Fire Control

[Gun Boat]

Question I cant really find a definitive answer for... bare with me.

How does a battleship aim? I understand that the primary director will aquire range/speed/bearing of the target. Does the director have full control over the turrets? By that I mean does the director have a actual control over each turret or is target data sent to each turret and it is the job of each turret crew to bring their turret to bare? (thats alot of turrets in one sentence)

And also is there some kind of automatic gyro based thing to fire the guns when the ship is completely level (not half way through a role on the waves) or is there an indicator of some sort (artificial horizon?) and its up to the crew to fire when they think the ship is level?

And... Can the director only track one target at a time? Or can it swap between a few? More to the point can the ship fire on 3 different targets (one assigned to each turret) at the same time under the directors.

Also... Is the ''primary director'' in control of the main turrets and the ''secondary director'' in control of the secondary armament or is it secondary because its a back up to the primary? And to follow onto that does each director aim for both the main and secondary guns?

[RustyBattleship]

Well, a ship such as a Battleship has two planes of level. One plane is basically how level the ship is in dry dock so bulkheads can be built vertical, etc.

The other is the "Fire Plane Level". Regardless of how level 2nd deck may be in dry dock, the foundations of all guns AND their directors are machined to the exact same plane.

The directors don't actually fire the guns but they bring the guns into position (azimuth and elevation) for firing. The 16" guns on the Fast Battleships are stabilized to compensate for ship's pitch and roll. So are the directors.

What the director "sees" is fed into the analog fire control "computer" which takes into consideration the range of the target, the speed of the ship, the direction the ship is going, the direction the target is going (if it is a ship) and --- believe it or not --- the curvature of the Earth and how far the planet move underneath the shell while in flight.

And there is not a computer chip in sight. It's mostly all cams and dials.

But it is necessary that the directors are on the same Fire Control Plane as the guns so to maintain relative accuracy between each other.

Additionally, the turrets can also act independently of the directors. But that is only when in visual and point blank range of the gun crews. Even then, when they lock their reticules on a target, servos activate the stabilizing system so the barrels don't move (in relation to the Earth) no matter how much the ship pitches and rolls.

[blidgepump]

And there is not a computer chip in sight. It's mostly all cams and dials.

.

Rusty, maybe this question is for GG ???

So who built the gunnery tables for Navy ships if the Army didn't contract for gunnery tables until 1943?

The following citation is from "Wiki"......

"ENIAC (pronounced /ˈɛniæk/), short for Electronic Numerical Integrator And Computer,[1][2] was the first general-purpose electronic computer. It was a Turing-complete, digital computer capable of being reprogrammed to solve a full range of computing problems.[3] ENIAC was designed to calculate artillery firing tables for the United States Army's Ballistic Research Laboratory, but its first use was in calculations for the hydrogen bomb.[4][5] When ENIAC was announced in 1946 it was heralded in the press as a "Giant Brain". It boasted speeds one thousand times faster than electro-mechanical machines, a leap in computing power that no single machine has since matched. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists. The inventors promoted the spread of these new ideas by teaching a series of lectures on computer architecture.

The ENIAC's design and construction were financed by the United States Army during World War II. The construction contract was signed on June 5, 1943, and work on the computer was begun in secret by the University of Pennsylvania's Moore School of Electrical Engineering starting the following month under the code name "Project PX". The completed machine was unveiled on February 14, 1946 at the University of Pennsylvania, having cost almost $500,000 (nearly $6 million in 2008, adjusted for inflation). It was formally accepted by the U.S. Army Ordnance Corps in July 1946. ENIAC was shut down on November 9, 1946 for a refurbishment and a memory upgrade, and was transferred to Aberdeen Proving Ground, Maryland in 1947. There, on July 29, 1947, it was turned on and was in continuous operation until 11:45 p.m. on October 2, 1955."

[RustyBattleship]

I am familiar with the Army computer used for gunnery trials. The Public Broadcasting Channel had an excellent series on computers a few years ago entitled "The Machine that Changed the World."

Yes, this digital electrical/electronic computer was built and used in WW II analyzing data of field artillery firings (crewed by "Rosie the Riveter" gunners). But the room needed to house the computer with all the passageways needed for maintenance and removal of "bugs" was at least as big as one of the Battleship turrets. Or a helicopter hangar on a Perry class Frigate.

As a matter of fact, when a computer has a "bug" in it, the term was based upon a technician (a woman interveiwed on the series) that was tasked to find out why this monstrosity of wires, tubes, condensers, etc. stopped working one day. So she went up the back aisles looking into the racks and racks of innards and found that a cockroach had shorted out a circuit (killed him too). So her official report was, "Found bug and removed it".

Those computers were far too large to put aboard a ship. Wait a minute. There was only ONE of them at the time.

Analog type computers using cams were very accurate (thanks to high tolerance machining techniques) and didn't take up too much room. As a matter of fact, when I took my turret mechanic course at Fort Irwin in the 1960's the M-48 "computer" was only a shoe box sized container with a handle and peep holes for the numbers when you wanted to change super elevation from Shot to HE or AP or whatever.

The "computer" for the M-41 was about the size of a duplex camera with a knob on it to turn it to what round you were going to fire. From that box ran steel rods, universal joints and links to reset the cross-hairs of the gunner's and commander's periscopes.

Electronics of those days were quite fragile and still used vacuum tubes. It wasn't until a frustrated engineer got angry and threw his unworking project into a glass of water. Surprisingly, it sort of worked then.

Thus was born the diode.

Then some guy down in Puerto Rico welded a couple of 16"/45 barrels together and launched mortar sized sub-orbital satellites into the air. To prevent the electronic components in them from squashing each other during "launch", he had them cast into resin.

The first circuit board was born.

This was long after WW II and it is still amazing that the Analog fire control computers aboard the Battleships are still so accurate though they were designed even before Hitler took over the Sudatenland.

By the 1990's so-called home computers were finally on the market. Thank goodness I waited a while or I'd be trying to sell a Commadore 64 on ebay.

[blidgepump]

Gizmo device cures all?

Rusty,

Reading your recital about addressing pre 1943 gunnery tables being addressed by means of the " gears and cams" device extends how far back in time? WW I ships?

[RustyBattleship]

Rusty,

Reading your recital about addressing pre 1943 gunnery tables being addressed by means of the " gears and cams" device extends how far back in time? WW I ships?

More likely during the Spanish-American War in 1898 when Admiral Dewey took on the Spanish fleet in Manila Bay. What looked like a clock on the forward end of the foremast was actually a range indicator.

So I think the idea of interfacing range finder devices with the guns themselves in the late 19th century may have been the start of modern fire control systems.

[USSWisconsin]

The gears and cams were alreay developed enough for Charles Babage to build his difference engine right after the American Civil War, but programming took longer, a lady named Ada Lovelace managed to program the difference engine in the late 1880's (not for artillery tables). The use of hyperbolic cams shaped like cones was a specialty of Enrico Fermi with his mechanical analog computers. Ada had a programming language used by the DoD named after her in the early 1990's

[Dreadnought]

How does a battleship aim? I understand that the primary director will aquire range/speed/bearing of the target. Does the director have full control over the turrets? By that I mean does the director have a actual control over each turret or is target data sent to each turret and it is the job of each turret crew to bring their turret to bare? (thats alot of turrets in one sentence)

Gunboat,
On the Iowas you have two main fire control directors and sights (Spot One, Spot Two) You could also include the fire control atop the Conning Tower as Spot Three if necessary. There are three modes of gunfire.

*) Primary. The Main Battery directors (Spots 1,2,3) actually anyone of them would do along with Gun Plot (and FCR computer). Then sending orders to the Turret for rotation and elevation.

1)Automatic. Main Battery FC directors and gun plot control the turrets automatically for train and elevation along with the gyros.

Indicating. Gun position (train and elevation) by the Turret crews in the "follow the pointer mode". Which means they both train and elevate the guns until their "indicating lights" light up in sinc with the persprective soultion from the FC computer, gyros etc.

Secondary: The turret (in this case say turret 1) acts as director for the other turrets along with imput to and from gun plot.

Local: Everything comes from the turret as far as train and elevation as well as solution however it will take in manual imputs and some data from other sources. The firing keys (or triggers) are located on the gun trainers handwheels. There are several locations aboard the triggers can be pulled from. The FC computers and the gyros will determin at which point the signal will be sent to the primers for ignition.

[Dreadnought]

And also is there some kind of automatic gyro based thing to fire the guns when the ship is completely level (not half way through a role on the waves) or is there an indicator of some sort (artificial horizon?) and its up to the crew to fire when they think the ship is level?

Yes there are gyros involved for the FC system including the ships main gyro compass .These gyros will determin the optimum angle (cross level and other info) after all information is fed to the FC system. There is also some delay (by means of a delay coil) in this process as an electronic signal is sent to the firing lock (after triggers are pulled) of the guns breech to ignite the primer for the powder. Merely seconds. All taken into account by by the FC computers.

[blidgepump]

Beached Iowa Class at Korea

"And also is there some kind of automatic gyro based thing to fire the guns when the ship is completely level (not half way through a role on the waves) or is there an indicator of some sort (artificial horizon?) and its up to the crew to fire when they think the ship is level?"

General David Howell Petraeus delivered a speech at the Truman Library last Friday to honor Korean Veterans.

This made me think about the story of a Iowa Class BB being beached on the mud flats at Korea to gain additional elevation for the 16-inch battery to fire a longer distance. Considering this thread about hitting something using gunnery tables and mechanical devices with cams and gears......

What Gun Captain figured out the idea of super elevating a barrel by beaching? Pretty cleaver if you dont mind waiting for the next tide to come in to lift your ship out of the mud. Was this a common event?

Is this where you let the stern anchor out as you move forward, to pull the ship back without grinding the props in the mud?

[Dreadnought]

And... Can the director only track one target at a time? Or can it swap between a few? More to the point can the ship fire on 3 different targets (one assigned to each turret) at the same time under the directors.

A short answer, no. The main directors sweep 360 around the ship. When they were updated they have ADT (Automatic Detection and Tracking)The turret is supplied with both a Turret Captains periscope and a Turret Officers periscope (all three). Turrets two and three also have the manual rangefinder inside where as Turret ones rangefinder was removed during the Korean War. In a manual mode, Spot Three atop the Conning Tower can be used as well to feed gunplot information. Also you could use the 5"/38 radars into the FC system. You have many radars that can track aboard the ship. All at one given time. A layered approach if you would and many redundant.

[Dreadnought]

Also... Is the ''primary director'' in control of the main turrets and the ''secondary director'' in control of the secondary armament or is it secondary because its a back up to the primary? And to follow onto that does each director aim for both the main and secondary guns?

Main battery directors are mainly for the main battery. You could aim the 5"/38's with them but it will only be good for the guns range even know you could see alot further via electronics. The same could be said for the Secondary/Main battery comparison,in this case the gun would outrange the directors capability.

Main Battery (Spots 1 & 2, possible 3 if necessary) for the 16"/50's. You have options wether in Auto or Local as to where you can get your info from.

Secondary you have 4 directors (Sky 1,2,3 & 4) for the 5"/38's. It would depend on what the radars range sweep capability is in train and raduis. They overlap each other in sweep so you dont have any blindspots.

[RustyBattleship]

"
This made me think about the story of a Iowa Class BB being beached on the mud flats at Korea to gain additional elevation for the 16-inch battery to fire a longer distance. Considering this thread about hitting something using gunnery tables and mechanical devices with cams and gears......

What Gun Captain figured out the idea of super elevating a barrel by beaching? Pretty cleaver if you dont mind waiting for the next tide to come in to lift your ship out of the mud. Was this a common event?

Is this where you let the stern anchor out as you move forward, to pull the ship back without grinding the props in the mud?

That was the USS Missouri (BB-63) that was answering a strike call on some NK bunkers on the other side of a bridge and pinning down the Marines who couldn't cross.

Technically, a ballistic projectile will reach its greatest range if fired at a 45 degree angle (to a level tangent of the Earth's surface). However, the guns on the Iowa class were restricted to only 42 degrees as it was calculated an elevation greater than that would put to much of a load on the rollers of the roller path. A lessoned learned the hard way on the Texas that started to flatten out its rollers.

To get the maximum range and still allow for "one over, one under", the Captain (I think his name was Brown) brought the Mo over a sand bar and flooded his trim tanks so the ship was not only "rock solid" but listing 4 to 5 degrees so the guns could elevate to 45 degrees relative.

This was touched on in the old TV series "Navy Log". Mo wiped out the bunkers with the first salvo.

A stroke of genius. And no sticking to the sand bar as later in Norfolk as all they had to do was pump out her trim tanks.

In my 39 years working for the Navy, I found Battleship captains to be very innovative and extraordinarily intelligent. I also found Destroyer captains to be very gutsy. I worked on one DD where the crew showed me some round welds in the exterior bulkheads. That happened during the Korean War and the DD had to get in REAL close to provide her needed fire support. So close the bow was in the sand on the beach and the round welds were covering bullet holes from enemy rifle fire.

That crew just loved that skipper. After backing off the beach and the ship reached safe waters (to weld up the bullet holes) the crew would gather on the fan tail for some relaxation. The skipper would come out with his guitar and join in.

Ah yes. The Greatest Generation was still alive and well even into the Korean War.

[Dreadnought]

Ah yes. The Greatest Generation was still alive and well even into the Korean War.

*And some of those war horses lasted until the end of the Vietnam conflict and further such as in J Edward Snyders case among many others.;)

[Gun Boat]

Interesting.

With so many different stations and the whole mechanical computer thing the room for error seems huge. You would have to assume the machinists turning out the fire control computer components would have to be the best. But even a hair or something inside the mechanicals could potentially put the shot fall out by many meters/feet?

Is there any form of memory in the FCR? Meaning can a target be kept in the computer whilst another is aquired and ranged?

On different note, what happens when when the ship is bombarding land? IS the computer still used along with maps or something? And with regards to the beaching to super elevate the guns I assume the gyro fire lock out could be bipassed?