Traveller Turret Terminology vs Historical Terminology

[Matt123]

Raised in another thread was the view that a historical "turret" = a Traveller "turret". The implication being that the authors intended a strictly historical interpretation of "turret" to be applied to space going craft in Traveller.

This has lead me on quite an interesting diversion to determine "historical" terminology. The documents I am reading appear to be scanned copies of US Navy documents collected by an enthusiastic US Navy seaman (retired?) and published on the web. The documents I have looked up cover the period 1937 to 1971 and are essentially scanned training manuals and the like.

I have selected quotes from a variety of US manuals. Whilst perhaps limited only to a US perspective, for the purposes of demonstrating a Traveller TL 10-15 space going "turret" does not equal a TL 5-8 wet navy "turret", it should suffice given the authors of Classic Traveller are US citizens.


This is the opening paragraphs of;
Naval Ordinance and Gunnery",
Volume 1 Naval Ordnance,
Prepared by the Department of Ordnance and Gunnery,
United States Naval Academy, 1957 edition.

This 'basic textbook' was used in the training of US Navy Midshipman and Officers.
http://www.eugeneleeslover.com/ENGINEERING/Naval_Ordnance_And_Gunnery/Naval_Ordnance_V1_Part1.pdf
(nb: they are all fairly large PDFs)

Chapter 7, Turret Installations

The type of gun emplacement called a turret is, in
general, that in which several heavy guns of at least
6-inch caliber are mounted in an armored structure
which is revolved on rollers by suitable machinery, the
guns being elevated independently of the structure.

The Bureau of Ordnance designates ordnance equipment
as gun mounts or as gun turrets according to the
division of cognizance between that bureau and the
Bureau of Ships. In general, if the equipment is massive
enough to require assembly of parts on the ship
as it is being built, it is called a turret. If the assembly
is made in a gun shop and then hoisted aboard as a
complete unit, it is called a gun mount.

Of note is that US Navy parlance circa 1957, has it that Turrets 'are massive enough to require assembly of parts on the ship as it is being built'.

Also of note is that guns are 'mounted in' the turret and that this definition of 'turret' does not preclude the turret having the components of 'gun mounts' as part of the assembly. A peruse of any of these manuals and thier many photos and illustrations will show you the Deck Lugs (carrage) and Gun Slides used to mount the guns themselves and together called the gun mount. A BB turret has from two to four gun mounts.

This next extract is from;
NAVORD OP 769
CHANGE 1
16·INCH THREE GUN TURRETS
BB 61 CLASS
PUBLISHED BY DIRECTION OF
COMMANDER, NAVAl ORDNANCE SYSTEMS COMMAND
15 OCTOBER 1967
CHANGED 1 NOVEMBER 1967

http://www.eugeneleeslover.com/ENGINEERING/OP769/OP-769_Part1.pdf

Chapter 1, Geneneral Description of the Turret
Turret Arrangements and Differances

Virtually identical, each turret comprises a gun
house and rotating structure, a barbette and fixed
structure, magazines, and ordnance installations.
These differ only in minor details, adapting each
turret to its ship location and the fire control plan.
The gunhouse, 50.63 feet long with a maximum
width of 36 feet, is mounted above and attached to
the rotating structure. Cylindrical and conical in
section, with a maximum diameter of 35 feet, the
rotating structure is supported by a roller path and
consists of six floor levels. Turret II has a seventh
floor level which is a part of the fixed structure.

The rotating structure, protected on top by heavy
armor plate of the gun house, is enclosed within the
upper and lower barbette sections. Cylindrical and
made of heavy armor plate, the upper barbette and
armor deck plates protect the rotating structure,
roller path, and foundation. The three upper barbettes,
each 37.25 feet in diameter, have different
heights because of trunnion axis elevation differences.
Conical and made of heavy steel plate, the lower barbette
is a supporting structure for the upper and differs
in height for each turret.

Of note here, is that a turret comprises the entire assemblage over 6 or 7 deck levels, including rotating and fixed components and ordanance instalations. Elsewhere it notes the entire turret assemblage is around 2000 tons.

US Navy Gunhouse is similar to a Turret in Traveller, in that both may hold 3 weapons and both are armoured, but there is a huge differance in scale.
US Navy Turret or Turret Mount might losely be construed in Traveller as Turret plus Hardpoint. Very loosely, as the weaponry in Traveller turrets is intended to be easily swapped/replaced and of course in Traveller, turrets themselves are easily swapped, do not reach into the bowels of the ship and do not weigh anything like 2000 tons.

Firepower wise a BB wet navy triple turret is more akin to 3 Bays in Traveller. Of course that ignores the obvious structural differances between Bays & Turrets. However, firepower wise, there is no space-going Turret equivilant in Traveller for 19th & 20th century wet navy turrets.


The next extract is from;
Priciples of Naval Ordnance and Gunnery
NAVPERS 10783-B
Training Publications Division
Washington DC, 1971
http://www.eugeneleeslover.com/US-NAVY-BOOKS/1-NO-10783-B-CHAPTER-5-PAGE-2.html

Chapter 5, Guns, Gun Mounts and Turrets
Turret Structural Arrangement
last paragraph

The general principles of a gun mount's major components discussed early in this chapter, also apply to the turrets component's with one major differance. In a turret, the slide, housing and gun barrel are supported by girders (fig 5-43). They serve the same purposes as a gun mount's carriage cheeks shown in figure 5-3.

BB turrets also contain gun mounts to allow the mounting of guns within the turret. Without the slide, housing and deck lugs (together forming the gun mount) the gun cannot be mounted.

In summary, the US Navy mounts guns in armoured Gunhouses that form the upper part of the turret assembly which weighs on BB's around 2000 ton. It is so large the turret has to be assembled whilst the ship is being built. A Traveller firepower equivalent to a BB triple turret, might be 3 Bay weapons.

In contrast, a Traveller space going turret 'weighs' 1-3 tons. Is easily removed and replaced at any starport, can hold a variety of weapons and sits on top of a surface hardpoint that takes up no interior space.

And all US Navy turrets, large and small, have the required components of gun/weapon mounts which allow the mounting of guns inside the turret.

 

[mike wightman]

Wasn't the term turret originally used do describe part of a castle...

 

[atpollard]

In common Traveller usage, the 'turret' is the rotating shell that gets mounted over a 'Hardpoint'. In LBB2/HG, the Turrets are all one dTon and are installed with the internal configuration to hold either one, two or three weapons. [EDIT: Remove bad data from post]

At the end of the day, who cares.

The bottom line is that stating that 'things will be so different in 500 years that modern language will have no meaning' leaves residents of the 20th - 21st century unable to play the game or visualize the core concepts. Who the heck wants to learn a new language (like DUNE) just to play Traveller. Describing concepts in the common vernacular of the day is essential to basic communication.

IM(ns)HO: A 'Turret' is a turret - like the big gun Turrets on the Iowa Class Battleship, or the 40 mm cannon turret on a tank/afv or the twin 50 cal turret of a B-29. It rotates and contains a weapon (or weapons) and shoots at the bad guys.

 

[BillDowns]

Matt,

The terms "gun house", "turret", "gun mount", etc. have changed over the years.

Back when the Omaha class light cruisers were being built, there was a big debate whether the rotating structures at the bow and stern were "turrets" or "gunhouses"; in general, either way, they were "gun mounts". I got this from Jane's Warships, BTW. The key point in that debate seemed to center on the point of armor: if armored, then they were "turrets"; if unarmored, then they were "gunhouses". The Omaha's had unarmored gunhouses.

If you are truly interested, lookup the MEKO ship system from Blohm und Voss. Then, you can get really confused

 

[BillDowns]

I need to correct that reference to Jane's American Fighting Ships of the 20th Century, pg 108. It is only a brief reference, but I did find other sources relating to the discussions in the naval circles about those "gunhouses"

 

[mike wightman]

In common Traveller usage, the 'turret' is the rotating shell that gets mounted over a 'Hardpoint'. In LBB2/HG, the Turrets are all one dTon and are installed with the internal configuration to hold either one, two or three weapons.

Emm....

no, they're not

Turrets in LBB2 are 'massless' it's the fire control that costs you 1t of internal space.

We don't actually know how 'big' single weapon mount, double weapon mount or triple weapon mount turrets are.

It is worth noting that one cannot simply add another 'weapon holder' to a single turret and make it a double turret. The single turret (and its integral weapon holding structure) must be completely removed and a double turret (with two integral weapon holding structures) must be installed on the hardpoint. Another quirk of Traveller word usage is the fact that some really large weapons (like the Particle Accelerator) can only be mounted in a triple turret - which can only hold one weapon.

Again...

no, well sort of

In HG the PA can only be mounted in a 3t turret (how many lasers could you mount in there, 9? ) or 5t barbettes (15 laser mountings?)

IM(ns)HO: A 'Turret' is a turret - like the big gun Turrets on the Iowa Class Battleship, or the 40 mm cannon turret on a tank/afv or the twin 50 cal turret of a B-29. It rotates and contains a weapon (or weapons) and shoots at the bad guys.

There's just one tiny problem with picturing a turret on a CT ship like a BB main gun set up or even like a tank turret. They are too large, you would be breaking the hull displacement vis jump drive rule.

Traveller ship turrets have to be really small to avoid their external volume increasing the size of the ship.

 

[pendragonman]

I hate to rain on anyone's parade, but...

Matt, wasn't this very discussion that you are trying to restart here recently locked for the rancor it causes?

It causes this rancor because (from my point of view) you refuse to see any merit to anyone else's point of view. Please cease and desist.

 

[atpollard]

Emm....
no, they're not
Turrets in LBB2 are 'massless' it's the fire control that costs you 1t of internal space.
We don't actually know how 'big' single weapon mount, double weapon mount or triple weapon mount turrets are.

Not from LBB2, but from HG a Beam Laser, Pulse Laser, Missile or Sandcaster “turret” is 1 dT:
“Weight is the tonnage of the turret containing the type of ordnance described, regardless of the number of weapons of that type mounted in it. Particle accelerators may be mounted only one per turret (or barbette). Plasma guns and fusion guns may be mounted two per turret. All other types may be mounted three per turret.”

Again...
no, well sort of
In HG the PA can only be mounted in a 3t turret

Point yielded … my bad … I stand corrected.

There's just one tiny problem with picturing a turret on a CT ship like a BB main gun set up or even like a tank turret. They are too large, you would be breaking the hull displacement vis jump drive rule.
Traveller ship turrets have to be really small to avoid their external volume increasing the size of the ship.

Really small as in zero? ANY size turret will increase the displacement of the ship … the rules simply choose to ignore the effects.

A 1 dT turret (like a triple laser turret in HG) might be 5 feet tall x 11 feet in diameter – sure sounds a lot closer to a Sherman’s Turret than a B-17’s turret – and as you pointed out to me, there are 2 dT and 3dT turrets and a 5 dT barbette (which is really just a big turret). Those are sounding pretty big to me right about now.

 

[mike wightman]

Difference being the HG design turrets take up internal volume (1, 2, 3 or 5 depending on weapon type), whereas the LBB2 turrets are zero internal volume but require 1t of fire control.

Now I'm in no doubt that the HG 1t turret is intended to be the same as the LBB2 turret, but really when revised edition CT came along in 1981 they should have got rid of fire control and just gone with 1t internal volume for the turret.

 

[aramis]

Difference being the HG design turrets take up internal volume (1, 2, 3 or 5 depending on weapon type), whereas the LBB2 turrets are zero internal volume but require 1t of fire control.

Now I'm in no doubt that the HG 1t turret is intended to be the same as the LBB2 turret, but really when revised edition CT came along in 1981 they should have got rid of fire control and just gone with 1t internal volume for the turret.

I concur.

CT-'81 probably should have unified HG design into the core, IMO.

 

[atpollard]

There are some guidelines on minimum turret size than can be inferred. For example, a standard turret missile is 1 meter long x 15 cm in diameter and a 'turret' can launch up to three at one time. Since none of the illustrations and none of the text suggest that missiles are vertical launch, at least 1 x 0.45 meter (0.03 dT) must project beyond the hull. A 1 meter diameter hemisphere (to allow for elevation) suggests that 0.26 dT would probably be closer to a practical minimum for the external volume of a turret.

 

[BillDowns]

I have always envisioned a triple missile turret as lloking like a Mk 13 mated with a Mk 26. The missile in the middle will be surrounded by the support for the launch arms. Soft like a T with a double base. Image links
http://www.seaforces.org/wpnsys/SURFACE/Mk-13-missile-launcher.htm
http://www.navysite.de/launcher/tartar.htm

Inferring from that premis, the turret will need a base housing for the rotating machinery; let's be optimistic and call it about 30 mm. Then, the height of the missile - 1m. Then some spacing because we don't want the missile base banging into something as the turret moves around - call it 15 mm, same as the missile diameter. THis gives an over-all external height of 1.5 m. For the width, we will need spacing between the misiles, not only for the support structures, but just to add safety margins. Then, the turret will have to rotate into a standard loading position for the missiles to come up into the arms. And additional space again on either side for safety margins. Being very generous, we could call that 7 missile widths or 1m.

Now, for the internals, as I assume some sort on internal loading mechanism and/or a ready magazine is desired. In the previous paragraph, we gave a width of 1m to the turret, so the loading platform beneath should also be that size, plus space for 9 missiles. The ready magazine would likely be a rotating ring, so rounding off to Traveller units, we would have 1.5m by 1.5m by 1.5 for the inner housing.

So, the conclusion is an installation of approx 1.5 to 2 dtons - 1dton internal, the rest external. And this is not including any fire control radar/lidar/whatever.

 

[mike wightman]

And you just broke the hull displacement rule

1t for fire control internal according to LBB2

1t for the whole turret internal according to LBB5

You go over your hull displacement by as much as 1t (probably less) and you now count as the next largest hull size for drive performance.

 

[BillDowns]

Oh, yeah, I know. But, I am just working from the base specifics from the canon books.

Looks like something is off somewhere to me.

 

[BillDowns]

I guess one could assume something like 9-cell Mk 29 IBPDMS. http://www.seaforces.org/wpnsys/SURFACE/Mk-29-missile-launcher.htm

That could be fitted into 1 dton, but would require EVA to reload.

 

[HG_B]

I've generally designed (deck plans) with a 1.5 meter radius hemisphere turret and a 2 meter "socket" directly beneath. If you replace a turret, you pull the whole assembly out and drop in another.

 

[mike wightman]

Oh, yeah, I know. But, I am just working from the base specifics from the canon books.

Looks like something is off somewhere to me.

It gave the GURPS Traveller ship designers problems I can tell you.

It's probably why by TNE a turret had become 3t

 

[mike wightman]

I guess one could assume something like 9-cell Mk 29 IBPDMS. http://www.seaforces.org/wpnsys/SURFACE/Mk-29-missile-launcher.htm

That could be fitted into 1 dton, but would require EVA to reload.

Well it does take 1000 seconds to reload one launcher

 

[Keep On Travellin']

Ditto on HGB's Modular unit. Makes the most sense. I also add that they are jettisonable via explosive bolts and a hardpoint seal.

I couldn't for the life of me, aside from small craft, figure out what was meant by "missile racks" but it's each turret slot having a launcher with three missles in it, right? So a fully loaded Triple Missile Turret has 9 in the chamber?

 

[aramis]

Ditto on HGB's Modular unit. Makes the most sense. I also add that they are jettisonable via explosive bolts and a hardpoint seal.

I couldn't for the life of me, aside from small craft, figure out what was meant by "missile racks" but it's each turret slot having a launcher with three missles in it, right? So a fully loaded Triple Missile Turret has 9 in the chamber?

1 fireable, 3 more in the ready reloads rack, per "missile rack".

Think of it like the cassette systems for current navy vessels: they have 2 on the rails, and 6-8 boxes for reloads; after firing, it lines up with a full box, and reloads the rail. The crew of the ship can reload the boxes.