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Lumituisku

What does "Range" mean in ammunition stats?

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Sooo, I have recently been more and more interested of manual range finding, and estimating lead.   I found this page from wiki to help me out to find velocities of different ammunition.  http://www.steelbeasts.com/sbwiki/index.php?title=Ammunition_Data

 

Then I noticed that there is "Range"  and  while in a way it seems obvious that it is somekind of effective range of ammunition. I got qurious if it really is so?  I believe it is possible to fire these rounds more far than range is. Yet... I wonder, what does that actually mean?

 

Should I take it that Range means  that at that distance, given penetration value is still achieavable?

 

If so, doesn't that mean that there is even more penetration potential on closer distances?

 

I think I have seen this topic discussed somewhere, but don't seem to be able to find it.  

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Posted (edited)

I haven't looked at the page but I think you'll find that "range" = "effective range" (unsure if the page defines effective - a combination of likelihood of hitting and ability to penetrate XXXXmm of RHA at Y degrees or something).

 

Certainly its not how far the round will travel.

 

For example our Leopard AS1 105mm APDS round had an "effective range" of around 2,000m.

 

The range template for "service sabot" though was 22,000m -so the penetrator would travel up to 22,000m if nothing got in the way, but at say 19,000m it would have far less kinetic energy (ability to penetrate a target) than it had at 1,500m.

 

Edited by Gibsonm

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Posted (edited)

Right, Thank you Gibsonm.

 

I wonder...  as there are Rha penetration values on same column,  does it mean that given Rha penetration is at that range or the best round can do on some other more optimal distance. 

 

I also wonder...  how much I could theoretically expect to lose from tank sabot round penetration, lets say... if round has to travel one more km after the effective range? perhaps something like  20%?   

 

Edited by Lumituisku

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There's several things behind it. First and foremost, it's the cutoff range for AI engagements. Even if the ammo flies farther out (e.g. up to 130km for 120mm APFSDS DM33) , computer-controlled units won't fire. You can try trick shots as a human gunner if you want, but your AI commander might order you to cease fire (in our simulation you may disobey the vehicle commander without fear of consequences, a highly unrealistic aspect).

 

Typically this range is derived from published data. It could be a limit of the ballistic computer not having values in the firing tables beyond a certain range. It could be the tracer burnout range after which you can't properly observe your fall of shot. In rare exceptions it could be that the ammo is so slow that beyond range X we decide to cut it off so that the AI won't waste a lot of ammo on targets that it can't effectively hit. I don't remember that we ever did this, but we reserve the right to do so for the sake of sanity.

 

Our RHA equivalent (=RHAe, not RHA) values represent the energy at the muzzle, for range-dependent rounds.

 

The energy of sabot rounds depends on a number of factors; where you look at a fixed design the impact velocity becomes the sole determinant, of course.

You may find this page useful, use it responsibly. A classic APFSDS round like 120mm DM33 loses about 50m/s velocity per kilometer travelled. Older rounds tend to slow down quicker, also Soviet designs with their larger fins due to the different sabot designs (less parasitic mass = higher muzzle velocity attainable, but more drag in exterior ballistic flight because the fins must reach bore dialeter in order to stabilize the projectile during the interior ballistic phase (while it's scraping the walls of the gun tube))

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RHA equivalency is probably not a term with which you can impress weapons design engineers in a conversation. It is problematic in a number of ways. At the same time it's incredibly handy to get a rough but reasonably useful idea. We're using it because we don't attempt to nail every aspect of terminal ballistics with scientific precision. We want to convey a sense of what would happen, no more.

 

MInd you, I'm not claiming "artistic license" here, which we certainly could. It's more the fact that reliable and standardized data are impossible to find. So, terminal ballistics is as much a matter of guesswork than it is of physics and parameter estimations. It's less of an issue with WW2 vehicles because as the archives are being opened you can read up the weapons test results, and the models and formulas that were used at the time, and calculate the parameters accordingly. Even then, what happens after the last armor plate has been successfully punched through is highly contentious. It starts with the question of the definition of plate failure. A visible bulge in the back plate? A crack? The white hot tip of the projectile poking through, saying Hello? A projectile's full-diameter or bigger hole? Once in a series of shots? In 50% of all shots? In the vast majority of them?

Then, what happens as the fragments start flying in the crew compartment; what's the mass and velocity distribution of them, which fragments "count" as being destructive for which component inside? Those who know can't tell, and they know only isolated test. Therefore, those who tell are either liars or traitors, and in any case they don't know the full picture across all nations.

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3 hours ago, Lumituisku said:

Right, Thank you Gibsonm.

 

I wonder...  as there are Rha penetration values on same column,  does it mean that given Rha penetration is at that range or the best round can do on some other more optimal distance. 

 

I also wonder...  how much I could theoretically expect to lose from tank sabot round penetration, lets say... if round has to travel one more km after the effective range? perhaps something like  20%?   

 

there are a few aspects of penetration values not taken into consideration in SB, namely "sabot wobble" during initial flight,  and advanced HEAT target interactions. 

the first causes penetration values to fluctuate for the first 500 meters of flight, by quite a significant margin, the second can either cause the warhead to fail detonating, or "bend" into a target before penetrating. 

 

as for post-penetration effects.. this relies on a number of factors. the most common for a full penetration would be the shotgun like spray you see in popular tank games like WOT and WT. 

other target interactions are possible however, such as "plugging" as well as non-penetrating hits that still cause spalling.

this effect can also be seen in numerous images from the gulf wars, along with a large number of declassified documents describing post-penetration effects, and it's effects on crew. 

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4 hours ago, Ssnake said:

There's several things behind it. First and foremost, it's the cutoff range for AI engagements. Even if the ammo flies farther out (e.g. up to 130km for 120mm APFSDS DM33) , computer-controlled units won't fire. You can try trick shots as a human gunner if you want, but your AI commander might order you to cease fire (in our simulation you may disobey the vehicle commander without fear of consequences, a highly unrealistic aspect).

 

Typically this range is derived from published data. It could be a limit of the ballistic computer not having values in the firing tables beyond a certain range. It could be the tracer burnout range after which you can't properly observe your fall of shot. In rare exceptions it could be that the ammo is so slow that beyond range X we decide to cut it off so that the AI won't waste a lot of ammo on targets that it can't effectively hit. I don't remember that we ever did this, but we reserve the right to do so for the sake of sanity.

 

Our RHA equivalent (=RHAe, not RHA) values represent the energy at the muzzle, for range-dependent rounds.

 

The energy of sabot rounds depends on a number of factors; where you look at a fixed design the impact velocity becomes the sole determinant, of course.

You may find this page useful, use it responsibly. A classic APFSDS round like 120mm DM33 loses about 50m/s velocity per kilometer travelled. Older rounds tend to slow down quicker, also Soviet designs with their larger fins due to the different sabot designs (less parasitic mass = higher muzzle velocity attainable, but more drag in exterior ballistic flight because the fins must reach bore dialeter in order to stabilize the projectile during the interior ballistic phase (while it's scraping the walls of the gun tube))

Cheesus... DM33 can fly up  up to 130km....  And just loses about 50m/s velocity per kilometer travelled.   😲

 

Umm...  So when most engagements are under 4km,  is it safe to assume that in Steelbeast all tank sabot rounds have full penetration up to around 4km? or atleast to "effective range"?  Unlike  "in popular tank games like WOT and WT." where tank rounds seems to purposefully lose penetration very rabitly.

 

I guess, and may have witnessed how... some older DM rounds seem to lose accuracy on long distances to be worth of trying to hit target without considerable change of missing tank sized targed beoynd the effective range?  

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The first question is, do you have the sensors for proper target identification.

 

The next, even if the velocity decay is gentle, it's still there. Suppose your ammo overmatches the armor protection value of your target by 5%, you lose those 5% energy in the first 650m of flight, so even the small loss can make a difference. Say, your target was at 6km and you could identify it, losing 330m/s over those 6km means losing 33% of the projectile's initial energy (starting from V0=1680m/s;   1350²:1680²=0.6726, don't forget that the velocity goes squared into the kinetic energy formula). So it only makes sense to fire at the target if you have still have an overmatch at that range, IOW 400mm RHAe or (preferably) considerably less. So, what targets does that leave, PT-76, T-55? And of course side-on shots against pretty much any target.

 

Accuracy is another issue. I heard rumors that the aluminum stabilization fins of 120mm DM33 heat up due to air compression at (initially) Mach 5 that they actually erode so that the projectile actually starts to flutter ever so slightly beyond 10km range. I haven't done the math and I can't say if that's even remotely possible (I don't think so, to be honest, although the tail section certainly receives some heat treatment while still inside the barrel, so... who knows). But if true, that would certainly be another limiting factor. Then there's (not) knowing the crosswind along the whole trajectory, and at really long ranges Coriolis force might start to play a role too (though the projectile spin is too slow for the Magnus effect, at least).

The Israelis fired tank guns at targets up to 10.5km against Syrian bulldozers (and hit them) during the Jordan water diversion project (just before the Yom Kippur war), but they used artillery observers and fired the guns blindly, so that would be a military historical example of extreme tank gunnery.

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Posted (edited)
14 hours ago, Ssnake said:

The first question is, do you have the sensors for proper target identification.

 

The next, even if the velocity decay is gentle, it's still there. Suppose your ammo overmatches the armor protection value of your target by 5%, you lose those 5% energy in the first 650m of flight, so even the small loss can make a difference. Say, your target was at 6km and you could identify it, losing 330m/s over those 6km means losing 33% of the projectile's initial energy (starting from V0=1680m/s;   1350²:1680²=0.6726, don't forget that the velocity goes squared into the kinetic energy formula). So it only makes sense to fire at the target if you have still have an overmatch at that range, IOW 400mm RHAe or (preferably) considerably less. So, what targets does that leave, PT-76, T-55? And of course side-on shots against pretty much any target.

 

Accuracy is another issue. I heard rumors that the aluminum stabilization fins of 120mm DM33 heat up due to air compression at (initially) Mach 5 that they actually erode so that the projectile actually starts to flutter ever so slightly beyond 10km range. I haven't done the math and I can't say if that's even remotely possible (I don't think so, to be honest, although the tail section certainly receives some heat treatment while still inside the barrel, so... who knows). But if true, that would certainly be another limiting factor. Then there's (not) knowing the crosswind along the whole trajectory, and at really long ranges Coriolis force might start to play a role too (though the projectile spin is too slow for the Magnus effect, at least).

The Israelis fired tank guns at targets up to 10.5km against Syrian bulldozers (and hit them) during the Jordan water diversion project (just before the Yom Kippur war), but they used artillery observers and fired the guns blindly, so that would be a military historical example of extreme tank gunnery.

I suppose that is very reason why it is said that some russian tanks have edge on longer distances with their tube lauched ATGMs 

 

Thank you all for your answers. Gibson, Dejawolf and Especially Ssnake.  I have learned a lot and I find all this rather valuable. 

 

There is one thing though that still bugs my thoughs.  On some vehicles and ammunition there is so called minimum range. I believe I saw piece of text in Cv9030(fin) tutorial where it says that APDS ammunition takes a little while to reach its full penetration potential, as sabot parts separate from the ammunition.  Those videos I have seen from sabot rounds though, suggest that separation is almost instant, though I suspect it may not be same for every ammunition?

 

Another instance where I have seen this minimun range is with some infantry weapons. I believe it was missiles and perhaps even RPGs?   With RPGs  what I have noticed is that if you fire those too close to tank... it can often be fatal to infantry nearby, because of fracments from explosion.

 

So my question and wish is as follows...  Is there do we have source or method to know minimum range? Could such data added to simulation in future perhaps next to ammunition range? 

 

 

edit:   Oh, I just though  that it could be that minimum range is more valuable with HEAT warheads?  Perhaps it has something to do with arming distance?  I may have messed some things up in my memory.  😣

Edited by Lumituisku

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Yes, usually it's the arming distance, and usually it's rather short.

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Posted (edited)

It can also be "gather" range on older ATGMs as the Operator tries to get it under control.

 

e.g. AT-3 Sagger is good for 300 - 3000m. The first 300 is used up trying the get the missile under control. One of the reasons why a BMP-1 has a 73mm gun too (to cover the gap where the missile isn't usable).

 

Edited by Gibsonm

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...where the 300m for MCLOS Saggers is a highly optimistic figure. 800m is probably more realistic. Our model is the SACLOS controlled AT-3d, which is brought under control by the guidance electronic much sooner.

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On 7/30/2020 at 11:40 PM, Lumituisku said:

I suppose that is very reason why it is said that some russian tanks have edge on longer distances with their tube lauched ATGMs 

 

Thank you all for your answers. Gibson, Dejawolf and Especially Ssnake.  I have learned a lot and I find all this rather valuable. 

 

There is one thing though that still bugs my thoughs.  On some vehicles and ammunition there is so called minimum range. I believe I saw piece of text in Cv9030(fin) tutorial where it says that APDS ammunition takes a little while to reach its full penetration potential, as sabot parts separate from the ammunition.  Those videos I have seen from sabot rounds though, suggest that separation is almost instant, though I suspect it may not be same for every ammunition?

 

Another instance where I have seen this minimun range is with some infantry weapons. I believe it was missiles and perhaps even RPGs?   With RPGs  what I have noticed is that if you fire those too close to tank... it can often be fatal to infantry nearby, because of fracments from explosion.

 

So my question and wish is as follows...  Is there do we have source or method to know minimum range? Could such data added to simulation in future perhaps next to ammunition range? 

 

 

edit:   Oh, I just though  that it could be that minimum range is more valuable with HEAT warheads?  Perhaps it has something to do with arming distance?  I may have messed some things up in my memory.  😣

HEAT rounds go subsonic between 1800 and 2000m, I have actually had them hit sideways on targets (real life not SB), no effect at all. Better to shoot close in or even Battlesight.

 

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Another aspect is that AP hits can be difficult to observe at long range. In Sherman tanks, where a range finder didn't exist, crews used to fire HE rounds first to determine the range, and after scoring a hit they switched to AP.

Edited by Iarmor

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Almost anything can deflect a round just look at around 10:20 how pumpkins can deflect a 122 mm round
 

 

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