GSprocket

Without any HEF, or TLGM the max engagement range is 3200-3300 as per AP.

With TLGM it is as high as 5000, but only using APFSDS and HEAT. Once these are expended it will use TLGM *only if* there are no APFSDS or HEAT remaining in stowed rounds, or an 'unwanted' HEF is present. If all 'ready' APFSDS and HEAT are expended and there is no HEF, the tank reloads APFSDS and HEAT in preference to expending TLGM.

(This is similar to the bad ammunition selection logic of e.g. the Challenger, where it will use HEP/HESH against long range moving APC, despite the high probability of a wasted round, this should be HESH/HEP against short range, or stationary targets only, with APFSDS used against movers, regardless of protection style ~ possibly with a bias towards engaging tanks over APCs in the moving case at longer range).

The T72 (and other similar vehicles (T-64 and T-80U)) will use their APFSDS and HEAT within their appropriate range constraints only when the other natures are not present.

Adding HEF will cause the vehicle to expend all of these natures at extended ranges before switching to TLGM or HEF when all other rounds are expended.

(I also note that once the last Carousel round is loaded into the gun it will reload the carousel, rather than expend this round).

Attached simple scenario with 4T72B north to south:

APFSDS, HEAT

APFSDS, HEAT, HEF

APFSDS, HEAT, TLGM

APFSDS, HEAT, HEF, TLGM

Quantities as default loadout for 'present' natures.

Target platoons of T55 advancing from 6km. The APFSDS of the southern vehicle are being expended from 5km (to minimal effect).

T55s are not set to hold fire, they probably should be.

Probably related to some complaints of 'uber Txx' as they fire from ~1-2km further out than is normal. Also some 'crap Txx' as they expend too much ammunition at ineffective ranges, and using inappropriate types.

T72AmmoUse.zip

BM42M... which is more advanced than anything fielded on a large scale by any eastern bloc country (Typically only BM42 WHA (and previously BM32 DU), with most users of T72 using BM9, BM12, BM15 or BM17 steel rounds).

No CR2 has ever faced anything more advanced than BM17 (and probably not even that).

The CR1 in ODS were predominantly facing off against T54 derivatives... which they fairly predictably butchered.

Doesn't the FCS apply both the required correction to the FCS and also counter-steer the turret to maintain the target aim point without gunner intervention?

It seems that if the FCS can accurately bring the gun to the correct alignment to both compensate the firer and target platforms' movement in the moving case, that it should also continue to do so as the target platform movement approaches (and eventually reaches) zero.

I can see that deriving target movement from noisy angular & (movement derived) range rates can increase error when this can be correctly and explicitly set to zero by a mode change, but this isn't the same as 'doubling the correction' or applying it twice.

Yeah... quite obviously only a TURDS Ballistic Compensator, FCS is going too far.

It doesn't seem credible for a 'war-round'. 95m/s faster than DM53, fired from a rifled barrel of similar length.

(This is *more* than the difference between L44 and L55 barrels firing DM53 (~80m/s)).

It is conceivable that a long-range 'prac' round might use such a high V0 to "match" distant trajectories with a much lighter round that decelerates faster, but there would be a significant cost in wear.

Even if this fantastic velocity were accepted, it would increase penetration only by ~10% over the assumed value at 'around' ~1670m/s.

The actual length isn't *too* critical though. The 25% increase in tube length L44>L55 gives less than 5% increase in muzzle velocity for properly tuned rounds, and less than 10% more kinetic energy. This is why the US finds the L44 still adequate, and why most upgrade programs for the Leopard were looking at L44 model gun tubes still (a few had L55 options, but there are compromises in accuracy, stabilisation and close-terrain flexibility with the longer gun).

I think the French 120mm is an L52, as are the Soviet 125mm guns FWIW.

Careful, because in our infinite wisdom the UK chooses to use L to designate it's individual model weapons/ammunition at just about everything else.

e.g.

L7 105mm gun is L/52 or thereabouts

L11 120mm gun and L30 120mm gun both L/55

L15 - a 120mm APDS round

L23, L26, L27, L28 - 120mm APFSDS rounds

L23 76mm gun is unclear ~ I've seen both L/23 and L/28 quoted for it.

L85/L86 are rifle and SAW in 5.56mm

etc, etc

Everything I've seen about the L28 projectile indicates that it is a cut down version of DM53 projectile fitted to a rifled-gun compatible sabot and fin protector, fired at similar velocities to DM53 from an L44 barrel.

Stowage requirements being the same for both (I can't imagine that L28 can be significantly longer than L27 as it has to fit the same racks, and L27 was the 'goal' development of the CHARM round.

With similar velocity, similar dimensions the difference in performance between L27 and L28 is going to be marginal ~ though it may favour L28 at shorter ranges.

Whether L27 is set at the correct level is arguable (though it may be correct-er than some of the other rounds... I'd assess many as being significantly optimistic based on known dimensions and the curve fits from Lanz-Odermatt for DU and WHA rods). In particular highly sloped impacts are more efficient than normal ones. 'Test' arrays are usually either large and highly sloped thin plates with perforation LOS given, or stacks of small, poorly constrained blocks hit normally when the penetration into the stack is given. Often the penetration into the stack approximates the perforation limit at 60-70 degrees (this stated and re-stated by Wili Odermatt on several occasions), and is some 15-25% more than the perforation limit in a normal impact (i.e. the maximum armour thickness than can be perforated at any angle).

PM me. i may be interested. Does it come with the hard disk?

Do you mean Codemeter USB Dongle? If so it is the only way that a permanent license can actually be delivered from an end-user.

E-Sim can sell licenses which you can upload onto an existing Codemeter stick, either as updates or full licenses.

It is *all* the same. The systems all take similar inputs of angles and angular rates, ranges and range rates and other sensor inputs (e.g. air temperature, wind, round temperature etc).

How the resulting lead calculation is applied varies slightly ~ some calculate a fixed FCS solution, others continually monitor the variables and update the lead dynamically as they change.

Within the vehicles of SB, the former case covers the Leopard AS1, ASLAV and similar vehicles, while the latter case covers all M1, Leopard 2 and many other vehicles.

The differences between Leopard 2, M1A1 and M1A2 are only in display of this result, and the minor detail of what controls are applied to impose it on the stabilisation system.

The M1A1 differs "obviously" as it has a single axis movement of the head mirror and a reticle that appears to "float" within the visual field in azimuth. The movement of the reticle with respect to the gun tube when invoking lead is identical for all three cases however.

The Leopard 2 has independent controls for driving the gun and applying the FCS calculated lead, while the M1A1 and M1A2 shares the palm switch for both duties. This is a relatively minor difference compared to the vast swath of identical functions. What is good practice with the M1A1 remains good practice with the other vehicles precisely *because* you can't see the impact of bad inputs to the quality of the tracking solution.

I personally find the M1A1 slightly easier to use than the Leopard 2 because I can see much more readily when I've screwed up the tracking or lasing.

There have been incidents in training with the base cap separating from the case. This spills loose granules of propellant all over the turret floor.

It is an irony that this is *more* dangerous with the lower cost training ammunition. Propellant fires tend to be much faster developing with the training propellants than with the inert war-rounds.

Still, once learned that one doesn't do this with training ammunition you probably just extend that to any natures.

Lap loading is also prohibited since fatal accidents involving hot base stubs and propellant casings.

Even in the days of brass casings I think it was generally 'fire what it loaded' then load a new nature if required.... as this is a lot faster than manually unloading a semi-automatic breech, and extracting and restowing the round, before loading the next.

Still sounds wrong. Dual Axis or Single axis merely reflects how the reticle is disturbed within the sight FOV, but the inputs are still derived from the same rate sensors.

There is less feedback from the displaced reticle and a slight tendency to chase it, but I don't see that the necessary integrations and differentiations can be done any faster than on the Leopard, which *does* require that the gunnery solution is 'lost' between slewing and tracking, either by waiting out the solution settling time, or by 'ending' the solution.

DAHA is an improvement, sure, but engineering wise it doesn't really change anything in *how* the solution is determined, nor in the importance of not including high rate errors into a steady track.

Hmm. You sure you don't need to dump lead in exactly the same situations as on the M1A1? It is only the head mirror that is driven differently, the FCS lead calculations are otherwise the same.

On the Leopard you should cease applying dynamic lead between engagements to avoid corrupting a track with a slew-rate input, and the same should apply to the M1A2 (except by default dynamic lead is "always" applied and needs to be 'dumped' rather than applied as needed). (The Leopard has palm switches and a separate lead button, the M1 series has lead applied with the palm switch, on calculation of a FCS solution, but which can be dumped by releasing the gun control after the calculation is done).

Challenger followed on from Chieftain, which presumably was the donor project for ammunition stockpiles.

Conqueror was a much earlier and less numerous project (Heavy tank, alongside Centurion "Medium"), while Chieftain was the main battle tank of the 1970s/1980s.

"Losing a track" can have several different consequences...

On firm ground, if the track remains on the vehicle, but the transmission seizes, then it will be as if full braking is applied to that side only. The vehicle will slew strongly to that side and may roll depending on speed. One or both tracks may jump as the vehicle turns uncontrollably.

If the track fails then braking is lost on that side. this may cause an uncontrolled turn away from the damaged track on firm ground, or if both are lost an uncontrolled coasting. (Also in the case of control of driver incapacitation it is possible).

On softer ground the vehicle will roll forward until it drives off the remaining track then bog on the damaged side, rapidly coming to a halt, again with a more or less strong turn. This is likely to be less severe than on very firm ground as the deeper sinkage causes much higher resistance and more rapid slowing to a halt, especially when turning.

If the second track isn't lost, then some *limited* ability to steer might be present ~ I wonder if SB gets this limitation correct for various extreme conditions (i.e. on very hard going the limited resistance of the undriven side may give little for the track on the other side to push against if the track is completely off, and in very soft going there may be insufficient traction to obtain any movement at all with the very deep bogging of bare wheel stations).

Here is a 2011 SB video which has the higher tank inertia movement and a narrower FOV.I think it looks perfect like this and makes you feel more like being inside the tank.

That one is definitely a ProPE video with the 'current' inertia and FOV. Perhaps the problem is what views you use within the vehicles, or what the terrain parameters are set at in your scenarios. There is a huge difference in 'silkiness' possible within the map/scenario design.

Wow, and look at 1:57 the way the impact hitting the target in the rear left swings it around. Would that ever happen in the current version? And/or is that realistic?

That was the nearside track being lost. The same effect is still seen in the current version (drag/traction/speed dependent). I see it quite often with the BMP, rather less with T55, which are my 'hard targets' for my most commonly played scenario (modified Australian TT).

Not pure luck, though that will have come into it (maximum dispersion is larger than target form being at least one part of the problem, and also difficulty in obtaining a clean lase from a small target at long range...). However, the FCS of Challenger 1 as far as I can tell was capable of generating a valid APFSDS solution at 5km, at a time when all other tanks 'cut off' at 4km or less (probably a result of the necessary computation for HESH engagements at more moderate ranges).

While other tanks can fire APFSDS to the same or longer ranges they cannot do so in their normal operation modes and need various workarounds to accomplish the result.

Several that I've seen discussed:

For a target at 'just over' 4km, setting the sight onto the target in emergency mode, setting the manual range to the same offset 'just under' and relaying centre of mass.

Using a different ammunition nature, and a conversion table for lased>manual range with the "wrong" nature loaded/indexed.

While the CH1 FCS is convoluted, it does have some helpful features too. The Ellipse is a very useful visual guide to whether the current range is appropriate for the target's distance. If the lased range is much too short for any reason, the Ellipse will be too large for the target which will not 'fill' it correctly.

The RHA equivalency given by Deja was 610mm, with "maximum thickness" being by elimination 700mm. The image seems to show a value of 800mm to that weld line, but this may not reflect the actual rear edge of the armour module (a 'lid' can extend beyond the edge of a hole providing more support). I'd go with the thickness being higher than 700mm though.

The first four minutes of

, to give you an impression.

Some really incorrect assertions there:

APFSDS can be made from DU, WHA or Steel, and can combine materials - eg a WHA or WC penetrator in a Steel body, or a light alloy sheath on a high L/D rod which is too weak on it's own.

Steel armour is (can be) sufficient on it's own to deform and erode any material used in APFSDS - it isn't very efficient, and too much material is needed to stop current practical penetrators without additional techniques for practical applications on MBT. This is extensible to Aluminium or Titanium, both of which are considerably less dense than steel, but slightly or significantly more 'mass effective'.

The diagram for the in-chamber APFSDS round is obviously wrong ~ the case is not in the breach area but considerably 'in-bore', with the breach face *outside* the mantlet.

Ceramics are harder than steel, and also WHA or DU, but not denser. One of their attractive characteristics is high resistivity for lower weight (at the expense of increased bulk and complexity).

"Attack" of penetrators is most efficient when varying levels of hardness and density are used, rather than just harder/denser being better. This causes the rod (or HEAT jet) to fracture into shorter segments, each of which can be rejected by the remaining plate(s), even if the total thickness is far below what the intact penetrator can handle.

The usual nonsense of 'significant overpressure and temperature' causing difficulties for the crew... which is probably the least of their problems in the case of a non-marginal perforation by a main gun round... I'd have thought the thousands of sharp fragments of penetrator and armour travelling at 1000m/s or over would be a bigger concern (i.e. this makes as much sense as describing the 'pressure, heat and light' from a defensive hand-grenade as being the primary effect... (the two, are as far as I can tell nearly directly comparable) - and in a confined space, at short distances it is obviously more likely that fragmentation will be the primary casualty producer).

Odd decision to use a WAD M1 'test' of the containment of ammunition fires to illustrate the 'cook off' and destruction of a tank. I'm sure there are better examples of what happens when stowed ammunition really does cause a K-Kill.

HEAT penetration is purely 'solid phase' - no melting (either of the jet or the armour). The flow is purely because of high pressure and in effect is similar to that of sand under attack by a water hose (used by the Egyptian engineers to do the "impossible" and breach the Suez "Bar Lev" line 'on the fly', rather than taking many hours of complex and vulnerable engineering works.

WHA can be a superior material, it does rather better than DU at higher impact velocities, and is only limited by it's relatively high cost (DU is essentially 'free' being a waste product from nuclear power enrichment processes, while W is scarcer more universally useful (excellent machine tool material for cutting hard materials).

DU has some advantages at marginal penetration cases as it is highly pyrophoric, but this doesn't change that at ordnance velocity it needs *more* energy for a given penetration than a well designed 'modern' WHA material (the case was different before monoblock penetrators became feasible).

At lower velocities (around 1580m/s) 'similar' geometry WHA and DU rods will have the same performance, so the 'better' DU probably comes from the era of the 105mm gun, where V0 was around 1450-1510 m/s. With the higher velocity 120mm gun, the material factor is changed ~ with the range of velocities from 1555-1680 (and the only two sub 1650m/s rounds being the DU M829A1 (1575) and M829A3 (1555), where the lower velocity was used to obtain *much* larger rods than previously possible for the material strength and gun performance).

None.

Look at IFV and APCs, why do you think the engine is in the front?

So the passengers can exit through a large door without climbing over under or around the engine.

It is true that a few APC/IFV do have rear mounted engines, but these tend to be conversions of standard obsolete Tanks, or are considered to have some issues with usability/armour protection.

(e.g. rear engine in BMD or BMP-3 with rear/roof exit for infantry, or rear engine(s) in BTR 60/70/80 series with dismounts exposed to fire from all round during mounting/dismounting operations (normal APC arrangement with rear doors permit the vehicle bulk to shield mounting operations when oriented on the enemy at least... though the side door does sort-of permit dismounting without halting if absolutely required (not something as easy to do with a ramp))

Just "invade" Finland ~ they've got lots of 'official' high quality GIS data freely downloadable. :bigsmile:

Muzzle velocity of M829A3 is significantly higher than it would be if it used aluminium sabots, or even the first generation composite sabot technology of M829A2.

The improvement in parasitic mass reduction is higher from M829A2 to M829A3 than it was from M829A1 to M829A2 (mostly change of sabot from Alu to Composites of similar 'design'), the M829A3 sabot is injection moulded (drastically reducing cost and improving efficiency of manufacture), and also optimised with material reduction in lower stress areas.

Projectile energy of M829A3 is significantly higher at 1555m/s than for M829A2 at 1680m/s, and the use of DU material favours the lower impact velocities for improved projectile strength and penetration depth for constant energy projectile mass/velocity pairs. (WHA prefers impacts at somewhat higher velocity/lower mass, though the differences are subtle).