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How does a fighter jet lock onto and keep track of an enemy aircraft? (2013)

251 points| KhalilK | 11 years ago |gizmodo.com | reply

85 comments

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[+] reduce|11 years ago|reply
The system has not performed "a lock on the target", at least not in the way that the language leads you to believe. The tool is making a prediction, that within a certain level of confidence, and given the present parameters, that firing the missile will result in the neutralization of the target.

There's growing number of ways, both active and passive, that targets can be tracked or future positions predicted. One of the answers on that page hints at this, the other answer is misleading and often not how it's done in many modern systems.

Source: engineered parts of these systems before.

[+] berkut|11 years ago|reply
The radar and weapon control systems are "locked on" to from the aircraft's perspective - I don't really understand what you're talking about...

A particular target has been identified, it is being tracked (maybe at the expense of scanning for other targets if its an older system, probably with track-while-scan otherwise), and based on this updates are being sent to the missile in order to control its initial trajectory when it gets launched to point it in the correct direction.

[+] ufmace|11 years ago|reply
Related anecdote - I worked with a coder a while back who was a naval aviator before he went back to school, flying carrier-based transports. I asked him once about whether he would have wanted to fly fighters instead, and he said that just flying transports was already a huge amount of work, as far as flight plans, training, practice, and such. Flying fighters apparently involved doing all of that same work, plus a bunch more for weapons, tactics, etc, so those guys never had any free time. Apparently, flying fighters wasn't nearly as fun as it sounds.
[+] demallien|11 years ago|reply
On the other hand, when you're the engineer maintaining the flight sims for the pilots, boy oh boy can you have fun in those machines :) I've logged over 100 hours on the F-18, and 20 for the F-111. Never got to experience those long high G turns though...
[+] bkohlmann|11 years ago|reply
believe me, flying fighters really is as much fun as it sounds. It is more work than the transport guys, but you get out what you put in. its all worth it coming in for a 450 knot overhead at 600', pulling six g's in the break, then catching the three-wire aboard the carrier.
[+] AceJohnny2|11 years ago|reply
> Apparently, flying fighters wasn't nearly as fun as it sounds.

Hm. I figure the glory you get from being a fighter pilot is one of the perks, so they might as well milk that for all it's worth.

My point is that it's interesting to note the professions that seem more glorious than they actually are, and beware those who sell themselves or the job based on that glory: it's an illusion.

[+] IgorPartola|11 years ago|reply
So why don't they include two radars, one for sweeps and one for tracking? I know, I know, weight, power, etc. At the same time, isn't that the obvious answer?
[+] _djo_|11 years ago|reply
No space. Take a look at this image, it's the standard AN/APG-63 on an F-15C fighter aircraft: http://commons.wikimedia.org/wiki/File:APG-63_radar_of_F-15_...

Note how the radar's processing units and dish take up the entirety of the aircraft's nose and how large the system is compared to the technician working on it. There simply isn't enough space to add another radar.

Nor would it make sense to split that into two smaller radars, as the size of the dish and processing units is strongly linked to its power and range. That's one reason larger aircraft like the F-15, F-14 and Su-27 have longer-ranged and more powerful radars than smaller fighter aircraft.

This track vs scan limitation is removed by Active Electronically Scanned Array (AESA) radars such as this AN/APG-63(V)2 retrofitted to a USAF F-15C: http://www.pacaf.af.mil/shared/media/photodb/photos/070720-F...

Rather than having a mechanically-slaved reflective dish, an AESA radar has hundreds of Transmit/Receive Modules (TRMs) each capable of acting like a tiny radar dish by transmitting or receiving on its own frequency and being steered its own direction.

So now, rather than having the radar dish jump between track and scan at rapid intervals, the system can just dedicate a few hundred of the AESA TRMs to tracking one or more targets while letting the remainder continue sweeping the skies. There's no limitation on azimuth because each TRM can be individually steered.

So in short, the answer is that the latest fighter aircraft don't have two radars, they have hundreds or thousands of tiny radars that can work together in a whole bunch of useful combinations.

Edit: Replaced initial image with a Wiki Commons link that doesn't have linking issues.

[+] theoh|11 years ago|reply
How is it an obvious solution if it is not practical? The electronically-scanned radars mentioned in the second answer can easily divide their time between the tasks (no mechanically-constrained dish to sweep) but there is definitely no space for two radar systems in the nose of a fighter.
[+] OldSchool|11 years ago|reply
Hmmm, I was kind of hoping for an explanation of how the control system determines how to modify the highly directional antenna's orientation to continue to maximally "illuminate" the target once it's been selected from a general scan.

Can anyone describe the solution to this?

Example idea: Once selected for "lock," the antenna scans in small circles and migrates its central point toward the point on the scanned circle that provides the strongest return, allowing for variation due to noise sources.

[+] ChuckMcM|11 years ago|reply
There is a book on it[1]. But suffice it to say that the radar is computing an "exit vector" when the target it moving away from center and applying a correction to the pointer. I built a similar system with LEDs when building a tracking system for two moving robots. In my case I used a parabolic dish (a solar cigarette lighter) and a line of LEDs (bar graph display) as detectors rather than lights. Since the target robot and the pursuing robot had their beacon and search dish in the same plane I could reduce the problem to a managable bit of 2D geometry. As the signal went off axis you could turn the robot to re-align by applying the opposite rotation.

[1] "Multiple Target Tracking with Radar Applications" - Sam Blackman (http://books.google.com/books?id=Ag9TAAAAMAAJ&q=tracking+mul...)

[+] toomuchtodo|11 years ago|reply
Are you asking if the antenna gets moved to illuminate the target once acquired? I apologize if I misunderstood. If that's the case, the antenna is a solid state phased array; no movement is required. Mobile communications (cellular and satellite) spot beams work under the same principal.

http://www.northropgrumman.com/Capabilities/MESA/Documents/a...

[+] ibisum|11 years ago|reply
Upon reading of RWR and its delights, at least one part of me, the techno-dweeb, goes "weeeh!" ..

Another part, more of a hippy tree-hugger, goes "wish we were using this to figure out where to drop the water/medicine/books instead of BOOMB devices" ..

I mean, seriously. Tell us where to drop the books, and BOOM there it is: how it should be.

[+] Someone1234|11 years ago|reply
Good response, worth the read. Heck the response alone could justify their own article.

As an aside: I hate quora' site design so much I have blacklisted it using Google Personal Blocklist. Somehow I dislike it more than Experts Exchange (which is also blacklisted), it is just super cluttered with nonsense, rolls into the comments section without warning and rarely offers good content (see Experts Exchange again).

That being said Yahoo! Answers also rarely has good content but at least with Yahoo! Answers you can determine that with a glance. You visit the page and you can see the answer (or lack of answer). So Yahoo! Answers remains in my search results, Quora and Expert Exchange have been vanished indefinitely.

PS - Quora also likes to spawn pop ups whenever you click anywhere on the page for no real reason (just asks for your Quora login details). For someone who randomly highlights blocks of text while reading this is pure hell...

[+] click170|11 years ago|reply
I remember you used to see experts exchange or the like come up in search results and you could block it right there, in your search results without having to go to a separate page. Since they've hidden it, I honestly thought they'd removed the ability to block websites. Thanks for letting me know I just have to hunt for it.

I wonder why they removed that option from search results?

[+] w1ntermute|11 years ago|reply
> Somehow I dislike it more than Experts Exchange

Someone needs to make a Stack Overflow to Quora's Experts Exchange (preferably by just using the Stack Overflow codebase/framework).

[+] sanderjd|11 years ago|reply
Which part is the nonsense? The stuff on the sides? What do you mean by "rolls into the comments section without warning"? (Honestly curious.)

I think the content is often pretty good! YMMV I guess.

[+] smegel|11 years ago|reply
> That being said Yahoo! Answers also rarely has good content

I would go even further and say it is the spiritual successor to YouTube comments before they were G-plussed.

[+] dangelo|11 years ago|reply
FWIW the "spawn pop ups whenever you click anywhere on the page" was a bug that was fixed.
[+] nether|11 years ago|reply
Holy shit, without fail the top comment on a Quora story is a rant about their design. Get over it. Don't click if you don't like it.
[+] AYBABTME|11 years ago|reply
This was a great read until I reached the truncated bottom of the post.

God I hate Quora. There's the `share=1` flag but still, the end of the article is truncated and you're asked to login.

Quora wouldn't piss me off so much if they were not so annoying about me logging in and linking a social account, if they didn't post crap from my friend's facebook account who do have an account, send me spam about whatever people I know might have done (or not done) on their platform.

This is trying to gather users by pissing them off. Likely I'd have created an account since if it weren't for their aggressive behavior.

[+] KhalilK|11 years ago|reply
That's odd. On the page with the signup box look for the id "__w2_LG4FatW_modal_signup_wrapper" and delete the whole div, that'll get rid of the box allowing to you to continue reading the top answer but not the others.
[+] krat0sprakhar|11 years ago|reply
Off Topic: Man! Reading this answer so makes me want to play those FlightSim games of the yesteryears like Apache Havoc, Commanche, Jane's F/A 18 Hornet etc etc. Does anyone have any suggestions for a modern Flight Sim game? Thanks!
[+] serf|11 years ago|reply
I don't know much about combat sims, but I have a blast with X-Plane. It's highly realistic and can practically scale to any performance computer. It has some combat-sim aspects, but I haven't played with that stuff enough to comment. Flying is tough enough for me without the weapons ;)
[+] shiftpgdn|11 years ago|reply
GOG.com has most of those games with a modern windows installer. They're still good fun. :)
[+] jameshart|11 years ago|reply
Fully expecting flightsims to make a glorious comeback with Oculus' full availability. It is too well suited to games which require you to sit still, and have your hands on controls.

Time to buy shares in joystick manufacturers.

[+] wtracy|11 years ago|reply
If you want something Free/Open Source to mess around with, try GL-117 (your distro probably has a package for it): http://www.heptargon.de/gl-117/gl-117.html

It doesn't compare well to the modern commercial flight simulators in terms of graphics or realism, but it's still a good time. :-)

[+] dsl|11 years ago|reply
http://en.wikipedia.org/wiki/Falcon_4.0

Falcon 4.0 is nothing short of amazing. It has been under non-stop development by the official developers and the community (thanks to a source code leak) since 1984.

Many of the community developers are former pilots and avionics techs.

[+] ibisum|11 years ago|reply
I probably ratched up 100 hours or more on F-117 Steal Bomber, for DOS, back in the day. There is no reason not to play it even now, still today: consider the pixelation more of a consequence of "HUD"/"IFR" and be done with it. Fact is, those old games still run, and still work for simulating the death cult and its machines ..
[+] hammock|11 years ago|reply
Ever play EF2000? It's not a modern one but it's an older realistic one that I remember fondly. That and Echelon (not realistic)
[+] vmp|11 years ago|reply
Lock On! used to be a favorite of mine, no idea how well it runs on modern OS'es.
[+] chollida1|11 years ago|reply
Meta Note

I'm not sure if its the software or the OP who added the "?share=1" parameter but thank you for including it in the link.

The flag makes reading quora possible. If HN doesn't add this parameter by default I think it would be a worth while upgrade to the site.

Lots of great content is locked in quora otherwise.

[+] KhalilK|11 years ago|reply
OP here. I've added it manually, been using that 'trick' for quite some time to get around their "social" integration.
[+] serf|11 years ago|reply
shared (share button'd) quora links add the parameter. copy-pasted hard-links don't.

quora defends the design by saying that it's their way of piping user-specific content.

I agree, it's super irritating and results in information being locked for those that don't know how to go around it.

[+] ufmace|11 years ago|reply
What does it normally do? I gave up and created a Quora account a while back. Even on Incognito, though, hitting the link without the share on it looks normal and doesn't do anything particularly annoying.
[+] readerrrr|11 years ago|reply
Since quora has problems in the money department, how is their competitor Stack Exchange maintaining profit?
[+] hueving|11 years ago|reply
Is there any way to view the rest of the answer hidden behind the "more" link without signing up for an account?
[+] Rapzid|11 years ago|reply
Interesting(I didn't read the whole article because I'm not logging into Quora). I wonder what the state of the art is? Certainly we have tech now to get all the info on all the aircrafts? I would think that software could be employed to fill in the gaps and extrapolate the info at the least. What with 3d video tracking and the like at the levels they are at today.