Naval Gun Support During Amphibious Landings.

[Graeme Sydney]

During the Pacific Island Hoping campaign how effective was US Naval Gun bombardment.

My understanding is Naval Gun fire has a very flat trajectory typically meaning gazing fire (and not plunging fire).

Did the US Navy make variation with trajectory and ammunition for Naval Gun bombardment or was it more morale support rather than damaging?

[Takao]

Effectiveness of bombardments varied, however this was usually due to the tendency to go after prominent visible targets. For instance, a sugar factory might be wiped off the map, but a less visible nearby bunker cluster would remain untouched.

Traditionally, yes, naval guns tend to have a flat high-velocity trajectory. However, for shore bombardments, reduced powder charges were used, this allowed the naval guns to achieve high-angle fire at the cost of reduced range and slightly longer prep time(as several gunfire control settings had to be adjusted to account for the reduction in shell velocity.

[OpanaPointer]

Effectiveness of bombardments varied, however this was usually due to the tendency to go after prominent visible targets. For instance, a sugar factory might be wiped off the map, but a less visible nearby bunker cluster would remain untouched.

Traditionally, yes, naval guns tend to have a flat high-velocity trajectory. However, for shore bombardments, reduced powder charges were used, this allowed the naval guns to achieve high-angle fire at the cost of reduced range and slightly longer prep time(as several gunfire control settings had to be adjusted to account for the reduction in shell velocity.

Yep, they were essentially huge howitzers.

As for effectiveness, the commanding general at Okinawa credited the Old Battleships (OBBs) with providing the punch that allowed his troops to break the Shuri Line. Elsewhere both von Rundstedt and Rommel noted naval gunfire, especially the battleships, were a serious impediment to their troop movements toward the beaches.

To better understand the power of these ships do this little experiment:

Find a nice straight road.
Note your starting point.
Drive twenty miles.
Note your end point.

BB guns could reach that far. They'd be offshore some distance, but from muzzle to ground that's the distance, conservatively in some cases.

[gambadier]

Howitzer, that would mean variable charges. I thought naval guns were fixed charges, with the implication of very flat trajectories and hence considerable dispersion at shorter ranges, and while fire would plunge at longer ranges (because the firing elevation angle would be heading toward 45 degrees), dispersion would still be considerable due to the ranges involved and the normal round to round variation in muzzle velocity. Dispersion at 35,000 yards is always considerable. Some of the large calibre (up to 31.5 inches) German rail guns could reach out to 60,000 yards and dispersion was considerable, but they were howitzers and had a choice of propelling charge sizes. The UK 14 in guns engaging fixed targets across the channel (ie 22 miles or so) were also notably ineffective due to dispersion at that range - and they didn't have to worry about being on a moving platform! The basic conclusion is that large calibre long range guns are very impressive at the firing end, but at the target end probably aren't worth the effort, unless you think causing a bit of enemy inconvenience is militarily useful. And generally speaking proper soldiers don't.

[OpanaPointer]

I was half-joking about "howitzers", the idea of 14" howitzers was funny to me. But you can get plunging fire out of a battleship battery, it's why the deck armor is so thick.

[Sheldrake]

I was half-joking about "howitzers", the idea of 14" howitzers was funny to me. But you can get plunging fire out of a battleship battery, it's why the deck armor is so thick.

You can have 14" and even 15" ones. Here is one in action on the Somme.
http://www.criticalpast.com/video/65675 ... s-lined-up
There were real limitations in using a 100 ton equipment gun that needed to be within 9km of the enemy.

[OpanaPointer]

I was half-joking about "howitzers", the idea of 14" howitzers was funny to me. But you can get plunging fire out of a battleship battery, it's why the deck armor is so thick.

You can have 14" and even 15" ones. Here is one in action on the Somme.
http://www.criticalpast.com/video/65675 ... s-lined-up
There were real limitations in using a 100 ton equipment gun that needed to be within 9km of the enemy.

I was referring solely to naval guns. Sorry if that wasn't clear.

[Sheldrake]

"Grandmother" WAS a naval gun. It was ordered by Winston Churchill from a firm in Coventry as 1st sea Lord and manned by Royal Marines. !

[gambadier]

Doesn't make it a 'naval gun'. IIRC those 15-in Hows were a bit of initiative by WSC. The Royal Artillery didn't want them (they had a plan for heavy artillery and it didn't include 15-in on siege mountings) and they were running the UK artillery effort, so they were dumped on the RM. IIRC there were only 4 of them, not sure if 15-in was a naval calibre but it wasn't used by UK rail or coast arty, so the propelling charges would certainly have been unique - for 4 Hows! Talk about gross inefficiency and diversion of resources, it verges on the criminal.

[Sheldrake]

Doesn't make it a 'naval gun'. IIRC those 15-in Hows were a bit of initiative by WSC. The Royal Artillery didn't want them (they had a plan for heavy artillery and it didn't include 15-in on siege mountings) and they were running the UK artillery effort, so they were dumped on the RM. IIRC there were only 4 of them, not sure if 15-in was a naval calibre but it wasn't used by UK rail or coast arty, so the propelling charges would certainly have been unique - for 4 Hows! Talk about gross inefficiency and diversion of resources, it verges on the criminal.

wah. I am aware of the history of these weapons.

[flakbait]

Think you are overlooking that in the age of the "big gun" navies that shooting a 14" (or bigger) shell 10- 15 miles on average from a moving platform and at least damaging (if not directly hitting) an opposing moving target that is in all likelihood attempting to return the favor while vigorously avoiding the same is no `small` feat of using the sciences of physics and was (and still is) heavily dependent upon the rapid but accurate application of mathematics (particularly trig and calculus) to calculate an ever changing and shifting "firing solution" to ensure an interception of the target by your shell(s) at a given point in both time and space. Naval gunfire control of necessity has generally always required a MUCH higher degree of accuracy than land based artillery...BTW while the use by ships of loading reduced charges in lobbing high angle gunfire ( plunging fire) is relatively uncommon due to ideally attempting to out range your opponent`s ships this tactic has been used murderously successfully by ships against land based targets such as fortifications, troop concentrations, ect particularly once spotter aircraft came onto the scene. Shooting reduced charges also helps reduce barrel wear during training...

[gambadier]

Yeah, but ships have height so in effect cover a bigger area from a flattish trajectory perspective, coupled with that a full broadside gives spread along the zone so a hit from one shell becomes good odds providing you've got closish to the correct range with all the fancy rangefinders and ideally made some allowance for the meteor conditions.

& shellducky, not everyone is.

[OpanaPointer]

There's a documented case of a USN destroyer shooting the spire off a church on D-Day because the forward observer thought it was being used to observe their movements. Took seven shots but they got it. (And, of course, in legend they did it with one shot.)

[Carl Schwamberger]

The Church spire shot appears in many histories. It is also noted some 1st Div infantry claimed they took casualties when naval gun projectiles hit a church they had captured a hour or two before. The time and location given in their accounts match the general time and location of the destroyers attack.

[Carl Schwamberger]

I was half-joking about "howitzers", the idea of 14" howitzers was funny to me. But you can get plunging fire out of a battleship battery, it's why the deck armor is so thick.

Looking at my old TFT the charts of Appendices A thru K show the parabola of the trajectory at various ranges. Once the canon elevation is at 15.25 degrees or less the projectiles start to skip or riccochette & the proportion increases as the elevation decreases. What constitutes 'plunging' fire is a bit subjective but a 20 degree angle of impact corresponds roughly to a 25 degree elevation of the cannon tube. 45 degrees elevation corresponds to 35 to 40 degree angle of impact.