Hello zadmiral! Thanks for your comments, compliments, research efforts and opinions! Your many years of research are indeed impressive.
Please be advised that this thread is intended for product announcements rather than hypothetical design discussions. But your comments are appreciated. Since you challenged my design here directly, please allow me to respond here directly. Afterwards, if you would like to continue the discussion, let's do that elsewhere.
Bottom line up front: computer 3D modeling confirms a longer 5"/38 cal. Mk.28 gunhouse doesn't work for the Montana class. The 5"/54 cal. Mk.16 gun doesn't fit in it. The Mk.28's gunhouse is not tall enough to allow the gun to fully elevate without shoving the breech through the floor.Until a Navy design sheet surfaces, suffice it to say, it is impossible to create an "accurate" design of an object that not only never existed, but whose design may never have been completed. Montana Builders Model. I recognize and agree it should be noted that the
Montana builder's model has what appears to be 5"/38 cal. Mk.28 gunhouses aboard it, the kind fit to earlier fast battleships. It is my opinion that there is consensus that the Mk.28 gunhouse would not have been fit to the Montana class. A new design, called the Mk.41 gunhouse, was intended for the Montana class. The fast battleship Mk.28 gunhouses' presence on the model tends to indicate that the design of the Mk.41 gunhouse was not yet designed, not yet complete, or otherwise not available to those who constructed the ship's builder's model. Perhaps the craftsmen who built the Montana model knew a Mk.41 was coming, but having nothing yet to work with, may have used the existing 5"/38 cal. gunhouse as a "placeholder". We may never know.
Analysis Methodology. So what might the actual Mk.41 gunhouse really look like? Since the Mk.41 gunhouse never existed, and without authoritative references, it is impossible to know. To offer a reasonable solution, we are fortunate to be able to analyze a 5"/54 cal. gunhouse that does exist in reality, the Mk.39 gunhouse used for the Midway class aircraft carriers, and try to understand why it looks the way it does. We can evaluate the Midway gunhouse seeking to learn how its size and shape are determined by the physical characteristics and space requirements of the very real and well-documented 5"/54 cal. Mk.16 gun. A critical factor in our understanding is to identify how that gun moves within the gunhouse from full depression to full elevation and to determine the space required to permit that movement. We'll also need to ensure sufficient space for the crew. This will tell us how long and how tall our gunhouse ought to be. This is the analysis methodology I followed when creating my hypothetical design.
Why the 5"/38 cal. Mk.28 gunhouse is too small for the Montanas. I started by replicating the basic shape of the 5"/54 cal. gun in 3D. Then I determined how much space it needed through its full range of motion. Then I placed that 3D model gun inside a 3D model 5"/38 cal. gunhouse I had previously designed from authoritative references. The CAD software allowed me to move the gun through its full range of elevation. The CAD software showed that a North Carolina/South Dakota/Iowa class mount's gunhouse was significantly too small in all dimensions.
The gun simply doesn't fit. At that point, it was immediately clear that the 5"/38 gunhouse, even one that was lengthened, was not suitable and had to be abandoned.
Finding a reasonable gunhouse. The design question then became, "since the 5"/38 cal. Mk.28 mount's gunhouse is too small for the 5"/54 cal. gun, what kind of gunhouse should we replace it with?" Since the Mk.41 gunhouse was never constructed, and despite searches by several at NARA, no surviving plans have been found to exist, nor have any photos of a Mk.41 mockup been found.
The next logical step was to evaluate the the single-gun Mk.39 gunhouse used by the Midways which did enclose a 5"/54 cal. Mk.16 gun, the same gun intended for the Montanas. Detailed plans and photos for the Midway class Mk.39 gunhouse and Mk.16 gun are available. Here's one good drawing.
Attachment:
5in-54 Mk.16 and Mk.39 for CVB cat-0462.jpg [ 130.59 KiB | Viewed 1632 times ]
Characteristics of the 5"/54 cal. Mk. 16 gun. Comparing Navy drawings of the 5"/54 cal. Mk.16 gun and it's position within a 5"/54 cal. Mk.39 gunhouse to the smaller 5"/38 Mk.12 gun within a 5"/38 cal. Mk.30 single-gun gunhouse, the 5"/54 Mk.16 gun
extends 21" further to the rear from the trunnion than does the 5"/38 cal. gun. This is probably because the 5"/54 cal. projectile and cartridge casing were much longer than the 5"/38's projectile and casing necessitating the Mk.16s much longer breech block, and possibly to balance the longer and heavier gun barrel.*
Busting the gunhouse floor. Computer 3D modeling confirmed that the longer breech means that the gun has to be positioned higher in the Mk.41 gunhouse than where the 5"/38 gun is placed in its gunhouse. That in turn requires the gunhouse to be taller, too.
When the gun barrel is elevated to it's design maximum of +85 degrees, the longer breech block extends downward further. If you put a 5"/54 cal. Mk.16 gun in a Iowa class 5"/38 cal. Mk.28 gunhouse, the gun can't be fully elevated because the breech comes into contact with the gunhouse floor long before the barrel reaches max elevation. To keep that from happening, the 5"/54's trunnion must be placed higher above the gunhouse floor than the trunnion of the 5"/38. Thus the gunhouse roof of any gunhouse enclosing a 5"/54 cal Mk.16 gun must be taller than a gunhouse enclosing a 5"/38.
Notice in the drawing above, the design of the Midway class Mk.39 gunhouse reflects the need for a taller gunhouse.
The trunnion on the real Mk.16 gun in the real Midway class Mk.39 gunhouse is positioned nearly 15" higher than the trunnion of the 5"/38 cal. Mk.12 gun in a twin-gun Iowa class 5"/38 cal. Mk.28 gunhouse. Compare:
Attachment:
5in-38 Mk.28 32 38 (small).jpg [ 345.57 KiB | Viewed 1629 times ]
Trunnion placement tends to confirm that
the 5"/38 cal. Mk.28 gunhouse is not just too short front-to-rear, but too short roof-to-floor, too, for the 5"/54 Mk.16 gun. We see that in the case of a very real and in-service gunhouse built for the 5"/54 cal Mk.16 gun, the designers built a much larger gunhouse to accommodate it. This tends to indicate that those designers fully realized that a single Midway Mk.16 gun would not fit in an enlarged gunhouse enclosing a single 5"/38 cal. gun and something entirely new was needed.
With that understanding, the same is likely to be true of the twin-gun Montana class Mk.41 gunhouse. Enlarging a twin-gun 5"/38 cal. gunhouse won't work either. That's why I used the existing Midway class Mk.39 gunhouse as the basis to design a
theoretical Mk.41 gunhouse, not an Iowa class 5"/38 Mk.28 gunhouse extended to rear.
Crew space. When I created my design, I lengthened the 5"/54 cal. Mk.39 mount to provide suitable, proportional pass-around space to the rear of the guns. This is an important characteristic of twin-gun turrets. My design is
not simply a wider Midway turret. If we add a second gun, we also need to provide more space at the rear, presumably to permit the passing of crewmen from one side of the mount to the other, if necessary, without fouling any of the gun crews at their stations. For example, the single-gun 5"/38 cal. Mk.30 mount on Fletchers, etc., has a certain space to the rear of the gun. But in the twin-gun Mk.28s (fast battleships), Mk.32s (carriers and cruisers) and Mk.38s (Sumner and Gearings) there is a lot more space behind the guns, proportionally so for each of the 5"/38 cal. Mk.28, Mk.32 and Mk.38 designs.
So, when I designed my theoretical Montana Mk.41 gunhouse design, I used the same single-gun to twin-gun proportional lengthening of the 5"/38s to determine how much to lengthen the Midway Mk.16 gunhouse to create a functional Mk.41.
That gives us a gunhouse appearance that looks like this:Attachment:
Model Monkey 1-350 5in-54 Mk.41 Mounts for Montana class a.jpg [ 119.02 KiB | Viewed 1632 times ]
I hope many of you will find my methodology sensical and the design I created pleasing and satisfactory.
zadmiral, please continue your research efforts! If you should find plans of the Mk.41 gunhouse, I hope you will share them with us. I will be very excited to create a design based on them.* The 5"/54 cal. Mk.16 gun fired a projectile that was 26 inches long. The casing was nearly 33 inches long. By comparison, the shorter 5"/38 cal. Mk.12 gun fired a projectile that was 20.75 inches long, more than 5" shorter than the Midway 5"/54 cal. projectile. The 5"/38 Mk.12 cal. shell casing was 26.7" long, more than 6 inches shorter than the Midway 5"/54 cal. Mk.16 gun's 33"-long shell casing.
The 5"/54 cal. Mk.16 gun is reported to have been unpopular because the weight of the larger shell resulted in faster crew fatigue. See also:
http://www.navweaps.com/Weapons/WNUS_5-54_mk16.php