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APDS and APFSDS whats the difference?

I am interested in modern tanks/how their ammo type works and I know that here are many tank "nerds" with their information of secret documents.

 

So I ask you this what is difference between APDS and APFSDS? Only fact which I know is that APFSDS is much much faster. And why Chieftains strong APDS dont penetrate T-64 front armor? 

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Hi!

The main difference between the APDS and APDSFS is the shape of the penetrating projectile.
While APDS fires a sub-caliber shell it looks more like a normal shell or a large bullet. 

APDS whell fires a slightly smaller caliber penetrator than the cannon caliber.
Whilist APDSFS has a rather long penetrating rod with fins at the back.
APDSFS fires a thin long rod.

Here you can see it on the picture:
 

Spoiler

AP%20projos%202.jpg

Left: APDS with sabot attached

                                  Middle: APDS penetrator

                                                     Right: APDSFS with sabot attached


APDS is mostly slower than it's FS brother, but the increased weight gives it around the same amount of kinetic energy.
Although it's larger size and greater air friction makes it lose energy faster while traveling long ranges.
The shorter length of the projectile handles sloped armor better.


Not sure if that was the answer you were looking for, but it's something... 
I hope more educated people on this topic are willing to share an answer.

Edit: About the Chieftain and T64, I'm not sure, but it's probably the T64's strong composite armor.

Spoiler

 

iSnBEAz.jpg

ecTLnAh.jpg

Also you should account for the highly sloped front. At 68 (32 deg angle of attack) degrees it might just beat the Cheiftans APDS. APDSFS is even less effective at these slopes.

Edited by VoidGamer
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1 hour ago, VoidGamer said:

APDSFS is even less effective at these slopes.

 

While the general explanation given was good the sentence above is untrue.

Basically APFSDS don't care about slope, it just dig in while slightly bending toward it

 

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upaC2x8.jpg

 

The method to defeat an APFSDS is not to stop it with enough armor but rather by trying to break it into several segments which will prevent the rod to apply all it's energy on a single point but rather disperse it, which is what NERA array (a type of composite armor) do.

 

Against an APDS you want an armor that will be able to keep it's structural integrity, withstanding the energy of the shell.

So for an APDS slope will matter, while for an APFSDS only LoS and composition of the armor will.

Edited by Alzoc
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30 minutes ago, gomine123 said:

that and IRL APDS was horrible inaccurate so they added the fins to massively increase effective range

 

 

The fins are needed when projectiles are shot out of smooth bore guns, no rifling to provide stability.

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In-game the difference is that APDSFS is meant to be the cool money making ammo so it makes more spall than APDS.

Edited by AraMacao
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44 minutes ago, gomine123 said:

that and IRL APDS was horrible inaccurate so they added the fins to massively increase effective range

No, APDS are very accurate rounds. The sabot transmits the spin and the round flies nicely. Its even easier to hit movers as the rounds are faster.

 

The fins on the APFSDS are a "necessary evil" (they induce more drag, make the round lose speed quicker)

1. Smooth bore guns don't get a spin on the round

2. For the longrod penetrator spin stabilization simply does not work. The center of gravity of the round and the center point for the spin momentum don't have the right distance...so spin will just not give any stabilizing effect.

Edited by Ronin_GE
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 In game? APDS is a useless piece of crap, with nerfed slope modifiers, nerfed against thick armor and nerfed damage. APFSDS is the end all be all free god shell that ignores slopes and wipes the entire tank, even crappy steel ones.

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Would be great if someone with knowledge would also explain post pen fragmentation difference :)

Edited by Godman_82
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17 minutes ago, Ometius93 said:

APFSDS is the end all be all free god shell that ignores slopes and wipes the entire tank, even crappy steel ones.

 

Well on that point the in game depiction is accurate.

 

15 minutes ago, Godman_82 said:

Would be great if someone with knowledge would also explain post pen fragmentation difference :)

 

For the second video rounds are:

1) HE

2) HESH

3) APFSDS

4) HEAT

 

Edited by Alzoc
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24 minutes ago, Ometius93 said:

 In game? APDS is a useless piece of crap, with nerfed slope modifiers, nerfed against thick armor and nerfed damage. APFSDS is the end all be all free god shell that ignores slopes and wipes the entire tank, even crappy steel ones.

This may be due to the very very very small map where only tank knife fights are possible in the game??

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29 minutes ago, Ometius93 said:

 APFSDS is the end all be all free god shell that ignores slopes and wipes the entire tank, even crappy steel ones.

Its pretty much the most accurate shell in the game in that regard.

28 minutes ago, Godman_82 said:

Would be great if someone with knowledge would also explain post pen fragmentation difference :)

Well,AFAIK the principle is pretty much the same.

Either way,heres the post-pen on that stuff:

HA11.jpg

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main differences between APDS and APFSDS is the system they use to maintain the direction while travelling.
 

APDS use the same gyroscopic effect you can see in older ww2 projectiles. They require a rifled barrel to be fired to acquire the angular momentum. This kind of barrels can only shot projectiles at slower speed, since rifling produce significant drag on projectile (thus requiring a lot more propellant to fire a round at the same speed of a smooth bore weapon) and very high speed can damage rifling.

 

APFSDS rounds use fins to stabilize their trajectory and can be used in smooth bore guns. Since gyroscopic effect is no more required, it is way more efficient to drop mass and increase speed: this resulted in the development thin rods that produce less drag and require less energy to penetrate an armor. 

APFSDS are usually longer than other shells because this particular shape move the center of mass away from the plate and it is particularly efficient to deal with sloped armors pretty common during cold war. You can see the rod as a 3 class lever with the fulcrum near the plate and the effort (the force applied from the armor to projectile to deflect it) just behind it. The resistance is represented by the inertia the rod has and since it is applied in the center of mass of the rod, the further it is from the plate, the more effort the armor need to produce to deflect the rod.
This result in the shell almost ignoring sloped armors.

Edited by Khurt
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2 hours ago, gomine123 said:

but when the US Army tested 1st gen APDS they couldn't hit anything beyond 100 meters

IIRC they were testing one of the first batches of British 17pdr APDS, which had sabot separation issues, resulting in poor accuracy.

Accuracy of the 17pdr APDS improved to a satisfactory level during the war, but it wasn't until 50's when British 20pdr APDS (still 1st gen) achieved literally laser accuracy.

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3 hours ago, gomine123 said:

but when the US Army tested 1st gen APDS they couldn't hit anything beyond 100 meters

 

16 minutes ago, _Wingman_ said:

IIRC they were testing one of the first batches of British 17pdr APDS, which had sabot separation issues, resulting in poor accuracy.

Accuracy of the 17pdr APDS improved to a satisfactory level during the war, but it wasn't until 50's when British 20pdr APDS (still 1st gen) achieved literally laser accuracy.

@Listy talked briefly about this recently on another thread:

 

Spoiler

L2yPGgM.png

 

It's probable that the US army received one of the earlier Mk's of APDS.

Edited by Time4Tea
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Quote

Well on that point the in game depiction is accurate.

 Are you trying to meme here? APFSDS rounds were, and still are, expensive as s*, same with APDS rounds, HEATFS was, and still is, cheap as s* to produce. Yet you know what we have in-game.

 And APFSDS being superior to 3rd gen APDS? Yes, maybe the more advanced APFSDS, definitely not the early russian steel APFSDS (and even the non-steel ones), specially compared to stuff like the insanely powerful L15A3, L15A4 and L15A5, which had better energy retention, more penetration, even better accuracy, etc.

 

 So no, it's not realistic.

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2 hours ago, Ometius93 said:

 Are you trying to meme here? APFSDS rounds were, and still are, expensive as s*, same with APDS rounds, HEATFS was, and still is, cheap as s* to produce. Yet you know what we have in-game.

 And APFSDS being superior to 3rd gen APDS? Yes, maybe the more advanced APFSDS, definitely not the early russian steel APFSDS (and even the non-steel ones), specially compared to stuff like the insanely powerful L15A3, L15A4 and L15A5, which had better energy retention, more penetration, even better accuracy, etc.

 

 So no, it's not realistic.

 

Yeah no, an APFSDS is just plain better than any APDS when handling slopes.

Sure the most advanced APDS have the potential to be barely better than the trashiest APFSDS in terms of penetration, but that's about it, in general any APFSDS will beat an APDS of equivalent caliber and energy.

 

Accuracy is about the same (rifled guns are not more accurate than smoothbore firing fin stabilized round)

True the most early APFSDS had some accuracy problem but it was fixed pretty quickly.

 

A rifled gun firing APDS will always be worst than a smoothbore firing APFSDS period.

And while a rifled gun can fire APFSDS with slipbands (to neutralize the spin) it will degrade the performance of the round because of the increased friction.

 

It's true that APFSDS are more expensive than HEAT-FS, however the reign of CE round (HESH, HEAT) was over when composite armour was introduced (T-64), to threaten an MBT with a shaped charge you'll have to use a much bigger and fancier one (ATGM).

 

HEAT-FS is still usefull against anything wich is not using composite armor but against an MBT just forget about it.

 

Now it's true that ingame APDS rounds don't perform as intended (as you said the slope coefficient is wrong), but APFSDS pretty much perform as they should.

Edited by Alzoc
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4 hours ago, gomine123 said:

how bout that

Still, accuracy problems got fixed soon.

Then APDS is became avery accurate ammo. APDS ammo is still widely in use for medium caliber auto-canons and even heavy maschine guns.

 

Again, the fins attached to APFSDS have nothing to do with accuracy problem of the APDS rounds...

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Spin stabilization limits the length to diameter ratio of the projectile. Fin stabilization allows much higher L/D ratios. Modern APFSDS is around 30/1 L/D. That allows much better slopes penetration. 

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