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Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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XM915 20mm debuted    Aircraft Guns

Started 21-Nov by gatnerd; 5892 views.
gatnerd

From: gatnerd

26-Nov

EmericD said:

I should have some radar data for the 20 x 139 mm and 30 x 113 mm somewhere..

That would be very cool. 

If you happen to know penetration data for either 20x103 or x139 with the HEI/SAPHEI projectile, that would also be very helpful for determining how it stacks up to 30x113's stated 25mm RHA @ 50 degrees 500m listed on the spec sheet. 

gatnerd

From: gatnerd

26-Nov

DavidPawley said:

PPS The reason that Apache aren’t the kick in the door force is because they’re shit at it

Could you expand on that?

gatnerd

From: gatnerd

26-Nov

poliorcetes said:

six words: 30x113 airburst for shoot down sUAS While 30x113 is going to be used as another Counter-sUAS layer from land platforms, it seems that helos are not going to be protected or used for protecting others like so Sorry, happy Thanksgiving for all you American

Happy honorary thanksgiving to you Poli. 

Kinda reminds me of when I was living in Europe as an exchange student on Thanksgiving. It proved impossible to track down a turkey or the specialized bread crumbs for making stuffing - so the thanksgiving party I hosted ended up just cooking a big chicken and getting our carbohydrate side dish via beers ;-) Ended up being one of the better Thanksgivings. 

In terms of counter UAS, that would be interesting if helicopters could 'shoot down' incoming drones while providing CAS to infantry. Although a pack of Stingers would likely be more practical and versatile. 

autogun

From: autogun

26-Nov

gatnerd said:

30mm has ~2.5x the mass of 20mm, so even with an inferior shape, it probably has a higher BC and velocity retention then 20mm. Beyond that, 20mm relies on kinetic energy for metal penetration, whereas 30mm uses a shaped charge HEDP, which should function pretty much the same across a wide velocity envelope (guess on my part based on 40x46/53 and various LAW/RPG HEAT/HEDP warheads penetrating steel well at 230-800fps)

I presume that the two new US 20mm (XM915 and Sky Viper Chain Gun) both use the standard 20 x 102; most projectiles weigh a fraction over 100 g (compared with 120 g for the 20 x 139 and 20 x 128)?

DavidPawley

From: DavidPawley

26-Nov

Sure.

The original concept for Apache operations was NOE battalion-strength BAI raids against massed Soviet armour. This was all pretty straightforward until the CONOPS came unstuck when facing dispersed enemy units. The time spent locating and identifying small units and individual vehicles left the Apache formations vulnerable to enemy counter-air for extended periods.

This came to a head in the deep strike raid on Karbala. After that terrible performance, Apache doctrinally no longer does deep strike and has been reroled as an armed reconnaissance and CAS platform.

These events and the doctrine changes are discussed here:

https://www.airforcemag.com/article/1003najaf/
& here:

https://www.cfc.forces.gc.ca/259/290/299/286/gautron.pdf

as preliminary references.

Deep strike CONOPS we’re predicated on ETO anti armour missions, but in pract there has only been one time that Apaches were really successful at deep-strike. 8 AH-64s (plus supporting UH-60s) were led and controlled by 2 AFSOC Pave Lows in Task Force Normandy in the SEAD mission that opened the air campaign in ODS on Jan 17 1991. When used as single type deep strike packages in later operations, they were not effective, ultimately leading to doctrinal changes eliminating their employment in the Army deep strike mission and tasking attack helicopters (by now only AH-64) as armed reconnaissance and CAS platforms.

TLDR; AH-64 can’t deep strike solo and since they’re the most vulnerable element of a strike package, leaving them out decreases the vulnerability of the fast air that’s needed to protect them as well as actually carry out the mission. Doctrine doesn’t employ AH-64 (or any attack helicopters) for deep strike, only for armed reconnaissance and CAS.

gatnerd

From: gatnerd

26-Nov

autogun said:

I presume that the two new US 20mm (XM915 and Sky Viper Chain Gun) both use the standard 20 x 102; most projectiles weigh a fraction over 100 g (compared with 120 g for the 20 x 139 and 20 x 128)?

Yes, 20x102mm like other US 20mm weapons. 

So its 100g @ 3400fps:

https://www.gd-ots.com/wp-content/uploads/2017/11/20mm-PGU-28-A-B-F-16.pdf

https://www.gd-ots.com/munitions/medium-caliber-ammunition/20mm-x-102-pgu/

Closest I could find to ballistics.

Tony, do you happen to know if impact velocity has any effect on HEDP / HEAT penetration of metal? If they are pretty velocity agnostic, then 30mm HEDP should be able to maintain a pretty constant level of performance against metal regardless of range. 

gatnerd

From: gatnerd

26-Nov

DavidPawley said:

TLDR; AH-64 can’t deep strike solo and since they’re the most vulnerable element of a strike package, leaving them out decreases the vulnerability of the fast air that’s needed to protect them as well as actually carry out the mission. Doctrine doesn’t employ AH-64 (or any attack helicopters) for deep strike, only for armed reconnaissance and CAS.

Thanks for that explanation. From what you've seen of FARA, does it make sense as a platform / program? Does the Army really need a recon helicopters vs say employing surveillance drones?

DavidPawley

From: DavidPawley

26-Nov

Yes, I think it does make sense (except deep strike, if that’s actually true and not just war is boring / the drive confusing recon and strike). 
Reasons to follow in a subsequent post. 

autogun

From: autogun

26-Nov

gatnerd said:

Tony, do you happen to know if impact velocity has any effect on HEDP / HEAT penetration of metal? If they are pretty velocity agnostic, then 30mm HEDP should be able to maintain a pretty constant level of performance against metal regardless of range.

As far as I know, the impact velocity of HEAT projectiles does not significantly affect their penetration.

However, the performance could be affected by the rotation speed, which of course gradually declines with range. I presume that the ammo designer picked the optimum combat range and designed the projectile and rifling combination to achieve best penetration. I really don't know whether that makes a major difference, though.

poliorcetes

From: poliorcetes

27-Nov

But if the threat of hordes of sUAS is high enough, then any manpads wouldn't do. Indeed, if nammo AB costs around 1000$ per pop, I assume that its equivalent in 30x113 would be more expensive.

If swarms are launched by the hundreds, we are in big trouble

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