P-61 Gun-Laying Radar
- Thread starter Zipper730
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Token
Senior Airman
AESA has a lot of advantages or potential advantages over other technologies. We could write pages on uses and potential uses for AESA. AESA is not really any more precise than other beam forming technologies, just more adaptable. AESA is also not really any more powerful than other technologies, but because of its building block nature if the goal is high power you can keep adding low power elements together to get whatever power level you want. You can do that with lump power source technologies also (such as adding multiple TWTs to achieve either higher peak power or higher average power), but less flexibly. AESA is not only a radar technology, but rather can be applied anywhere a beam or scan is needed, but it is still (today) primarily radar.
Addressing your statement: I was talking specifically about AESA radar, AESA has the ability to produce multiple simultaneous beams. They can be at different frequencies and looking different directions. So yeah, you can use that to your advantage. However, if talking about a AESA radar it will only do so across a fairly limited (by jammer standards) frequency range. So you can maybe jam or mess with enemy radars or receivers if they are in the same band as your radar.
For radar applications, AESA has an advantage of being able to produce both nulls and beams, simultaneously, in multiple directions. This can make such radars highly jam resistant. In addition to forming the beam you want, pointed in the direction you want, you can place an intentional null where you want it, for example over the bearing of a jammer trying to hit you. Advanced PESA can do this also, but less flexibly.
AESA is the way forward in phased arrays, for whatever application, PESA is probably a dieing branch of the tree. Adaptations of the same technology are the way ECM systems will go (example, Next Generation Jammer), but probably a bit slower than radars themselves. I have worked with both AESA and PESA radars.
But we seem to have wandered rather far afield
T!
- Thread starter
- #244
From what I remember, they said the power output was 250000-387000 times higher (not sure which is right) than the radar the F-94 was based on, or the radar the F-94 used.
It had to do with something said during the YF-12 development, when they were testing the radar: They would have a rotating red light and markings to cordon off the area that the radar would sweep along at. From this particular point, people would sometimes walk across the line not realizing how serious this is. Many of the people seemed unconcerned because "they know radar", but they didn't realize just how much more powerful this particular radar was.
So they ultimately, as a way of ironing home the point, put a 4 x 8 in front of the beam. It was not actively scanning, but after a short period of time a black spot formed and smoke began to appear, and a little bit after that it was on fire.
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- #245
So basically it knows where it is because it knows it's not in that location, and the error signals drive it to where it's supposed to be. When these change, it attempts to correct for this again and again until it's in the right spot, or until either the power is turned off, the radar fails, the plane crashes, or the cows come home?
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What an amusing verbal conundrum that video is! And all that location hogwash really only applies to an inertially guided ballistic or cruise missile. Those missiles in the picture are SAMs, and they don't give two hoots about all that is-was location crap. If they're beam riders, they just try to stay in the center of the beam and trust the ground radar to steer them to the target. If they're simple homers (early AIM9s) they just keep the target right on their nose which means in the case of a deflection shot, they get sucked around into a tail chase. If they're lead prediction homers, they just keep doubling the error until their proximity fuse detonates them. That is, if they see the target has gained five degrees error to the left, let's say, then the missile steers to put the target ten degrees to the right of its nose. That sort of constant correction will put it on a collision course.
Cheers,
Wes
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- #247
Yeah, I heard something of that sort years back (probably a decade or two) which involved navigation systems.
I'd have to probably draw it out (a picture of the missile with arrows pointing to the background -- where you aren't --, and a circle around the missile -- where you are) to make it simple.
They do have a mirror which would compute lead. Not exactly sure about all that, but you had a spinning seeker in the nose, and a mirror. There were rollerons on the wings.
The end result is bad for the missile and the bomber, but great for the guy that fired it
That's in later versions. Early ones had an "eyeball" IR sensor that centered itself on the IR source, and then the missile steered itself to put the eyeball at the missile's 12 o'clock. I remember walking across in front of a Luftwaffe F104 out of Luke AFB that was transient at NAS Memphis and was undergoing some troubleshooting, and was powered up with a GPU cart. The seeker heads in the wingtip mounted Sidewinders were tracking me as I walked past. The nosecones were transparent and you could clearly see the "eyeballs".
Cheers,
Wes
Token
Senior Airman
It is not meant to be taken literally, but rather as a general, humorous, description and teaching technique of how things happen.
Long range SAMs, however, do often use this technique. At a nuance level, so do short range SAMs. They don't have to know where they are, they just have to know where the target is, which is where they are not, where it will be at some time constant in the future, and where they want to be at that time. Location, in this case, is not some cartesian defined position in space, but rather just a relative position in some aspect.
Beam riders, self guiding IR missiles (of any guidance model), CLOS, etc, all have severe range limitations. Either the detection technique (in the case of IR) cannot see at long enough ranges, or the guidance technique (in the case of BR or CLOS) cannot guide with enough accuracy at longer ranges. So these techniques are generally good for short to medium ranges, but not long range.
Pure semi-active gets past the accuracy limitations of CLOS, but at the cost of a stupid missile and having to keep the target illuminated until intercept.
But smarter missiles can get past this range limit. They could be active missiles, SAGG, or some other technique, but something in the missile has to be contributing to the track as the missile gets out in range. And in general, in order to get to that point, the handover from or mixing of external / internal, requires a knowledge, at some level, of where you are.
There have been various missiles in the past that have mixed guidance techniques, in fact most missiles (including SAMs) mix techniques to some extent. A missile (many of them) might be ballistic until the guidance system takes over. A missile might fly out on inertial nav and then turn on a guidance system at some point in flight. A missile might be CLOS for the first part of flight and go to something else for the terminal phase. And MANY missiles will bias the track in the end game, in an IR missile this can lead to an impact point forward of the heat source being tracked, in an RF missile it can overcome control loop or control surface response limitations.
T!
Token
Senior Airman
Later versions had the same basic mechanism, however with opaque optical domes. The "eye" was a spinning mirror in a Schmidt cassegrain configuration.
I have a Rolleron from a very early, pre-production, version on my desk as a paperweight.
T!
Token
Senior Airman
The mirror is part of the spinning seeker, not a separate part.
In this paper ( ) the first picture is a cut away view of a -9M. You can see the optics looking off axis, and the main mirror is clearly seen. Not as clearly seen is the subreflector in the optical path, it is under the dark gray / black sun block on the left side of that assembly.
T!
- Thread starter
- #252
I'm not sure if this is an optical illusion, but it looks like one antenna is in front of the other. Is that correct and, if so, how does the larger rear radar transmit through and receive signals through the smaller dish?
From what I remember the AN/APQ-72 was designed to detect targets at up to 400 nm and track at 350 nm, though in practice, it was said to be able to detect at ranges that were somewhat less: It would appear that reliable detection/searching occuring at some distance above 300 nm (if I was to make a guess, I'd assume 325 nm as it's more than 300 nm and less than 350 nm) with tracking possible around 250 nm (courtesy of X XBe02Drvr ).
While I'm not sure if this source is correct, it would appear that it had a 25% greater radar range.
Does what you heard conform to this estimate?
Was it more/less reliable than SAGE? I ask because the USAF had kind of entrusted it to protect the entire United States airspace...
So, there was a serious concern the enemy could spoof it?
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The AWG10 had more tricks up its sleeve and required more attention to maximize its capabilities. Enough to task saturate a solo pilot in combat.
Naturally. The F106 was designed to operate in a GCI environment, the F4, beyond GCI/AWACS support.
SAGE was predicated on more primitive technology than the F4's datalink. But it's an oft repeated experience that fancy electronics and other high tech stuff tend to fall short of expectations when first deployed in a salt environment, thus acquiring a bad reputation they have to live down.
- Thread starter
- #254
Okay, so more operational modes and features. I remember F-106A pilots often talking about how their aircraft's fire-control system, while remarkable, took considerable time to master all it's features (supposedly about 2 years): There were two exchange officers from the USN who they outright said were great stick-and-rudder pilots, but because of the time to master the features of the plane, by the time they did, their tours were over!
Okay, so it was more the environment than it was the computer equipment itself...
Always the case at sea. It's a hard life for delicate technology. Cats and traps and salt and spray, oh my!
