Old radar gun sight vs Modern gun funnel

[marcos]

Which is better?

[IvanK]

The Funnel gunsight goes back as far as WWI. The French were the first to use the funnel concept...albeit in a static presentation.

 

Edited May 28, 2013 by IvanK

[marcos]

Interesting. I've noticed that modern planes seem to have devolved back to it though. At least the A-10C anyway. Are other planes different in that regard?

[Jona33]

Interesting. I've noticed that modern planes seem to have devolved back to it though. At least the A-10C anyway. Are other planes different in that regard?

 

If BMS is correct the F-16 uses a kind of combination, with a funnel, but a dot you put on the target in the funnel.

[Weta43]

modern planes seem to have devolved back to it though. At least the A-10C anyway

I wouldn't take the A-10C's funnel as a sign of the funnel's superiority. The A-10 doesn't have a radar or IRST to do the calcs for anything but a funnel.

As far as I can see, systems that can provide a firing solution (a 'radar gun sight') do so while they are able, but fall back to a funnel when they can't..

[GGTharos]

^^^^

 

What Weta said (what, we agreed on something?)

 

Any system that has more data coming in that can act on it is superior. For that reason, the F-15's LCOS can be superior to a funnel, and the GDS will be superior to the LCOS.

 

The F-18's gunsight is reportedly quite the thing.

 

The F-16 has a very complex gunsight which, IIRC, can begin with something like a funnel, then gather data if you manage to track your target visually and compute a 'death dot', somewhat like the F-15's LCOS but with more detail. And if you involve the radar, you get a death dot like the GDS. In terms of placing a shot, be it a snap or tracking, the GDS superior in traditional saddle-up attacks, and takes the cake when it comes to out-of-plane snapshots and other fun things.

[Weta43]

;)

I agree with you a lot of the time - I just don't tell you in case it makes you doubt yourself :)

[Nealius]

The F-16 I think actually has two different gunsights. The only one I'm familiar with is the funnel, and the "death dot" is only available when the target is locked up on radar....I think. I haven't done many gun fights recently, but I'm pretty sure that without radar lock, it functions the same as the A-10's sight.

 

There's also LCOS but I've never used it.

 

Apparently there's also a third, "snapshoot line" but again, never used it so I have no clue.

[marcos]

Good info.

 

Are funnels computed for lead though? I was lead to believe they just show the ballistic path of the bullets over distance, so if the death dot is in the funnel, surely it isn't computed for lead either, or am I wrong?

 

Also, if a target is locked on A-10 TGP and lased, then what prevents an accurate lead solution being calculated based on the targets velocity?

 

Found this on the LCOS sight.

 

http://www.dtic.mil/dtic/tr/fulltext/u2/786464.pdf

 

The later F-16s use something called EEGS apparently. The older version was called Snapshoot. Some have both.

 

http://www.f-16.net/f-16_forum_viewtopic-t-1527.html

 

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA192615

[GGTharos]

The TGP OFP modeled in DCS A-10C doesn't have that function (or at least, we aren't allowed to have it), I hear more modern ones just may.

 

As or funnels, you can definitely use them to get proper lead.

[marcos]

As or funnels, you can definitely use them to get proper lead.

Isn't that just pilot's guess though? They're not actually showing where the enemy is going to be relative to the burst, they just show the path of the bullets through the air or am I wrong? Maybe that's just for the A-10???

Edited May 29, 2013 by marcos

[winz]

Not at all if done correctly. Imho the computer assumes you're flying pursuit, matching the target maneuvers. It can then use the amount of G you're pulling to compute the offset between you and the target required to hit it. Because distance is unknow for the computer, this offset is computed for a distance range, and displayed as the funnel. You then 'select' the right distance-offset pair by placing the wingtips of your target on the funnel.

Edited May 29, 2013 by winz

[marcos]

Not at all if done correctly. Imho the computer assumes you're flying pursuit, matching the target maneuvers. It can then use the amount of G you're pulling to compute the offset between you and the target required to hit it. Because distance is unknow for the computer, this offset is computed for a distance range, and displayed as the funnel. You then 'select' the right distance-offset pair by placing the wingtips of your target on the funnel.

Ah, so most gun funnels are lead calculated based on the enemy's velocity.:thumbup:

[Nealius]

Are funnels computed for lead though? I was lead to believe they just show the ballistic path of the bullets over distance, so if the death dot is in the funnel, surely it isn't computed for lead either, or am I wrong?

 

Winz already answered most of your question, but about computing lead, in the F-16's EEGS when the target is locked on radar the "death dot" is the computed lead.

[GGTharos]

No, they're calculated based on shell time of flight and target distance. Maybe your tracking is factored in also, but that would require some time to settle. You definitely do not know the target's velocity or g in terms of measuring.

 

So the deal is that to use the funnel properly you do need to saddle up and stabilize. The idea is that you input the wingspan into the FCS and then match up the wings to they touch the edges of the funnel - that gets you proper distance.

 

Ah, so most gun funnels are lead calculated based on the enemy's velocity.:thumbup:

[Nealius]

I also read that it's a good idea to pull the sight through the target while zipping off rounds. Don't know how true it is...

[GGTharos]

It depends on the sight and the type of fight as well. When you're saddled up, one technique is to pull the sight just in front of the target, slightly relax the g's and hold down the trigger so that you put rounds along the length of the target. It's a real life technique, and it maximizes damage for obvious reasons.

 

Doing it the other way (increasing g's and shooting from tail to nose) can also be done, but it's probably less practical and possibly more prone to error.

[mvsgas]

F-16 EEGGS is one of the best systems, providing all information with or without lock. Obliviously with a Radar lock it will be more accurate.

Enhanced Envelope Gun Sight (EEGS) Symbols.

The EEGS symbols provide gunnery data for the EEGS submode in five levels. The level of symbology displayed depends on whether the radar is locked on the appropriate target and,

if so, the settling time of the target state estimator. The possible EEGS symbology consists of a fixed boresight cross, a funnel, multiple reference gunsight (MRGS) lines, a T-symbol, a bullets-at-target range (BATR), firing evaluation display set (FEDS), pippers, target designator with in range cue, and a level V pipper

Boresight cross – The boresight cross is used in all levels.

Funnel display – Used in levels 2, 3, 4, and 5, the funnel display is based on the principles of the traditional LCOS. Each midpoint in the funnel represents the target at a specific range for which the gun is correctly aimed at the present range. The width of the funnel at a particular point of interest is the angle subtended by the wingspan of the target at the

corresponding value of range. The minimum range, corresponding to the top of funnel, is approximately 600 feet, depending slightly on altitude and airspeed. The maximum range at the bottom of the funnel is approximately 3000 feet, depending on altitude and airspeed. If the target is smaller than the bottom of the funnel, it is out of range.

MRGS – The MRGS lines in levels 2 and 3 are useful in high aspect attacks (60 to 120 degrees) against relatively high speed targets. Each line represents a lead angle of the same magnitude but in a different direction. For conceptual purposes, it is useful to consider each line as a reference target flying in a direction that, if it continued on path, would be hit by the rounds fired at that instant.

T-symbol – Used in levels 3, 4, and 5, it provides lead angle boundaries for the target. The cross in the open T-symbol is the lead angle required for an unaccelerated target. The lower (smaller) horizontal bar is the lead angle for a target executing maximum sustained rate of turn. The length of the horizontal bar extending from the funnel represents the

maximum evasive potential of the target in an out of plane maneuver at this range.

BATR – The BATR for levels 3, 4, and 5 is a 6 mr pipper and is displayed as the first simulated round passes through target range and disappears immediately after the last round has passed. In a typical beam quarter attack, the BATR initially appears just in front of the target nose.

FEDS – The FEDS provides scoring in level 2 only. The symbol consists of a series of dot pairs that are used to estimate whether the bullets at target range are falling behind the target (dots wider than wingspan), ahead of the target (dots narrower than wingspan), or hitting the target (dots equal to wingspan).

Pippers – In levels 3 and 4, there are two pippers displayed: a 4 mr cross (+) giving gun solution for a 1.0g target and a 4 mr dash (-) giving the gun solution for a 9g target. In level 5, when inside the maximum effective gun range, the level

5 pipper is displayed: a 4 mr circle giving the gun solution for present target g.

Target designator – In form of a clock analog of range, the target designator is centered on the target and each o’clock position equals 1000 feet. Maximum gun range, corresponding to a specific time of flight, is indicated by a dot on the periphery of the designator. The maximum range dot is removed from the EEGS display in levels 3, 4, and 5 when the target is closer than maximum range minus 1000 feet. The maximum range dot reappears when the target aircraft has an opening velocity and exceeds the calculated maximum range.

[mvsgas]

More on EEGS

 

2.7.2.2 Air-to-Air Gunnery Mode. The DGFT and GUN modes provide aiming symbology for passive (manually ranged) or active (radar tracked) gun attack. DGFT is selectable hands-on via the DGFT/MSL OVRD switch on the throttle. GUN is selected via the A-A master mode button on the ICP and OSB 1 on the SMS AAM page. In the GUN mode the enhanced envelope gunsight (EEGS) gunnery symbology is incorporated. This section will cover the EEGS air-to-air gunnery submode and its associated displays and controls.

2.7.2.2.1 In addition to the M55A1 ball cartridge (practice round), the M53 armor-piercing incendiary cartridge, and the M56A1 high explosive incendiary cartridge, the PGU-28/B semi-armor-piercing high explosive incendiary cartridge may also be fired from the internal 20mm gun. The ammo type (mnemonic M56 or PGU28) must be loaded either through the SMS menudriven data entry MDDE page or via the DTE.

2.7.2.2.2 The EEGS submode provides gunnery solutions for tracking targets visually and is refined when radar range, velocity, and acceleration data are available. The EEGS algorithm is presented in five functionally separate levels, each dependent on the availability of target data from the radar and a training level (Figure 2-313). The algorithm is designed to

automatically transition through the levels as target range, velocity, and acceleration become valid and usable (e.g., filters using data have settled). Levels 3 and 4 are considered transition levels which typically last for a few seconds.

2.7.2.2.3 Level 1 is displayed in the event of a rate data failure. The gun boresight reference is the only sight available.

2.7.2.2.4 Level 2 is displayed when the RSU is good, but either there is no radar lock or the INS data is invalid (or not available). It consists of a funnel, multiple reference gunsight (MRGS) lines, and firing evaluation display system (FEDS) symbology. The funnel is a stadiametric ranging cue that aids in aligning the gun with the flight path of the target. The variable

length MRGS lines aid in minimizing lateral gun error in high aspect/large lead angle level 2 shooting. The MRGS lines are variable based upon the value entered for the target wingspan via the UFC DED or DTE.

2.7.2.2.5 The FEDS are used to assess a gun shot (real or simulated) in level 2 EEGS. A series of dot pairs touching the target’s wingtip indicate that rounds should be impacting the target. There are approximately 20 rounds between each dot pair.

The FEDS symbology is displayed on the HUD corresponding to a trigger pull in level 2 EEGS only when scoring is selected on the MFD.

2.7.2.2.6 Level 3 consists of the funnel, the T-symbol, aspect angle data, and the MRGS lines. Level 3 is the transition from level 2 once a radar lock and a valid target range are obtained. Level 3 is used in the same manner as level 2 except that the Tsymbol provides additional cues on when to shoot. Also, a 6 mr pipper for the bullets-at-target-range (BATR) will appear after a

trigger pull if gun scoring is selected.

2.7.2.2.7 Level 4 consists of a lengthened, stiffened funnel (target’s plane), aspect angle data, and the T-symbol. Level 4 is the transition from level 3 once the target velocity has settled. The MRGS lines are no longer displayed.

2.7.2.2.8 Level 5 consists of the funnel (target’s plane) as in level 4, the T-symbol, aspect angle data, and a 4 mr pipper. Level 5 is the transition from level 4 once the target acceleration has settled. The level 5 pipper (4 mr circle) represents the most

accurate lead angle with available data.

2.7.2.2.9 EEGS Training Level, without radar lock-on, consists of Level II symbology. Once radar lock-on has been achieved, EEGS Training Level consists of Level II symbology with the exceptions that BATR is displayed rather than FEDS, and Target Slant Range and Target Closure Range are displayed

[marcos]

No, they're calculated based on shell time of flight and target distance. Maybe your tracking is factored in also, but that would require some time to settle. You definitely do not know the target's velocity or g in terms of measuring.

 

So the deal is that to use the funnel properly you do need to saddle up and stabilize. The idea is that you input the wingspan into the FCS and then match up the wings to they touch the edges of the funnel - that gets you proper distance.

So you need to match the target's velocity because matching the wing tips only gives you the right distance???

 

When was the last air-to-air gun kill?

[159th_Viper]

 

When was the last air-to-air gun kill?

 

26 February 1999.

[GGTharos]

His velocity doesn't matter that much; only round TOF.

 

So you need to match the target's velocity because matching the wing tips only gives you the right distance???

 

When was the last air-to-air gun kill?

[marcos]

26 February 1999.

This one?

 

The Eritrean–Ethiopian War took place from May 1998 to June 2000. On February 26, 1999, Ethiopian Capt. Aster Tolossa flying an Su-27S killed an Eritrean MiG 29UB with 30mm. She first fired two missiles which the MiG evaded, but then killed him with guns. She is also the first female pilot to have a confirmed air combat kill.

 

Interesting bit about R-27s used in that conflict.

 

http://en.wikipedia.org/wiki/Vympel_R-27#Ethiopia_and_Eritrea

 

In the 1999 Eritrean-Ethiopian War, Eritrean MiG-29s fought Ethiopian Su-27s both piloted by Russian mercenaries.[6] There were possibly as many as 24 R-27s fired by both sides, but they were evaded by their targets. Only one R-27 fired by an Ethiopian Su-27 at an Eritrean MiG-29 proximity-fuzed near enough the MiG that the damaged aircraft eventually crashed on landing.[7][8]

Edited May 30, 2013 by marcos

[marcos]

His velocity doesn't matter that much; only round TOF.

That can't be correct. An aircraft moving at say 250m/s could move ~100m in the time it takes a round to travel 320m. If that's straight ahead and the round is fired from directly behind at an aircraft of equal speed then the funnel solution works but if the enemy is pulling lateral g then surely it goes out the window without lead computation. But then I guess you must be going in near the same direction to get the wingtips to touch the funnel???

Edited May 30, 2013 by marcos