First Thoughts

[ottoramsaig]

It seems the M1A1 is somewhat difficult at engaging moving targets. The M1A1 FCS utilizes a rate tachometer and rate sensor for auto lead. The tachometer is use when your tank is stationary firing at a moving target. The gunner tracks the target for 1.5 seconds fires the laser rangefinder that in turn offsets the reticle behind the moving target. The gunner then places his GPS reticle center of visible mass. This induces the auto lead offset that takes into concideration the targets range, deflection and the rate at which your turret is traverseing. I have noticed that the GPS is quirky at best. For some reason I am lined up in the horizontal plane but my vertical (range) is way off. Guess I just got to get use to it.

19K40H8

Edited July 24, 2010 by ottoramsaig
added info

[sabot_ready]

For some reason I am lined up in the horizontal plane but my vertical (range) is way off. Guess I just got to get use to it.

Are you indexing the correct ammo ? Are you getting multiple returns on lase?

[Tacbat]

Did you RTFM? :wink:

[Volcano]

It seems the M1A1 is somewhat difficult at engaging moving targets. The M1A1 FCS utilizes a rate tachometer and rate sensor for auto lead. The tachometer is use when your tank is stationary firing at a moving target. The gunner tracks the target for 1.5 seconds fires the laser rangefinder that in turn offsets the reticle behind the moving target. The gunner then places his GPS reticle center of visible mass. This induces the auto lead offset that takes into concideration the targets range, deflection and the rate at which your turret is traverseing. I have noticed that the GPS is quirky at best. For some reason I am lined up in the horizontal plane but my vertical (range) is way off. Guess I just got to get use to it.

19K40H8

Well, unless you have an actual gunner's power control handle then gunner will take some getting used to, that is for certain. The mouse is probably better for preciseness, the joystick is very difficult to get fine tuned movement. However, the joystick is good for quick movements.

[ottoramsaig]

Nice, Just got to get used to it. APFSDS, 1200m battle sight indexed, Armed Last Return, against a moving Tank. Compensated for quirky auto lead with a 2.5 mil lead. I am really going to like this game and the Forum.

Otto Charlie Mike............out

[3Star]

A common 'new gunner' mistake, even on the real tank, is to chase the reticle around. Example:

The gunner tracks the target for 1.5 seconds fires the laser rangefinder that in turn offsets the reticle behind the moving target. The gunner then places his GPS reticle center of visible mass

If you were correctly tracking the target, the reticle will not have moved off centre mass after having lased. Your statement is correct for the SABCA FCS as found on the Leo1AS (And a few others of the era, eg IFCS on Chieftain), but not correct for the M1A1.

What happens when you lase in the A1 is the turret 'jumps' to lead the target. Before you lase, with the reticle in the centre fixed position, the turret and gun are pointing at the same place as the reticle. When lead is calculated and applied, let's say for a target going right-to-left, the gun has to be aiming to the left of the target so that the round and target meet. i.e. lead. To do this, the turret has to traverse left a fraction, which also will result in your entire field of view moving left, because Abram's gunsight mirrors do not have a traverse function: They are fixed to the turret. However, the reticle projector is mounted on a gimbal which can traverse independently to the turret. This allows the 'point of calculation' to remain the same, even though when looking through the field of vision which is fixed to the turret, it appears to have jumped to the right. If the calculated lead is correct, not only will the reticle jump to the right in your field of vision, so will everything else including the target. There should be no need to move the reticle onto the target.

Let's say, for the sake of example, you were underspeeding when you lased. This would result in insufficient lead being calculated, and the reticle (and target) would jump too little to the right. After a fraction of a second, the reticle would be behind the target (remember, you weren't traversing fast enough, so the computer thinks the target is slower than it really is), so you increase traverse rate to compensate and bring the reticle back onto target. Remember that the computer is still calculating lead all the time, and the sudden increase in traverse rate tells the computer that the target has just sped up. So it increases lead to compensate as well. If you then fire as soon as the target is back under the reticle, your round will fall to the left (ahead) of the target, and you will miss. The reticle flying around is the visual representation of the constantly-updated fire control solution. Depending on how far off-centre it is, that shows you how much lead the gun is currently applying.

The correct process is that if, after you lase, you find that the reticle is not still centre mass, to accept that you've screwed up, dump lead (Press P), and try again.

NTM

[Retro]

The correct process is to buy Leopard 2

Fixed that for you

Very interesting post, one thing I'm wondering about..

When lead is calculated and applied, let's say for a target going right-to-left, the gun has to be aiming to the left of the target so that the round and target meet. i.e. lead. To do this, the turret has to traverse left a fraction, which also will result in your entire field of view moving left, because Abram's gunsight mirrors do not have a traverse function: They are fixed to the turret. However, the reticle projector is mounted on a gimbal which can traverse independently to the turret

How aprupt is this movement? I would image the turret moving (and also accelerating/decelerating) too fast could cause the gunner to flinch somewhat on his controls and get off-target?

[Ssnake]

The turret's acceleration and deceleration is noticeable but wouldn't influence your aim.

[Ssnake]

It seems the M1A1 is somewhat difficult at engaging moving targets.

I strongly recommend going through the tutorials in the numbered sequence, and read the briefing texts carefully, even if you know it all already.

[ottoramsaig]

Reticle offset in the M1A1 FCS is influenced by the type ammo selected in the ASU. Sabor = 2.5 mils, HEAT-T = 5.0, HEP-T = 7 mils. Therefore the lead offset in the GPS will be greater and noticable with the slower ballistic rounds. I am not sure if the "Cross Wind Sensor" effects the ballistics in the game. In the stationary mode the "Cant" sensor also effects the ballistics match.

Just a note: HEAT-T becomes subsonic at around 2000 meters and the drag on the projectile will effect the range of the round.

Love this game!

Otto.............out

[3Star]

Reticle offset in the M1A1 FCS is influenced by the type ammo selected in the ASU. Sabor = 2.5 mils, HEAT-T = 5.0, HEP-T = 7 mils

Where are you getting that silliness from? (Not least, M1A1 can't fire HEP, that's a 105mm round).

Second, think about it for a second. The lead cannot be a constant. If you're firing a HEAT round at a target moving at 5mph left to right, you only need a little bit of lead. If you're firing a HEAT round at a target moving 40mph left to right, you need quite a lot of lead.

You are correct that sabot will need less lead than HEAT which would need less lead than HEP (on a 105 tank), but the numbers are not fixed.

Now, in the case of lead calculation failure (i.e. the computer no longer works), and you have gone to Emergency Mode gunnery, 2.5mil for Sabot/MPAT and 5mil for HEAT are listed in the manual as suggested initial lead factors for the gunner to aim off, but they are obviously just estimates in the hope that they're appropriate and the gunner needs to adjust his point of aim by observing the impact.

NTM

[ottoramsaig]

I stand corrected, you are right about the 120mm and HEP-T got confused with the M1IP (its been awhile). I will keep my comments to myself. I was always trained to apply the basic lead value during degraded mode gunnery and as you said apply BOT if the round missed.:frown:

[Michael F]

Otto, don't get down about your comments. I'm having fun reading them. Come on, I taught myself tank gunnery in a simulator simply because I wanted to run in a tank. I'm always up for hearing more interesting things.

I know you had a little bit of trouble getting everything up and running, and you're excited about it, and maybe being forced to run through the tutorials with no experience with the vehicle gave me a leg up for the program, but it's a very quick learning curve. I just wish my computer didn't eat that AAR with my 1600 meter no-FCS shot I did that one time. Yes, it was luck as much as skill.

Anyway, this is easily my favorite purchase in many years, and I think you'll enjoy it as well, but just think of it like a new vehicle. You have to get used to this particular one.

[ottoramsaig]

Really appriciate the comments Michael F. Can't believe I said M1A1 and not M1IP:) I grew up on the M48A5 then the M60A1 and my first taste of a dynamic FCS was with the M60A3. Then came the M1 (Slick) followed by the M1IP. I have to be honest though and admit that I loved the old M60A3. She was slow on the move but what a fantastic FCS in the defense. I remember looking through the GPS on the M1 and being very disapointed. Its been 10 years since my last tank manuver.................really miss it.

The lead values are found in the 17 Manual. I remember there was a method for detirming speed but was not part of the Worm Formula.

Edited July 24, 2010 by ottoramsaig
added comments

[3Star]

I was always trained to apply the basic lead value during degraded mode gunnery

That is correct, don't forget that the computer does not apply that estimate. It works out exactly what the lead is, be it one mil or seven. And the reticle should not jump off the target. I'm impressed that you remember the values off the top of your head, mind, but they're being inappropriately applied when it comes to normal mode gunnery.

The lead values are found in the 17 Manual. I remember there was a method for detirming speed but was not part of the Worm Formula

The current manual does not bother with a manual lead calculation. It just instructs the gunner to work off those initial lead values and adjust accordingly. They probably figured it was quicker to fire two shots than trying to do maths.

NTM