Target heading on MFD
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Dear all,
I am learning target geometry using radar.
In my knowledge, when I lock target, the target aspect angle and heading are shown on the left upper position on MFD.
I made single mission for training. My training partner is B52 heading from east to west, heading of 255.
I checked this in ACMI. But When I locked this shown in 270.
Is there uncertainty to measure the target heading? The difference is so large 15 degs to me.
I attached the screenshot.
I headed to ~255 and the target aspect angle 0 meaning but the target heading on MFD is 270, not ~255 degs.If you need ACMI file, I could upload it.
Thanks,
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The screenshot is 258. I wonder how possible it is that the aircraft ahead is at say 261? The display is only accurate to the nearest ten degrees, so it should be showing 260, not 270. Could be a code bug? i.e. if above 260 read 270, instead of if above 265 read 270?
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Isn’t it true course instead of magnetic heading? I’m sure it’s track and not heading. And I think it’s the nearest 15°.
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Isn’t it true course instead of magnetic heading? I’m sure it’s track and not heading. And I think it’s the nearest 15°.
its supposed to be magnetic ground track, to the nearest 10°. Whether thats the case in BMS, who knows.
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When I look the real dash 34 manual, it says, Blu3wolf mentioned, it is magnetic ground track.
Does it mean the track on magnetic north?.
For me to get true heading of target, do I need to correct the value? true heading = magnetic heading + ?? degs
How much correction do I get? In this example shows 270=258+12. 12 degs correction value.And I am curious that the compass is influenced on magnetic north and when I looked the compass at the same situation, the heading reads ~258.
I attached three figures. One is compass heading in that situation.
Others are true headings of mine and B52. It can be seen in the external view.
Three indicate 258 degs.
If the magnetic north is implemented in BMS, why does the compass heading indicate the true heading?Thanks,
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There is no such things in BMS
There is no variation, there is no deviation
All headings are relevant to the same North
The North in BMS. Call it any way you like (I’d call it BMS North or Sim North)
Because it’s not true, it’s not magnetic, it’s not compass. -
How much correction do I get? In this example shows 270=258+12. 12 degs correction value.
To the nearest 10°, remember. So that is more like 258 + 12 ± 5.
If the magnetic north is implemented in BMS, why does the compass heading indicate the true heading?
If indeed. I thought BMS had only one north, and all sensors use that. Which is why I did not bring up magnetic heading in my original response.
@Red:
There is no such things in BMS
There is no variation, there is no deviation
All headings are relevant to the same North
The North in BMS. Call it any way you like (I’d call it BMS North or Sim North)
Because it’s not true, it’s not magnetic, it’s not compass.Well, that clears that up. It does still raise the question of why the FCR displays 270 when it should display 260.
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Wind?
difference between Course and track?
Really not sure, thinking out loud.Maybe it would help to get the same screenshot with the wind in the DED and with the ASEC displayed too
Red Dog
Reality if for ppl who can't handle simulation -
Well, that clears that up. It does still raise the question of why the FCR displays 270 when it should display 260.
I don’t know for sure, but I would hazard a guess that a certain degree of error has to be allowed for. I imagine a radar can only make a “best guess” of a heading based on speeds at which it receives returns, etc. Even variable windspeed can introduce drifts which cannot be completely accounted for. If we’re being honest, an error of 10 degrees when running, for example, an intercept won’t be a big deal in the grand scheme of things.
Just my £0.02
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I don’t know for sure, but I would hazard a guess that a certain degree of error has to be allowed for. I imagine a radar can only make a “best guess” of a heading based on speeds at which it receives returns, etc. Even variable windspeed can introduce drifts which cannot be completely accounted for. If we’re being honest, an error of 10 degrees when running, for example, an intercept won’t be a big deal in the grand scheme of things.
Takes only a couple seconds to upgrade a track from position only information to acceleration information. Heading depends on velocity information, which is quite reliable.
Being honest, an error of 10 degrees can make a pretty big deal.
@Red:
Wind?
difference between Course and track?
Really not sure, thinking out loud.Maybe it would help to get the same screenshot with the wind in the DED and with the ASEC displayed too
We can already determine the wind in that screenshot. We know the airspeed, and we know the heading and track. And we can tell from the small deflection of the FPM from the AC heading, that it isnt a 10° difference.
Im sorta used to course and track being synonyms. Perhaps you meant the difference between track and heading? In the screenshot, we can see the aircraft are closely aligned in heading. Both aircraft are close, so if they are stabilised relative to one another they share a common track too.
Warrants testing anyway. Good catch Mack97.
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This topic reminds me of the missing degree symbol right next to the target heading to make it more intuitive as well as replicate the real jet.
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Being honest, an error of 10 degrees can make a pretty big deal.
Well, yes, perhaps, but surely if you were flying an intercept and had closed to any kind of range as depicted in the first post, you’ll have long since dropped the radar info in favour of visual cues and backed up by HUD feedback?
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Im sorta used to course and track being synonyms. Perhaps you meant the difference between track and heading? In the screenshot, we can see the aircraft are closely aligned in heading. Both aircraft are close, so if they are stabilised relative to one another they share a common track too.
Yep you’re right, I meant CAP and ROUTE, hence heading and track. Forgive my french
That said you can’t determine wind, at least NOT precisely. You might be able to guess estimate it. But if you look at that picture you can also see that the B-52 is crabbing. So they are not aligned in heading - They might be in track. After all a B-52 should be more prone to drift than a F-16
The added info I suggested will certainly rule out the possibility or not. Which is better than a guessRed Dog
Reality if for ppl who can't handle simulation -
Dear all,
Ok, I prepared without wind.
I tested again, the result is
The target heading is 259 degs.
MFD shows 270degs.
I attached cockpit, external views before and after merge.I also uploaded acmi file, https://drive.google.com/open?id=0B_PAbMP9vVw8ZHBuTlZyek14Umc
Another strange thing is that Tacview shows the heading of me and target are 256.2 degs.Thanks,
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This topic reminds me of the missing degree symbol right next to the target heading to make it more intuitive as well as replicate the real jet.
Interesting. All the diagrams Ive seen of the FCR also miss the degree symbol. Which real jet has the degree symbol there?
EDIT: More interesting. Ive checked some more and it seems to depend on which page the diagram is on, as to whether it has the ° symbol or not. Seems like that might warrant investigation.
@Red:
That said you can’t determine wind, at least NOT precisely. You might be able to guess estimate it. But if you look at that picture you can also see that the B-52 is crabbing. So they are not aligned in heading - They might be in track. After all a B-52 should be more prone to drift than a F-16
A B-52 should be exactly as prone to drift as an F-16, actually. If they are flying at the same airspeed, in the same wind conditions, they will both have the same ground speed. And after 60 miles, they will both have the same drift.
Using vector trigonometry, we can calculate the wind, to a value as precise as our inputs. Our heading is precise to the nearest degree, and our track is precise to within ± 1 degree. If we know our airspeed (we do), we can calculate windspeed as well.
Though its certainly possible to rule it out as mack97 has just done.
Well, yes, perhaps, but surely if you were flying an intercept and had closed to any kind of range as depicted in the first post, you’ll have long since dropped the radar info in favour of visual cues and backed up by HUD feedback?
Well yes, by the time you have that particular sight picture the intercept is already over. Point is, 10 degrees difference between what is shown and what is supposed to be shown is not insignificant, just minor.
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A B-52 should be exactly as prone to drift as an F-16, actually. If they are flying at the same airspeed, in the same wind conditions, they will both have the same ground speed. And after 60 miles, they will both have the same drift.
go back to the first pictures (the example with wind) and tell me if these guys have the same speed?
And in a normal scenario who usually flies fastest? the fighter or the big fat bomber?Using vector trigonometry, we can calculate the wind, to a value as precise as our inputs. Our heading is precise to the nearest degree, and our track is precise to within ± 1 degree. If we know our airspeed (we do), we can calculate windspeed as well.
thank you for stating the ovbious - I have a flight computer as well you know
But once again, we are talking a very specific example where you don’t have the data to calculate all that. You have headings & IAS from the picture but you don’t have drift angle, thus you don’t have track and GS - and you don’t have winds.
So you talk theory but you can’t give me the precise wind to the nearest degree calculated from the first screenshots - just like I said
Hence why I suggested to redo the same with the wind displayed to rule out the possibility, which Mack did and reports still the same discrepancy. So that ruled out the wind didn’t it?
So that discussion has run it’s courseWe’re discussing a given example trying to make sense of a discrepancy and you either use specific exception or general theoric calculation method when all data are known
Both are irrelevant to the example we’re discussing because in both case you can’t solve the problem exposed with the data at your disposal
you’re just blowing into the windsRed Dog
Reality if for ppl who can't handle simulation -
@Red:
go back to the first pictures (the example with wind) and tell me if these guys have the same speed?
And in a normal scenario who usually flies fastest? the fighter or the big fat bomber?But once again, we are talking a very specific example where you don’t have the data to calculate all that. You have headings & IAS from the picture but you don’t have drift angle, thus you don’t have track and GS - and you don’t have winds.
So you talk theory but you can’t give me the precise wind to the nearest degree calculated from the first screenshots - just like I saidAs you are well aware, the two aircraft have a speed difference. If you have an E-6B, you should be quite familiar with how wind works. We have headings and KCAS from the picture (which at this airspeed approximates KIAS to a high degree), and we also have drift angle. The horizontal angular difference between the FPM and the gun cross is our drift angle.
In short, we can solve the problem exposed with the data available, and the correct solution is to confirm that the wind is irrelevant to the issue. Which was confirmed by the follow up post.
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Bug.
Okay. Back to the aeronautical engineering discussions.
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This topic reminds me of the missing degree symbol right next to the target heading to make it more intuitive as well as replicate the real jet.
Me too. That’s one of my little pet peeves with BMS when I’m locked in something that’s heading 240 and going 350 knots or the other way around and someone asks me what his heading is. I have to start doing my FCR/HSD interpretation instead of just noticing the degrees cause I always forget which one is above which OSB lol
