Bullseye
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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.
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@jc1:
When setting up a TE and you right-click on the map, what is the option “Set Bullseye” for?
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.
Thanks. Now why would you change STPT 25?
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IRL, you do not have only one bulls on a combat theater. On a theater like the North Korea, I can easily imagine 10 to 20 different bulls.
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…what Dee-Jay says…+1.
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IRL, you do not have only one bulls on a combat theater. On a theater like the North Korea, I can easily imagine 10 to 20 different bulls.
…what Dee-Jay says…+1.
@jc1:
Thanks. Now why would you change STPT 25?
In real life, how are the bullsyes distinguished from one another? In BMS, if I set a new bullseye, does the FCR and HSD depict the original Kaesong bullseye and the new bullseye? Also in BMS, why set a new bullseye if AWACS doesn’t know it?
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By coded name I would think.
No, if you move STPT 25 then in-cockpit display moves BZ indication to new 25 position.
AI do know new BZ location… if you set it in 2D map.