Modernised heavy howitzer

So I'm currently working on creating a little alternate reality novel. As part of that if we had never moved away from using properly heavy howitzers, something like a nine, ten inch barrel diameters, what kinds of ranges could we achieve with the tech we have today and any developments we can reasonably expect to come within the next 10-15 years?
 
Heavy and super heavy howitzers were in active development right up till the end of the 50s, with systems such as Oka, Kondensator, but after that were rapidly supplanted by first ballistic and then guided missile technology, as well as the growing effectiveness of fast jet air support.
To keep heavy howitzers as a primary long range fire support option, you would have to avoid the technologies that gave rise to effective missile weapons. The issue with that however is that without those technologies the effectiveness of howitzers will not increase much beyond where it was just post WWII. Certainly the rocket assisted GPS guided shells now becoming available to 155mm pieces would not be possible.

Even avoiding that, it is unlikely that heavy howitzers would be used. 155 has been standardized on because it strikes an optimal balance of mobility, rate of fire and target effect. With modern technology the 155 shell can be just as accurate and nearly as long ranged as guided missile weapons, negating the need for area saturation or very large shell weights. As weapons become more accurate the trend has been for less destructive power, as less is needed to achieve the same effect.

This is the same reasons why western airforces are now beginning to arm warplanes with very small missiles, and have mostly abandoned dumping huge numbers of dumb bombs out of big bombers.


To awnser your question directly though. A modern 8 to 10 inch howitzer with rocket assist and gps guided shells would probably have similar if not slightly better performance to the AGS, the current pinnacle of big gun technology. Which would be a range of around 100-120 miles, and a CEP of about 50m.

However this would be up against cruise missiles which have ten times that range and a CEP a fifth the size, whilst costing not that much more.
 
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We should start with defining a howitzer so that we don't confuse it with other high angle artillery, assault guns and most SPGs. Per Wikipedia,

howitzer /ˈhaʊw.ɪts.ər/ is a type of artillery piece characterized by a relatively short barreland the use of comparatively small propellant charges to propel projectiles over relatively high trajectories, with a steep angle of descent.

The British 9.2" howitzer had a range of more than 9 kilometers https://en.m.wikipedia.org/wiki/BL_9.2-inch_howitzer

800px-9.2inch-Howitzer-MkI-Mother-IWM-August2006.jpg


Unless you're using rockets, magnets or other means to propel the shell beyond the relatively small (a defined requirement of the type) explosive charge, I suppose a modern howitzer would have about the same performance. Propellant, ballistics, etc. are about the same.
 
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Unless somehow you have a much powerful engine combined with extremely heavyduty autoloading mechanics, anything beyond 155mm is mechanically chanllenging.

Another thing to consider is the geopolitical situation. currently just about the only good places for such SP howitzers are densely populated frontline locations (Korea) or extreme conditions that prevent other methods from being efficient/effective (Finland).
 
To awnser your question directly though. A modern 8 to 10 inch howitzer with rocket assist and gps guided shells would probably have similar if not slightly better performance to the AGS, the current pinnacle of big gun technology. Which would be a range of around 100-120 miles, and a CEP of about 50m.

However this would be up against cruise missiles which have ten times that range and a CEP a fifth the size, whilst costing not that much more.

Those are some huge assumptions. 155mm guns only get 20% or so more range with RAP, what makes you think 203mm gun will be able to double or triple its range with RAP? Why do you also think accuracy would only be CEP 50m? The 155mm M982 has CEP of less than 2m, there is no reason the same tech in a 203mm gun couldn't do exactly the same thing.

Cruise missiles are US$1m each or more while GPS artillery shells are in the US$50k range.
 
Those are some huge assumptions. 155mm guns only get 20% or so more range with RAP, what makes you think 203mm gun will be able to double or triple its range with RAP? Why do you also think accuracy would only be CEP 50m? The 155mm M982 has CEP of less than 2m, there is no reason the same tech in a 203mm gun couldn't do exactly the same thi

Cruise missiles are US$1m each or more while GPS artillery shells are in the US$50k range.

I was referring to the AGS program which claims to achieve up to 100 mile range with LRLAP, and when tested achieved around 50m CEP. Excalibur has achieved CEPs of 2 to 5m, but only at ranges of around 35 miles. Even with guidance CEP increases with range.

Whilst Excalibur and M795 are vastly cheaper than cruise missiles, their range is also vastly less. LRAP and the similar ERGM have capabilities approaching that of cruise missiles, but with a very high price tag per round. In fact due to cut back in LRLAP production they now cost almost the same as tomahawks. Which is why the program has been dropoed by the US Navy.

Of course AGS is a very large naval weapon, whilst it might be possible to mount a similar weapon on an SPG, it would not be very mobile tactically or strategically and would probably suffer performance reductions even then. Most viable spgs would have much shorter barrels, and thus shorter ranges.
 
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Excalibur has achieved CEPs of 2 to 5m, but only at ranges of around 35 miles. Even with guidance CEP increases with range.

Citation needed.

GPS does not suffer from drift so there is no reason to think accuracy would decrease with range. The CEP of LRLAP was given as less than 50m, not 50m. This is both older technology (2005) and was likely designed to hide the weapon's true capabilities.

Whilst Excalibur and M795 are vastly cheaper than cruise missiles, their range is also vastly less. LRAP and the similar ERGM have capabilities approaching that of cruise missiles, but with a very high price tag per round. In fact due to cut back in LRLAP production they now cost almost the same as tomahawks. Which is why the program has been dropoed by the US Navy.

You said it yourself the program was massively cut back and thus a production run of 90 rounds is not indicative of a production unit cost.

Of course AGS is a very large naval weapon, whilst it might be possible to mount a similar weapon on an SPG, it would not be very mobile tactically or strategically and would probably suffer performance reductions even then. Most viable spgs would have much shorter barrels, and thus shorter ranges.

The projectile also weighs 102kg which will slow down loading. 203mm guns had similar projectile weights and terrible reloading times, something like one round every 45s or so in rapid fire, 2m a round in sustained.
 
Citation needed.

GPS does not suffer from drift so there is no reason to think accuracy would decrease with range. The CEP of LRLAP was given as less than 50m, not 50m. This is both older technology (2005) and was likely designed to hide the weapon's true capabilities.



You said it yourself the program was massively cut back and thus a production run of 90 rounds is not indicative of a production unit cost.



The projectile also weighs 102kg which will slow down loading. 203mm guns had similar projectile weights and terrible reloading times, something like one round every 45s or so in rapid fire, 2m a round in sustained.

GPS does not suffer drift but that is not the issue. Guidance maneuvering bleeds energy. This is not a big problem when your weapon is powered to target like a cruise missile. But with a guided shell it swiftly becomes inescapable, each course correction bleeds a bit of energy, altering the ballistic flight path, requiring yet more course correction, initially this is minor but over time is builds up to the point at which further course correction will make the round fall drastically short of it's target.
At short ranges such as the Excalibur round is currently employed this does not factor much, but in the 100 mile plus range envisioned by AGS and the LRLAP there comes a point where increased accuracy by guidance is impossible. A large part of the LRLAP expense is the sophisticated electronics to mitigate these factors as much as possible.

The production cost of LRLAP even before the purchase cutback was high, not as much as afterwards of course (each round costing the same as a Tomahawk was what got the program canned, paying that would have been absurd).
 
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