because I couldnt find this acronym in the Dash-1. For me it is always called the tadpole.
haaa…if GCSC is the tadpole i.e. the small circle in the hud etc…then there is indeed a bug…when correct heading is taken , diamond , tadpole and fpm shall be aligned and the indicator on the heading tape shall indicate the nose heading then (because you can’t see neither fpm, tadpole or diamond in extreme situations).
=> Bugtracker
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To take wind into account just align fpm and diamond
Real pilot to confirm
Correct … and in this pic: https://www.benchmarksims.org/forum/attachment.php?attachmentid=15748&d=1365459294
… if the pilot maintain present HEADING, he will not (should not) overfly the way point but pass left of it. So basicaly, according to the pic, the Tadpole isn’t guiding the jet on the waypoint (track) but just give a steering cue to put the nose on it (heading)
No more Falcon on my computers, so I can’t try, but will do it as soon as I have it back.
I think it is the way it is working in real. The GCSC does not take wind
I am not sure. (?) IMO, the tadpole should work as a flight director in “direct to” mode. (need to be crosschecked in -34)
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Correct … and in this pic: https://www.benchmarksims.org/forum/attachment.php?attachmentid=15748&d=1365459294
… if the pilot maintain present HEADING, he will not (should not) overfly the way point but pass left of it. So basicaly, according to the pic, the Tadpole isn’t guiding the jet on the waypoint (track) but just give a steering cue to put the nose on it (heading)
No more Falcon on my computers, so I can’t try, but will do it as soon as I have it back.
I am not sure. (?) IMO, the tadpole should work as a flight director in “direct to” mode.
TBH DJ what you are saying has no sense.
tadpole should guide the AC to the waypoint !!! so when everything is fine tadpole / fpm and diamond aligned.
else tadpole is useless:!
BUG for me
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Looks good to me. strong crosswind (29 knots from the right (28 degrees off)) ‘blows’ the fpm to the left. the tadpole is inclined to the right (1pixel - hard to see) and indicates that the direction needs to be adjusted.
or does puting the fpm over the tadpole always (crosswind???) lead to the steerpoint in the real jet?
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The fact that the tadpole is on the same level as the FPM, and not the guncross for example, is in JP’s favor, IMO.
The tadpole should be an indicator of where to go to overfly the waypoint : ie, putting the FPM on it means you are goind directly toward the waypoint regardless of drift and where is your nose pointed at.