What was the most effective naval anti-aircraft gun of WW2?

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Re: What was the most effective naval anti-aircraft gun of W

Post by Dave Saxton » Wed Dec 05, 2012 8:32 pm

Yes, the scale of combat tells us nothing about how the AA technology compared in terms of capability.
http://en.wikipedia.org/wiki/HMS_Prince_of_Wales_(1939)
Sensors and processing systems:
Type 279 radar added
Type 284 radar added.
Radars added in May 1941.
4 x Type 282 and Type 285 radars added.
Radar added between June–July 1941.
Type 271 radar added.
Don't trust Wiki. PoW had Type 281 not type 279.
Did any of those new systems ever actually down any significant number of planes? I think not. Limited as my current knowledge, coming from pre-internet books as it does, can not remember any single instance of any of those newest systems downing a single plane. While I might, probably am, wrong in that assumption
Well you are wrong in that assumption. Tirpitz did down several aircraft using these equipment during 1944. The Germans couldn't deploy these in large numbers because they had so few major warships operational. It was 100% of their battleships. :lol:
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Re: What was the most effective naval anti-aircraft gun of W

Post by dunmunro » Wed Dec 05, 2012 9:11 pm

Neoconshooter wrote:
dunmunro wrote:
Neoconshooter wrote:
How did the system you mention above couple the range as found by the Radar to the FCS?
Type 280 and type 279 both had a precision ranging panel which transmitted the radar range AND range rate directly to the HACS table (computer) via magslips (syncro motors) with power follow-up for the range rate (radar operator would match the range rate to the target and that rate would continue to be transmitted to the table as long as the target maintained a steady course.
I guess we have different ideas about what the word precision means? Also, how timely was the transmission of the Plotting Table info, originally intended to control surface fire against ships, sent to the AA guns? When compared to late war USN equipment in wide spread use, just how effective were these two types?
Did they save PoW and Repulse? Not actually a fair question. How many planes did those two ships down before they were sunk? A better question would be how many planes did the Royal Navy shoot down in the entire war using either of those systems?
My point is that conversion of a surface FCS into a AA-FCS is very much harder than it looks from the internet of hind sight. See Frieden's tome "Principles of Naval Weapons Systems" from the Naval Institute Press, 1985.

http://en.wikipedia.org/wiki/HMS_Prince_of_Wales_(1939)
Sensors and processing systems:
Type 279 radar added
Type 284 radar added.
Radars added in May 1941.
4 x Type 282 and Type 285 radars added.
Radar added between June–July 1941.
Type 271 radar added.
Type 279 and type 280 were accurate to about 25 yds (essentially the limit for any WW2 radar) and both were designed primarily for AA search and FC, with a secondary surface FC capability - transmission to the HACS table was instantaneous. HACS was a dedicated AA FC system. PoW and Repulse shot down more planes than the entire USN carrier task force AA at Coral Sea (according to Lundstrum), despite the fact that PoW's radars were largely U/S. USN AA didn't save Lexington, Yorktown or Hornet...despite the large number of USN ships in the accompanying task forces.

Up to March 28 1941, the RN had made the following AA kill claims:
Certain kills: 234
Probable kills: 116
Damage claims: 134

Up to Dec 31 1942, the RN had made the following AA kill claims:
Total kill claims: 740.
Total probable claims: 266.
Total damage claims: 448

So in the year and 3/4 from March 1941, the RN claimed 504 AA kills. The USN initially claimed 447 AA kills up to Dec 31 1942, but in 1944 they revised these claims downward by 55% to a total of 228. Actual USN AA kills for 1942 probably amount to about 100, based post upon post war analysis. The initial USN claims probably even swayed many RN officers that USN FC was superior, but we now know that this wasn't the case, based upon the two navies actual AA kills, based upon post war analysis.

I don't have the figures for the rest of the war, but RN AA almost certainly shot down more aircraft than the USN during 1942, using post war data to verify the kills. The USN was prone to wild overclaiming, and BuOrd made no attempt to accurately access the kill claims made by USN ships, and made AA weapon efficiency claims based upon these wildly inflated claims - for example at Santa Cruz the USN claimed 127 kills (including 26 by South Dakota) but Lundstrum's assessment indicates only about 25 AA kills total for all USN ships involved. USN kill claims against Kamikazes have never been accurately tabulated against IJ records, and as such are almost certainly inflated, probably by a factor of 2 or more. In any event most Kamikazes were shot down by close range weapons (~70% according to the USN), and made for relatively easy kills during their final approach to the the target ship, while most 5in AA kamikaze kills were made at close range using VT ammo, typically with close range directors, or over open sights using local control.

The Royal Navy's late war AA FC systems were quite impressive, and included technologies such as GRU/GRUB, ABU, and CPU that were still not present in the USN, however the RN never encountered large numbers of kamikazes, and had nowhere near as many ships in the Pacific as the USN.

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Re: What was the most effective naval anti-aircraft gun of W

Post by dunmunro » Wed Dec 05, 2012 9:25 pm

Thorsten Wahl wrote:
Neoconshooter wrote:, one or even a few does not count when compared to the THOUSANDS of planes downed by the USN in the last stages of the war. !
Do you have an official account or even a educated guess onkills of japanese aircraft by USN AA-Fire?

Compared to the US maritime campaign on the Pacific the air war against shipping at the european theater was much more a secondary theater. So pure counts on attacks and kills were not comparable.
The USN claimed 2256 AA kills for the entire war, including 1285 from July 1944 onward. But these claims are probably about twice the actual number shot down.

see
http://www.ibiblio.org/hyperwar/USN/rep ... index.html
for more info.

and
http://www.sfu.ca/~dmunro/images/USN_AA ... ims_42.pdf
for USN kill claims to Dec 31 1942.

The RN, in European waters, faced far more aircraft attack sorties than the USN in 1942, and over the course of the war, and far more aircraft attack sorties where the defending ships had no air cover and/or were in detached service or small formations, where a large volume of AA fire was thus not possible.

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Re: What was the most effective naval anti-aircraft gun of W

Post by Neoconshooter » Thu Dec 06, 2012 4:15 am

dunmunro wrote:
dunmunro wrote: How did the system you mention above couple the range as found by the Radar to the FCS?
Type 280 and type 279 both had a precision ranging panel which transmitted the radar range AND range rate directly to the HACS table (computer) via magslips (syncro motors) with power follow-up for the range rate (radar operator would match the range rate to the target and that rate would continue to be transmitted to the table as long as the target maintained a steady course.
I guess we have different ideas about what the word precision means? Also, how timely was the transmission of the Plotting Table info, originally intended to control surface fire against ships, sent to the AA guns? When compared to late war USN equipment in wide spread use, just how effective were these two types?
Did they save PoW and Repulse? Not actually a fair question. How many planes did those two ships down before they were sunk? A better question would be how many planes did the Royal Navy shoot down in the entire war using either of those systems?
My point is that conversion of a surface FCS into a AA-FCS is very much harder than it looks from the internet of hind sight. See Frieden's tome "Principles of Naval Weapons Systems" from the Naval Institute Press, 1985.

http://en.wikipedia.org/wiki/HMS_Prince_of_Wales_(1939)
Sensors and processing systems:
Type 279 radar added
Type 284 radar added.
Radars added in May 1941.
4 x Type 282 and Type 285 radars added.
Radar added between June–July 1941.
Type 271 radar added.[/quote]

Type 279 and type 280 were accurate to about 25 yds (essentially the limit for any WW2 radar) 25 yards? acording to Wiki, the pulse width was 2-3 US indicating a maximum un ambiguos range error possible of 1.2 Kilometers? = 2 US= 600 M short or long of indicated Poss.and both were designed primarily for AA search and FC, with a secondary surface FC capability - transmission to the HACS table was instantaneous. HACS was a dedicated AA FC system. PoW and Repulse shot down more planes than the entire USN carrier task force AA at Coral Sea (according to Lundstrum), despite the fact that PoW's radars were largely U/S. USN AA didn't save Lexington, Yorktown or Hornet...despite the large number of USN ships in the accompanying task forces. True! The USN did loose all of those ships and many more too!

Up to March 28 1941, the RN had made the following AA kill claims:
Certain kills: 234
Probable kills: 116
Damage claims: 134

Up to Dec 31 1942, the RN had made the following AA kill claims:
Total kill claims: 740.
Total probable claims: 266.
Total damage claims: 448

So in the year and 3/4 from March 1941, the RN claimed 504 AA kills. The USN initially claimed 447 AA kills up to Dec 31 1942, but in 1944 they revised these claims downward by 55% to a total of 228. Actual USN AA kills for 1942 probably amount to about 100, based post upon post war analysis.Would you please post a link to this source datat? The initial USN claims probably even swayed many RN officers that USN FC was superior, but we now know that this wasn't the case, based upon the two navies actual AA kills, based upon post war analysis.
This is news to me. Can you provide a link to this "Post War" data source? Just where were all of these RN claims made and when?
I don't have the figures for the rest of the war, but RN AA almost certainly shot down more aircraft than the USN during 1942, using post war data to verify the kills.Seems reasonable, but I am curious as to how and by which ships. Also, the USN was barely engaged in 1942. The USN was prone to wild overclaiming,Absolutely true! and BuOrd made no attempt to accurately access the kill claims made by USN ships, and made AA weapon efficiency claims based upon these wildly inflated claims - for example at Santa Cruz the USN claimed 127 kills (including 26 by South Dakota) but Lundstrum'sWho is Lundstrum? assessment indicates only about 25 AA kills total for all USN ships involved. USN kill claims against Kamikazes have never been accurately tabulated against IJ records, That is also true, but we do know the approximate numbers and a certain order of magnatude figure.and as such are almost certainly inflated, probably by a factor of 2 or more. In any event most Kamikazes were shot down by close range weapons (~70% according to the USN),The book I mentioned before states just the oposite! Smaller AA Machine guns, IE 20-40 MM were much less effective at downing Kamikazi planes because of the limited damage and close range, which let the heavily damaged, or even destroyed plane still damage it's target. and made for relatively easy kills during their final approach to the the target ship, while most 5in AA kamikaze kills were made at close range using VT ammo, typically with close range directors, or over open sights using local control.
Again this is in direct contradiction of other sources. Would you please post a link to this data?
The Royal Navy's late war AA FC systems were quite impressive, and included technologies such as GRU/GRUB, ABU, and CPU that were still not present in the USN, however the RN never encountered large numbers of kamikazes, and had nowhere near as many ships in the Pacific as the USN.[/quote]
This site lists three destroyed and many damaged, but I wonder what the IJN records have to show?
http://en.wikipedia.org/wiki/Sinking_of ... nd_Repulse

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Re: What was the most effective naval anti-aircraft gun of W

Post by dunmunro » Thu Dec 06, 2012 9:31 am

You need to read both volumes of "First Team" by John Lundstrom. He details USN carrier combat in 1942 and analyses IJAAF and IJNAF losses to USN AA and fighters. If you add up his numbers they come to about 100 for 1942. Lundstrom states that the USN CV TG AA shot down 3 aircraft during Coral Sea, while Force Z shot down 4 (3 immediately and one that crashed later) according to Shores, in Bloody Shambles.

RN AA claims can be found here:

http://en.wikipedia.org/wiki/HACS#Wartime_experience

Type 279 and 280 had a range accuracy in FC mode of about +/-25yds. Again, there are various sources for this info. The best is The Application of Radar and other Electronic Systems in the Royal Navy in WW2 A good short article is:
" NAVAL FIRE-CONTROL RADAR*"
By J. F. COALES, M.A., Associate Member,t H. C. CALPINE, B.A.,f and D. S. WATSON, B.Sc,
Associate Member.!
*(The paper was first received 11th February and in revised form 20th February, 1946. It was read at the RADIOLOCATION CONVENTION
3rd April, 1946.)

Type285-Mechanical Ranging Panel-HACS:
Image

I provided a link to the official USN AA summary for WW2, above, and it indicated that CIWS claimed about 70% of kamikaze kills. Other useful USN publications:
http://www.ibiblio.org/hyperwar/USN/rep ... index.html
http://www.ibiblio.org/hyperwar/USN/rep ... index.html
http://www.ibiblio.org/hyperwar/USN/rep ... index.html

Ammunition Performance

Tables V and VI give data on ammunition fired in suicide and non-suicide actions, respectively during the period of 1 October through January. Statistics include figures on rounds expended, planes shot down by various calibers, and rounds-per-bird by caliber.

Two features stand out in these tables:

The success of the automatic weapons.

The poor performance of 5-inch batteries, especially during suicide attacks.

Credit for approximately 80 percent of all plane kills in suicide actions goes to the automatic weapons (50 percent to 40mm. and 27 percent to 20mm.), leaving 20 percent to 5-inch batteries, which fired disappointingly small quantities of ammunition at the many targets presented.

Against planes in non-suicide actions the 5-inch weapons were more successful, getting credit for 34% of all kills.

http://www.ibiblio.org/hyperwar/USN/rep ... ary-2.html
During Santa Cruz, Captain Gatch estimated that 5in guns accounted for only 5% of South Dakota's AA kill claims.

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Re: What was the most effective naval anti-aircraft gun of W

Post by Byron Angel » Thu Dec 06, 2012 12:37 pm

No time to track down the exact citation this morning, but one of the late-war/post-war USN AAA analyses mentioned that unconventional Japanese approach tactics during the mature phase of their kamikaze campaign made AAA target acquisition a relatively difficult matter. Attacks were often made singly or in small penny packet numbers at odd hours and altitudes, along random azimuths, and in marginal weather and visibility conditions (made possible by the fact that the US fleet was largely static, as around Okinawa for example), with Japanese a/c also discreetly "tagging along" behind returning US a/c formations. Detection/acquisition ranges as low as 4,000 yards are discussed. This was well inside the 5/38's engagement envelope and may serve in part to explain the reduced effectiveness of the 5/38 against kamikaze targets.

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Re: What was the most effective naval anti-aircraft gun of W

Post by Dave Saxton » Thu Dec 06, 2012 2:56 pm

25 yards? acording to Wiki, the pulse width was 2-3 US indicating a maximum un ambiguos range error possible of 1.2 Kilometers? = 2 US= 600 M short or long of indicated Poss.
Your confusing resolution (or discrimination) for range with accuracy for range. They are not the same things. It is possible as with the American Mk8 radar, for example, to have a resolution for range of 75 -100 yards while having range accuracy of 0.1% of the range +/-15 yards. At 30,000 yards the range accuracy would be on the order of 45 yards. Or the older Mk3 makes a good example. The resolution for range was 400 yards, but the range accuracy was 0.1% of the range +/-45yards.

With normal pulse radar the pulse travels 300 meters every 1us. A pulse width of 2us means that the pulse is 600 meters long. However, the leading edge of the pulse will have already bounced off the target before the trailing edge reaches the target. Therefore, the range resolution is 1/2 that of the pulse distance in practice. A pulse duration of 2us results in a resolution for range of 300 meters. The British Type 284M introduced during 1942 had the pulse duration decreased to 1us giving a resolution for range of 150 meters, so Wiki has mislead you again. Type 284M had a nominal range accuracy of 120 yards according to British primary documents and reported by Howse in Radar at Sea . The so called Precision Range Panal allowed the range to be read off the indicator with greater accuracy by using the electronic sweep time on an A-scope; the accuracy alluded to being the accuracy of the instrumentation.

Resolution for range is not always dependent upon the pulse width in all radar designs, however. The German Seetakt design marked the flanks of the each pulse and sent a reference to the receiver and to the fine range indicator system. The fine range indicator system featured a delay line which allowed the pulse to be spread out and intra-pulse data extracted and placed onto the exactly correct position on the crt indicator, which could be zoomed in or out to present as much range short or long of the selected target as desired. The result was a resolution for range as fine as 10 meters on the late war fine ranging system for artillery, despite the use of a 2us pulse width (for all production Seetakt). On the coarse indicator the resolution for range remained 300 meters.
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Re: What was the most effective naval anti-aircraft gun of W

Post by Neoconshooter » Tue Dec 11, 2012 1:52 am

Dave Saxton wrote:
25 yards? acording to Wiki, the pulse width was 2-3 US indicating a maximum un ambiguos range error possible of 1.2 Kilometers? = 2 US= 600 M short or long of indicated Poss.
Your confusing resolution (or discrimination) for range with accuracy for range. They are not the same things. It is possible as with the American Mk8 radar, for example, to have a resolution for range of 75 -100 yards while having range accuracy of 0.1% of the range +/-15 yards. At 30,000 yards the range accuracy would be on the order of 45 yards. Or the older Mk3 makes a good example. The resolution for range was 400 yards, but the range accuracy was 0.1% of the range +/-45yards.

With normal pulse radar the pulse travels 300 meters every 1us. A pulse width of 2us means that the pulse is 600 meters long. However, the leading edge of the pulse will have already bounced off the target The problem with this idea is the much later, in the 1950s, discovered fact that the leading edge of the pulse may not bounce off the target at all! What does in fact happen is that there is no way at all to know whether the first or last part of any pulse it that part of the pulse that is detected by the receiver. Minute changes in the aspect and RCS of the target changes the nature of the reflected energy. See Principles of Naval Weapons Systems, edited by David R. Frieden, pages 27-88 before the trailing edge reaches the target. Therefore, the range resolution is 1/2 that of the pulse distance in practice. Again, this is wrong. It is TWICE the pulse durration that determins the absolute certain range increment resolution. A pulse duration of 2us results in a resolution for range of 300 meters. No, 600 Meters! The British Type 284M introduced during 1942 had the pulse duration decreased to 1us giving a resolution for range of 150 meters, so Wiki has mislead you again. Type 284M had a nominal range accuracy of 120 yards according to British primary documents and reported by Howse in Radar at Sea . The so called Precision Range Panal allowed the range to be read off the indicator with greater accuracy by using the electronic sweep time on an A-scope; the accuracy alluded to being the accuracy of the instrumentation. The term "Read off the indicator" means that there is interpretation in the findings. Either by a person or some sort of mechanical device, but there is no possible way for ANY War time set to find the true range to 25M! There are just way to many sources of range errors.

Resolution for range is not always dependent upon the pulse width in all radar designs, however. This is absolutely true! But NONE of those systems from WW-II could be expected to actually deliver this performance in fact! The German Seetakt design marked the flanks of the each pulse and sent a reference to the receiver and to the fine range indicator system. The fine range indicator system featured a delay line which allowed the pulse to be spread out and intra-pulse data extracted and placed onto the exactly correct position on the crt indicator, which could be zoomed in or out to present as much range short or long of the selected target as desired. This worked IF the returning Pulse contained both of the discretion markers The result was a resolution for range as fine as 10 meters on the late war fine ranging system for artillery, despite the use of a 2us pulse width (for all production Seetakt). On the coarse indicator the resolution for range remained 300 meters.
All of these systems, regardless of details failed to determine the actual range with in those limits, when tested on dedicated radar ranges in the post war 40s and early 50s. Signal processing had to get several orders of magnitude more complex before those types of accuracy were attainable in fact. Regardless of what they claimed at the time.
If those kinds of accuracy were attainable in fact, then AAA would have been many times more effective than it was in fact. Note that the primary restriction of performance of the 5-38 was the number of VT fuses available to mix in with the conventional time fused ammo. (At least according to the documents you linked to.) Instead of posting links to performance data from the early time line of Radar R&D, why not post links to much later documents and manuals?
Think of it this way; IF they knew the true range to plus or minus 12.5, or 25 Meters, depending on the definition used which is not stated, tracking accuracy over several dozen of seconds, would lead to a expected track where a single VT Fused 5"-38 round fired would have a nearly 80% chance to down the target at 5-6000 Meters range. The "Effective" bursting radius of said 5" shell being 70' Vs a target Poss error of 41' to 82'. While that looks like a LOCK, the fragment pattern is not spherical, but fan shaped, perpendicular to the length of the shell. Try calculating the available volume given the stated accuracies in all of the above posts! IE, less than 1 degree angular and 25M in range at 6,000M. ( It is a cylinder <90M OD, by 25 M long! But if you believe the fractional degree accuracy claims under service use, the the cylinder becomes <9 M OD by 25 M long!)) Given the 140' / 43M burst diameter along the flight vector AND the distribution of the probable target locations with in that cylinder, such that half of the targets will be with in <11.25 M of the aim point! (Which at < 1 MoA for any given shell, is less than the typical CEP/dispersion of the 5"-38 gun.)
The reality of the situation is that true operational accuracy of said systems was no where near what was published back then. There were so many sources of discrepancies that they did not even know of back then that it took them several decades to track them all down and they could not even start to look for them until the building of long range presigion Radar ranges in the late sixties and Mid seventies.

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Re: What was the most effective naval anti-aircraft gun of W

Post by dunmunro » Tue Dec 11, 2012 10:16 am

The problem was not ranging accuracy, as WW2 radars did have the range accuracy I stated earlier. The problem lay in the fact that WW2 AA computers could only predict against straight-line targets, so any departure from straight-line flight caused a loss in accuracy (which effected almost all targets), 2ndly the MT fuzes had inherent errors and there was errors arising from loading and firing the gun with incorrectly set fuzes. 3rdly there was always small errors in bearing and/or altitude and all these errors added up to cause a considerably loss of accuracy when using MT fuzes.

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Re: What was the most effective naval anti-aircraft gun of W

Post by Thorsten Wahl » Tue Dec 11, 2012 12:07 pm

Instead of posting links to performance data from the early time line of Radar R&D, why not post links to much later documents and manuals?
The essential difference between their postings and yours is, that they post things based on documented information and yours is not backed with anything tangible.
you say for example
...count when compared to the THOUSANDS of planes downed by the USN in the last stages of the war...
under conditions of absolute air superiority one can exept higher kill ratios for the side with absolute air superority.
your figure "Thousands in the last stages" seem excessive compared to the published figures. Its on your part to present some documents that supports your information.

So, to summarize, 5/38 Caliber gun, with either on mount, or remote mount Radar and FC Computer, shooting proximity fused ammo is the king of WW-II guns.
...
The possibility that such a system could have saved Tirpitz is beyond question
the documents linked by dunmunro shows the following amunition expenditure for a japanese plane downed (including high deflection shots)
1944 figures
5" MT ---1,157 projectiles per downed aircraft ->thrown projectile mass per aircraft ~63,774 lb (ROF 20 shots per minute per gun)
5" VT ------421 projectiles per downed aircraft->thrown projectile mass per aircraft ~ 23.205 lb (ROF 20 shots per minute per gun)
3" -------1,257 projectiles per downed aircraft-> thrown projectile mass per aircraft ~ 16,341 lb (ROF 20 shots per minute per gun)
40 mm- 2,364 projectiles per downed aircraft -> thrown projectile mass per aircraft ~ 4,692 lb (ROF 120 shots per minute per gun)

data for 3" gun apparently only MT fuzed.

it seem to me that 3 inch and 40 mm bofors were much more efficent in thrown weight for a kill compared to the 5/38 - considering that available space for ammunition was a rare ressource on ships

starting from the figures above it appears to me that 58 barrels of 5"/38 guns had to fire for approximately one minute to achieve a single aircraft kill with MT(statistically)
or 21 5"/38 guns with VT
or 62 3" guns probably with MT
or 23 40mm bofors
using VT for the 3" should reduce their ammunition expenditure comparable to the figures of the 5"

The problem became more complicated if 30 aircraft or so simultaneously attack a more or less single ship within two minutes as it happened with Tirpitz at limited all round view.
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Re: What was the most effective naval anti-aircraft gun of W

Post by Byron Angel » Tue Dec 11, 2012 12:48 pm

I would venture to say that the principal intended task of the 5/38 was not necessarily to engage individual a/c targets (although they undeniably did so), but to engage and break up approaching formations of a/c.

Also, the 3/50 is a curious case as to whether its RPB (rounds per bird) figure represents MT or VT fuzed rounds. The 3/50 was designed on the basis that it was the smallest, fastest firing AAA gun whose projectile could combine a VT fuze and an effective HE charge. The VT fuze was quite large (by modern standards) and took up a large volume within the projectile.

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Re: What was the most effective naval anti-aircraft gun of W

Post by Dave Saxton » Tue Dec 11, 2012 3:31 pm

Neoconshooter wrote:All of these systems, regardless of details failed to determine the actual range with in those limits, when tested on dedicated radar ranges in the post war 40s and early 50s. Signal processing had to get several orders of magnitude more complex before those types of accuracy were attainable in fact. Regardless of what they claimed at the time.
If those kinds of accuracy were attainable in fact, then AAA would have been many times more effective than it was in fact. Note that the primary restriction of performance of the 5-38 was the number of VT fuses available to mix in with the conventional time fused ammo. (At least according to the documents you linked to.) Instead of posting links to performance data from the early time line of Radar R&D, why not post links to much later documents and manuals?
Think of it this way; IF they knew the true range to plus or minus 12.5, or 25 Meters, depending on the definition used which is not stated, tracking accuracy over several dozen of seconds, would lead to a expected track where a single VT Fused 5"-38 round fired would have a nearly 80% chance to down the target at 5-6000 Meters range. The "Effective" bursting radius of said 5" shell being 70' Vs a target Poss error of 41' to 82'. While that looks like a LOCK, the fragment pattern is not spherical, but fan shaped, perpendicular to the length of the shell. Try calculating the available volume given the stated accuracies in all of the above posts! IE, less than 1 degree angular and 25M in range at 6,000M. ( It is a cylinder <90M OD, by 25 M long! But if you believe the fractional degree accuracy claims under service use, the the cylinder becomes <9 M OD by 25 M long!)) Given the 140' / 43M burst diameter along the flight vector AND the distribution of the probable target locations with in that cylinder, such that half of the targets will be with in <11.25 M of the aim point! (Which at < 1 MoA for any given shell, is less than the typical CEP/dispersion of the 5"-38 gun.)
The reality of the situation is that true operational accuracy of said systems was no where near what was published back then. There were so many sources of discrepancies that they did not even know of back then that it took them several decades to track them all down and they could not even start to look for them until the building of long range presigion Radar ranges in the late sixties and Mid seventies.
You seem to be shooting down your own arguments in previous posts about the effectiveness of radar directed flak. Did you change your mind? Are you saying it was better to shoot through the target?

Your comments about the physics of radar if correct do not bode well for the ranging precision of Allied radar during WWII. The doctrines held dear in certain quarters, such as long range gunnery, seem to be dependent on that precision. Or does that matter? However, there's no indication within the documents to indicate that the claimed range precision, based on testing, was not attainable on fairly consistent basis. I can agree that discrimination for range could be somewhat dynamic on occasion.

On the other hand it speaks well of the German approach. That being coherent radar operation with a Central Impusle Geraete incorporating a phase lock. And explains why the Germans initially dropped the magnetron.
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Thorsten Wahl
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Re: What was the most effective naval anti-aircraft gun of W

Post by Thorsten Wahl » Fri Feb 15, 2013 8:36 pm

some technical drawings about german AA guns (Unterrichtstafeln für Geschützkunde, Band II Flak, 138 pages)

https://docs.google.com/file/d/0B12aaMD ... lQTkU/edit
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dunmunro
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Re: What was the most effective naval anti-aircraft gun of W

Post by dunmunro » Wed Feb 27, 2013 1:57 am

There's an interesting article by Mark Brady here on RN destroyer armament and the AA capability of the Tribal-JKN class destroyers:

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

Mark Thomason
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Re: What was the most effective naval anti-aircraft gun of W

Post by Mark Thomason » Mon May 27, 2013 7:13 am

Bgile wrote:Isn't it true that at least some of the 8" AA cruisers (LOL) had their gun elevation reduced when they had major overhauls?

I don't see why the Japanese would be surprised since they had AA shells for the Yamato's main battery.
According to Shattered Sword, by Parshall & Tully, the Japanese from the beginning of the war used those heavy guns at long range to direct the attention of the CAP fighters (which had no or poor radios) at spotted incoming raids as far out as possible. It would also have alerted other ships. By Leyte Gulf they made some (failed) attempt to hit incoming aircraft formations, but that was just using what they had rather than a big design decision compromise.

When the design decision was made to have 8" AA in Japan and Britain, the USN still had a force of Zeppelin type craft, and many expected such craft would play an important part in civil air transport and in war. An 8" gun battery would have a much better chance of hitting a slow, huge Zeppelin lurking nearby for a day of spotting than a speeding monoplane incoming raid of WW2. It seemed useful because the Zeppelins were expected to lurk far out of range of the other AAA, watching and reporting.

They were not stupid, or unrealistic, just designed for ideas long out of date by WW2.

Later, some reports are that the British attempted to improve reliability in their 8" mounts by changes which included reduced max elevation. They would have done that after the Zeppelin idea had not worked.

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