Tribal class dd

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tameraire01
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Tribal class dd

Post by tameraire01 » Tue Sep 16, 2014 8:01 pm

Could the tribal class DD be used as AAA platforms for Capital ships?
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Re: Tribal class dd

Post by Steve Crandell » Tue Sep 16, 2014 9:38 pm

I presume you mean AA escorts. Of course they could, but their 4.7" guns were not the best for that purpose and they didn't have a lot of effective smaller AA weapons. As the war progressed some of the 4.7" guns were replaced by weapons more appropriate for AA defense. It depends on what point in the war; like all nation's ships of all types they tended to get better AA weapons as the war progressed and they got yard periods. No one had really good AA weapon systems at the beginning of the war.

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Re: Tribal class dd

Post by pgollin » Wed Sep 17, 2014 9:42 am

.

Post-war the RCN modernised their Tribals with 4 x twin 4-inch - which would make them good AA escorts.

( During the war, four of the L-class were completed with 4 x twin 4-inch guns. )

.

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Re: Tribal class dd

Post by paulcadogan » Wed Sep 17, 2014 1:59 pm

Steve Crandell wrote:I presume you mean AA escorts. Of course they could, but their 4.7" guns were not the best for that purpose and they didn't have a lot of effective smaller AA weapons. As the war progressed some of the 4.7" guns were replaced by weapons more appropriate for AA defense. It depends on what point in the war; like all nation's ships of all types they tended to get better AA weapons as the war progressed and they got yard periods. No one had really good AA weapon systems at the beginning of the war.
Specifically the X 4.7-inch mount was replaced by a twin 4-inch in most Tribals in 1940-41. I believe the 4.7's did have AA capability, but early wartime experience (I think the losses of Afridi and Gurkha off Norway to air attack?) led them to replace X mount with the 4-inch and cut down the mainmast and aft funnels to improve the arcs of fire. The other light AA included a quad 2-pdr pom pom and two quad Vickers 0.5-inch. The Vickers guns would have later been replaced by 20 mm singles or twins.
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Re: Tribal class dd

Post by Matrose71 » Wed Sep 17, 2014 5:38 pm

I don't see any AA capacity with an elevation of 40 degree.

http://www.navweaps.com/Weapons/WNBR_47-45_mk9.htm

Elevation ;Twin Mounting CPXIX: -10 / +40 degrees

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Re: Tribal class dd

Post by paulcadogan » Wed Sep 17, 2014 6:37 pm

Matrose71 wrote:I don't see any AA capacity with an elevation of 40 degree.

http://www.navweaps.com/Weapons/WNBR_47-45_mk9.htm

Elevation ;Twin Mounting CPXIX: -10 / +40 degrees
Unless it's vs. low flying aircraft such as torpedo bombers......they'd be pretty hard pressed to deal with anything else without that 4-inch twin. Wonder why only 1 mount was replaced...
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Re: Tribal class dd

Post by dunmunro » Wed Sep 17, 2014 8:14 pm

tameraire01 wrote:Could the tribal class DD be used as AAA platforms for Capital ships?
The Tribal class were the first class of RN destroyers that were, in fact, intended to provide AA protection for the Battle fleet.
The Royal Navy equipped the Tribal class with a comparatively heavy anti-aircraft armament; all eight 4.7in guns could engage aircraft with predicted fire using the FKC computer, and thus provide a powerful augmentation to the battle-fleet's AA defence.[9] The close range AA armament of a quad 2pdr and two quad Vickers machine guns was a marked advance over previous destroyer classes[10] and heavier than most other nation's close range destroyer armament in 1939.[11] However, prewar, the Royal Navy assumed that destroyers would be acting mainly as escorts for the battle-fleet,[9] and would not be the primary focus of aerial attack...

9) Harding, editor, The Royal Navy, 1930–2000: innovation and defencep 19-41:, Pugh, Managing the aerial threat.
10)Hodges and Friedman, Destroyer weapons of WW2, P23-24.
11) Hodges and Friedman, Destroyer weapons of WW2, Previous to the Tribal class, Royal Navy destroyers carried either 2 x 2pdr AA guns or twin quadruple .5" Vickers machine guns. USN destroyers, in the same time frame, usually carried 4 x .5" Browning machine guns.
https://en.wikipedia.org/wiki/Tribal-cl ... yer_(1936)
Here's the Tribal's FC Schematic showing that it had an AA FC system which delivered AA time fuze settings to all 4.7in and 4in guns:

Image

To see the entire image right click on it and select "open in new tab".

Also read the article by Mark Brady starting on page 24:

http://www.royalnavalmuseum.org/documen ... mn2012.pdf

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Re: Tribal class dd

Post by dunmunro » Wed Sep 17, 2014 8:38 pm

paulcadogan wrote:
Matrose71 wrote:I don't see any AA capacity with an elevation of 40 degree.

http://www.navweaps.com/Weapons/WNBR_47-45_mk9.htm

Elevation ;Twin Mounting CPXIX: -10 / +40 degrees
Unless it's vs. low flying aircraft such as torpedo bombers......they'd be pretty hard pressed to deal with anything else without that 4-inch twin. Wonder why only 1 mount was replaced...

Of course low flying aircraft such as torpedo or glide bombers constituted the primary attack mode used by the Axis in the ETO, despite the common misperception that it was dive bombing by Stukas. Against dive bombers, the 4.7in twin could engage them prior to their dive and then switch to an umbrella barrage to cover the ship being attacked. Of course this presupposed that the dive bombers were not attacking the Tribal class destroyer itself and for that reason, as well as to provide topweight compensation, the much lighter 4in twin was substituted for the X mount 4.7in twin. Top weight compensation was needed to allow for increasing heavy radar installations and augmented CIWS.

The RN was loath to reduce the Tribal's surface fire power so they added just one 4in twin mount. Post war analysis showed that the heavy AA guns were not very effective against dive bombers anyways:
"...On the other hand, US pre-war destroyer designs did not include provision for many automatic AA weapons, partly because the slow development of the 1.1in machine gun made this a moot point for many years. The 5in gun was considered useful for breaking up horizontal bombing formations, and perhaps for dealing with torpedo bombers flying at low level (eg by firing into the water to create splashes); but it was useless as a counter to the two other major airborne threats, the dive bomber and the strafer. Against the latter, most pre war destroyers were armed with the .5in water-cooled machine gun. The 1.1in weapon was intended to deal with dive bombers, but pre-war destroyers generally limited by treaty to 1500 tons could not accommodate it, the only exceptions being the 1850-ton destroyer'Leaders'. By 1937 many people in the fleet wanted the 1.1in gun aboard destroyers, but that appeared impossible until the design of the large Fletchers. 'Impossible' turned out by 1941 to mean rather 'impossible unless some other weapons were sacrificed', and much of the story recounted here is the story of the variety of 'trade offs' made between traditional destroyer weapons and the weapons required for close range air defence..."
Destroyer Weapons of WW2, Hodges and Friedman, p106.

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Re: Tribal class dd

Post by Steve Crandell » Wed Sep 17, 2014 10:41 pm

paulcadogan wrote:
Unless it's vs. low flying aircraft such as torpedo bombers......they'd be pretty hard pressed to deal with anything else without that 4-inch twin. Wonder why only 1 mount was replaced...
A couple of the later ships of the class had 8x4". Of course, the 4.5" DP eventually replaced the 4.7" in the fleet anyway and that weapon did have a comparatively better AA capability as well as reasonable surface capability, so two different weapons weren't needed anymore.

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Re: Tribal class dd

Post by dunmunro » Wed Sep 17, 2014 11:06 pm

Steve Crandell wrote:
paulcadogan wrote:
Unless it's vs. low flying aircraft such as torpedo bombers......they'd be pretty hard pressed to deal with anything else without that 4-inch twin. Wonder why only 1 mount was replaced...
A couple of the later ships of the class had 8x4". Of course, the 4.5" DP eventually replaced the 4.7" in the fleet anyway and that weapon did have a comparatively better AA capability as well as reasonable surface capability, so two different weapons weren't needed anymore.
AFAIK, all wartime Tribals were built with 8 x 4.7in or 6 x 4.7in and 2 x 4in. Due to a shortage of 4.7in/50 twin mounts four L class destroyers were fitted with 4 x twin 4in.

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Re: Tribal class dd

Post by Steve Crandell » Thu Sep 18, 2014 3:19 pm

dunmunro wrote:
Steve Crandell wrote:
paulcadogan wrote:
Unless it's vs. low flying aircraft such as torpedo bombers......they'd be pretty hard pressed to deal with anything else without that 4-inch twin. Wonder why only 1 mount was replaced...
A couple of the later ships of the class had 8x4". Of course, the 4.5" DP eventually replaced the 4.7" in the fleet anyway and that weapon did have a comparatively better AA capability as well as reasonable surface capability, so two different weapons weren't needed anymore.
AFAIK, all wartime Tribals were built with 8 x 4.7in or 6 x 4.7in and 2 x 4in. Due to a shortage of 4.7in/50 twin mounts four L class destroyers were fitted with 4 x twin 4in.
I thought the 4" weapons were there because they were better AA weapons. I take it they weren't, and the only reason they were installed was because the RN screwed up their order for 4.7" guns and built more destroyers than gun mounts?

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Re: Tribal class dd

Post by dunmunro » Thu Sep 18, 2014 6:23 pm

Steve Crandell wrote:

I thought the 4" weapons were there because they were better AA weapons. I take it they weren't, and the only reason they were installed was because the RN screwed up their order for 4.7" guns and built more destroyers than gun mounts?
I doubt they were better AA weapons than the 4.7in/50 but in any event the L class destroyers that received the 4in twin mounts only got them because the 4.7in/50 twin was in short supply, so much so that for a time it was feared that most of the 4.7in/50 armed L class might have to make do with only 2 of the 3 planned 4.7in/50 mountings, according to March. Later there was such a severe shortage of 4in/4.7in gun mounts that some RN destroyer classes were completed with recycled Mk V 4in mounts of near WW1 vintage.

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Re: Tribal class dd

Post by Steve Crandell » Fri Sep 19, 2014 2:42 am

dunmunro wrote:
Steve Crandell wrote:

I thought the 4" weapons were there because they were better AA weapons. I take it they weren't, and the only reason they were installed was because the RN screwed up their order for 4.7" guns and built more destroyers than gun mounts?
I doubt they were better AA weapons than the 4.7in/50 but in any event the L class destroyers that received the 4in twin mounts only got them because the 4.7in/50 twin was in short supply, so much so that for a time it was feared that most of the 4.7in/50 armed L class might have to make do with only 2 of the 3 planned 4.7in/50 mountings, according to March. Later there was such a severe shortage of 4in/4.7in gun mounts that some RN destroyer classes were completed with recycled Mk V 4in mounts of near WW1 vintage.
I'm confused. I was under the impression that the 4.7" guns on the Tribals were 45 cal, not 50 cal.

This quote from Navweaps is in error?

"9) Many of the Tribal class had "X" mounting removed and a twin 4"/45 (10.2 cm) HA/LA mounting installed in its place in order to increase their anti-aircraft capabilities. For similar reasons, the Abdiel class had their three 4.7" (12 cm) twin mountings replaced with three twin 4"/45 (10.2 cm) HA/LA mountings. Destroyers of the A-I classes reconfigured as ASW escorts had "A" and "Y" guns removed in order to ship more depth charges and to add a Hedgehog launcher."

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Re: Tribal class dd

Post by dunmunro » Fri Sep 19, 2014 8:44 am

Steve Crandell wrote:
dunmunro wrote:
Steve Crandell wrote:

I thought the 4" weapons were there because they were better AA weapons. I take it they weren't, and the only reason they were installed was because the RN screwed up their order for 4.7" guns and built more destroyers than gun mounts?
I doubt they were better AA weapons than the 4.7in/50 but in any event the L class destroyers that received the 4in twin mounts only got them because the 4.7in/50 twin was in short supply, so much so that for a time it was feared that most of the 4.7in/50 armed L class might have to make do with only 2 of the 3 planned 4.7in/50 mountings, according to March. Later there was such a severe shortage of 4in/4.7in gun mounts that some RN destroyer classes were completed with recycled Mk V 4in mounts of near WW1 vintage.
I'm confused. I was under the impression that the 4.7" guns on the Tribals were 45 cal, not 50 cal.

This quote from Navweaps is in error?

"9) Many of the Tribal class had "X" mounting removed and a twin 4"/45 (10.2 cm) HA/LA mounting installed in its place in order to increase their anti-aircraft capabilities. For similar reasons, the Abdiel class had their three 4.7" (12 cm) twin mountings replaced with three twin 4"/45 (10.2 cm) HA/LA mountings. Destroyers of the A-I classes reconfigured as ASW escorts had "A" and "Y" guns removed in order to ship more depth charges and to add a Hedgehog launcher."
We are talking about two different classes of the destroyer, the Tribal class and the L class. The Abdiel class were fast minelayers with very little need for a dual purpose gun. You cannot trust anything Navweaps has to say about RN weapons. The Abdiel Class never carried 4.7in twin mounts and the decision to fit the 4in/45 twin was made before the ships were laid down, and that decision revolved around weight reduction as much as any thing else. The original design was for 2 x twin 4in/45 mounts which was felt to be inadequate and the ensuing design debate revolved around whether or not to fit them with 2 x 4.7in/50 mounts or to go with 3 x twin 4in/45 mounts. Two twin 4.7in/50 mounts would increase displacement by 60 tons versus 3 x twin 4in/45 mounts and so the proposal for to fit the 4.7in/50 was dropped.

To clarify:

All wartime built Tribal class were armed with either 4 x 4.7in/45 twin mounts or 3 x 4.7in/45 twin mounts and 1 x 4in/45 twin mount. None were given an all 4in armament. I suspect that all the 4.7in/45 twin mounts removed from the Tribals were re-used in the N class destroyers. In surviving Tribal class destroyers 4in twin mounts replaced the 4.7in/45 twin mount in the "X" position. The 4in twin was much lighter than the 4.7in/45 and the reduced topweight allowed for an increased weights elsewhere, including the CIWS and various radars. The 4in twin had the elevation to engage divebombers and high altitude aircraft but it had little advantage over the 4.7in/45 in engaging aircraft that attacked within the 40 deg elevation engagement envelope of the 4.7in/45, and despite notions to the contrary, many, perhaps most, aerial attacks were glide or torpedo bomber attacks. The 4.7in/50 twin mount had 50deg elevation.

4 x L class destroyers were were armed with 4 x 4in/45 twin mounts due to a severe shortage of 4.7in/50 twin mounts.

The shortage of 4.7in/50 twin mounts, and other naval armament shortages was largely a result of Britain having to undertake crash armament programs to re-equip and the expand the Army after Dunkirk and boost aircraft output, while at the same time suffering from Luftwaffe bombing.

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Re: Tribal class dd

Post by Steve Crandell » Fri Sep 19, 2014 5:29 pm

dunmunro wrote:
We are talking about two different classes of the destroyer, the Tribal class and the L class. The Abdiel class were fast minelayers with very little need for a dual purpose gun. You cannot trust anything Navweaps has to say about RN weapons. The Abdiel Class never carried 4.7in twin mounts and the decision to fit the 4in/45 twin was made before the ships were laid down, and that decision revolved around weight reduction as much as any thing else. The original design was for 2 x twin 4in/45 mounts which was felt to be inadequate and the ensuing design debate revolved around whether or not to fit them with 2 x 4.7in/50 mounts or to go with 3 x twin 4in/45 mounts. Two twin 4.7in/50 mounts would increase displacement by 60 tons versus 3 x twin 4in/45 mounts and so the proposal for to fit the 4.7in/50 was dropped.

To clarify:

All wartime built Tribal class were armed with either 4 x 4.7in/45 twin mounts or 3 x 4.7in/45 twin mounts and 1 x 4in/45 twin mount. None were given an all 4in armament. I suspect that all the 4.7in/45 twin mounts removed from the Tribals were re-used in the N class destroyers. In surviving Tribal class destroyers 4in twin mounts replaced the 4.7in/45 twin mount in the "X" position. The 4in twin was much lighter than the 4.7in/45 and the reduced topweight allowed for an increased weights elsewhere, including the CIWS and various radars. The 4in twin had the elevation to engage divebombers and high altitude aircraft but it had little advantage over the 4.7in/45 in engaging aircraft that attacked within the 40 deg elevation engagement envelope of the 4.7in/45, and despite notions to the contrary, many, perhaps most, aerial attacks were glide or torpedo bomber attacks. The 4.7in/50 twin mount had 50deg elevation.

4 x L class destroyers were were armed with 4 x 4in/45 twin mounts due to a severe shortage of 4.7in/50 twin mounts.

The shortage of 4.7in/50 twin mounts, and other naval armament shortages was largely a result of Britain having to undertake crash armament programs to re-equip and the expand the Army after Dunkirk and boost aircraft output, while at the same time suffering from Luftwaffe bombing.
As far as I know, no-one mentioned the L-class except you. I was talking about the Tribal class, which is the topic. I mentioned replacing the 4.7"/45 with 4"/45 because the latter were better AA weapons, and you said you doubted the 4"/45 were better AA weapons than the 4.7"/50. As far as I can see, that is not relevant because 4.7"/50 guns were not installed on Tribal class destroyers.

With respect to the 4.7"/45 guns installed on the Tribals, they could traverse at only 10 degrees per second. If you are being attacked by aircraft, your ship is usually maneuvering radically. I don't know the turn rate of a Tribal, but I suspect it is high enough to make tracking aircraft problematic when you have a gun which traverses so slowly. This is particularly problematic when a weapon gets wooded due to a turn and has to re-engage on the other side, but just tracking an aircraft in a turn could also be a big problem. That is why DP guns normally were given a high traverse rate on the order of two times that of the 4.7"/45 or more.

As an aside, the USN's 5"/51 gun was not considered for AA use because it was too heavy and it's traverse and elevation rate was too slow. They went to a 5"25 cal gun for AA use, but in practice it was being used to engage surface targets where it's ballistics weren't really up to the task, and my understanding is that that is why the 5"/38 was introduced ... a compromise between the two conflicting requirements.

Finally, I can understand if you have credible information which conflicts with the navweaps site, but why exactly should I believe you over them in this case? As far as I know, they are capable of doing the same sort of research as you are.

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