Modern CIWS vs WWII Kamakazi

**2DREZQ** · 18 Feb 12,, 19:21

I think I know the answer to this one, but I'm curious what some of you think.

This is for a short story I am working on.

It's 1945, and some bright people have built an electrically-driven gatling-gun upgraded to the then-current 20mm cannon round. It goes to sea aboard two heavy cruisers that have sacrificed some of there 8-inch magazine capacity to make room for a LOT of 20mm ammo, and an advanced feed system to the guns. The contractor claims that a "wall of projectiles" will make any ship that can carry the system immune to such attacks.

Sighting system? Automatic range/trajectory compensating sight? Any way for it to make use of the contemporary radar systems? Could a WWII destroyer even carry enough ammo and not sacrifice to much in the way of other capabilities?

**JRT** · 18 Feb 12,, 20:07

Originally Posted by 2DREZQ

I think I know the answer to this one, but I'm curious what some of you think.

This is for a short story I am working on.

It's 1945, and some bright people have built an electrically-driven gatling-gun upgraded to the then-current 20mm cannon round. It goes to sea aboard two heavy cruisers that have sacrificed some of there 8-inch magazine capacity to make room for a LOT of 20mm ammo, and an advanced feed system to the guns. The contractor claims that a "wall of projectiles" will make any ship that can carry the system immune to such attacks.

Sighting system? Automatic range/trajectory compensating sight? Any way for it to make use of the contemporary radar systems? Could a WWII destroyer even carry enough ammo and not sacrifice to much in the way of other capabilities?

CIWS is a precision weapon system. It doesn't put up a wall of DU. It fires a burst, sends a shot string on a trajectory to a projected intercept of the target on its flight path.

A vast magazine of ammo is of little use when the barrels have a comparatively short life. The barrels last a little longer with shorter duty cycles, shorter bursts, but barrel life is a constraint.

I think that the technology needed to develop and build an electrically driven and primed gatling canon is within pre-WW2 capability. The rest of the system is a much bigger problem.

**2DREZQ** · 18 Feb 12,, 23:50

Originally Posted by JRT

CIWS is a precision weapon system. It doesn't put up a wall of DU. It fires a burst, sends a shot string on a trajectory to a projected intercept of the target on its flight path.

A vast magazine of ammo is of little use when the barrels have a comparatively short life. The barrels last a little longer with shorter duty cycles, shorter bursts, but barrel life is a constraint.

I think that the technology needed to develop and build an electrically driven and primed gatling canon is within pre-WW2 capability. The rest of the system is a much bigger problem.

I know it doesn't put up a wall, That's just what the manufacturer used as a sound byte to sell the idea to the senate appropriations committee (even in alternate realities, some things are a constant)

My main problem is, indeed, with aiming the darn thing. Still, when the kamakazi's nose was pointed straight at the ship, wouldn't hitting and destroying or deflecting him have been easier than hitting a high speed anti-ship missile is today? The story has to have SOME degree of plausability, you can ask the reader for a certain degree of suspension of disbelief, but there are limits.

**ace16807** · 19 Feb 12,, 00:30

I feel like you could just use manual targeting though? It's probably within the realm of feasibility of manually targeting something going only half the speed of what the CIWS is designed to neutralize. However, given the sacrifices that the CIWS comes in terms of traditional AA, it might not be worth it.

**RustyBattleship** · 19 Feb 12,, 01:33

The other responders are correct. The Radar tracking of the CIWS can even track its own bullets and correct for windage and elevation while tracking the incoming target at the same time.

The most notable "WALL OF STEEL" that occurred in WW II was when the South Dakota with its massive number of 20 mm's took out 26 Japanese airplanes in a single battle. I knew the shipfitter that installed the foundations for the guns but even he forgot how many he put on. So the number of gun mounts is still questionable.

**2DREZQ** · 19 Feb 12,, 02:37

Originally Posted by RustyBattleship

The other responders are correct. The Radar tracking of the CIWS can even track its own bullets and correct for windage and elevation while tracking the incoming target at the same time.

The most notable "WALL OF STEEL" that occurred in WW II was when the South Dakota with its massive number of 20 mm's took out 26 Japanese airplanes in a single battle. I knew the shipfitter that installed the foundations for the guns but even he forgot how many he put on. So the number of gun mounts is still questionable.

But didn't it take something the SIZE of a battleship to carry that much AA? And if an aircraft "survived" (that's an interesting way of putting it, no?) to impact the ship, a battleship would fare pretty well. (It happened a few times IIRC)

I'm thinking of something a smaller, thin-skinned vessel could carry as a last line of defense, would it have made any sense in that setting, given the technology available at the time?

BTW, I loved reading the stories about the AA fire put up by the USS Houston in defense of otherwise helpless allied ships.

**tbm3fan** · 19 Feb 12,, 03:35

Just out of curiosity here is a what if. What if the plane wasn't spotted right away since many like to come in with the sun behind them. Not talking the planes down low. Suppose the pilot, and a few did, knew that coming in at altitude, and that once they hit their push over point it was darn near impossible to hit a plane coming down at 70 degrees. Very much like the best dive bomber pilots of both sides. I have read that it was pretty much a given fact that if the plane did that it was almost sure to hit and there wasn't much that could be done after push over. I sure many have seen shots of a kamakazi almost vertical when they hit a carrier.

**RustyBattleship** · 19 Feb 12,, 06:34

Originally Posted by tbm3fan

Just out of curiosity here is a what if. What if the plane wasn't spotted right away since many like to come in with the sun behind them. Not talking the planes down low. Suppose the pilot, and a few did, knew that coming in at altitude, and that once they hit their push over point it was darn near impossible to hit a plane coming down at 70 degrees. Very much like the best dive bomber pilots of both sides. I have read that it was pretty much a given fact that if the plane did that it was almost sure to hit and there wasn't much that could be done after push over. I sure many have seen shots of a kamakazi almost vertical when they hit a carrier.

That's quite true. Unless an AA round hit the bomb the plane was carrying or blew the engine open and set the fuel in the wing tanks to blow, the momentum of the plane at that angle would still carry it on through to the target, no matter how long the pilot was dead.

I don't know if there is any official records around, but I have heard that quite a number of casualties from air attacks (on both sides) were a result of the "downed" plane crashing into residential areas. The bombs were bad enough, but the burning fuel could take out a whole block of homes.

**Chogy** · 19 Feb 12,, 13:50

The limiting factor in your story is the precision and speed of the radar system. Digital systems were still in the future. Radar aiming was in its infancy.

The hypothetical ship would have to have systems that were unavailable in 1944; or, they could be replaced with a human and an optical system. WW2 optical sights were impressive given the technological base.

The motorized gatlings had already been done. Sometime around 1900, the U.S. Army did some experiments with 19th century Gatlings retrofitted with electric motors, and rates of fire surpassing 5,000 were noted.

**Gun Grape** · 19 Feb 12,, 16:18

The radar sights of the day were pushing the limits of tech.

The 5/38s were radar controlled already.(Mk-37) The 40mm were either optically aimed with computers figuring lead angles and electronically controlled (Mk-51 FCS), or towards the end radar controlled.

Multiple 40mms controlled by a single Mk-51 was the WW2 equivalent of todays CIWS

Notice in the picture of the 40mm firing, no one is sitting in the gunners seat. All controlled, but the loading, from the Mk-51

**Gun Grape** · 19 Feb 12,, 16:40

Originally Posted by 2DREZQ

[FONT="Book Antiqua"][SIZE="3"]I think I know the answer to this one, but I'm curious what some of you think.

This is for a short story I am working on.

It's 1945, and some bright people have built an electrically-driven gatling-gun upgraded to the then-current 20mm cannon round. It goes to sea aboard two heavy cruisers that have sacrificed some of there 8-inch magazine capacity to make room for a LOT of 20mm ammo, and an advanced feed system to the guns. The contractor claims that a "wall of projectiles" will make any ship that can carry the system immune to such attacks.

Boost it up to 40mm. The Navy was disappointed with the 20mm and its lack of knock down power against Kamikaze.

They did test the quad 20mm Thunderbolt on the Massachusetts. And it was deployed/tested on a few PT boats in the Med. Aimed with the Mk-14 gyro sight. But the 20mm still lacked knockdown power

Thunderbolt and the Mk-14 sight installed on a single mount

**Gun Grape** · 19 Feb 12,, 17:01

Originally Posted by RustyBattleship

The most notable "WALL OF STEEL" that occurred in WW II was when the South Dakota with its massive number of 20 mm's took out 26 Japanese airplanes in a single battle. I knew the shipfitter that installed the foundations for the guns but even he forgot how many he put on. So the number of gun mounts is still questionable.

Lets not forget North Carolina during the battle of the Eastern Solomons. In a 8 min period, she knocked out 14 planes and put up so much fire that the Enterprise called and asked if she was on fire. And that was before 40mms were installed.

**Dreadnought** · 19 Feb 12,, 18:26

CIWS, It can indeed put up a "wall of steel" in has more integration with the operator then ever before in the Block 1b system. Yes, it can and will wear out the barrels and they will need to be changed. However, with those two radars in the dome (one tracking target, one tracking the bullets coming from the gun) in will adjust fire automaticly and can traverse the envelope in both trane and elecvation in mear seconds. Faster then any operator could ever adjust it. On the early model (Block 0) they were hydraulic motors, they are no longer they are air powered and much faster then the early models. They have also cut its reload time drastically when compared to the Block 0's.

Also consider for a long time since the early 80's they used Uranium depleted rounds, now days I suspect they are Tungsten penetrators.

What was the main achelleis heel with the Japanese planes? No armor. A CIWS would chew it up in mere seconds and no doubt the pilot is dead before the plane hits the water.

I do agree with the gunnys point. They were good systems for time period and 40mm instead of the 20mm such as CIWS.

IMO, A CIWS vs Kamikaze is not a fight, its an exercise in futility. Especially if the condions are matched within both the 40mm & 20mm ranges.

*A burst (100 round which CIWS can do and more) would take mere seconds compared to the 40mm. There is no way capable that a WWII Japanese plane is going to survive it.

*Barrel life for the CIWS is not the standard anymore:

Optimized Gun Barrels
The original M61A1 gun barrels were designed for short bursts and are subject to wear and increased dispersion patterns. The new OGBs are 18 inches longer, substantially thicker and include both a barrel brace and muzzle restraint to improve life expectancy and projectile dispersion patterns. In addition, the optional Enhanced Lethality Cartridge (ELC) will provide a 50 percent increase in penetrator mass.

Modern CIWS can also:

Operational Features

Autonomous detect, prioritization, track, engagement and kill assessment of air targets from wave-top to steeply diving.

Day/night detect, identification, track and engagement, and kill assessment of surface craft and low-speed aircraft.

Remote designation available from other ships’ sensors against air and surface targets
Interface and control to provide fire-control and search sensor capability for other shipboard gun and missile systems.

IMO, If you are even going to compare the two gun systems then they need to operate within range of both under their normal conditions. Otherwise there is nothing comparible if the plane is within range of the 40mm but not CIWS 20mm.

I also left out CIWS's FLIR system.

Theres that dam double word glitch in the matrix again.

**zraver** · 19 Feb 12,, 20:23

Originally Posted by Chogy

The limiting factor in your story is the precision and speed of the radar system. Digital systems were still in the future. Radar aiming was in its infancy.

The hypothetical ship would have to have systems that were unavailable in 1944; or, they could be replaced with a human and an optical system. WW2 optical sights were impressive given the technological base.

The motorized gatlings had already been done. Sometime around 1900, the U.S. Army did some experiments with 19th century Gatlings retrofitted with electric motors, and rates of fire surpassing 5,000 were noted.

IIRC John Gatlin patented the idea in 1893 and it was the US navy which installed them on MTB and river boats as anti-boarding weapons. GE came across one in a warehouse and the M61 idea was born.

**tbm3fan** · 20 Feb 12,, 02:46

I think if I were behind one of these pointed straight up and there was a kamakazi coming straight down on top of me I'd quickly look for another job, battle station, ship or whatever...

The Red Oak has been working on theirs from before and after.