LCOS lead solution

[OutOnTheOP]

Lovely that A/A1 is implemented and working now; it definitely makes things a lot easier.

 

I'm not sure if it's a bug, an intentional feature, or just that my tracking shots are not steady enough, but it seems to me that the reticle doesn't give *quite* enough lead to result in good hits in A/A1. It's close; I find that I get solid center-of-mass hits if I put a solid tracking pipper right at or a foot in front of a turning target's nose; it misses aft or just gets tail hits with pipper on center-of-mass. This might be a result of different ballistic characteristics of the different ammo types- is the reticle maybe calibrated for the API ammo instead of HEI? I would think the A/A sights would be calibrated for the more typical HEI A/A load.

 

Also, might be a feature (my reading of the F-5E weapons employment manual didn't seem to cover it), but the pipper stops tracking and locks into a fixed position when I get inside the minimum range warning. I'm not surprised that it stops giving lead computations (to discourage under-min-range shots), but it doesn't actually stow the reticle back in the boresight position, it stows it about 20-30 mils low. Is that intended behavior?

[autogyro]

The A/A1 gunsight lead computing doesn't mean you place the pipper on the target. You still have to provide lead in front of the pipper for maneuvering targets.

 

Someone correct me if I'm wrong but it is a real time sight to show the position of the bullet now in real time if it was fired one bullet time of flight (ToF) ago, taking into consideration target range, target range rate and your movement.

 

Dogfight Guns mode and I believe the 2 normal guns modes boresights the reticle 4.7 degrees below the ARL in line with the radar boresight... that could be what you're experiencing.

[OutOnTheOP]

The A/A1 gunsight lead computing doesn't mean you place the pipper on the target. You still have to provide lead in front of the pipper for maneuvering targets.

 

Someone correct me if I'm wrong but it is a real time sight to show the position of the bullet now in real time if it was fired one bullet time of flight (ToF) ago, taking into consideration target range, target range rate and your movement.

 

Dogfight Guns mode and I believe the 2 normal guns modes boresights the reticle 4.7 degrees below the ARL in line with the radar boresight... that could be what you're experiencing.

 

But against a constant rate maneuvering target, that should still be a center-of-mass hold. If it were increasing it's rate of turn, sure, but I'm talking about a lazy sustained turn. Normal procedure is still to "walk" the pipper through the target tail to nose, but it just doesn't seem to be predicting at *quite* the right place. Pretty sure it computes pretty much the same way the K14 does (rate from gyros), only with radar providing ranging; with the K14, a solid center-of-mass hold will give good hits.

 

No, it centers lower than that at min; if I cancel out after closing to min range and then go immediately back to DG, it raises the reticle back to the start point.

Edited August 15, 2016 by OutOnTheOP

[tom_19d]

I think I have to agree with autogyro on this one.

 

Quoting from the manual page 164 regarding the DG mode (which is similar to AI)

 

"It is recommended to perform target search and acquisition in 10-mile range

before selecting DG mode. After mode selection, if the target is within the

range of 500 to 5600 feet, the radar automatically locks on to the target.

 

The pilot’s task in the DG mode is to place the reticle pipper forward of the

target motion based on a lead angle. "

 

When discussing A2 mode the manual on page 167 says

 

"The mode is primarily used in short-range air-to-air combats against

unaccelerated constant rate maneuvering target. It is recommended to

perform target search and acquisition in 10-mile range before selecting A/A2

mode. After mode selection, if the target is within the range of 500 to 5600

feet, the radar automatically locks on to the target. In this mode sight system

calculates the lead angle.

 

The pilot’s task is to place the reticle pipper on the target."

[IvanK]

Guns A/A1 is fundamentally different to Guns A/A2.

 

Guns A/A1should be thought of as a Snapshot sight you don't need to stabilize the sight or even achieve the the targets plane of motion. Guns A/A2 is the conventional LCOS sight that requires steady tracking for the sight settling time x the bullet time of flight. See below the excerpt from the manual that illustrates the completely different sight handling available in A/A1. As can be seen Open fire can commence prior to pipper target co incidence

 

[OutOnTheOP]

Guns A/A1 is fundamentally different to Guns A/A2.

 

Guns A/A1should be thought of as a Snapshot sight you don't need to stabilize the sight or even achieve the the targets plane of motion. Guns A/A2 is the conventional LCOS sight that requires steady tracking for the sight settling time x the bullet time of flight. See below the excerpt from the manual that illustrates the completely different sight handling available in A/A1. As can be seen Open fire can commence prior to pipper target co incidence

 

 

Errr... you're talking (and the lower half of that page as well) about using A/A1 for a snapshot TECHNIQUE. In the upper half of that same page, it speaks about using A/A1 (and A/A2) for tracking shots.

 

"28.4.2 Tracking Solution.... when tracking, the pipper remains one time-of-flight away from target future position to provide a continuous solution to the aiming problem. Keep the pipper motionless on the target to get maximum concentration of hits. Any pipper motion with respect to the target can result in misses. The tracking solution is primarily (not exclusively!) used in A/A2 gun mode"

 

And "28.4.3 Nontracking solution... the task is to project target and pipper motion to a point of intersection and fire approximately one time-of-flight before this occurs... pipper displacement occurs because of the relative motion of the target to the pipper...an attack in the plane of the target makes estimation easier"

 

In other words, you fire when the pipper and target are moving to where they will intersect one TOF in the future. Aiming in A/A1 is NOT supposed to be "put the pipper at the spot in space where the target will be 1 TOF in the future", it is "fire when the relative motion between the pipper and target will make them converge 1 TOF in the future". The second sketch illustrates this well: it instructs you to drag the pipper from behind the target, start firing while the pipper is still behind the target, and cease firing as the pipper drags up to the nose of the target.

 

Thing is, if you're in A/A1 and holding a steady track, then the pipper and target ARE moving to a point of intersection. They're already AT that point of intersection, and are constantly moving to other, future points of intersection.

 

As I described earlier, I was conducting attacks in which I would drag the pipper through the target's plane of motion from rear to front, opening fire when the pipper moved through the tail of the target and cease fire as the pipper left the front of the target. As described in the document. And would get no hits. Instead, in DCS I have to drag the pipper from the tail of the target, through the target, open fire at point 3 (pipper ahead of target), and drag the pipper even further ahead of the target (ceasing fire at point 4) to get good hits. This means I have to fire, in A/A1 mode, when the relative motion between the target and pipper are diverging (the pipper is ahead and getting farther ahead) instead of when they are converging (when the pipper is behind and catching up).This behavior doesn't match the posted document, nor does it match 1F-5E-34-1-1 manual on nonnuclear weapons employment (which is pretty much verbatim to the posted document).

 

Obviously, if the target changes vectors between firing and impact, any mode will miss.

Edited August 18, 2016 by OutOnTheOP

[Azazel]

I could benefit from a video demonstration/tutorial between the two and on how and when to properly employ them both.

[IvanK]

For what its worth the USAF manual is a little firmer in its recommendations as to which mode should be used for Snapshots.

 

[OutOnTheOP]

For what its worth the USAF manual is a little firmer in its recommendations as to which mode should be used for Snapshots.

 

...which isn't what I said, anyway. I never said A/A2 should be capable of snapshots, I said that A/A1 should be capable of steady tracking pipper-in-center-of-mass shots. The manual says snapshots are A/A1 only. The manual says that tracking shots are primarily A/A2, but does not say that A/A1 cannot conduct them.

 

The description of how snapshots are executed in A/A1 furthermore reinforces that tracking shot CAN be accomplished with A/A1 through a steady, center mass tracking shot, because a tracking shot meets all the requirements of moving the pipper on an intercept course with the target in relative motion and timing the shot for when the pipper will intercept (or in this case, *still* be intercepting) the target in relative motion 1 TOF in the future. In fact, the snapshot description even says that lower relative convergence rates between pipper and target are desirable (and zero is as low as it gets!) One of the A/A1 snapshot sketches depicts opening fire while the pipper is still behind the target, but moving to coincidence. One of them depicts opening fire while the pipper is beside the target but moving to coincidence. Both depict taking a shot when the pipper is 1TOF away from intercepting the target in relative motion. None of them show that you must place the pipper ahead of the target in real space, only that they need to be converging to coincidence in relative position on the gunsight.

 

The only document that states the pilot is supposed to put the pipper in front of the target when using A/A1 mode is the Belsimtek manual, which is obviously a very early draft, given all the grammar errors and poor translations.

 

I strongly suspect BST implemented A/A1 slightly incorrectly, based on a misinterpretation of A/A1 engagement sequence (or the graphics depicting them) in the original USAF manuals.

Edited August 18, 2016 by OutOnTheOP

[acdelta57]

I too can +1 a video tutorial on "best case scenario to use A1/A2 DG modes" and "proper" employment of them

[PiedDroit]

I too can +1 a video tutorial on "best case scenario to use A1/A2 DG modes" and "proper" employment of them

 

Hello, I know it's an old thread but I only started using the F-5E now.

 

On the A1 vs A2 question:

 

A1: "Start to fire one projectile time-of-fligh before the pipper reaches the target future position", "The task is to project target and pipper motion to a point of intersection and to fire approximately one projectile time-of -flight before intersection would occur."

 

This looks like a description of "historical" type sight, which means it's showing where the bullets you would have shot X seconds ago would be now.

Where X is the TOF.

Since it seems to try showing the actual bullet flight path, it is more suitable for snapshot.

What you need to do is to predict when the target will cross the path, and shoot to take in account the time of flight of the bullets.

 

For example: my time of flight is 1 second. I'm maneuvering so I know that the target will cross the piper. I need to shoot 1 second before the target meets the piper.

Note that this is how the M-2000C's sight is working (picture it without the snake).

 

A2: "The pipper is displayed one projectile time-of-flight from the gun line for the rate the attack aircraft is turning and target range."

 

This is LCOS sight, it only computes lead, which means it's showing where the bullets you shoot NOW would be in X seconds, taking in account the attack aircraft aircraft's motion and the range, where X is the computed TOF.

With this sight, you need to shoot when you have achived tracking and target is on top of the piper, if the target doesn't maneuver it will be hit.

 

Hope this helps

Edited January 2, 2017 by PiedDroit

[shaunwallis21]

Ok guys hope this helps. currently the guns have a bit of accuracy problems the dispersion is like a meter spread at 100 meters witch they probably are working on. you should see accuracy similar to the mig 21's laser cannons in the near future only then should we be able to accurately judge the calibration of the Lead Computing Gun-sight. as for accuracy with different ammo types. according to the Book "Cartridges Of the world" the MOA accuracy of the different ammo types are Identical. Until the accuracy is resolved there is gonna be allot of spray and praying.