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air to air radar question

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air to air radar question

Old 4th Apr 2015, 20:43
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air to air radar question

Just curious about the operation of air defence radar on interceptor types (F3) or fighters (Sea Harrier etc). How did the operator find and then track a target, and how was this presented to the pilot/wso?

I am very familiar with using ship-borne radar - but this in only 2D albeit in 360 degree around the ship. Also I am familiar with aircraft weather radar which has a basic 3D capability in that it scans an arc ahead of the aircraft and can be scanned up and down by a few degrees. But where does air defence radar fall between these two examples? Did the pilot/wso rely mostly on the ground based fighter controller for an approximate bearing/elevation/range to a target, then use the onboard radar only for close range refinement? Or was the system more powerful and autonomous?

And did the radar also serve as weather radar, or was the wavelength too long to be useful for this purpose?
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Old 4th Apr 2015, 21:30
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Modern AD radars try to avoid being affected by weather, by design. The acquisition process is much the same with any radar, although fighter radars cover, generally, about 120 degrees based on the aircraft centreline, more using electronic scanning - not 360 yet.

Due to a different beam width, search mode requires consecutive sweeps at stepped elevations, but the display is not much difference, apart from using a range/closure against azimuth display rather than the plan display you would be used to. That causes a distortion of the display, but offers much better azimuth resolution at closer ranges, where it counts.

Other modes are available.
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Old 4th Apr 2015, 21:48
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When larger Pulse Doppler radars came to be fitted (Phantom, F3 in RAF service),then low flying targets were usually detected first by the interceptors rather than Ground-based radar. Depending on distance offshore, medium and high targets would be detected by Ground first. If AWACS was available, it would often detect all kinds of targets first. The interceptor was often the first to discover raid size if targets were concentrated.
The radar operator (Nav,WSO,RIO) could adjust radar mode, scan width, height spread,and where the radar was pointing. A wider scan covers a bigger area, but of course takes longer before it updates each contact. Beyond Visual Range tactics attempted to get enemy fighters confused, by changing tracks when they were wide scanning, or suddenly changing direction out of a tighter scan (e.g. vertically down, known as a 'post-hole' manoeuvre because of what the a/c does if you don't pull out fast enough!)
Pulse mode allowed a weather radar/ground mapping display of sorts. Operator experience was key here. An old salt could get a lot more useful info than a new nav.
The display was normally B Scope, as Courtney says. The pilot has a repeater of the Nav's display. The Tornado also had a plan view display.

The Tornado could hold tracks in memory when they weren't being scanned, which would generally reassociate (after 1990) when rescanning if the target hadn't turned.

Who controlled the intercept depended on whether the fighter could detect the target early enough to execute the required intercept geometry. Lightning required a fair bit of help from GCI for many target profiles. Initial GCI geometry was often useful for high level, very high speed targets (say M1.8+) whatever the fighter. Phantom and Tornado could handle pretty much everything else.

Sometimes it was advantageous to keep the fighter radars in standby and use GCI for geometry until just before missile launch range. This was especially useful when acting as, or against, fighter sweep in front of the bombers. When JTIDS came in on Tornado, use of this tactic increased.

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Old 4th Apr 2015, 22:04
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How did you use it?

You angled your radar to look in one piece of sky - usually on the nose, with a search either side of your heading, angled up or down by a number of degrees - or using aircraft software to search a particular height band at a certain range. Hopefully you had a friend nearby to search the bit you were missing. So in an example a pair of fighters would commit off towards a contact, as detected by someone else, each looking 20 degrees either side of track and one looking low, the other looking high.
When one got a contact he would tell the other, but you would maintain the radar posture so no one else could leak through. In the Sea Jet a designated track would look like a block on the radar screen with a small stick showing where he was going. At the bottom of the screen you would be shown his heading, height, speed etc. You had a set of target markers (think mouse but controlled with left thumb) and by them would be a digital read out of the height you were scanning.
So you could, for example, be contracted to scan from surface to 20k at 20 miles - but have a detection at 30 nm, and as your altitude was 35k your target marker would say something like 10 k to surface when you put it over your radar contact.
The automatics could trick you because they would want to scan centre on the contact whereas your job was to scan airspace until such a point as you bit the bullet and intercepted that particular chap - with tactics varying depending on who he was and what you actually wanted to do.
Most radar displays were/ are similar. Little tadpoles showing tracks, blocks showing un correlated hits, lines showing interference.
The F3 had an A scope I think - that I was shown in debriefs but it had a utility I didn't understand.
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Old 4th Apr 2015, 22:18
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Here is a picture of 'the boot' in a F3. TAC display on the right and NAV display on the left. The Nav/WSO operated the kit and the pilot had a head down repeater in the front - the only RADAR control for the pilot were 4x HUD queued modes but they could not manipulate the RADAR.



Courtney Mil has some more detail (on his webpage although he invorrectly calls it AI25, when it was AI24!): Tornado F3 at RAF Leuchars, the AI24 Foxhunter Radar, Op Deny Flight and all about Medicine.

It shows the RADAR display on the left hand screen (or TAB as they were known):



LJ
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Old 4th Apr 2015, 22:24
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This page from Flight Global, 1984,may help
tornado | target | 1984 | 0499 | Flight Archive

It shows the 'tadpoles' Orca described on a PPI, and on the B Scope display.

The A scope was useful for,among other things, detecting and defeating some forms of velocity ECM, such as chaff. It required a sharp backseater to be effective.
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Old 4th Apr 2015, 22:40
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The old steam operated H2S radar as carried on all three V bombers could be modified for limited use as an air to air radar to facilitate the closing stage of an RV. The Victor (and possibly Valiant) had a facility known as Fishpool, where the centre of scan, normally in the middle of the screen, was delayed to give a circle equivalent to the altitude of the aircraft (typically 5 - 6nms) in radius in the centre of the display. Any aircraft within this range could be clearly seen as a response in this circle and then guided to the tanker in conditions of poor vis, or at night. I rarely used it "in anger" as our steely eyed fighter jocks usually picked us up visually before it was needed, but it did come in handy on a few occasions. Available scan was quite good - around 240 degrees, as I recall, but we couldnt look aft.
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Old 4th Apr 2015, 22:53
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.and as a 'hat tip' to the tanker crews, I can recall several occasions when we had just plugged in for fuel and another raid was called. The tanker, unbidden, turned to fly the initial heading for the intercept whilst we remained plugged in. Having gulped an important bit extra, we unplugged and continued the intercept, letting him run away bravely back to the towline before the enemy got too close..
(worked out their own geometry too on bullseye calls; impressive!)
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Old 5th Apr 2015, 06:30
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Game based, but a good description of a B-scope display and raster scan pattern. I'll let the F4 guys explain conical scan, ranging in PD and VID modes

Anyone remember when FMICW stood for F**k Me It Can't Work...

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Old 5th Apr 2015, 09:54
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letting him run away bravely back to the towline before the enemy got too close
Too right! All we'd got was a Very pistol
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Old 5th Apr 2015, 10:03
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Remember that Verey pistol like yesterday. We went night night tanking against a Victor one dark night on 92. As we rolled in behind the Victor at a mile or so, the obliging crew fired a Verey flare; everything stopped for a few minutes while we got our night vision back......

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Old 5th Apr 2015, 10:25
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During one JMC, we were refuelling a pair of F-4s. Our grumpy old navigator 'Uncle Chuckles' spotted a contact which I confirmed visually as a pair of FRADU Hunters - the 'enemy'. So we called the threat, the F-4s unplugged and whilst waiting for their MCS to fire up, Chuckles gave them initial snap vectors - he'd once been on AEW, although I can't remember whether that was on Shacks, Gannets...or Neptunes.

The Hunters were promptly despatched by a couple of AIM-9G Fox2s, then back came the F-4s to resume AAR!

Happy times - JMC was always guaranteed to involve chaotic control from Roger Waitout and his cronies!
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Old 5th Apr 2015, 19:47
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Quote F3WMB
"(worked out their own geometry too on bullseye calls; impressive!)"

There was some good mutual support when able.

Have managed air to air aquisition on Wx radar (with large Tgt) using 1:60 and ESP.

OAP
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Old 5th Apr 2015, 21:24
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IIRC in the F4, the target was usually detected using the god-like skills of the back-seater, and the intercept managed using the combined awesome, finely tuned crew cooperation of both crew members.
GCI and AWG11-12 helped a lot too (pre AWACS)!

In a later reincarnation, I once cleared a 'snagged' Bendix wx radar during a ground run on a Kingair, by picking up and tracking, on radar, an airborne target- Single Otter on floats at 7 miles, then visually acquiring same and pointing it out to the base engineer, who WAS impressed!
Fox2, Fox 2,splash one Otter!
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Old 5th Apr 2015, 22:08
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Bike2lv, you seem to have struck this particular nail on its rusty little head.

Leon, thank you. I was wondering how to explain without going into huge detail. Much more work to do there before I would refer anyone there. Suggestions welcome.
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Old 5th Apr 2015, 22:08
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BEagle

Chuckles was on Gannets and Shacks, but not Neptunes.

The E190 was actually quite good for A to A work. You could see an F4 at 15nm, and a Bear at 35nm.

At one point we also had Verey cartridges with chaff. How useful they would have been with a VC10 or Victor target is unknown. To that end we stuffed bundles of chaff in the baskets of the Victor wing pods in 82.
With only large aircraft to refuel ( unless tanking Harrier/SHAR ) we would not be using them. The plan was to trail the hose to deploy the chaff, but with no ECM of worth, how would you know when to do it?
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Old 5th Apr 2015, 23:05
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Tengah Type, that sort of Int appraisal was almost as incisive as the ridiculous idea which came into Daisy's head at Antalya in that fine summer by the Sheraton....

At the time. we had 2 crews and 2 jets on the Det. One jet (a K2) had utterly woeful air conditioning (only 2 blowers), but did have an RWR. Whereas the other (a K4) had excellent 4-blower air conditioning, but no RWR. Sod's Law being what it was, one lucky crew (mine) always seemed to fly the K4, whereas the other poor buggers sweltered in the old K2.

Then one day, for some engineering reason or other, the other crew were due to fly the K4. Except that it coincided with some PKK anniversary, so DetCo Daisy decided that the threat matrix had moved up a notch and that they should therefore have the benefit of an RWR - so they found themselves in the sweaty old K2 again!

But quite why Daisy thought that an RWR would have been much use to warn of any potential PKK IR ManPad threat was something known only to him....ar$e!
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Old 6th Apr 2015, 01:04
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Think how busy the pilot must have been in the Dog Sabre! Fly the airplane, manually track the other guy, put the range gate on him, no automation etc. etc.
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Old 6th Apr 2015, 02:41
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Once did a trip in the T5 Frightning in fishbowl conditions. Low level OPEX off Flambo with Staxton doing broadcast, ships looking like they were above, no horizon and the altimeter showing us at 50 fathoms.

Pilot working out were we and txt were on his knee pad, whilst working the AI23 hand controller, head alternating between rubber scope eyepiece, instruments and sky whilst talking me through the intercept. Asked him how he knew what height we were at and he told me he was watching the size of our shadow on the surface.

Understood that day why they were nicknamed one armed paper hangers.
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Old 9th Apr 2015, 08:51
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Courtney,
I believe that when discussing any modern fighter radar it is important to discuss the weapons system. In most TWS radars the Tracker is as important as the radar. In the Tornado F3 targets were tracked automatically. The tracker had the capability to track up to 30 tracks at one time and promote or demote the tracks in a data base dependent on pre-set criteria. Due to the Fox Hunter being High PRF it’s detection capability was quite good but presentation to the crew was poor. Initially, due to a poor tracker the radar was not able to support TWS on very long range or highly manoeuvring targets. Later improvements in the Stage2 overcame most of these deficiencies.

The introduction of Link16 to the F3 made a significant difference to the weapons system performance. Each fighter was able to see tracks provided by any co-operator. Again, the comprehensive tracker enabled good track correlation. The F3 was also configured to continuously view the Surveillance Picture provide by an E3 or Link16 equipped surface vessel. The F3 WSO was able to use filters to allow a usable picture to be displayed. Radar and Link tracks could be displayed on both the Radar Display and the Tac Display. Both displays had easy to use BullsEye information in either True or Magnetic. The Tac Display could be viewed either North Up or Track Up depending on requirement. By the time the aircraft was axed by the MOD it’s weapons system, and weapons, were among the very best in the world. A shame about the platform!

Aircraft more modern than the F3 use other sensors such as IRST to support tracks in the weapons system. How well these different sensors interact and how well the sensor fusion works is the heart of a modern weapons system. There will always be a debate whether the system should be fully automated or how much manual intervention should be allowed/required.
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