Strategic Capabilities Office - Hypervelocity Gun Weapon - Missile Defense

[Scott Kenny]

The French 100mm is a single-piece fixed round (~23kg), while 127mm is a two-piece semi-fixed round (total ~50kg). That complicates the loading process.

Depends entirely on where you mate the shell and the casing. If you mate the two in the ready ammo rack instead of the breech, you can get a very high rate of fire till the ready ammo is expended.

I think I'd want to focus on being able to fire a fast burst of 3-6 rounds, rather than on sustained high RoF.

Longer burst, but yes. Give me a good 18-24 rounds at some 60rpm and we're good.

 

[Moose]

The guns on the Sherman Class DDs and their sister classes did have a 48 rpm gun in the Mark 42.

But the Hydraulics at the time couldn't take it so they ended up being derate to 28ish after Vietnam. Later they did get rerated for 38 for short bursts in basically PANIC AT INCOMING mode.

With the Current MK45 mount 20 rpm being a result of that experience. The navy wanted a gun thats goes blam the first time every time til its mags empty, reload and go again. THE 45 does that well.

So any replacement for that is going to need similar reliability.

I'm not here to impugn the reputation of the Mk45, but today's Mod4 is is still the mount designed for ERGM (whoops) and the top-line Otobreda 127/64 pips it comfortably. A Mod5 capable of increasing RoF should be very do-able as a bare minimum step. A rapid-firing 155mm using STANAG ammo (not LRAP silliness) should at least be looked at.

 

[Scott Kenny]

A rapid-firing 155mm using STANAG ammo (not LRAP silliness) should at least be looked at.

Challenge with that is 155mm Army is separate-loading ammunition: shell, bagged charge, and primer. (primer may be part of the charges, but it's still at least two things to load)

So you'd need to design a 155mm casing big enough to hold artillery Super Charge. Or go to an 8" bore with saboted 155mm and go back to the US 8"/55 Mk16/Mk71

 

[TomS]

Challenge with that is 155mm Army is separate-loading ammunition: shell, bagged charge, and primer. (primer may be part of the charges, but it's still at least two things to load)

So you'd need to design a 155mm casing big enough to hold artillery Super Charge. Or go to an 8" bore with saboted 155mm and go back to the US 8"/55 Mk16/Mk71

A naval gun could adopt the same charge being developed for the Army Multi-Domain Artillery Cannon, which will probably be rather similar to the one-piece cased supercharge developed for ERCA. That was too big to manhandle, but both MDAC and naval guns should eliminate that step in loading.

 

[Moose]

A naval gun could adopt the same charge being developed for the Army Multi-Domain Artillery Cannon, which will probably be rather similar to the one-piece cased supercharge developed for ERCA. That was too big to manhandle, but both MDAC and naval guns should eliminate that step in loading.

Yeah my thoughts exactly

https://twitter.com/x/status/1321109378368417794

View: https://twitter.com/JonHawkes275/status/1321109378368417794

 

[Firefinder]

That and well.

You just got to make sure the shells work in the gun.

You can just put the MCAS powder in a brass case and call it a day.

Hell as is the Super charge is bout 10 pounds more then the old 6/47 used in ww2, with zone 6 charges being less at 30 pounds to the 6/47 33 pounds.

The biggest difference between a case and bag guns is the shape of the breech and chamber. You can put a Bag gun shell in a Case gun just fine so long as the bore the same.

The Des Moines 8 inch guns were prime example of this, they used the same Shells as the older cruisers but used brass cases compare to Baltimore class Bags.

As for the shells themselves?

The Army switch over to a new insensitive explosives back in 2015, the IMX-104. Which has a higher safety factor then the Navy's PBXN-9. With the PGK fuse having similar hero safety standards.

 

[Scott Kenny]

Though if we're using ERCA Super, going to need polymer driving bands on the shells.

 

[Moose]

Though if we're using ERCA Super, going to need polymer driving bands on the shells.

The good news is neither MDAC nor our theoretical 155mm RF would likely be slinging conventional shells with a supercharge. They would be shooting HVP in its sabot with supercharge to engage missiles/UAVs/etc. If they needed to engage a ground/surface target they'd use standard shells on a reduced charge or potentially an XM1155 for extreme range. So design the polymer or new alloy band into the sabot rather than tinkering with standard ammo.

 

[apparition13]

Speaking of naval guns:

Sweden 120 mm/46 (4.7") TAK120 - NavWeaps

www.navweaps.com

the Swedish 120mm/46 TAK120, at 80 rpm and 28 tons for the mounting. Scale it up to 127 and you could use DART or HVP.

 

[A Tentative Fleet Plan]

Speaking of naval guns:

Sweden 120 mm/46 (4.7") TAK120 - NavWeaps

www.navweaps.com

the Swedish 120mm/46 TAK120, at 80 rpm and 28 tons for the mounting. Scale it up to 127 and you could use DART or HVP.

Simply scaling it up wouldn't work, it's designed to work with lightweight fixed ammunition used for a land-based anti-aircraft gun, not the heavier and two-piece ammunition used by the Mk 45.

 

[Scott Kenny]

Simply scaling it up wouldn't work, it's designed to work with lightweight fixed ammunition used for a land-based anti-aircraft gun, not the heavier and two-piece ammunition used by the Mk 45.

I've got an idea for the two-piece ammunition problem: have the ready racks loaded with both shell and case so there's a single loading action needed into the gun. Yes, that pre-supposes your ammunition requirements, but if you are doing either DART/HVP or prox HE/frag it doesn't matter. Reloading the ready racks would be slower than the gun could fire, of course.

 

[A Tentative Fleet Plan]

I've got an idea for the two-piece ammunition problem: have the ready racks loaded with both shell and case so there's a single loading action needed into the gun. Yes, that pre-supposes your ammunition requirements, but if you are doing either DART/HVP or prox HE/frag it doesn't matter. Reloading the ready racks would be slower than the gun could fire, of course.

Would need an entirely new feed system, given the longer round, it wouldn't just be a simple scaling up of an already existing design.

 

[Scott Kenny]

Would need an entirely new feed system, given the longer round, it wouldn't just be a simple scaling up of an already existing design.

The ready racks would be longer versions of the 120mm. Depending on how they were laid out, might need another 2 sets of rails to hold the shell and casing properly.

The shell elevators from the magazine would have to be different, designed from scratch. Or copied from a 5" piece.

But I admit I really need to physically see the two guns to decide what can be scaled up and what needs to be bespoke.