This one is interesting CV9040 and the limitations of the gun and ammo storage 

 

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40mm Bofors Cannon - CV9040 FIREPOWER

CV90 IFV include the CV9040 with 40mm gun and the export variant, the CV9030 with 30mm gun. The CV9040 has been in service with the Swedish Army since 1993 w...

Now, I am wondering about the 40mm CTA, which I think is a much better gun. But RoF is low. 

How hard would it be to increase the RoF of the current gun? I am vaguely wondering whether a 40mm SPAAG would not be better off with a twin (next to each other and mirror imaged. Electrically triggered for alternate fire to avoid muzzle inteference).

graylion said:

How hard would it be to increase the RoF of the current gun? I am vaguely wondering whether a 40mm SPAAG would not be better off with a twin (next to each other and mirror imaged. Electrically triggered for alternate fire to avoid muzzle inteference).

I agree that the ROF of the current CTA40 is to low to be a good choice for an AA weapon.

But a twin mount seems wastefull.

The question is: is there another option? As has been brough up the ammo of the CTA40 is specifically designed for the push trough feed and ROF of the gun. Its design neither flexible nor sturdy enough to use a different feeding method or more violent treatment.
If this is true this for me is a major shortcoming. Basically its a return to the old days where a company would develope a gun and special ammo for one specific purpose for one customer. Instead of using established and standardised ammo for as many applications as possible.

RoF is low for flak jobs using direct impact ammo, but is fine for other uses, especially if you can afford the fancy programmable shells.

Turkey did develop a twin 35mm flak recently, no?

Otherwise, there's also 35mm guns with high RoF if direct impact flak is your thing.

The 35mm Millennium gun uses tungsten shrapnel (AHEAD) and fires at 1000 RPM

renatohm said:

RoF is low for flak jobs using direct impact ammo, but is fine for other uses, especially if you can afford the fancy programmable shells.

I am really not convinced of this.
 

To create a fragmentation cloud to ensure target destruction especially a longer ranges and with fast moving and highly manoeuverable targets quite a number of shrapnel type shells is needed. The number is significantly lower compared to a direct hit but its not one, two or a few. We talk about 10+ shot bursts at a ROF above 15 rps.

With the rounds being fired at a lower ROF and thus further appart there could be holes in the fragmentation coverage the target can slip trough. Or the number of fragments that hit are insufficient to kill the target.

The ROF of the 40CTA is about half of a modern 40 mm AC based on the Bofors design. And even these are often used in twin mounts for AA and CIWS purposes.

So it seems the 40CTA would rather need a quad mount the get the required density of fire for serious AA, C-RAM and CIWS work.

schnuersi said:

So it seems the 40CTA would rather need a quad mount the get the required density of fire for serious AA, C-RAM and CIWS work.

been thinking that too. Not sure I follow on the 'wasteful' argument. I'd go with a quad turret (4 tightly together in the centre and the devil's own feeding mechanism) and 2 groups of VSHORAD missiles like StarStreak or (what I'd still like) StarStreak LR with a bigger first stage.

graylion said...

(4 tightly together in the centre and the devil's own feeding mechanism)

I think you are grossly under selling how complex that feed mechanism would have to be. I think you'd be better off designing new ammunition and a new gun with an entirely novel feed system than trying to fit 4 CT40 coaxially and feed and eject on all of them.

RovingPedant said:

I think you are grossly under selling how complex that feed mechanism would have to be. I think you'd be better off designing new ammunition and a new gun with an entirely novel feed system than trying to fit 4 CT40 coaxially and feed and eject on all of them.

well, I am think you'd have to mirror image the guns on either or both planes depending on position.

The whole gun is designed to be on the axis for feeding and ejecting purposes. You could fit two on one axis by mirroring them but they'd need enough space between them to eject the cases. Given the length of the case that's about half a metre between guns.

Moving the guns off the elevating axis, which you'd need to do to mount more guns vertically spaced, would require entirely new feeds or moving the entire feed system with the gun.

One of the selling points of a CTA gun is that you can up the rate of fire more easily than a conventional gun because you aren't accelerating the round as much. Other factors being equal. If that translates into practice I don't know.

The Skyguard system using shrapnel shells only runs a single gun per turret compared to two in the Gepard, so perhaps more modern ammunition and fire control doesn't need as high a rate of fire. Certainly slower and less agile targets don't need as high a rate of fire.

Personally I'd look into increasing the number of air defence capable systems rather than piling relatively short ranged systems onto one vehicle that is fractionally more effective but can only ever be in one position at once. Make sure your standard autocannon turret on IFVs and recce vehicles can engage air threats and have additional systems that can be added for detection purposes. The latter would only be fitted to one in a large number of vehicles or specialised sub-units, like the CV9040.

With the benefit of hindsight, my personal preference for the optimum calibre in this class of gun is the 35 x 228 Oerlikon. The ammunition can use AHEAD loadings for anti-aircraft, anti-missile and C-RAM, can also use APFSDS effective against most armour short of tanks. Finally, it can be necked-out to 50mm.

The guns include low-RoF long-recoil versions (KDE - 200 rpm), up to 1,000 rpm KDG, plus the Bushmaster III and the WOTAN. And it's tried and tested, and much cheaper than CT40.