CGS:upgrading challenger and warrior.

But a Bofors 40mm is acceptable despite firing a projectile of the same weight at the same muzzle velocity with a modest increase in firing rate?
Or a bushmaster is acceptable despite firing lighter projectile (albeit at a slightly higher velocity) at the same rate?

The CTA 40mm has a quoted maximum range of 5kms. The 40mm L70 has a quoted maximum range of 12.5kms.

Anyone know why that is ?
 
The CTA 40mm has a quoted maximum range of 5kms. The 40mm L70 has a quoted maximum range of 12.5kms.

Anyone know why that is ?

Off the top of my head, a guess at longer barrel, and recoil stroke to give a Higher MV. Also not so concerned with keeping everything compact enough to fit in a turret.
5Km's is more than adequate for ground targets.
 
Off the top of my head, a guess at longer barrel, and recoil stroke to give a Higher MV. Also not so concerned with keeping everything compact enough to fit in a turret.
5Km's is more than adequate for ground targets.

So in theory, if you spend more money the Armed Forces haven't got, you could match or improve on the performance of the L70 ?
 
The CTA 40mm has a quoted maximum range of 5kms. The 40mm L70 has a quoted maximum range of 12.5kms.

Anyone know why that is ?

Because brochures...

If you were to dig into the detailed (and classified) specs of each system, you’ll probably find loads of context and caveats that define maximum effective range. In many cases, is depends on “effective against what?”


Sent from my iPhone using Tapatalk
 

PhotEx

On ROPS
On ROPs
But a Bofors 40mm is acceptable despite firing a projectile of the same weight at the same muzzle velocity with a modest increase in firing rate?
Or a bushmaster is acceptable despite firing lighter projectile (albeit at a slightly higher velocity) at the same rate?

40CTA: 200rpm out to 4000m effective
Bofors: 300rpm out to 6000m effective

Incoming transonic target is doing 330m/s - and both guns need a ≥5 round burst to get a good pK
And if its something serious doing M2 or better, 40CTA is getting its last round off just as the incoming bites you, which is why CTA don't claim any fast mover capability.

40 RapidFire
"The RapidFire® anti-aircraft system 40, designed in partnership between Nexter and Thales, performs short-range self-defense missions. Thanks to the accuracy and efficiency of the CTAI (Joint Venture Nexter and BAE) 40 mm gun and ammunition, the RapidFire® T40AA system is capable of intercepting helicopters, drones or light craft up to a distance of 4000 m. This performance is achieved through a viewfinder with electro-optical day/night cameras and a moving target tracking function."

Bofors Mk4
"Full war conditions
The system is vital for defence against hostile ships, attack aircraft, anti-ship missiles and shore targets."
 
So in theory, if you spend more money the Armed Forces haven't got, you could match or improve on the performance of the L70 ?

Well I'd argue we could, in theory make a 120mm gun super accurate out to 24km.

Of course it'd be bloody expensive, horribly complicated, very heavy and quite big. All for the reason of... what? Firing at targets 5km away? It's wasted capacity that could be employed elsewhere.

40CTA: 200rpm out to 4000m effective
Bofors: 300rpm out to 6000m effective

Incoming transonic target is doing 330m/s - and both guns need a ≥5 round burst to get a good pK
And if its something serious doing M2 or better, 40CTA is getting its last round off just as the incoming bites you, which is why CTA don't claim any fast mover capability.

40 RapidFire
"The RapidFire® anti-aircraft system 40, designed in partnership between Nexter and Thales, performs short-range self-defense missions. Thanks to the accuracy and efficiency of the CTAI (Joint Venture Nexter and BAE) 40 mm gun and ammunition, the RapidFire® T40AA system is capable of intercepting helicopters, drones or light craft up to a distance of 4000 m. This performance is achieved through a viewfinder with electro-optical day/night cameras and a moving target tracking function."

Bofors Mk4
"Full war conditions
The system is vital for defence against hostile ships, attack aircraft, anti-ship missiles and shore targets."

I'd suggest that if you're firing at something 'transonic' with a 40mm on an IFV you've got **** all chance of a hit. We went through this with the RARDEN gun on all its assorted mounts. The Original RARDEN was expected to have a 6 round box magazine, and full auto as well as single shot. We quickly realised that there was a sub -1% chance of a hit, and the additional sights needed would add a few thousand quid to the price. So we binned the idea. The Germans on the other hand gave a higher priority to AA and so selected a belt fed 20mm, accepting the lack of range and hitting power agaisnt ground targets, for a higher chance of a hit agaisnt hostile air.

Naval stuff is a very different kettle of fish, where you'll have the stand off range to use, so you might as well fill it with as much HE as you can, and here we come to the main point: Why the hell are we comparing an IFV's primary armament for dealing with light APC's and soft targets to a ship borne AA weapon?
 
And if its something serious doing M2 or better, 40CTA is getting its last round off just as the incoming bites you, which is why CTA don't claim any fast mover capability.
660 m/s over 4000m is 6 seconds. A 5 round burst takes 1.5 seconds.
If you were adding flight time* to maximum range and only starting to fire as the target comes into range** and counting the time that the last shell reaches max range as “last round off” then you might have a point***, except the target is closing so the time to range is shortened.

Using the same assumptions and firing as soon as a 660m/s target reaches 4km means that the target will be at about 2.5km when the first shell shell gets there. The last shell leaves when the target is at 3km so will meet the target at a little under 2km.

* and considering velocity constant
** With modern fire control you’d be firing to intercept so you’d commence beyond effective range if the target is predicted to be in range by the time the shell gets there
*** i.e. you don’t
 

jrwlynch

LE
Book Reviewer
The CTA 40mm has a quoted maximum range of 5kms. The 40mm L70 has a quoted maximum range of 12.5kms.

Anyone know why that is ?

Difference between "effective" range (can get rounds close enough to the target to make them change what they're doing) and "ballistic" range (what's the furthest we can get a shell to fly).

4.5" Mk 8 had an AA mode, and a maximum range of 29km, but that didn't mean you'd be bringing down enemy aircraft ten miles away with it...
 
Naval stuff is a very different kettle of fish, where you'll have the stand off range to use, so you might as well fill it with as much HE as you can, and here we come to the main point: Why the hell are we comparing an IFV's primary armament for dealing with light APC's and soft targets to a ship borne AA weapon?
It came out “where else would we use an auto cannon also used on IFVs”
I suggested ships because we already use guns also used on IFVs on ships (which pre-date CT40) and plan to acquire different guns which are also used on IFVs and which are also not CT40 despite post-dating it into service.

PhotEx is doing his usual poor justification of his prejudices.

I still think that the CT40 wasn’t the right choice. If you accept being tied in to existing ammunition then there were numerous better choices. If you can front new ammunition then you could make a substantially better gun while still providing much the same performance and a similar sized gun/feed system.
 

jrwlynch

LE
Book Reviewer
...and here we come to the main point: Why the hell are we comparing an IFV's primary armament for dealing with light APC's and soft targets to a ship borne AA weapon?
"Forget it, Jake, it's PhotEx."

He's looking at a ship's close-range armament (there to slap small surface craft about at 2-3km max) with IFV armament and obsessing about both of them being able to shoot down supersonic ASMs, sink Kirov-class cruisers and so on, all through a lens of "whatever the UK does must be wrong".

If the UK put the 40mm Bofors he's burbling about on our ships, it would be the Worst Idea Ever and we should have fitted 40mm CTA instead, because of a similar half-digested regurgitation of press releases and Wikipedia.
 
If the UK put the 40mm Bofors he's burbling about on our ships, it would be the Worst Idea Ever and we should have fitted 40mm CTA instead, because of a similar half-digested regurgitation of press releases and Wikipedia.
It’s slated to go on the Type 31s.
 

PhotEx

On ROPS
On ROPs
660 m/s over 4000m is 6 seconds. A 5 round burst takes 1.5 seconds.
If you were adding flight time* to maximum range and only starting to fire as the target comes into range** and counting the time that the last shell reaches max range as “last round off” then you might have a point***, except the target is closing so the time to range is shortened.

Using the same assumptions and firing as soon as a 660m/s target reaches 4km means that the target will be at about 2.5km when the first shell shell gets there. The last shell leaves when the target is at 3km so will meet the target at a little under 2km.

* and considering velocity constant
** With modern fire control you’d be firing to intercept so you’d commence beyond effective range if the target is predicted to be in range by the time the shell gets there
*** i.e. you don’t

you really, really don’t want anything inside of a mile when you take it, incoming supersonic bits of debris are still very dangerous.
 

PhotEx

On ROPS
On ROPs
"Forget it, Jake, it's PhotEx."

He's looking at a ship's close-range armament (there to slap small surface craft about at 2-3km max) with IFV armament and obsessing about both of them being able to shoot down supersonic ASMs, sink Kirov-class cruisers and so on, all through a lens of "whatever the UK does must be wrong".

If the UK put the 40mm Bofors he's burbling about on our ships, it would be the Worst Idea Ever and we should have fitted 40mm CTA instead, because of a similar half-digested regurgitation of press releases and Wikipedia.

A radar directed, fully automagic Bofors was the preferred RN option in the mid 70’s.
might have made things a bit less fraught in 1982 having a very high performance close in AA gun.
but alas, experts decided the day of gun was past, and missiles were the future...

and here we are, nearly 50 years on, and once more, it’s Back to the Future - and a radar directed, fully automagic 40mm gun is the thing.

Were getting there......slowly.

In the immediate post war wash up, the future was decided.... a 5” automagic main gun, a 3” automagic medium gun for Frigates etc, and a 40mm gun for everything else.

Well!

we’ve finally got the 5” - after 70 years
we got the 3”, then ditched it
we had the 40mm, ditched it, and are now bringing it back.
 

jrwlynch

LE
Book Reviewer
A radar directed, fully automagic Bofors was the preferred RN option in the mid 70’s.

Was it? Which ships was this "preferred option" fitted to? Didn't we stop using radar-directed, fully-automatic Bofors guns when Vanguard (which had lots of them in sextuple mounts) retired in 1960?

Is this one of those "preferences" that were so "preferred" that nobody bought and fitted them?

Then, by the 1980s, we realised that any gun solution less than a full CIWS was basically just "try to distract a manned aircraft, Sweet Fanny Adams use against missiles"...

might have made things a bit less fraught in 1982 having a very high performance close in AA gun.
but alas, experts decided the day of gun was past, and missiles were the future..

What, a radar-directed gun system?

Like the radar-directed weapon systems (gun and missile) that didn't have time to acquire, track and engage in San Carlos?

What idiots those experts were, for refusing to fit a radar-directed gun that wouldn't have worked!

There was a very fast-reaction gun system available for short-range engagements, up to and including missile threats, but given that it was a US system and their first operational fit only went to sea in late 1981, the RN weren't going to be able to outfit many ships with it in 1982 (as it was, Illustrious had two of them before she went south that year)

(Here's a little hint - when you don't know what you're talking about, it helps to fall silent rather than prove your ignorance...)
 

jrwlynch

LE
Book Reviewer
you really, really don’t want anything inside of a mile when you take it, incoming supersonic bits of debris are still very dangerous.

Which, if true, does rather kill the idea of using a 40mm gun for antiship missile defence...

(Of course, that would make 20mm Phalanx, and 30mm Goalkeeper, ADMG-630 and Kashtan all completely useless, and the navies operating them absolute idiots for persisting with completely ineffective solutions, but - as usual - PhotEx knows far more than they do, and surely isn't merely relying on a garbled, half-remembered and misunderstood discussion of DSRFs he heard many years ago...)
 
CTA on board ships has an argument for commonality and economies of scale especially with smart fused ammo. Its an improvement over 30mm HE if dealing with swarms of little boats. If its the same gun, logistics and training for the blokes wot fix it can be centralised.
5km range is plenty for ground roles or keeping light watercraft at bay. In peacetime there's limitations on when you can start firing, and 5ks is a long way away to say some bloke in a rib posed a threat. In wartime 5kms is far enough away to be able to engage light AFVs or if shipborne, in defensive fire against light surface craft.
 
you really, really don’t want anything inside of a mile when you take it, incoming supersonic bits of debris are still very dangerous.
Good thing it’s still a bit outside of a mile then.

In terms of ballistic capability the only thing visible in the available stats that the Bofors has going for it is rate of fire, and I’m not convinced that would make much difference to effective range. Maybe it’s the mounts?
 

PhotEx

On ROPS
On ROPs
And here we are 5 years of arguing, with the ARRSE green experten claiming I was wrong, Challenger would never have an auto loader, and here we are…

Challenger is getting exactly what I said all along, a pimped German Leo A7 turret, with the German 120mm smoothbore gun, all served by the French GIAT autoloader.
 

PhotEx

On ROPS
On ROPs
Which, if true, does rather kill the idea of using a 40mm gun for antiship missile defence...

(Of course, that would make 20mm Phalanx, and 30mm Goalkeeper, ADMG-630 and Kashtan all completely useless, and the navies operating them absolute idiots for persisting with completely ineffective solutions, but - as usual - PhotEx knows far more than they do, and surely isn't merely relying on a garbled, half-remembered and misunderstood discussion of DSRFs he heard many years ago...)


Phalanx is best described as a last brave gesture of defiance
 
And here we are 5 years of arguing, with the ARRSE green experten claiming I was wrong, Challenger would never have an auto loader, and here we are…

Challenger is getting exactly what I said all along, a pimped German Leo A7 turret, with the German 120mm smoothbore gun, all served by the French GIAT autoloader.
I thought you said that we would get a bunch of Abrams FOC?
 

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