Super Cannon Thread

Denv2

Just asking some questions for my timeline about really big cannons in a WW2 environment.

Would it be useful to get a 240mm cannon on a self propelled chassis and employ these en masse? The T92 Howitzer Motor Carriage moved quite slowly but it also used a Heavy Tank chassis. Could the armor is stripped off until it is Humvee level thin? This is supposed to be used as artillery and not in direct tank to tank battles. Would groups of these things be useful in supporting tanks during battle? In the story these things are being brought to destroy fortifications but a nearby tank group gets into a fight so these things open fire on the enemy.

Now the hypothetical army has a lot of 240mm self propelled cannons traveling around would it be worth it to make a 280mm self propelled cannon in the WW2 environment. This second vehicle would have something akin to the M65 Atomic Cannon that fires conventional shells and instead of being hauled around by two other vehicles it is carried around by a single purpose built vehicle. Seems a bit of a hassle to have a completely separate vehicle class if you already have 240mm vehicles available for dealing with fortifications but the extra range (30km for the 280mm as opposed to the 20km for the 240mm) seems useful. Would it be practical to have a few 280mm mixed in or would it be more practical just to go for 240mm vehicles whenever a fort assault is needed. Perhaps use the 280mm to deal with any defensive 240mm cannons the enemy may have?
 

Garrison

Donor
There were weapons that size deployed in WWII and they were all rail guns. If you look at the images of them you can see why:
240cm_ry_gun.jpg


By US War Department - Japanese Artillery Weapons, CINPAC-CINPOA Bulletin 152 451 July 1945, Public Domain, https://commons.wikimedia.org/w/index.php?curid=24512282

If you try to put that on a tracked vehicle it is going to look like this act of insanity:
P1000_ratte_scale_model.png

By Author -
https://flic.kr/p/2boY7PN
, CC0, https://commons.wikimedia.org/w/index.php?curid=73962664

Landkreuzer P. 1000 Ratte - Wikipedia

en.wikipedia.org en.wikipedia.org
 

Denv2

@Dorknought will certainly look into that.

@Garrison I certainly can see how designing these weapons could get out of hand. Those pictures certainly are hilarious.

Regarding the top picture of the 240mm cannon, although challenging to get such a cannon on a self propelled gun, it was done. I haven't quite figured out how to attach pictures but this link shows a T92 Howitzer Motor Carriage: https://en.wikipedia.org/wiki/T92_Howitzer_Motor_Carriage
Seems to have a 240mm cannon and built by the Americans in WW2. That thing was mounted on a heavy tank chassis. Keep the frame, the engine, loose the armor, if the T92 can work then perhaps the same thing but with less armor might work.

A 280mm tracked vehicle does seem quite silly but it seems that the Americans had figured that one out too. Again can't attach a picture but this link depicts an M65 atomic cannon: https://en.wikipedia.org/wiki/M65_atomic_cannon

It was intended to fire atomic shells but perhaps this alternate version could be modified to just fire conventional shells? That picture depicts the thing being carried by two tractors using a similar method to Schnabel Cars. This thing was built and was reported to even reach 56km/h. I do admit that this thing was built in the early 1950's but perhaps in the 1940's a similar thing could be built, although with a less powerful 1940's engine? Slower, yet still functional.
Perhaps we can do away with the two tractors and just have a purpose built vehicle to carry it? If you need the engines of those two tractors you can use an engine twice as powerful or use the same two engines in the new vehicle. The configuration of the real M65 seems to suggest that it was placed down on the ground before being used so perhaps this vehicle has some kind of mechanism holding it up and lowers it before firing.

Would that work? It seems part of the insanity of the Landkreuzer P.1000 was due to the turret being enclosed, all of those extra guns, the fact that it had to carry some of its own ammunition and had to carry that armor. This thing acts more like a giant howitzer, the alternate version might have a few vehicles carrying ammunition separately and the area where the firing crew operates is not enclosed.
 

Garrison

Donor
Denv2 said:
@Dorknought will certainly look into that.

@Garrison I certainly can see how designing these weapons could get out of hand. Those pictures certainly are hilarious.

Regarding the top picture of the 240mm cannon, although challenging to get such a cannon on a self propelled gun, it was done. I haven't quite figured out how to attach pictures but this link shows a T92 Howitzer Motor Carriage: https://en.wikipedia.org/wiki/T92_Howitzer_Motor_Carriage
Seems to have a 240mm cannon and built by the Americans in WW2. That thing was mounted on a heavy tank chassis. Keep the frame, the engine, loose the armor, if the T92 can work then perhaps the same thing but with less armor might work.

A 280mm tracked vehicle does seem quite silly but it seems that the Americans had figured that one out too. Again can't attach a picture but this link depicts an M65 atomic cannon: https://en.wikipedia.org/wiki/M65_atomic_cannon

It was intended to fire atomic shells but perhaps this alternate version could be modified to just fire conventional shells? That picture depicts the thing being carried by two tractors using a similar method to Schnabel Cars. This thing was built and was reported to even reach 56km/h. I do admit that this thing was built in the early 1950's but perhaps in the 1940's a similar thing could be built, although with a less powerful 1940's engine? Slower, yet still functional.
Perhaps we can do away with the two tractors and just have a purpose built vehicle to carry it? If you need the engines of those two tractors you can use an engine twice as powerful or use the same two engines in the new vehicle. The configuration of the real M65 seems to suggest that it was placed down on the ground before being used so perhaps this vehicle has some kind of mechanism holding it up and lowers it before firing.

Would that work? It seems part of the insanity of the Landkreuzer P.1000 was due to the turret being enclosed, all of those extra guns, the fact that it had to carry some of its own ammunition and had to carry that armor. This thing acts more like a giant howitzer, the alternate version might have a few vehicles carrying ammunition separately and the area where the firing crew operates is not enclosed.
Click to expand...
Even the atomic cannon is nearly 90 tons, that is going to be rough in WWII terms, especially given I suspect that gun benefitted from post war technical developments. To put it in perspective the Tiger I which was 60 tonnes struggled with mobility.
 

RamscoopRaider

Donor
Denv2 said:
Just asking some questions for my timeline about really big cannons in a WW2 environment.

Would it be useful to get a 240mm cannon on a self propelled chassis and employ these en masse? The T92 Howitzer Motor Carriage moved quite slowly but it also used a Heavy Tank chassis. Could the armor is stripped off until it is Humvee level thin? This is supposed to be used as artillery and not in direct tank to tank battles. Would groups of these things be useful in supporting tanks during battle? In the story these things are being brought to destroy fortifications but a nearby tank group gets into a fight so these things open fire on the enemy.

Now the hypothetical army has a lot of 240mm self propelled cannons traveling around would it be worth it to make a 280mm self propelled cannon in the WW2 environment. This second vehicle would have something akin to the M65 Atomic Cannon that fires conventional shells and instead of being hauled around by two other vehicles it is carried around by a single purpose built vehicle. Seems a bit of a hassle to have a completely separate vehicle class if you already have 240mm vehicles available for dealing with fortifications but the extra range (30km for the 280mm as opposed to the 20km for the 240mm) seems useful. Would it be practical to have a few 280mm mixed in or would it be more practical just to go for 240mm vehicles whenever a fort assault is needed. Perhaps use the 280mm to deal with any defensive 240mm cannons the enemy may have?
Click to expand...
The T92 did have the armor removed, it was down to 25mm to protect against artillery splinters, speed was limited by the suspension and engine power. The point of the T92 was to make the 240mm M1 "Black Dragon" Howitzer more mobile rather than being towed as it was. The 240mm was used as an Army group level weapon, it wasn't meant to support groups of tanks, or even full armored divisions, it was to be used as directed by the staff of the Army group, its worth noting that the Allies never had more than 5 Army groups active at any one time across the whole planet. Your boys in tanks should never see one much less have much to do with one

In story they might fire on an enemy in support of tanks, if they were available and the situation was such that all nearby artillery assets were to hammer that target. But they'd be pretty far away and never see what they'd be shooting at and the tanks would have smaller artillery pieces either organic or attached at a lower level to do shooting first

For the US probably not worth it for a 280mm gun before nuclear shells, the US could substitute air power for railway guns, only reason you need more is basically counter battery against long range guns, long range harrassment fires and fortress busting, all of which the US could do with airpower. Germany and the USSR had different needs so may find it useful for them, hence why the Germans planned to self propel 280mm guns
 

Denv2

@Garrison that's a fair point. So the 280mm stays limited to the realm of rail cannon and perhaps gets replaced by air power.

240mm might still be on the table though.

@RamscoopRaider the armor was stripped back a fair amoint on the T92. Could we strip off even more armor? I see Sherman armor ranges from 12.7 to 177.8mm. Could we have a useful T92 variant with 12.7mm armor all over? Would that be a relevant weight saving?

Good point about them being pretty rare. That might make a good story point with the characters coming to save these rare pieces when the enemy tries to make a push towards them.

Could it be practical for an alternate military to make them more common in the armed forces? Still pretty rare but perhaps an alternate military could have them on an army or corps level. That would mean having roughly 5 (for army level) to 20 (corps) times more of these things mixed in with the smaller stuff. Good point about them not being able to see what they are shooting at perhaps the characters mostly just arrive to see defences reduced to rubble or just watch while the artillery hammers the enemy from beyond visual range.

Some of this fighting takes place in a decaying Eastern Roman Empire. The attack is into the area we would call Greece after a naval invasion and making its way to Constantiople, the way being littered with Sigfried line like defensive lines.

Might swap out 280mm artillery for air power.
 

RamscoopRaider

Donor
Denv2 said:
@Garrison that's a fair point. So the 280mm stays limited to the realm of rail cannon and perhaps gets replaced by air power.

240mm might still be on the table though.

@RamscoopRaider the armor was stripped back a fair amoint on the T92. Could we strip off even more armor? I see Sherman armor ranges from 12.7 to 177.8mm. Could we have a useful T92 variant with 12.7mm armor all over? Would that be a relevant weight saving?

Good point about them being pretty rare. That might make a good story point with the characters coming to save these rare pieces when the enemy tries to make a push towards them.

Could it be practical for an alternate military to make them more common in the armed forces? Still pretty rare but perhaps an alternate military could have them on an army or corps level. That would mean having roughly 5 (for army level) to 20 (corps) times more of these things mixed in with the smaller stuff. Good point about them not being able to see what they are shooting at perhaps the characters mostly just arrive to see defences reduced to rubble or just watch while the artillery hammers the enemy from beyond visual range.

Some of this fighting takes place in a decaying Eastern Roman Empire. The attack is into the area we would call Greece after a naval invasion and making its way to Constantiople, the way being littered with Sigfried line like defensive lines.

Might swap out 280mm artillery for air power.
Click to expand...
Not that much, you are talking maybe 5 tons or so on a 58 ton vehicle

The thing is as high level artillery they are going to be way in the back, a 23km range means they are likely at least 10km behind the front lines in most cases, and as self propelled weapons they can leave on their own when the enemy starts punching through the front lines

The problem with making big guns more common is that they need a lot more supply, replacing 8" howitzers with 240mm ones means having to ship in twice the weight of ammo, 155mm ones quadruple the weight of ammo. If you don't need the extra range, accuracy or penetration, then generally for most duties 4 155mm shells are better than 2 203mm are better than 1 240mm. Only when you need the extra range and accuracy to reliably hit the target, or you have a hard target is going heavier worth it

Swapping out for airpower only works when you can guarantee air superiority, the OTL US pretty much could, if your state thinks that the enemy will control the air, or that the contest will be even, then having an SP 280mm piece might be useful, or possibly even larger pieces if you are talking about really heavy pre-war built fortresses

Of course for a naval invasion to succeed, that implies naval superiority hence the ability to bring in a battleship with 8-12 guns of 14" and up, or failing that a monitor with a pair or so that can be pretty shallow draft and get closer to shore, fire further inland, and be risked easier
 
marathag

marathag

Banned
Denv2 said:
@Dorknought will certainly look into that.

@Garrison I certainly can see how designing these weapons could get out of hand. Those pictures certainly are hilarious.

Regarding the top picture of the 240mm cannon, although challenging to get such a cannon on a self propelled gun, it was done. I haven't quite figured out how to attach pictures but this link shows a T92 Howitzer Motor Carriage: https://en.wikipedia.org/wiki/T92_Howitzer_Motor_Carriage
Seems to have a 240mm cannon and built by the Americans in WW2. That thing was mounted on a heavy tank chassis. Keep the frame, the engine, loose the armor, if the T92 can work then perhaps the same thing but with less armor might work.

A 280mm tracked vehicle does seem quite silly but it seems that the Americans had figured that one out too. Again can't attach a picture but this link depicts an M65 atomic cannon: https://en.wikipedia.org/wiki/M65_atomic_cannon

It was intended to fire atomic shells but perhaps this alternate version could be modified to just fire conventional shells? That picture depicts the thing being carried by two tractors using a similar method to Schnabel Cars. This thing was built and was reported to even reach 56km/h. I do admit that this thing was built in the early 1950's but perhaps in the 1940's a similar thing could be built, although with a less powerful 1940's engine? Slower, yet still functional.
Perhaps we can do away with the two tractors and just have a purpose built vehicle to carry it? If you need the engines of those two tractors you can use an engine twice as powerful or use the same two engines in the new vehicle. The configuration of the real M65 seems to suggest that it was placed down on the ground before being used so perhaps this vehicle has some kind of mechanism holding it up and lowers it before firing.

Would that work? It seems part of the insanity of the Landkreuzer P.1000 was due to the turret being enclosed, all of those extra guns, the fact that it had to carry some of its own ammunition and had to carry that armor. This thing acts more like a giant howitzer, the alternate version might have a few vehicles carrying ammunition separately and the area where the firing crew operates is not enclosed.
Click to expand...
Replace the Crane of a walking dragline excavator with a big cannon

Walkers appeared just before WWI
 

Coiler

Sounds like this fits your idea most. Big gun on a big chassis (that's actually more practical than the multi-turret monster that was the original T-35), and it comes in several varietes-six and eight inch, as well as unarmored for indirect fire and armored for direct engagement (ie, blasting through the Mannherheim Line IOTL)
 

Denv2

@RamscoopRaider good point. Will note that and go for lots of smaller stuff. Mix of air of ground artillery seems that way to go. Was also wondering about the use of artillery some of the fight further inland. Perhaps without the ships the bigger artillery might be useful for dealing with mountain forts?

@marathag like a artillery mech. Nice.

@Coiler that seems like exactly what might fit for this situation.

For that 240mm mobile gun idea, would it be practical to put 2 engines into it to reduce the strain on the vehicle's engine? Those vehicles' weights are starting to reach the higher end of WW2 vehicles and some vehicles such as the Tiger tank reported problems due to breakdowns. They collectively would apply the same energy but perhaps less chance of the strain causing engine damage if there are two of them sharing the load. These super artillery guns are quite rare relative to other vehicle types too, reducing the total cost of giving all of them two engines.

Just had another question too. In WW2 there are coastal defensive emplacements with some pretty big guns but would it be practical to use the really big guns to defend land sites really far from where navy can operate? I thinking really big guns such as 46cm/45 Type 94 Naval guns in a 3 gun to a turret arrangement that the Yamato had. Use those turrets to defend important mountain passes and place them behind your other defenses. Perhaps a defensive site could be 4 of these spread out with the turret itself free to rotate inside a concrete shell of comparable thickness to a flak tower with the gun able to protrude through a gun slit.
 

RamscoopRaider

Donor
Denv2 said:
@RamscoopRaider good point. Will note that and go for lots of smaller stuff. Mix of air of ground artillery seems that way to go. Was also wondering about the use of artillery some of the fight further inland. Perhaps without the ships the bigger artillery might be useful for dealing with mountain forts?

@marathag like a artillery mech. Nice.

@Coiler that seems like exactly what might fit for this situation.

For that 240mm mobile gun idea, would it be practical to put 2 engines into it to reduce the strain on the vehicle's engine? Those vehicles' weights are starting to reach the higher end of WW2 vehicles and some vehicles such as the Tiger tank reported problems due to breakdowns. They collectively would apply the same energy but perhaps less chance of the strain causing engine damage if there are two of them sharing the load. These super artillery guns are quite rare relative to other vehicle types too, reducing the total cost of giving all of them two engines.

Just had another question too. In WW2 there are coastal defensive emplacements with some pretty big guns but would it be practical to use the really big guns to defend land sites really far from where navy can operate? I thinking really big guns such as 46cm/45 Type 94 Naval guns in a 3 gun to a turret arrangement that the Yamato had. Use those turrets to defend important mountain passes and place them behind your other defenses. Perhaps a defensive site could be 4 of these spread out with the turret itself free to rotate inside a concrete shell of comparable thickness to a flak tower with the gun able to protrude through a gun slit.
Click to expand...
It doesn't really work that way, 1 big engine is much the same as two smaller engines if they get the same horsepower, in fact some big engines were literally two small ones welded together. Tigers breakdowns were result of tonnage creep, rushed development and lack of access to strategic materials, they won't apply to every heavy tank or vehicle on a heavy tank chassis

The issue is what the heck are you shooting at that needs an 18" gun in the mountains? The only mobile things worth shooting that at are ships, otherwise its only bunkers and in that case you want a mobile platform to bring forward to the bunkers to shoot at them. Shooting at exposed targets you really only need 6", 8" and up was for blowing up fieldworks. A long range but small caliber gun would work just as well and probably be cheaper, like the German 28cm railway guns or the Allied experiments on 8-10" hypervelocity weapons

Be better to have prebuilt railway gun turnstyles with nearby shelters, given that you will be firing indirectly you don't have to worry that much about counter battery, and have the shelter for that. Mounting the guns on a railcars means you can move them forward or back depending on how the war is going. Furthermore by mounting them on railway cars it is easier to take the guns to the rear so the barrels can be changed, big naval guns like Yamato's only got 150-250 shots before you needed to change the barrel, easy enough on a ship that can pull up to a dockside crane, for a fixed turret you need the crane nearby plus a nearby set of train tracks to bring the 150 ton replacement barrels forward on a railcar, and if you have to build the train tracks anyway, why not put the gun on a railcar?
 

RamscoopRaider

Donor
Jimbo808 said:
Could a cannon in Kent fire shots into Berlin? With existing WWII technology
Click to expand...
No, the record was 115km, the Germans planned up to 190km using a sleeved down Gustav firing rocket boosted shells, you could improve on that slightly, but probably not by much. Berlin is over 750km from Kent, basically only way to realistically do that is to have a "gun" used to provide a kick to a ballistic missile, but the rocket motor would have to do almost all the work and you basically gain nothing over making a slightly larger rocket engine and lose a bunch of accuracy
 

HexWargamer

In ww2 you can't get the accuracy when firing at targets beyond the horizon. Such guns would be about as usefull as the early RAF bombers (send out a couple dozen to bomb a bridge == all miss and half get shot down). Don't even think about aiming at a moving target ... rate of fire will be hours per shell, rather than shells per hour. Then, after a few hundred shots the barrels will be worn out ....
About the only target you could expect to hit with more than one shell in 100 would be a major town or city ...
So no, they are not going to be of much use 'in a tank battle', even assuming they can be fired when the barrel is depressed to a low enough angle 'direct fire' mode ..
 

RamscoopRaider

Donor
HexWargamer said:
In ww2 you can't get the accuracy when firing at targets beyond the horizon. Such guns would be about as usefull as the early RAF bombers (send out a couple dozen to bomb a bridge == all miss and half get shot down). Don't even think about aiming at a moving target ... rate of fire will be hours per shell, rather than shells per hour. Then, after a few hundred shots the barrels will be worn out ....
About the only target you could expect to hit with more than one shell in 100 would be a major town or city ...
So no, they are not going to be of much use 'in a tank battle', even assuming they can be fired when the barrel is depressed to a low enough angle 'direct fire' mode ..
Click to expand...
Not true, artillery regularly did hit things over the horizon as early as WWI (horizon is only 5.1km at ground level), the trick is to have someone available with a radio to tell you where your shots land relative to the target to perform corrections, do that and depending on the gun in WWI hits were scored against fairly small targets (bridges) as far as 33km away with big enough guns

Even Schwerer Gustav managed more than one shell an hour (1.5-2), and under combat conditions at that, the 240mm guns mentioned in the OP did 30 shots an hour

The 240mm guns the OP mentions were used successfully against tanks IRL in their towed configuration at Elsenborn Ridge alongside other guns, trick is that you aren't aiming at a specific tank, rather just dropping artillery on a grid square containing tank concentrations and hoping to land close enough by using a lot of guns firing a lot of rounds
 

Pelranius

I know this is a bit out of the OP's timeframe, but it's hypothetically possible to build a 240mm self propelled, autoloaded howitzer nowadays.

You could put it on a modified 8X8+ TEL (it's possible to put it on tracked chassis, but that would likely bring the maximum weight of the whole thing into the 80-100 ton range, which is probably unfeasible). Of course, it'll have the logistical footprint of an MRBM/IRBM launch unit, with much less range.

Another problem is that while modern artillery shell range extension tech (i.e. ramjets or base bleed) could probably get 300+km ranges for your 240mm SPH, you might be better off spending that money on modern solid fueled, precision guided SRBMs (outside of a few niche scenarios like the Taiwan Straits and Korean DMZ).

Sure, you could make the 240mm cannon a vertical gun to save weight, increase range and rate of fire, but then it's more of a glorified boost system for rockets, as opposed to a super cannon.
 
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Carl Schwamberger

RamscoopRaider said:
Not true, artillery regularly did hit things over the horizon as early as WWI (horizon is only 5.1km at ground level),
Click to expand...

Thats if the forward observer is down around one meter altitude. At between two and three meters above a lake surface I've measured the horizon at 13.4 km distance (8.3 miles). With a hill I could observe fires out past 15 km range in the Mojave desert. Tho spotting the burst with standard binoculars that far is difficult. Battle ships in WWII were observing the enemy, getting accurate range fixes, and occasionally hits out past 25km. The record ship to ship hit was IIRC at 28,000 yards. Need to check that.
 
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