Notching & BVR Tactics, help for new fighter pilots (FC3)

[badger66]

What exactly does notch mean please ?

[159th_Viper]

What exactly does notch mean please ?

 

Old post by BRD:

 

When a transmitted pulse hits a target aircraft and is reflected back to the radar, then if the aircraft is flying toward/away from the radar, there will be a slight change in the frequency of the pulse caused by the doppler effect. Measurement of this will give a rough idea of the speed of the "target".

Most modern radars use a filter to get rid of spurious clutter returns by ditching any pulses from "targets" that exhibit too slow a doppler speed, ie. it assumes these can't really be an aircraft (might be birds, rain, the ground, waves at sea, etc.)

 

 

If you draw a graph of speed against rejection/acceptance, it kinda looks like a straight line with a notch cut in it, hence the term doppler notch:-

 

 

--------\____/--------

 

 

A bandit can exploit this doppler rejection by turning to fly a course at 90 degrees to the radar that makes his speed toward/away from the radar seem too slow to be a genuine target.

 

It is said that in the early versions of AWACS aircraft that they would detect trucks driving on roads as genuine targets unless the doppler rejection speed was set to (eg) 80 miles per hour.

[ZaltysZ]

What exactly does notch mean please ?

 

I do not know the etymology, but notch filter is a filter which passes almost everything except some chosen stopband. In context of doppler pulse radar, the notch filter rejects radar returns from stationary objects (i.e. ground). Stationary objects are those, which cause 0 doppler effect (i.e. have 0 closure rate). Notching basically means "forcing to be filtered out by enemy radar". That is achieved by flying a tangential trajectory in relation to radar beam.

[Siskin]

I do not know the etymology, but notch filter is a filter which passes almost everything except some chosen stopband. In context of doppler pulse radar, the notch filter rejects radar returns from stationary objects (i.e. ground). Stationary objects are those, which cause 0 doppler effect (i.e. have 0 closure rate). Notching basically means "forcing to be filtered out by enemy radar". That is achieved by flying a tangential trajectory in relation to radar beam.

 

Almost correct.

Flying a tangential trajectory in relation to radar beam, is called "beaming".

Beaming + flying bellow the enemy radar to further confuse it with ground clutter = notching.

 

If i'm mistaken, please correct me.

[GGTharos]

It's possible that some radars may be notchable in a look-up situation as well. It all depends on how the filtering logic is set up.

[159th_Viper]

Beaming + flying bellow the enemy radar to further confuse it with ground clutter = notching....

 

Still beaming according to Capt Pitts and even then not always fail-safe....radar can still pick them up in a look-down situation:

 

USAF F-15C 85-0101 (Capt R Tollini) and 85-0114 (Capt L Pitts), 58 TFS, 33 TFW vs Iraqi AF Mig-25, 19 January 1991, Iraq (Operation Desert Storm)

 

Captain Rick Tollini's four-ship got gas and started

to form up for the sweep, which was scheduled to take

them north up central Iraq in advance of an F-16

strike on Al Qaim, a gas and germ warfare center

northwest of Al Asad.

 

"As soon as we came off the tanker" said Captain Larry

Pitts, "AWACS started calling MIGs close to the

border."

 

The MIGs were in two groups. One was directly in front

of them. They were two MiG-25 Foxbats, perhaps fifty miles away at ten thousand feet, coming fast. The other

group was roughly the same distance away but

northeast, towards Baghdad- a pair of MiG-29s.

 

Tollini's "Citigo" flight shot north and started

searching with their radars. They got blips from both

groups at about forty miles. Since the Eagles had

already gotten confirmation of "bandit" status from

AWACS, and their cockpit indications were the same,

they prepared for relatively easy BVR shots- right to

the faces of the oncoming enemy planes. Being on the

eastern flank of the advancing four-ship, Pitts

thought he might get a shot at the one of the easterly

Fulcrums, but they suddenly turned back north. Either

they were race-tracking on a CAP or trying to "bait"

the Eagles. In any case they were "no longer threats"-

at least for the time being.

 

They turned their attention solely to the Foxbats,

which had now closed to around twenty miles. Both

groups were at ten thousand feet, still head on with

each other. Sorting and targeting, Tollini and Captain

Jon Kelk prepared to shoot when the Foxbats came into

range, Tollini actually locking one of them. Pitts and

Williams searched on their radars for other possible

bandits.

 

Suddenly the Foxbats turned ninety degrees and

executed a "beam" maneuver, heading west and

perpendicular to the Eagles line of flight. As it was

supposed to, the tactic banished the Foxbats from the

four Eagle's radars and broke Tollini's lock. Now the

Eagles were in trouble, because two MiGs were

presumably in range of shooting them and unseen -

until, luckily, at about five miles in front of them

and very low, approximately five hundred feet from the

desert floor- they picked up the radar blip of one of

the Foxbats rocketing in front of them, from west to

east at seven hundred knots.

 

It was another "beam" maneuver, said Pitts, but this

time it was being executed too close to the Eagles to

work. "Since I was on the east side, it was easiest

for me to engage him," he said. He radioed Tollini his

intention and dove after the MiG as it passed below.

As he did so, the MiG began a wide 270 degree arcing

turn beneath him, back south, west and eventually

north. The large oval and resultant loss of speed by

the MiG-25 enabled Pitts, who had visually acquired

the MiG as he'd converted on it, to cut across the

Iraqi's turn circle and rendezvous on his tail.

"I'm able to roll in a mile and a half behind him and

start shooting," he said.

 

The next sequence of events happened very fast.

Pitts was so close to the MiG's exhausts that his

first shot was a heat-seeking Sidewinder. But the

Iraqi decoyed it with flares.

 

Gaining on the Iraqi, he fired a Sparrow, but it

didn't explode. The Iraqi didn't try any evasive

maneuvers. He just kept running straight and level

north- still very low, his exhaust still beckoning.

Pitts shot another Sidewinder. The Iraqi decoyed it

with flares again. Pitts was getting frustrated. Any

closer and he'd be out of missile envelope and have to

go to guns.

 

He fired a fourth missile, another Sparrow.

Meanwhile , up above Tollini, now functioning as Pitts

wingman, had been watching and decided he'd better

jump in and help. He dove toward the fight and fired a

Sidewinder of his own at the fleeing Foxbat. But

before it got there, Pitts final Sparrow either went

up the Foxbats tailpipe or right near it, and

exploded, causing a small fireball. " It was like a

sparkler, " he said. Tollini's missile then impacted

the fireball. The MiG stayed relatively intact but

went down into clouds. Pitts saw the canopy come off

and the "explosion" as the pilot's ejection seat fired

out. But he didn't see a parachute because " I know

the second guy is still out these and I immediately

start looking for him."

 

Coming back up, pointing west, he spotted the second

Foxbat, It was coming east, about five miles in front

of them, going belly up as it tried to turn north in

front of them and run, Pitts speculated. Kelk and

Williams, low on fuel had already left. Tollini, who

had his radar on "auto guns" now, didn't visually see

the bandit until Pitts called him out, but the "auto

guns" setting would have automatically locked the

Iraqi anyway. First Tollini fired a Sidewinder. It was

decoyed with flares. Chasing in afterburner, he fired

a Sparrow. The radar missile hit, disintegrating the

MiG-25. These were the ninth and tenth Allied air to

air kills of the war.

 

From Wings of Fury by Robert K Wilcox

[GGTharos]

This describes the 'wall of eagles' tactic - you can notch a couple of them, but not all of them. As datalinks are installed, the walls get wider and the distances at which the notch cannot work against the wall becomes longer.

 

Still beaming according to Capt Pitts and even then not always fail-safe....radar can still pick them up in a look-down situation:

[arteedecco]

This describes the 'wall of eagles' tactic - you can notch a couple of them, but not all of them. As datalinks are installed, the walls get wider and the distances at which the notch cannot work against the wall becomes longer.

 

At 5 miles the Mig would pretty well have to have visual on the Eagles in order to maintain proper beam while in the notch (right?)... since your angular rate of change relative to the Eagles would be quite fast... hard when Eagles are 10K up above and you're hauling at over 700knots at 500 feet AGL (not a lot of time to let your eyes stray from the ground).

 

Plus... Eagles radar more powerful that close in and as you say... you may beam one, but because of the offset of the others Eagles in the flight... you probably won't be beaming at least one of the others.

 

Interesting.

[GGTharos]

They should definitely want to have visual, yes. At 5nm an eagle should be visible. The outer range of 'WVR' for large fighters is considered to be around 7-8nm, but conditions can make this longer/shorter. Small fighters like the F-5 and MiG-21 are visible at around 4nm, but you can still visually lose them closer in under the right circumstances.

 

In any case, at 5nm, they may have been hoping to close in in a 'notch to the merge' maneuver, but why a MiG-25 pilot would want to merge with anyone, I don't know - it's a 5g airframe. Even a C-130 will out-turn it (no, I'm not kidding).

[arteedecco]

They should definitely want to have visual, yes. At 5nm an eagle should be visible. The outer range of 'WVR' for large fighters is considered to be around 7-8nm, but conditions can make this longer/shorter. Small fighters like the F-5 and MiG-21 are visible at around 4nm, but you can still visually lose them closer in under the right circumstances.

 

In any case, at 5nm, they may have been hoping to close in in a 'notch to the merge' maneuver, but why a MiG-25 pilot would want to merge with anyone, I don't know - it's a 5g airframe. Even a C-130 will out-turn it (no, I'm not kidding).

 

Possibly hoping Eagle flight would pass overhead and then could ambush them. Odd to me that the Mig-29 flight ran while the Mig-25 flight pursued then realized they were hosed and ran... maybe trying to draw out Eagles to bait them into Mig-29 flight that had retreated.

 

Course... could be the Mig-29s had lots of stuff non-operational on their airframes and anyway... 2 v 4... 29s to 15s head on... die die die, especially w/ AWACS and probably limited / no GCI supporting Migs.. not trying to devolve this conversation from it's original topic of BVR tactics.

[GGTharos]

Possibly hoping Eagle flight would pass overhead and then could ambush them. Odd to me that the Mig-29 flight ran while the Mig-25 flight pursued then realized they were hosed and ran... maybe trying to draw out Eagles to bait them into Mig-29 flight that had retreated.

 

Maybe - who knows. Once way or another it was a mistake.

 

Course... could be the Mig-29s had lots of stuff non-operational on their airframes and anyway... 2 v 4... 29s to 15s head on... die die die, especially w/ AWACS and probably limited / no GCI supporting Migs.. not trying to devolve this conversation from it's original topic of BVR tactics.

 

The 29 pilots in that conflict did some clever things some times, but the Eagle pilots knew better and wouldn't bite - this includes trying to make the eagle pilots follow them into SAM traps.

 

On one occasion a 29 locked onto a 15 from about 4nm, that eagle pilot went defensive right away, and his wingman immediately launched a sparrow, shooting the 29 down.

[arteedecco]

On one occasion a 29 locked onto a 15 from about 4nm, that eagle pilot went defensive right away, and his wingman immediately launched a sparrow, shooting the 29 down.

 

Question here is... how did a 29 get w/in 4nm of a 15 w/out the 15 being aware of its presence?

 

Since that kind of stealthy approach would be nice to emulate in DCSW.

[GGTharos]

There was nothing stealthy about it. The IFF interrogation showed him (or his wingman, I don't recall the specifics, but there was an ID problem) as friendly, and they committed to a VID.

[arteedecco]

LOL got it. Equipment failure... not a tactic to depend upon!

[GGTharos]

Here's a real notch:

 

Watch from 9:15. If you don't understand the HuD I'll explain it.

[GGTharos]

Ah, and here's the story, from wikipedia ... so what did happen is that the F-15's got sort of cornered by multiple groups. They do train to deal with this, though surprisingly they weren't able to sort or otherwise engage on both fighters quickly enough.

 

Incidentally, the bit about the computer inhibiting launch is not correct, insofar as I know; he didn't launch because he got a friendly ID back.

 

Rodriguez, call sign "Rico" scored the first two air-air direct hits of his Air Force career in the Gulf War. His first hit occurred when he and his wingman Craig "Mole" Underhill came across two Iraqi MiG-29 "Fulcrums". The two F-15s quickly locked up the MiG-29s, which turned east to avoid them. However, an AWACS then reported two more MiG-29s coming in fast at them from the west a mere 13 miles away. The two F-15s and two MiG-29s charged straight at each other. Underhill quickly fired an AIM-7 at the first MiG. At the same time, the second MiG-29, piloted by Captain Jameel Sayhood, "locked up" Rodriguez, who then quickly executed a dive down to the deck to avoid the radar lock and nearly collided with the AIM-7 Sparrow fired by Rodriguez's wingman which, seconds later, destroys the lead MiG. After seeing his wingman killed, Sayhood decided to bug out briefly. Rodriguez rejoined with Underhill until Sayhood reappeared. Underhill locked him up, though his computer would not let him fire the AIM-7 missile to destroy the MiG because of a glitch in his IFF which told him that the MiG was a friendly aircraft. Rodriguez and Sayhood then proceeded to merge, whereupon they both turned left and promptly got into a turning fight. As they descended towards the ground, Sayhood attempted to execute a split-s maneuver. However having insufficient altitude (about 600 ft instead of he crashed into the ground. Rodriguez was credited with a maneuvering kill.[3]

Edited January 15, 2013 by GGTharos

[arteedecco]

Here's a real notch:

 

Watch from 9:15. If you don't understand the HuD I'll explain it.

 

Cool... I wasn't able to find it so thanks for posting the link. Yeah... I see that he's got missile lock (I'm assuming this is training) then bandit notches (probably pre-briefed) and you see the contact drop. Then you hear the IP (?) give guidance on visual acquisition and the pilot boresights and regains lock.

 

Did I get all that right?

[GGTharos]

Yes, that is correct. It's two F-16's traning. From our PoV, the F-16 picks up the bandit at whatever distance it started, and appears to be readying to launch a 120. You hear him call fox-3 at some point, I believe.

 

You'll also notice that the 'bandit' notches right at Rtr, and then like you said, the IP gives some guidance and the pilot re-acquires his bandit as it comes out of the notch.

 

It's important to realize however that certain radars won't just drop a notching contact like that, they'll continue a mini-raster scan to find him again, or in the case of TWS, maintain the track until it is either re-acquired or it times out.

[lunaticfringe]

GG, do you have the link to that Wikipedia article? There's a massive amount of commentary there that doesn't jive with the "official" story *or* Rico/Mole's recollections, and I'd love to see if there's more there based on attributed sources.

 

Especially the supposed re-engagement of the wingman; he was in excess of ten miles range and heading back *in* to the F-15 pair within thirty seconds of the lead being down. To have a telling claim that he was essentially inbound, turned out, then turned back in, puts him at a good fifteen to twenty miles in trail to the first Fulcrum, meaning he's not really in formation to begin with.

 

There's also something particular about the recovered HUD camera image from the lead MiG-29 that calls BS on this as well...

[GGTharos]

Yep, I noticed it wasn't quite what I recall either, but it was close enough for now.

 

Here's the link: http://en.wikipedia.org/wiki/Cesar_Rodriguez_%28United_States_Air_Force_pilot%29

 

As for the HUD camera thing, I don't know; there's also this infamous 'last thing the camera recorded' image of a 120 in the HuD floating around the net, but that could well be from a drone, too.

[lunaticfringe]

If you're referring to this image:

 

http://i544.photobucket.com/albums/hh347/Sluggo_357/Faceshot.jpg

 

it's misattributed- that's an AIM-7. I've seen a true print of it, and at actual size you can in fact see a receding F-15.

[GGTharos]

Yes, that's the one.

 

If you're referring to this image:

 

http://i544.photobucket.com/albums/hh347/Sluggo_357/Faceshot.jpg

 

it's misattributed- that's an AIM-7. I've seen a true print of it, and at actual size you can in fact see a receding F-15.

[lunaticfringe]

One of the surviving Iraqi MiG-29 drivers, a supposed ace from the war with Iran, stated that he was the one flying that particular Fulcrum. Unless he was already *out* of the airframe at the point that image was recorded by the camera, he'd have been killed. Hence, I've never found one of my contacts to believe that claim was legitimate.

 

On that note, whoever did the click-through article on the name of the supposed wingman

 

http://en.wikipedia.org/wiki/Jameel_Sayhood

 

is full of *. Even Dogfights wasn't enough to make the contention that "just before Sayhood could pull out, he crashed into the ground. He managed to eject from his MiG, however it is unknown if he survived. He may have died in the desert heat."

 

That's comedy.

[Mowgli]

Very Informative Thread - learned lot's from all the info and tactics sherd here:book:

 

"you talk the talk - do you walk the walk?"

 

[GGTharos]

How is proportional navigation not 'a true intercept path'?