Bullseye
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Only when you are using it fly directly to this TACAN aiming an overfly (which should be relatively rare, because usually you should aim a given radial and distance to join a point given in approach plate). But when you use it to know your location you are working FROM and read the tail of the needle.
So it is only confusing for ppl how are not used to use the TACAN for its 2nd primary function which it “localization” of own ship.
Yes - if you’re on a missed approach back-course then you might find yourself using “FROM” sensing…or if ATC tells you to fly “outbound, 250 from Kxyz TACAN” then you might dial up a “FROM”. Or handing off between stations…I’ve found myself in such situations in RL - I used to overfly VORTACS and fly outbound quite a bit between stations. As I’ve flown about the USA I’ve found that depending on where you are in the country (west vs farther east) one navigation technique may be preferred over another - I learned out west…where signals are much stronger, for some reason. So I was spoiled when I moved east…
What I really like using to fix position is RNAV…“move” the station, and then use you secondary radio to tune a crossing radial - if you’re on course you always have a fix…using just one station. If you work the geometry right in selecting stations.
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Not directly. What you can use that may be helpful, is the B/E marker. There is a pointer on the B/E marker, which points in the direction of B/E. So if you are B/E 180/20 miles, and the marker is pointing down on the display (behind you) then you are facing south.
Once you get used to using bullseye, I find that you just keep track of which way you are going (there is a heading tape in the HUD which helps a lot) and what your current B/E is. In particular for air ops, I tend to take note of the fight axis, so that I know which way to head out (180 degrees from the fight axis) and which way to recommit after an out maneuver. I also tend to spend a lot of time checking back and forth between the FCR and HSD, so the FCR not having a north marker doesnt hurt too badly.
What I’m mainly looking for is a faster intuitive way to know which way to turn to a bogey call at “bull xxx at yy” without having to do math in my head…right now I tend to level-s to figure it…but now that I think, I should/could probably just slew my cursors left/right and observe the heading closure in the same manner…then execute my turn.
Once I have my pit built I’ll also have my EHSI to glance at…that will really help.
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Cant help much with that. I dont do math, but I just sorta “get it” for those calls. Im BE 130/40 miles, I get a call “BANDSAW, SINGLE GROUP BE 240/30 MILES, 23 THOUSAND HOSTILE TRACK SOUTH” and I just guesstimate really. Id turn and head west. Mentally, I plot me from BE on a polar graph, and the other guy from BE on the same graph, and graphically subtract my vector from his. No numbers so its a rough guess, but it works fairly quickly to get a heading and range estimate. When Im roughly in the right direction, the FCR cursors give me actual numbers that I can match to the contacts.
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Fastest, most intuitive way is mental picture from two BZ points. It’s not math as a picture to very rough results. Quick what is BZ 289 75 from BZ 013 166? West 75 from North 150, South South West for 200 miles (distance going to be between 166 and 166+75, so ~200).
How close is that? 172 at 219°. Close enough to point at it. More precise? That’s a plotting board (GIS “maneuvering board”) or the pencil trick with the HSI but that’s mucho slower. It’s the kind of tricks developed for what’s known as point to point navigation around VORs and TACANs.
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What I’m mainly looking for is a faster intuitive way to know which way to turn to a bogey call at “bull xxx at yy” without having to do math in my head…right now I tend to level-s to figure it…but now that I think, I should/could probably just slew my cursors left/right and observe the heading closure in the same manner…then execute my turn.
…
This website has a way: www.combatsim.com/htm/aug99/bullseye2.htm It gives guidance as to when to turn left or turn right, and how much left or right. But the table shown in the website is only for a bandit with a maximum difference in bullseye distance of 20 miles. I don’t know how the table was calculated.
Cant help much with that. I dont do math, …
OK, I’ll ask Frederf.
… More precise? That’s a plotting board (GIS “maneuvering board”)…
Could you calculate the table for distances like 30 miles, 40 miles etc? Better yet, what would be the mathematical formula?
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Vector subtraction is the way to do it with math. If your position is vector A, and his position is vector B, then his position relative to your own is B - A.
This is simple trigonometry, although I confess my mental maths does not extend to trig. I will do simple arithmetic in my head for speed/distance/time calcs, but trig I rely on a calculator for. Sometimes, a graphical calculator like a whiz wheel, suffices.
More interesting would be calculation of the collision bearing, but the jet will do that for you if you bug the contact, by displaying the CATA symbol.
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For bandit B/E theta/x, and my B/E gamma/y, then we can draw a triangle with B/E at one point, the bandit position vector A along bearing theta, x miles from B/E, and my position vector B along bearing gamma, y miles from B/E. If we label the sides of this triangle, with the bandits side being labeled a and of length x, my side being labeled b and of length y, and the resultant being labeled c (and being vector C) and its length being the distance between our aircraft. We can call that z.
We know both theta and gamma. The difference between them is the angle of the triangle between lines a and b. We know the length of both a and b (x and y respectively). Knowing an angle and the two lengths adjacent that angle, high school trig tells me that we can apply the Cosine Rule to determine the length opposite the known angle, which is z. z^2 = x^2 + y^2 - 2xy*cos(| theta - gamma |)
We know range now. We can also determine the bearing to travel on using the Sine rule, knowing an angle and two lengths, one of them opposite the angle. Using the same notation as prior, note that aleph is the absolute value of the difference between theta and gamma, delta is the final intercept heading, and omega is the absolute value of the difference between delta and the reciprocal heading of gamma (the reciprocal heading of gamma being between 0 and 360 and having a HCA of 180 from gamma). We know that sin(aleph) / z = sin(omega) / x, and that multiplying both sides of that equation by x gives us xsin(aleph)/z = sin(omega) and it follows that arcsin(xsin(aleph)/z) = omega. Omega + the reciprocal heading of gamma (direction from you to the bullseye) = delta, the final intercept heading.
Of course, I find it a lot quicker and fluid to just guesstimate based on a mental image of bullseye, than to do this just after being given a commit by AWACS.
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If you divvy it up into some right angled triangles, you can do it with simpler trig again. If you determine some component of the bandits position vector that lies along the same bearing as your position vector, you can work out a resultant intercept heading just using right angled triangle trig - SOHCAHTOA rules. Simpler math, more calculations. Maths being what it is, there is probably easier ways of doing it, too.
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Yes, it’s vector subtraction at heart. The given is ownship and target relative from bullseye which is a third position that is not either ownship nor target. What you want is relative position of target from ownship. We realize this is easy if we are at the center of our measurement scheme so we imagine a new bullseye (for fun I’ll call it cow’s eye) such that we are always Cowseye 0/0. What we want is Cowseye to target which comes in two steps: We chain together vector by adding “-A” (from us to BZ, i.e. negative our BZ) and “B” (target BZ) which gives vector direct from us to target.
Do pilots actually do this mentally? Maybe. I don’t. I tend to imagine the plotting board in front of me and very roughly position both objects in front of me and imagine the arrow from me to it. The most exact I would expect while in flight (and probably behind a desk too) is drawing it out paper and pencil. Exact math would be breaking each vector down into horizontal and vertical components and adding -Ax to Bx and -Ay to By and then constructing the resultant out of those two horizontal and vertical sums. A graph is nearly impossible as it’s a 4-input 1-output function which requires very expensive paper. It can be compacted into a sheet of more affordable paper by changing the two ranges into a ratio of ranges (my range divided by target range) and the two angles into the measure from one and the other. That’s a 2-input 1-output function but requires some more math to make use of the 2 outputs. A graph of direction vs these inputs is not a pretty thing and unusable to be followed with a fingertip in the air.
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I did this:
http://i1276.photobucket.com/albums/y477/ASharpe/101_0296_zps572dae3a.jpg
If you look carefully, there’s a transparency there with a Bullseye drawn on it (on the backside) with permanent marker. Before flight, I check the Bullseye location and then draw my flight plan (roughly to scale) on the Bullseye transparency over the map. Now, when I get a bearing relative to bullseye, I just drop a dot on the map with a dry erase marker. And, by knowing what steerpoint I am at/heading towards/flying from I can easily see the relative position of the contact.
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After just reading this its made me think. When i get a vector to threat reading from AWACS, it looks easier to find that threat using the HSD rather than the FCR. I dunno, what do you guys do when finding a threat in relation to bullseye? do you just use your FCR cursor?
Good Day, CNS.
Using Bullseye gets better with practice. For me at least, whether to use FCR or HSD depends on where I’m at in the mission. If I’m ingressing and want an overview, I like to use the HSD so I can see where the threat is in relation to my flight path. Once in closer I switch over the the FCR as SOI. -
I was trying out the Bullseye Trainer ( http://www.185th.co.uk/squad_info/training/basic_n&b.htm ) the other day. It goes way too fast for me (you have to understand ownship position, heading, bandit position, and then decide what action in what sector) even on the easy setting. But it makes a great random number generator to practice. I got pretty good at looking at the BZ+heading information and putting my fingers up in the air around an imaginary BZ point facing the right way even after 10-15 min of practice. On my more ambitious runs I got 1-2 correct maneuver responses in a row.
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Cant help much with that. I dont do math, but I just sorta “get it” for those calls. Im BE 130/40 miles, I get a call “BANDSAW, SINGLE GROUP BE 240/30 MILES, 23 THOUSAND HOSTILE TRACK SOUTH” and I just guesstimate really. Id turn and head west. Mentally, I plot me from BE on a polar graph, and the other guy from BE on the same graph, and graphically subtract my vector from his. No numbers so its a rough guess, but it works fairly quickly to get a heading and range estimate. When Im roughly in the right direction, the FCR cursors give me actual numbers that I can match to the contacts.
That’s what I’m looking to get to…I know there’s a way to look at the display and just “get it”…I haven’t gotten there yet. I’ve gotten close, when I’m head down and can cross-check the compass rose on the HSI…so I’m anticipating things getting far easier once my pit is built. I have the EHSI from Pegasus, and it’s a gem.
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Fastest, most intuitive way is mental picture from two BZ points. It’s not math as a picture to very rough results. Quick what is BZ 289 75 from BZ 013 166? West 75 from North 150, South South West for 200 miles (distance going to be between 166 and 166+75, so ~200).
How close is that? 172 at 219°. Close enough to point at it. More precise? That’s a plotting board (GIS “maneuvering board”) or the pencil trick with the HSI but that’s mucho slower. It’s the kind of tricks developed for what’s known as point to point navigation around VORs and TACANs.
That’s all I want to know, which way to point. Once I get scan volume on then I know where/how to steer - for that I only need to figure heading/“radial” diff and which direction gets directed to target quickest - I don’t really have to care about distance for that. My problem is that I can’t see the entire pit…and I’m purposely not desk flying just now so I don’t re-train my scan discipline. I’m building a full pit - once I have that done I expect it all to get easier.
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I did this:
http://i1276.photobucket.com/albums/y477/ASharpe/101_0296_zps572dae3a.jpg
If you look carefully, there’s a transparency there with a Bullseye drawn on it (on the backside) with permanent marker. Before flight, I check the Bullseye location and then draw my flight plan (roughly to scale) on the Bullseye transparency over the map. Now, when I get a bearing relative to bullseye, I just drop a dot on the map with a dry erase marker. And, by knowing what steerpoint I am at/heading towards/flying from I can easily see the relative position of the contact.
YES - I have seen pilots use this in RL…and it’s what I use mentally, and why having the HSI in my scan is such a big help. I just imagine bull at the center of the HSI instead of the airplane and cross-check the HSD - this gives me an actual visual picture I can figure my turn direction from. I don’t care about distance until I’ve competed my turn and am on the ingress - I just want to know which way to turn to get there quickest. Having both the HSI and HSD to look at together does it for me.
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I was trying out the Bullseye Trainer ( http://www.185th.co.uk/squad_info/training/basic_n&b.htm ) the other day. It goes way too fast for me (you have to understand ownship position, heading, bandit position, and then decide what action in what sector) even on the easy setting. But it makes a great random number generator to practice. I got pretty good at looking at the BZ+heading information and putting my fingers up in the air around an imaginary BZ point facing the right way even after 10-15 min of practice. On my more ambitious runs I got 1-2 correct maneuver responses in a row.
Cant help much with that. I dont do math, but I just sorta “get it” for those calls. Im BE 130/40 miles, I get a call “BANDSAW, SINGLE GROUP BE 240/30 MILES, 23 THOUSAND HOSTILE TRACK SOUTH” and I just guesstimate really. Id turn and head west. Mentally, I plot me from BE on a polar graph, and the other guy from BE on the same graph, and graphically subtract my vector from his. No numbers so its a rough guess, but it works fairly quickly to get a heading and range estimate. When Im roughly in the right direction, the FCR cursors give me actual numbers that I can match to the contacts.
My original question at post #31 of this thread had to do with asking for a mathematical solution to creating tables for distances from ownship to target greater than 20 miles, as described in www.combatsim.com/htm/aug99/bullseye2.htm. My question was never answered (but I did appreciate the work you two guys did in response). Anyway, the description of the Bullseye Trainer described how a bullseye drawn on a piece of plastic could eliminate complex mathematical calculations when the distance was greater than 20 miles. Bullseye Trainer looks like a good tool to get good at making use of the bullseye in Falcon.
Thanks for this Fix to Fix description. It is also shown in a BMS Falcon 4 video by John Giannellis at
, beginning at 3:20. -
Besides mental training, for quick in-cockpit orientation, I use one of the available HSD lines to paint a N/S and E/W cross.
when the BE is visible on HSD,
it improves my general SA about where a given BE position.Disregard the line you see on top of the HSD. Normally, when I use positions close to the map borders to draw the line, that to line is not visible on HSD.
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VERY nice idea!!!
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When setting up a TE and you right-click on the map, what is the option “Set Bullseye” for?
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You can move it around (same in campaign). BZ is also set by STPT 25 position in the avionics. Of course if you change your STPT 25 position the AI will continue to refer to the old true BZ position but your displays will reference the other place.