Main (primary) Armament

[ 03-30-05 ] [ 02-28-03 ] [ 04-11-02 ]

California’s primary armament consists of 4 triple 7/32" turrets with a firing interval of 6 seconds per turret. Each turret may fire independently, as part of a fore or aft pairing, or as part of a broadside. Consideration is being given to independent rotation, and also to the standard practice of rotating as fore and aft pairs. The performance requirements are that the turrets be able to sustain a full speed broadside exchange for a period of 1 minute, delivering 120 rounds maximum.

The aborted MK III project of 1997 produced a compact canister cannon operating on the reverse firing valve principle, where the cannon is fired by the removal of pressure, not the application of it. While the original design called for the entire cannon to rotate, the final configuration included a rotating magazine assembly similar to the Indiana cannon commonly in use. There was no way to realistically rotate the entire unit.

There is a potential for the combination of 12 X 7/32" barrels, firing at 6 seconds intervals, to overwhelm the dominant 9 X 1/4" cannon arrangement. To weigh the damage producing ability, consider that damage dealt is strictly a measurement of the size of the holes created for the purpose of flooding. Measure the area of the rounds being fired, equalize the rates of fire, and factor the number of barrels involved. Since 1/4" cannons fire at 8 second intervals, and 7/32" at 6 seconds, we must chose a number of salvos that will reflect a coordinated measurement. At 24 seconds, both systems will have been able to fire starting at the same time, and be ready to fire again in sync.

The area of a 7/32" round is .3434", and that of a 1/4", .3925".
The area of 12 7/32" rounds comes to 4.12", and that of 9 ¼", 3.53".
In 24 seconds, the 7/32" ship will deliver 12 X 4 rounds with an area of 16.48".
In the same period of time, the 1/4" ship will deliver 9 X 3 rounds with an area of 10.59".
The 7/32" ship has a broadside area 155% that of the other.

With one triple turret out of action, the 7/32" damage delivered is 12.36", or 116% that of the 1/4" ship. While it is true that water will flow faster through a 1/4" hole, the tendency here is obvious. The 7/32" ship armed with 12 barrels is clearly at an advantage.

California’s secondary armament of 8 .177" cannons per side is capable of delivering 26.67" per 24 second period. Together with main armaments, BB-44 would be able to deliver 43.15", or 180% of a Bismarck armed with 8 1/4", 4 .177" secondaries and 3 1/4" torpedoes per side (23.92").

The largest counterpoint to these seemingly out of balance figures is that of flow rates. There are no current and comprehensive data on the rate of water flow through these various openings. The tendency is for equal areas, formed by differing calibers, to favor greater total flow through the larger caliber holes, though exactly how much is open to testing and debate. So, while the area of the 7/32" rounds is much greater, the overall flooding effect will likely not match percentile for percentile. Still, there are other effects to consider, such as blow-outs resulting from concentrated fire, the greater likelihood of a flooding hit due to the greater number of rounds fired, and the points scored by individual hits (which are not affected by differences in caliber).

03-30-05 Notes

The new CNC mill soon to be received by the California Armory, (the armaments bureau of the Shipyard), will enable the project to move ahead with some sort of certainty. Once it has gone through its trials, workup will commence for MK-V prototype and development work.

02-28-03 Notes

The Whole Unit Rotation concept has taken a back burner position. In the long months since the last project update, many other issues have arisen to take precedence over design and construction. Still, in the few moments of free time available, work proceeded on the MK-IV. If any one area can be said to have run away with the game, it would have to be the design of the pressurized rotation fitting. The principle of complete rotation requires a gas line connection that can rotate, while under pressure, without leaking, and with minimal service demands. The three designs that came about were either too complex for manufacturing repeatability, or too large.

As a result of this, the MK-IV has taken what might seem to be a step back to the MK-III. The top half of the cannon will now rotate independent of the base. This allows for a safety circuit (which doesn't require tandem or siamesed rotational gas couplings). Gas lines will remain stationary with the base.

The good news for the newer MK-IV (mod 2, or MK-V?) is that the accumulator remains intact, the rotation base circle for the magazine is much larger than on an Indiana (no magazine rocking during firing), and the overall height is a mere 2.65".

Yet another positive bit of news is that a way has been found to seal, or partially seal, the breech tubes. This is an automatic function with only one moving part. This, combined with the short gas path, is what will make this cannon's efficiency climb far above what currently exists. Along with the short height, this cannon will fit places where others can't, hit hard, and still rotate and depress. The 2.65" height makes it the only cannon that will fit in California's Y turret location, and retain all expected BB functionality.

The following image is a simple graphic representation of what the cannon currently looks like.

04-11-02 Notes

California's main weaponry must meet certain physical size requirements. It is absolutely necessary that all four turrets have the ability to rotate. Historically, the gun furthest aft has been a fixed unit in our hobby. This is because of the severe height limitations of the early split deck US battleships. PC has been working on a design that will allow whole unit rotation in a compact canister design. This design carries the designation of MK-IV ACC - WUR. When a few more details have been worked out, several key parts will go out to a CNC mill shop for cutting. Consistency of manufacturing is one key to matched performance.

The MK-IV Advanced Canister Cannon - Whole Unit Rotation, exists on paper only. However, the design behind its valving and its overall operation was proven in the form of the MK-III canister. Currently, the MK-IV measures 2.8" tall, including base plate. Its accumulator volume is 4 times the volume of the manifold and barrels combined, based on a ¼" triple-barreled gun. The entire assembly rests on a pressed bearing, mounted in the base, and can be rotated using conventional O-ring or Steel Cable Drive. There is also provision for an alternate method currently under development by another party.

The MK-IV may include a sealed breech. Rather than incorporating a movable breech block, dipping magazine, or selector piston, the MK-IV would raise a section of magazine floor at the breech. The design calls for a domed roof in the feed tube, right at the breech entrance. The next-in-line round rises slightly with the floor and is trapped under the roof. It can not move, and plugs the feed tube until gas pressure falls and lets the floor return to its resting position. There is very little movement of the floor. This feature will eliminate most of the gas lost through the magazine feed tubes, and allow for slightly lower pressures in the accumulator. In traditional magazines, muzzle velocity drops as the magazine is depleted, and gas diverts into the magazine via the feed tubes. When the magazine is near empty, the gun is at its weakest. With a sealed breech system, pressure in the barrels is not affected by ammunition counts.

A concave magazine floor works with the breech seal to increase efficiency. Its bowl shape has an effective average slope angle of between 3 and 4 degrees. This is sufficient to encourage most rounds to seek the center of the magazine, and drop into the breech feed tubes. When the magazine nears empty, the rounds will still feed positively, and not slop around as in flat magazine units. When a multi-barrel cannon fires with fewer than all barrels loaded, gas pressure is wasted through the open barrel (s). Gas pressure seeks the path of least resistance quite happily. With the overall pressure dropping rapidly, the loaded barrels do not fire at full power. Even with the magazine nearly empty, a cannon with some method of positively guiding the rounds to the feed tubes will still be in the fight long after traditional units have become combat ineffective.