Meet the IRL XM246

[STGN]

Got some new issue reports if you want to support:
XM246 Historically wrong magnification // Gaijin.net // Issues
XM246 Historically wrong magazines size // Gaijin.net // Issues
XM246 Missing Optical Tracking mode v4 // Gaijin.net // Issues
XM246 Radar Name historically wrong // Gaijin.net // Issues
XM246 Radar scan pattern historically inaccurate // Gaijin.net // Issues

I learned something new General Dynamics called the XM246 the MADS or 35mm Mobile Air Defense System.

Magnification should be 3x to 8x:

60 rounds of APDS should be in the gun shield:

The FCS should have an optical track mode similar to ADATS:

The Radar name should be fix and changed to the “Mobile Air Defense System Radar” or MADS Radar:

And the radar should scan up to 74 degrees:

[memer4life9000-psn]

You are an absolute legend. Hopefully the devs implement these fixes soon and not 100 years from now like usual.

[MrBombastic8]

Absolute mad lads

Also have you look at hull protection of M247 being lower than every single other M48 chasis in the game? Im pretty sure its missing like 50mm

[Chocolate_Pasta]

Get ready for 8.7 XD

[TIGER_TANK_1]

A good and fun tank. I use in arcade battles to kill light armor vehicles. Works ok against things that are not heavy tanks, T-55 and M60

[AspectOfTheRAGE]

Quite late to this but oh well.

Thought I’d quickly help clearing up some confusions regarding the ammuntion;

The “AP” round that is mixed with the HEI rounds is infact the APHEI-T/SAPHEI-T.

The designation “APHEI-T” (Armour Piercing High Explosive Incendiary - Tracer) is Oerlikons and the Bundeswehr’s type-designation for the round, however the nato designation for such rounds is SAPHEI-T.

As for context, all APHE rounds are Semi Armour Piercing by definition (in part because their penetration is limited by the fuze going off and detonating the round before it may reach its maximum technically achievable penetration-depth)

The exact Oerlikon company designation is: PLD
which stands for:
Panzersprengbrand, Leuchtspur, D-Serie
Translated:
Armour Piercing High Explosive Incendiary, Tracer, D-Series (Refers to KD-Series, i.e. cannons with 35x228mm cartridge)

The Bundeswehr operated this round under the designations: “DM 13 AP-HEI-T” and “DM 13 A1 AP-HEI-T”

As such, rest assured - the “APHEI-T” and “SAPHEI-T” are the exact same round.

On FlakPz Gepard it was used in mixed belts together with HEI (DM 21 - much more commonly) or HEI-T (DM 31) commonly in a ratio of 2x APHEI-T + 3x HEI.

The APDS-T was the round that XM246 carried in its auxiliary belts between the guns.

Oerlikons’ designation was: TLD
which stands for:
Treibspiegel-Hartkern, Leuchtspur, D-Serie
Translated:
Discarding-Sabot Hard-Core, Tracer, D-Series (“”)

The Bundeswehr also operated this round under the designation: “DM 23 HVAP-DS”

The HEI round that was apparently fitted with a new fuze (although the regular one also had a slight delay) would be the following:

Oerlikon-Designation: MSD
Which stands for:
Minensprengbrand, Spurlos, D-Serie
Translated:
Mine-High Explosive Incendiary, Tracerless, D-Series(“”)

Also operated by the Bundeswehr under the designations:
“DM 11 A1 HEI” and “DM 21 HEI”

Note: This round had a higher explosive filler mass of 112g of Hexal P30 compared to the HEI-T’s (MLD, DM 31) 98g.

^ Oerlikon MLD Type HEI-T (DM 31 HE-T in Bundeswehr Service)

---

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Reference-Pictures for the Bundeswehr DM designations:

From: WTS (Wehrtechnische Studiensammlung) in Koblenz

[Caernarvon02]

Wait so…

35mm KDA ammo should be nerfed from APHE ballistics to SAP ballistics?

[AspectOfTheRAGE]

I can’t recall the ballistics differing from SAPHEI to APHEI whatsoever.

Also again, please remember that there is a big difference between base- and nose(PD)-fuzed SAP/APHEI rounds:

e.g. this is 35x228 APHEI-T (nato-designation “SAPHEI-T”)

It features a base-fuze and is structured like “regular” APHE rounds…

This round (found on M247) is also SAPHEI under nato-designation and modelled as such (SAPHEI) in-game.

(even though its technically HCHE)

The second round is SAPHEI because it features a delayed action PD-fuze, wheras the first round is SAPHEI because every APHEI round is also SAPHEI by definition - yet the differences between the structure of these rounds should be more than evident.

[STGN]

Preamble
It a longer story now, when I fist made the post I was unavare of the dedicated ammunition program that was run for ARGADS later DIVAD. The Americans chose a different approach than the Germans had done for the Gepard. I added a bit of info to my original post a while back, but I should actually update it, with all the new info I have gotten since I made it.

The reason for the inital confusion was frazing the uses of the word “intersperse” in the most detailed description of the DIVAD test program available said that AP rounds:

When I first read it it made me think that it might mean that APDS was in the HEI belt to make up for the low round count. 164 M811 rounds vs (what I thought was) 40 35mm APDS rounds but the muzzle velocity and tracer would screw up that concept.
So I started started researching if there existed a tracerless AP-HEI round for 35mm and Oerlikon had discontinued in the mid to late 1970ties, the PSBH/B round, so I thought that it was a possibility that they had made a special run.

My current understanding:
The Americans developed their own HEI fuzes under a program called XM714.

The program made fuzes for many calibers in two types, instant and delayed. The XM741 fuze was more sophisticated than the German one and allowed the fuze to trigger on steeper surfaces.
Here are two versions of the design the instant on the left and the delayed on the right. (These are the fuzes for 20mm):

For ARGADS(later DIVAD) they chose delayed fuzes for 30mm, 35mm and 40mm. The idea was to be an all around optimized ammunition. Against aircraft the delayed feature resulted in the round exploding inside the aircraft after traveling about 9 inches instead of exploding on the skin. This 300ms delay in triggering also made it semi-armor piercing.
The DIVAD requirement was to be able to engage light armor at up to 4km in range. The 35mm delayed fuze was apparently not enough on it’s own. Which is why the APDS was required as it did more than enough at that range. Precisely how much the 35mm could pen is still unknown to me but the 25mm equivalent is able to pen 13mm@30° at 1000meters so it’s likely around 17mm for the US 35mm HEI round, given that it has ~27% more kinetic energy

The 35mm delayed fuze was designated XM760,

and the 40mm was designated XM761, the delayed fuze used in the M811, see the similarity of the exterior design.

So actually, the only round in common between XM246 and Gepard is the APDS round, the US SAPHEI and PX-HEI used similar bodies but different fuzes so neither DM11 nor DM13 is applicable to the XM246 prototypes.

So is the high pen SAPHEI impossible?
Now about the interspersing of rounds that set this off. The tests of XM246 and XM247 was Phase 1, but there was also a Phase 2 proposal that would become the contract vehicle. As the XM246 lost, this proposal is largely unknown/uncertain as to what it contained. And we can only guess what changes were made between tests and selection proposal.
So it might explain what the interspersing comment, might not.

Our options:

1. It’s literal, APDS-T and SAPHEI was interspersed in the same belt, like a reverse A-10 GAU-8 belt with more HEI instead of AP.
2. It’s literal but the AP round is not the APDS-T rather one of the Oerlikon SAPHEI, perhaps this tracer less variant:
   
3. It’s was an explanation of a limitation, the author wanted to point out a limitation of the belt fed system but this configuration was not actually proposed.
4. It’s mistakenly referring to the secondary magazine.

[AspectOfTheRAGE]

As a quick follow-up;
(Summary of additional information)

PSBH/H is a old APHEI round from Oerlikon and not the one used by XM246 - the difference between it and PLD / PSD are very noticeable when looking at cutaways:

(top: PSBH/H, bottom: PLD)

Most notable differences: Fuze, Tracer compartment (empty on PSD), filler-cavity & penetrator cap.
Filler weight is still the same (22g of Hexal P30).

If SAPHEI was used and in-fact tracerless, then it’d be PSD (Panzersprengbrand, Spurlos, D-Serie // Armour Piercing High Explosive Incendiary, Tracerless, D-Series)

35mm TLD (APDS-T) ------- 35mm PSD (SAPHEI) ------- 35mm PLD (SAPHEI-T) ------- 35mm MSD (HEI)

As far as I can tell, PLD and PSD are essentially identical with the sole difference being that PSD has the tracer in the compartment filled with a counterweight to retain the same weight and ballistic characteristics as PLD.

Oerlikon Advertisements do however list SAPHEI-T instead of SAPHEI;

But then there are such that dont mention the SAPHEI at all;

(note: 2nd advertisement predates the first one and doesnt specifically say that only the listed rounds were selected but that those listed are among the selected ones)

Final conclusion is still hard to make though, given that the sources themself are quite contradictory.
Known for sure is though that both SAPHEI and SAPHEI-T rounds existed and (in case of SAPHEI-T) were already in service and serial production.

The proximity fuzed HEI round appears to be identical to MSD (has the same filler mass; 112g) but isnt available in-game sadly.

Spoiler: 35x228 HEI w/ Proximity Fuze

[Ghostmaxi]

@AspectOfTheRAGE

Panzersprengbrand, Spurlos, D-Serie // Armour Piercing High Explosive, Tracerless, D-Series)

You forgot Incendary.
Its PanzersprengBRAND, brand means Incendary.

[AspectOfTheRAGE]

idk how I missed that lol
corrected.

[Make_a_wish_kid]

@乌拉尔

cool

REALLY cool

@STGN

Same round with a proximity fu ze called the Motorola Proximity Fuze(MPF).

i dont care if it gets moved up to 10.7+ but can we get proxy fuze for xm246 please? would be straight up C-RAM on steroid lol, would be crazy at danger close distance and enemy CAS munitions interception

[STGN]

I think you have to wait until Gaijin adds another SPAA at 8.3 for that to happen but I can see it 9.7-10 with Proxy, APDS, Stingers and a propper radar scan speed and elevation.

[Make_a_wish_kid]

i dont think US need a replacement at 8.7 if this thing gets HE-VT and moved up in BR. I think the M163 is okay enough to bridge the US AA gap between 7.3 up until 9.0, yea the M163 isnt great but it’s not complete trash either.

I feel like XM246 getting HE-VT and moved to ~10.7 would be great to bridge the AA gap at 10.0 and 11.7

[P51ACE1943]

The whole point of the XM246 getting added was to bridge the gap between the M163 and M247. Sure I’d like to see the XM246 get its HE-VT as there were several other competitors in that program that didn’t make it. My pick would be the General Electric proposal.

[BSpiel8-live]

@P51ACE1943

The whole point of the XM246 getting added was to bridge the gap between the M163 and M247.

Then it was not the right choice. Adding vehicles intentionally nerfed into the ground to fill a niche is a terrible practice that directly contradicts Gaijin’s claim to add vehicles based on historical stats.

There are around half a dozen or more options we could’ve gotten instead at 8.3, not including the paper proposal in your image. Only Gaijin is to blame here.

[STGN]

To be fair to Gaijin here, hindsight is 20/20. The XM246 was largely undescribed, publicly I don’t think anybody prior to me had done much in the way of gathering information on the system. And they quickly adjusted to give the system a more accurate armor design, magazine design, but chose to remove the APDS to keep it where it was supposed to go BR wise. Everything considered I think they have done well, they just wanted a Gepard in the US tech-tree.

[PercussionCap]

@BSpiel8-live

is a terrible practice that directly contradicts Gaijin’s claim to add vehicles based on historical stats

Does not, ammo has always been a balancing factor.

[BSpiel8-live]

Depends, I’d say there’s a significant difference between an APFSDS shell with more pen than its predecessor and a proximity shell that fundamentally alters the vehicle’s overall effectiveness against aircraft.

That being said, in an ideal world every vehicle could get the most powerful ammo it does/would have used in service, and then more stuff would be added to then fill the resulting gap.