Tank’s gun vertical angle deviation and hull down position

[Sigurd]

When pointing downwards, tank’s gun have a maximal angle deviation (as compared to horizontal) of about 10°. It’s easy to understand : the end of the gun inside the turret would otherway hit the turret’s top. On another hand, the uwards possible gun’s elevation are higher (around 30°, practical for indirect fire too, as praticed by US tanks I believe), as the space downwarsds the inside ring can easilier be made free for the gun to come in this zone.

Now, we all use hull down positions, where sometimes guns clearly are off the 10° downwards limit. In RL, in such positions, the gunner wouldn’t be able to aim target, but in CMBx he can

The (rouhly) 10° and 30° angles limits come from some tank’s technical drawings seen on various WWII sites, including battlefield.ru

So my questions are :

1°) Does the game engine not reflect (as I suppose) this downwards gun’s elevation limit ?

2°) What are your feelings about such a « gamey » trick. I’ve seen numerous complaints on some of the game’s engine limitations, but not yet on this. But I consider it important, it would be the end of those deadly tank ambushed on a slope behind a ridgeline.

3°) Aren’t you willing to see it corrected in CM2X ?

[Thin Red Line]

I think the graphical representation of the gun angle is just an abstraction. The slope may be in reality not a steep as what is shown in-game, hence the actual angle of the barrel no so large.

And i hope we will not see the end of tanks ambushed behing ridgelines, because it is a common tactic in real tank warfare.

[Mud]

Elevation/depression limits aren't reflected in the game, IIRC.

It would be another bit to fix, but perhaps it'll have to be paired with finer-resolution terrain as well, and maybe a true "gunner's perspective" viewlevel.

[Redwolf]

Both CM games ignore the issue of max gun depression. It was discussed repeadently in CMBO times.

For the eastern front the problem is actually more severe since the difference in max gun depression between Western and Soviet tanks is pretty big. In fact, this remains a serious problem with Soviet tanks designs to this day. Modern tactical manuals practically all mention that most Soviet tanks cannot tanke advantage of most hulldown positions because they have to continue up a ridge until they are horizontal, exposing themself completely. This hulldown position at the slope of a ridge is the most common in CM.

So there is a slight unrealistic advantage for Soviet tanks in CMBB, but I don't think it is that big a deal, since Soviet tanks are usually used better in swift moves anyway than by taking duels from hulldown positions.

One question for those in the know: what is the max depression of Soviet assault guns and tank destroyers. For SU-85 and SU-100 a bigger gun depression would make a lot of sense. Anybody with data?

[Sigurd]

thanks for the info

hopefully that will be taken into account for the rewrite.

I yet find strange to me BFC didn't model it in the first place, as the AFV models are very detailed in other much more complex areas (armor brittleness, quality, the math penetration model, all the different rounds, ...)

[John D Salt]

Originally posted by redwolf:

For the eastern front the problem is actually more severe since the difference in max gun depression between Western and Soviet tanks is pretty big. In fact, this remains a serious problem with Soviet tanks designs to this day.

It's true that Soviet tanks generally have smaller maximum depression, and this was disadvantageous in e.g. the 1967 and Yom Kippur wars, where T-55s and T-62s, despite their smaller overall silhouettes, exposed more of themselves in hull-down positions than did Centurions and M-48s or M-60s.

Still, let us recall that form follows function; I think that the reason the Soviets designed tanks with less depression was that, in the more gently-sloped terrain of the Ukraine, it wasn't really necessary.

If you've played CM:BB on the very gentle grades of a Kip Anderson map, you'll understand how tiny changes in elevation can have significant tactical effects in predominantly flat terrain. One can see much the same phenomenon in WW1 battles in Flanders -- Hill 60 had little geographical significance, but enormous tactical significance.

Originally posted by redwolf:

One question for those in the know: what is the max depression of Soviet assault guns and tank destroyers. For SU-85 and SU-100 a bigger gun depression would make a lot of sense. Anybody with data?

The early SU-100s had depressions small even by Soviet standards, only two or three degrees from memory, and AIUI this meant that considerable care had to be taken in siting them in defensive layouts without them having large "dead" zones in their field of fire.

All the best,

John.

[Redwolf]

Originally posted by Sigurd:

thanks for the info

hopefully that will be taken into account for the rewrite.

I yet find strange to me BFC didn't model it in the first place, as the AFV models are very detailed in other much more complex areas (armor brittleness, quality, the math penetration model, all the different rounds, ...)

It is not only a question of armor model.

It is also a question of StratAI, TacAI and player commands. If you had to get as far forward as neccessary for gun depression then you would have to give the player a tool to reliably order his vehicle in a position to do so, and to stop when achived. Then you need to teach the StratAI how to use this command as well, otherwise singleplayer games have lots of non-shooting opfor tanks. Last but not least some TacAI details could also be tuned towards this.

[dima]

Originally posted by redwolf:

For SU-85 and SU-100 a bigger gun depression would make a lot of sense. Anybody with data?

For SU-85, SU-100, SU-122 it is 3deg down, for SU-152 5deg down

Source is in russian http://redtanks.bos.ru/tanks.htm

[ January 24, 2003, 10:58 PM: Message edited by: dima ]

[Redwolf]

Speaking of it, any recommendations for learning russian, anyone tried one of the teaching CDs? It's for read-only purposes only.

[JasonC]

3 degrees is a little over 50 mils. At 1 km range, that means the LOS has dropped about 50m from the horizontal, or 10 CM elevation levels on a "steep" contour map. 5 steep levels or 10 ordinary ones at half that distance, naturally. So once the tank has reached or passed horizontal, the height of ground it is on will rarely make this an issue - only close ranges to very steep drops.

But it is a realistic issue with smaller elevation changes when the tank is still on the rising ground before a crest. Take a normal contour map with the height changing on average 1 CM level in 3 tiles. That is a 1/24 rise over run. The 3 degree down is very roughly about 1/20 (50 out of 1000 mils, again roughly), so the tank can hit target level with the rise but hardly any below that. If the climbing slope is steeper, like a +1 normal CM contour in 2 tiles, then the tank realistically could only fire at targets higher than itself, until it started over the actual crest.

[John D Salt]

Originally posted by JasonC:

3 degrees is a little over 50 mils. At 1 km range, that means the LOS has dropped about 50m from the horizontal, ... [snips]

But it is a realistic issue with smaller elevation changes when the tank is still on the rising ground before a crest.

"The SU-100 was a most successful design... Its greatest fault lies in the very small degree of depression obtainable on the gun, 2 deg on earlier marks, improved to 4 deg after the war, which makes the engagement of a target from a reverse slope position a difficult matter without exposing the vehicle."

Bryan Perret, "Fighting Vehicles of the Red Army", Arco, New York, 1969.

"The great limitation which the SU-100 suffered in the anti-tank role was its severely limited depression. Its maximum was 2 deg. This meant that on a reverse slope of about 1/20 -- equivalent to 2 deg -- it could only fire down to the horizontal plane. This was such an insuperable handicap that the Russians had to resort to digging in the SU if they could not site it in defilade."

Col. E. F. Offord, DSO, MBE, "Armour in Profile number 21: SU-85 and SU-100 Tank Destroyer", Profile Publications, Great Bookham, 1968.

All the best,

John.

[SgtMuhammed]

Soviet tanks also have more restricted elevation. During the Yom Kippur War the Israelis were able to clobber a bunch of Egyptian T54/55s by taking positions on a ridge. The Egyptians were unable to raise their tubes enough to effectivly engage the Israelis.

The main reason for the lack of vertical movement is the desire to keep their tanks small (at least in modern tanks). This is also one of the reasons the Russians use auto loaders while western tanks use a human loader. Soviet tactics promoted the practice of driving balls out to close range with the enemy (who should be suppressed with a massive arty prep) and so limit his ability to find and use favorable terrain. The fact that their own tanks were unsuited to use most terrain was not really a concern as it wasn't a major factor in their doctrine.

[Redwolf]

Originally posted by John D Salt:

"The SU-100 was a most successful design... Its greatest fault lies in the very small degree of depression obtainable on the gun, 2 deg on earlier marks, improved to 4 deg after the war, which makes the engagement of a target from a reverse slope position a difficult matter without exposing the vehicle."

I reallt don't see the problem. Just remove 75% of the charge and get all the downshots you want

[SgtMuhammed]

Then you can watch the round as it slides out of the tube and rolls down hill at the enemy.