How close was the final battle?

[Byron Angel]

Hi Byron,
thanks again for corrections to my wrong understanding, for explanations and additional info on 284 capabilities in 1941.

It looks clear that in 1941 284 was able to receive echoes from distant ships (even up to 28.000 yards) but that "usable" ranging was possible only below 18.000 yards because over that distance echoes were usually weak, intermitttent and fluctuating. Possibly, a well tuned 284 might have been able to start effective ranging and range rating from 20.500 yards (see KGV on May 27) or even more (Hood test) .

Re. "effect of inclination", not only Bismarck was mainly bow on (weaker signal), but her erratic course was affecting her echo strength (as you suggested in the past), making it stronger or weaker: that might have further confused 284 operator.

We can only speculate re. what 284 operator was seeing on his "A" scope on May 27 between 08:48 and 08:53, but he explicitly thought he was able to evaluate first salvo from KGV as "short", therefore clearly he was getting at least 2+ separate echoes: one he interpreted as Bismarck and other(s) as fall of shells (https://www.kbismarck.org/forum/downloa ... hp?id=4180).
If 284 set was actually unable to receive fall of shells echoes from 24.600 yards (KGV) and/or 23.500 yards (Rodney) (at open fire), then his operator might have been misled by mere noise (in this case we have confirmation that enemy echo was anyway so weak to be easily confused with noise, therefore not usable for gunnery purposes), and this continued to happen during all first minutes of battle, when 284 operator looked for Bismarck always at around 25.000 yards, apparently misleading Gunnery Control, until 08:53 (https://www.kbismarck.org/forum/downloa ... hp?id=4164 & https://www.kbismarck.org/forum/downloa ... hp?id=4169), despite in the meantime he was receiving also "correct" echoes from Bismarck (download/file.php?id=4190), still initially so weak and intermittent to be apparently confused with noise and/or fall of shells. Only at 08:51 (22.000 yards distance) 284 operator started to realise that Bismarck could have been closer than he was looking for, only at 08:52 (21.000 yards) this "correct" echo became constant, and only at 08:53 AFCT personnel accepted the "correct" range of 20.500 yards and tuned range plot (and gun range) accordingly.

IMHO KGV (my speculation, suggested by GAR statements) fired at around 25.000 - 24.000 yards all the time before 08:53 (more and more "over" as time passed), while Rodney (a fact, as we luckily have her salvo plot available) fired at 23.500 (08:47)- 22.000 (08:50), much "short" and then "corrected" firing at 24.000 (08:50) - 22.500 (08:53) yards ("over"). Actually, Bismarck distance was reducing almost constantly from 26.000 to 20.500 between 08:47 and 08:53.

hans

Hi Hans,
I did some further digging on precision range panels versus range-gating. Following per "Radar at Sea" Derek Howse.

pg. 136
"A similar remote CRT was used in type 284M, but this was generally positioned in the below-decks
fire control centre for for surface fire (the Transmitting Station) and not in the director. With an expanded
range display of 4,000 yards centred on the target, this allowed splash spotting in range, and estimates of
range 'over' or 'short' to be passed directly to the Fire Control Table, although shell splashes could only be
seen out to about half the maximum range of the main armament and misses right or left were difficult to
estimate from the range tube."

pp. 137-138
"Early in 1941, it was decided to exploit the ability of early radars to give good ranges and range rates to
improve barrage fire, without waiting for further advances in blind aiming by radar. A precision ranging
panel displaying 6,000 yards with ranging errors not exceeding 25 yards was rapidly developed. This panel,
designated L22, employed an electronic 'step' marker with a high order of setting accuracy, and a highly linear
potentiometer controlled by the operator's rate-aided handwheel to align the marker with the target echo. By
this means, accurate range and range-rate were immediately available. Panel L.22 was used in conjunction
with with the Auto Barrage Unit, generally located in the High Angle Control Position below decks. The ranging
panel fed the target's range and range-rate into a mechanical calculator in the ABU which then determined the
correct moment to open fire to obtain to achieve the predetermined future range already set on the shell fuzes.
This provided a better control of barrage fire than was possible with the early type 285 sets controlling AA guns
and became available for fitting in 1941.

When added to the type 282 sets with improved transmitters and receivers and beam-switching, the L.22 accurate
ranging panel converted them to type 282P, corresponding to the type 284P and 285P sets which had the new
precision ranging panels L.24 for longer range working. During 1942, it was decided to produce a version of 282P
which could be mounted on special barrage-fire directors so that large ships could use the surface armament for
anti-aircraft barrages in addition to their specialized AA weapons.

- - -

If I am interpreting correctly, British surface gunnery radars did possess a range-gating capability similar to USN
surface gunnery radars. But British "precision control panels", although apparently employing similar technology,
seem to have been an anti-aircraft gunnery aid.

FWIW.

Byron

[hans zurbriggen]

Hi Byron,
I agree: it looks like this is an a.a. aid only.
I'm convinced that, in 1941, an 'average' 284 was limited to anti-ship gunnery usable range of 18.000-20.000 yards, as per precious 'Handbook' you kindly posted here (https://www.kbismarck.org/forum/viewtop ... 770#p91770). Fact that, on selected occasions, 'first class' 284 radars were receiving weak and intermittent echoes from much longer maximum distances (up to 28.000 yards) is perfectly credible, under special conditions, but such maximum distance echoes (possibly weak and intermittent) were correctly considered unusable to create a range rate plot useful for gunnery.
On other side, again occasionally, same Suffolk's 284 set that could get Bismarck's echo from 22.000+ yards was unable to detect her until distance was 14.000 yards:

Suffolk RDF message.jpg (7.58 KiB) Viewed 228326 times

Thus, as per "Handbook", excluding exceptional and occasional cases when echoes were received from larger distances, 284 could be used as a gunnery aid only from shorter distances while at longer range it could possibly be used as warning system only, provided echo was interpreted correctly.


On contrary, on May 27, when 284 operator was convinced that Bismarck was still at 25.000 yards, intermittent (but correct) echoes received from Bismarck at shorter distances until 08:51 were considered doubtful. Even when echo was constant and 284 personnel was finally convinced it was from Bismarck (08:52, at that point usable for gunnery purposes), apparently some time passed before ranges were passed to TS and AFCT personnel accepted correct even shorter range of 20.500 yards, at 08:53 only (https://www.kbismarck.org/forum/downloa ... hp?id=4164).

Re. salvo spotting fall of shells, even if 1941 284 version was actually unable to spot them, even occasionally, from 22.000 yards (Rodney's fall of shells at 08:49), then it's obvious that radar officer and 284 personnel, at that time, were convinced of the opposite and that 284 operator was misled by noise peak(s) when reporting first KGV salvo, fired at 24.600 yards as "short" (https://www.kbismarck.org/forum/downloa ... hp?id=4180).
In no other way 284 operator could have reported to Gunnery Control a salvo as 'short' than comparing two different echoes received on his panel.
His error (together with spotting officer same error + fact that 284 operator was still convinced Bismarck was at 25.000 yards in following minutes) caused KGV to fire upper ladder(s), keeping gun range at around 25.000 for following salvos, while Bismarck was instead closing, and explains rather "bitter" GAR comment to R.D/F report ( https://www.kbismarck.org/forum/downloa ... hp?id=4169), for having "wasted" initial 5 minutes battle.

hans

[dunmunro]

Hi Byron,
I agree: it looks like this is an a.a. aid only.
I'm convinced that, in 1941, an 'average' 284 was limited to anti-ship gunnery usable range of 18.000-20.000 yards, as per precious 'Handbook' you kindly posted here (https://www.kbismarck.org/forum/viewtop ... 770#p91770). Fact that, on selected occasions, 'first class' 284 radars were receiving weak and intermittent echoes from much longer maximum distances (up to 28.000 yards) is perfectly credible, under special conditions, but such maximum distance echoes (possibly weak and intermittent) were correctly considered unusable to create a range rate plot useful for gunnery.
On other side, again occasionally, same Suffolk's 284 set that could get Bismarck's echo from 22.000+ yards was unable to detect her until distance was 14.000 yards:


Suffolk RDF message.jpg


Thus, as per "Handbook", excluding exceptional and occasional cases when echoes were received from larger distances, 284 could be used as a gunnery aid only from shorter distances while at longer range it could possibly be used as warning system only, provided echo was interpreted correctly.


On contrary, on May 27, when 284 operator was convinced that Bismarck was still at 25.000 yards, intermittent (but correct) echoes received from Bismarck at shorter distances until 08:51 were considered doubtful. Even when echo was constant and 284 personnel was finally convinced it was from Bismarck (08:52, at that point usable for gunnery purposes), apparently some time passed before ranges were passed to TS and AFCT personnel accepted correct even shorter range of 20.500 yards, at 08:53 only (https://www.kbismarck.org/forum/downloa ... hp?id=4164).

Re. salvo spotting fall of shells, even if 1941 284 version was actually unable to spot them, even occasionally, from 22.000 yards (Rodney's fall of shells at 08:49), then it's obvious that radar officer and 284 personnel, at that time, were convinced of the opposite and that 284 operator was misled by noise peak(s) when reporting first KGV salvo, fired at 24.600 yards as "short" (https://www.kbismarck.org/forum/downloa ... hp?id=4180).
In no other way 284 operator could have reported to Gunnery Control a salvo as 'short' than comparing two different echoes received on his panel.
His error (together with spotting officer same error + fact that 284 operator was still convinced Bismarck was at 25.000 yards in following minutes) caused KGV to fire upper ladder(s), keeping gun range at around 25.000 for following salvos, while Bismarck was instead closing, and explains rather "bitter" GAR comment to R.D/F report ( https://www.kbismarck.org/forum/downloa ... hp?id=4169), for having "wasted" initial 5 minutes battle.

hans

Type 284 was a primarily a gunnery radar and it's aerial was fixed to the forward DCT. Bismarck could be right alongside Suffolk and Type 284 would not detect Bismarck until the DCT was pointing towards BIsmarck...to maintain all round warning required continuous slow rotation of the DCT. This should be obvious to you and it highlights the problem of using a directional gunnery radar for surface search duties. There is no mention in Suffolk's RoP of Type 284 failing to range at 14000 yds. In fact it states:

3. 1810 (B). Turned through south to 1900 (B) position 67° 02' N., 24° 38' W., and set course 240°, 18 knots, clear of the broken ice.

Adjusted arc of sweep of Type 284 as requisite to cover bearings on which visibility was below 8 miles. Type 279 kept listening watch but was not used for transmitting.

At 1915 (B) the arc of sweep was made Green 40° to Red 170°, there being mist between those bearings which, however, was tending to clear ahead and extend northwards.

Period from Sighting Enemy until 2359 (B)/23

Phase 1922 (B) to 2028 (B) . (Tactical Plot Diagram 1)

4. 1922 (B). Sighted Bismarck, followed by a large cruiser (Prinz Eugen), bearing 020° (Green 140°), 7 miles, course 240°; Suffolk's position 66° 59' N., 24° 51' W.

Made first sighting report on 210 kc/s, 8,290 kc/s, 500 kc/s and 138 kc/s.

5. 1923 (B). Full speed ahead; altered course to 150° to take cover in the mist, and to make for gap between Q.Z.X. 241 and Q.Z.X. 363 if unable to round Q.Z.X. 363 while keeping out of sight.

6. 1930 (B). Altered course to mean course 210°, and adjusted speed as requisite, to round the north-west end of Q.Z.X. 363 while keeping in the mist, which proved possible.

7. 1934 (B) to 2023 (B). Obtained Type 284 ranges and bearings as requisite. Those used for making deductions of enemy's position, course and speed are shown on the tactical plot.

Note.- The bearings shown on the tactical plot herewith have been corrected to "mid-bearings," though at the time those taken at 1944 and 1953 were actually "right cut-off bearings" and were plotted without correction to mid-bearing; the consequent error being 5° and 3° respectively. The 1934 and 2023 bearings were observed (accurate) mid-bearings, and reported and plotted as such.

(1) Paragraph number, not in the original, have been inserted

Page 158

The plot gave enemy's initial speed as 20 knots (period 1922-1934); and his speed by 1953 as 28 knots (period 1934-1953).

2000 (B). Having rounded Q.Z.X. 363, manoeuvred as requisite to work unseen on to enemy's port quarter.

2017 (B). Altered course 310° to steer out of the mist to sight the enemy.

Reports.- Made reports at 1922, 1934, 1948, 1957, 2024 and 2026 during the above phase; all except the 1922 (first-sighting) report being based on information from Type 284.

As I've explained, the RN had conducted very limited long range live firing with Type 284, up to May 1941 and it's operators were unsure what to expect, and the combination of both Rodney and KGV engaging the same target, along with the fault in KGV's Fall of shot warning horn, must have been very confusing, as the optical spotters were claiming short salvos when the radar operator was getting intermittent signals.

Ranging panel L12:

145. Range Display is on panel L12 in the radar office. Range scales are 0-24,000 and -
0-48,000 yds. giving accuracies of 125 and 250 yds. respectively. Arrangements are also made
to be able to use the ranging panel L18 (part of type 272/273R) in the T.S. as a standby or
ito get get better range accuracy. Range scale of panel L18 is 0-40,000 yds. with accuracy
of 25 yds. (from the same source as above)

So the reference to looking around 25000 yds most probably means that the radar operator was using the 0-48000 yd range scale on panel L12. Panel L12 displays the all contacts made on the display, regardless of their range. The operator cannot exclude ranges from his display.

[dunmunro]

Suffolk RDF message.jpg






hans

What is the time of transmission?

Another try to place the image of the RP L12 inline:

RPL12a.jpg (59.38 KiB) Viewed 228274 times

[Byron Angel]

Hi Byron,
I agree: it looks like this is an a.a. aid only.
I'm convinced that, in 1941, an 'average' 284 was limited to anti-ship gunnery usable range of 18.000-20.000 yards, as per precious 'Handbook' you kindly posted here (https://www.kbismarck.org/forum/viewtop ... 770#p91770). Fact that, on selected occasions, 'first class' 284 radars were receiving weak and intermittent echoes from much longer maximum distances (up to 28.000 yards) is perfectly credible, under special conditions, but such maximum distance echoes (possibly weak and intermittent) were correctly considered unusable to create a range rate plot useful for gunnery.
On other side, again occasionally, same Suffolk's 284 set that could get Bismarck's echo from 22.000+ yards was unable to detect her until distance was 14.000 yards:


Suffolk RDF message.jpg


Thus, as per "Handbook", excluding exceptional and occasional cases when echoes were received from larger distances, 284 could be used as a gunnery aid only from shorter distances while at longer range it could possibly be used as warning system only, provided echo was interpreted correctly.


On contrary, on May 27, when 284 operator was convinced that Bismarck was still at 25.000 yards, intermittent (but correct) echoes received from Bismarck at shorter distances until 08:51 were considered doubtful. Even when echo was constant and 284 personnel was finally convinced it was from Bismarck (08:52, at that point usable for gunnery purposes), apparently some time passed before ranges were passed to TS and AFCT personnel accepted correct even shorter range of 20.500 yards, at 08:53 only (https://www.kbismarck.org/forum/downloa ... hp?id=4164).

Re. salvo spotting fall of shells, even if 1941 284 version was actually unable to spot them, even occasionally, from 22.000 yards (Rodney's fall of shells at 08:49), then it's obvious that radar officer and 284 personnel, at that time, were convinced of the opposite and that 284 operator was misled by noise peak(s) when reporting first KGV salvo, fired at 24.600 yards as "short" (https://www.kbismarck.org/forum/downloa ... hp?id=4180).
In no other way 284 operator could have reported to Gunnery Control a salvo as 'short' than comparing two different echoes received on his panel.
His error (together with spotting officer same error + fact that 284 operator was still convinced Bismarck was at 25.000 yards in following minutes) caused KGV to fire upper ladder(s), keeping gun range at around 25.000 for following salvos, while Bismarck was instead closing, and explains rather "bitter" GAR comment to R.D/F report ( https://www.kbismarck.org/forum/downloa ... hp?id=4169), for having "wasted" initial 5 minutes battle.

hans

Hi Hans,
Turned up a couple of other items of interest regarding KGV's opening of fire against Bismarck -


[ 1 ] I recollect reading that Tovey had made one or perhaps more radio transmission while in process of closing in upon Bismarck (still looking for the reference and citation). Note the below commentary of the effect of radio transmission upon radar.

CB 4182/45
RADAR MANUAL
(Use of Radar)

CHAPTER FIVE I Limitations of Radar.
Page 54

Interference from friendly radio transmissions
43, W/T and R/T transmission (including W/T beacons) in own ship or in the vicinity may cause serious interference. R/T is usually the worst. The trouble can be alleviated by a suitable choice of communication wavelengths, or sometimes by ré-siting the communication aerials. Little can be done at the radar end, as the wavelength and aerial position are fixed, though special “filters” have proved useful in some cases.

Note that with KGV presumably making ~18 knots and Bismarck making ~10 knots on mutually closing headings, the range would have closed to approximately [18 + 10] x 100 x 1.667 = ~4,700 yards in the five minute period between 0848 and 0853. If the 0848 gun range was 25,500 yds as mentioned, then a closure of 4,700 yds would have made the 0853 gun range at <<<roughly>>> 25,500 - 4,700 = 20,800 yds, which is not far off from 20,500 yds. Note that I'm guesstimating the respective speeds of KGV and Bismarck.

----------

[ 2 ] Note the entries for 0848, 0853 and 0859. I have not had a chance this evening to check on KGV's effective salvo output prior to opening her A Arcs at 0859.

SERVICE HISTORIES of ROYAL NAVY WARSHIPS in WORLD WAR 2
by Lt Cdr Geoffrey B Mason RN (Rtd) (c) 2003

https://www.naval-history.net/xGM-Chron ... orge_V.htm

At 0848 hours, with the BISMARCK sailing directly towards the flagship, KING GEORGE V opened fire at a range of about 25,500 yards. The gunnery department at first had a difficult task in obtaining the range because of BISMARCK's head-on approach and the squally weather.
At 0853 hours the operator of the Type 284 radar finally obtained an accurate range of 20,500 yards and KING GEORGE V obtained her first straddle.
At 0859 hours, when the range had reduced to 16,000 yards, KING GEORGE V turned to starboard on to a course of 175¼ and opened her 'A' arcs.
At 0905 hours, when the range had reduced to 14,000 yards, KING GEORGE V opened fire with her port 5.25in guns.
At 0910 hours BISMARCK scored her only near miss on KING GEORGE V when a salvo fell 400 yards over.
At 0913 hours, when the range had reduced to 12,400 yards, her Type 284 radar was put out of action through blast damage.
At 0914 hours KING GEORGE V commenced a turn to port.
At 0920 hours, when the range had reduced to 12,000 yards, KING GEORGE V settled on a course of 000¼.
At 0921 hours KING GEORGE V opened fire with her starboard 5.25in guns.
At 0922 hours her 14in guns, which since first opening fire had operated faultlessly started to give problems. The loading mechanism of A-turret jammed putting all four guns out of action and a similar fault occurred in Y-turret. A-turret was out of action for ten minutes and Y for seven minutes.
At 0951 hours with the range down to 6,000 yards, KING GEORGE V had an almost stationary BISMARCK on her starboard beam. The flagship then commenced a 360¼ turn.
At 1005 hours the CinC ordered Captain Patterson to close the BISMARCK and attempt to finish her off.
At 1015 hours the CinC Home Fleet signalled the Admiralty, 'The BISMARCK is a wreck, without a gun firing, on fire fore and aft and wallowing more heavily every moment. Men can be seen jumping overboard, preferring death by drowning in the stormy sea to the appalling effects of our fire. I am confident that the BISMARCK, will never get back to harbour and that it was only a matter of hours before she sinks'.
At 1021 hours KING GEORGE V fired her last salvoes from Y-turret; these salvoes not only caused damage to the enemy but also blast damage to the flagship. KING GEORGE V in company with the RODNEY now set course north easterly; both battleships were dangerously low on fuel. During the action the Admiralty had signalled all ships, warning that U-Boats were en route to the area, so this was a further reason for the ships to withdraw. In the action KING GEORGE V had fired 339 x 14in shells and 660 x 5.25in shells. Gunnery performance was below the expected standard because of design deficiencies in the interlock system to protect against explosions during loading of the 14in guns. For 7 minutes she was firing at only 80% efficiency and at 40% for 23 minutes. Only B-Turret, the twin, was 100% trouble free. In addition the low freeboard forward caused significant flooding of shell rooms in the heavy weather.
At 1023 hours a Swordfish approached KING GEORGE V to request her to cease fire so that the Swordfish could make another torpedo attack on BISMARCK, but the Swordfish was fired at by the flagship's AA battery.

(As he withdrew the CinC made a signal to ships in company; 'Any ship with torpedoes to close the BISMARCK and torpedo her'. The only ship in contact with torpedoes was the DORSETSHIRE, whose CO, Captain Martin had already anticipated the order. Closing to 2600 yards on BISMARCK's starboard beam, she fired two torpedoes, both of which hit. She then went round the other side, and from 2000 yards fired another, which also hit)

At 1035 hours the BISMARCK sank in approximate position 48-10N, 16-12W.
.At 1039 hours Tovey signalled the Admiralty, 'BISMARCK has sunk'.


Very interesting exercise.

Byron

[hans zurbriggen]

Hi Byron,
thanks again for your new info and reference !

I find a sentence from G. Mason quite interesting. He obviously analysed KGV GAR (as we are doing here; https://www.kbismarck.org/forum/viewtop ... 787#p91787 and in earlier posts) to summarize what happened during the engagement on May 27 and re. first minutes battle he says:

"At 0853 hours the operator of the Type 284 radar finally obtained an accurate range of 20,500 yards and KING GEORGE V obtained her first straddle."

I'm happy to see he is interpreting KGV GAR exactly in same way as we are: "...finally obtained..." means he is reading KGV GAR exactly as we have done: before this time, KGV range plot was unreliable (despite Bismarck ranges were intermittently, later constantly, obtained by 284 set, but apparently "ignored" by 284 operator and/or AFCT personnel). Only at 08:53, TS finally got and accepted a first "correct" range.

He also says "... obtained first straddle..." (while KGV GAR indicates that this "lucky" salvo, finally fired with correct range data, obtained both a straddle and a hit), as he agrees that first hits against Bismarck happened much later (as per Norfolk official report and as per Bismarck survivors accounts). Even a straddle at very first salvo fired "correctly" is anyway a very good achievement, under those bad weather conditions.

hans

[Byron Angel]

Hi Hans,
A couple of offhand thoughts .....

Radar - Reading the original “user manuals”, I noted with interest the emphasis placed upon:

> careful calibration of the radar device itself.

> further calibration of the radar in connection with the gun battery itself.

> the skill, training and experience required of the radar operator to correctly interpret what he was viewing on the screen.

However scientific radar was, there was clearly an “art” component involved as well in obtaining best results. This first generation electronic technology was new and unfamiliar. It was arguably not like a vending machine, where one drops in a coin and out pops a nicely wrapped candy bar.

- - -

Fuel state of the British BBs .....

I knew from reading Wellings that RODNEY had been desperately low on fuel. I did not appreciate that KGV was as well. If that Swordfish torpedo had not crippled Bismarck’s steering, does she outrun her pursuers and safely reach Brest?

Byron

[dunmunro]

Hi Byron,
I agree: it looks like this is an a.a. aid only.
I'm convinced that, in 1941, an 'average' 284 was limited to anti-ship gunnery usable range of 18.000-20.000 yards, as per precious 'Handbook' you kindly posted here (https://www.kbismarck.org/forum/viewtop ... 770#p91770). Fact that, on selected occasions, 'first class' 284 radars were receiving weak and intermittent echoes from much longer maximum distances (up to 28.000 yards) is perfectly credible, under special conditions, but such maximum distance echoes (possibly weak and intermittent) were correctly considered unusable to create a range rate plot useful for gunnery.
On other side, again occasionally, same Suffolk's 284 set that could get Bismarck's echo from 22.000+ yards was unable to detect her until distance was 14.000 yards:


Suffolk RDF message.jpg


Thus, as per "Handbook", excluding exceptional and occasional cases when echoes were received from larger distances, 284 could be used as a gunnery aid only from shorter distances while at longer range it could possibly be used as warning system only, provided echo was interpreted correctly.


On contrary, on May 27, when 284 operator was convinced that Bismarck was still at 25.000 yards, intermittent (but correct) echoes received from Bismarck at shorter distances until 08:51 were considered doubtful. Even when echo was constant and 284 personnel was finally convinced it was from Bismarck (08:52, at that point usable for gunnery purposes), apparently some time passed before ranges were passed to TS and AFCT personnel accepted correct even shorter range of 20.500 yards, at 08:53 only (https://www.kbismarck.org/forum/downloa ... hp?id=4164).

Re. salvo spotting fall of shells, even if 1941 284 version was actually unable to spot them, even occasionally, from 22.000 yards (Rodney's fall of shells at 08:49), then it's obvious that radar officer and 284 personnel, at that time, were convinced of the opposite and that 284 operator was misled by noise peak(s) when reporting first KGV salvo, fired at 24.600 yards as "short" (https://www.kbismarck.org/forum/downloa ... hp?id=4180).
In no other way 284 operator could have reported to Gunnery Control a salvo as 'short' than comparing two different echoes received on his panel.
His error (together with spotting officer same error + fact that 284 operator was still convinced Bismarck was at 25.000 yards in following minutes) caused KGV to fire upper ladder(s), keeping gun range at around 25.000 for following salvos, while Bismarck was instead closing, and explains rather "bitter" GAR comment to R.D/F report ( https://www.kbismarck.org/forum/downloa ... hp?id=4169), for having "wasted" initial 5 minutes battle.

hans

Hi Hans,
Turned up a couple of other items of interest regarding KGV's opening of fire against Bismarck -


[ 1 ] I recollect reading that Tovey had made one or perhaps more radio transmission while in process of closing in upon Bismarck (still looking for the reference and citation). Note the below commentary of the effect of radio transmission upon radar.

CB 4182/45
RADAR MANUAL
(Use of Radar)

CHAPTER FIVE I Limitations of Radar.
Page 54

Interference from friendly radio transmissions
43, W/T and R/T transmission (including W/T beacons) in own ship or in the vicinity may cause serious interference. R/T is usually the worst. The trouble can be alleviated by a suitable choice of communication wavelengths, or sometimes by ré-siting the communication aerials. Little can be done at the radar end, as the wavelength and aerial position are fixed, though special “filters” have proved useful in some cases.

Note that with KGV presumably making ~18 knots and Bismarck making ~10 knots on mutually closing headings, the range would have closed to approximately [18 + 10] x 100 x 1.667 = ~4,700 yards in the five minute period between 0848 and 0853. If the 0848 gun range was 25,500 yds as mentioned, then a closure of 4,700 yds would have made the 0853 gun range at <<<roughly>>> 25,500 - 4,700 = 20,800 yds, which is not far off from 20,500 yds. Note that I'm guesstimating the respective speeds of KGV and Bismarck.

----------

[ 2 ] Note the entries for 0848, 0853 and 0859. I have not had a chance this evening to check on KGV's effective salvo output prior to opening her A Arcs at 0859.

SERVICE HISTORIES of ROYAL NAVY WARSHIPS in WORLD WAR 2
by Lt Cdr Geoffrey B Mason RN (Rtd) (c) 2003

https://www.naval-history.net/xGM-Chron ... orge_V.htm

At 0848 hours, with the BISMARCK sailing directly towards the flagship, KING GEORGE V opened fire at a range of about 25,500 yards. The gunnery department at first had a difficult task in obtaining the range because of BISMARCK's head-on approach and the squally weather.
At 0853 hours the operator of the Type 284 radar finally obtained an accurate range of 20,500 yards and KING GEORGE V obtained her first straddle.
At 0859 hours, when the range had reduced to 16,000 yards, KING GEORGE V turned to starboard on to a course of 175¼ and opened her 'A' arcs.
At 0905 hours, when the range had reduced to 14,000 yards, KING GEORGE V opened fire with her port 5.25in guns.
At 0910 hours BISMARCK scored her only near miss on KING GEORGE V when a salvo fell 400 yards over.
At 0913 hours, when the range had reduced to 12,400 yards, her Type 284 radar was put out of action through blast damage.
At 0914 hours KING GEORGE V commenced a turn to port.
At 0920 hours, when the range had reduced to 12,000 yards, KING GEORGE V settled on a course of 000¼.
At 0921 hours KING GEORGE V opened fire with her starboard 5.25in guns.
At 0922 hours her 14in guns, which since first opening fire had operated faultlessly started to give problems. The loading mechanism of A-turret jammed putting all four guns out of action and a similar fault occurred in Y-turret. A-turret was out of action for ten minutes and Y for seven minutes.
At 0951 hours with the range down to 6,000 yards, KING GEORGE V had an almost stationary BISMARCK on her starboard beam. The flagship then commenced a 360¼ turn.
At 1005 hours the CinC ordered Captain Patterson to close the BISMARCK and attempt to finish her off.
At 1015 hours the CinC Home Fleet signalled the Admiralty, 'The BISMARCK is a wreck, without a gun firing, on fire fore and aft and wallowing more heavily every moment. Men can be seen jumping overboard, preferring death by drowning in the stormy sea to the appalling effects of our fire. I am confident that the BISMARCK, will never get back to harbour and that it was only a matter of hours before she sinks'.
At 1021 hours KING GEORGE V fired her last salvoes from Y-turret; these salvoes not only caused damage to the enemy but also blast damage to the flagship. KING GEORGE V in company with the RODNEY now set course north easterly; both battleships were dangerously low on fuel. During the action the Admiralty had signalled all ships, warning that U-Boats were en route to the area, so this was a further reason for the ships to withdraw. In the action KING GEORGE V had fired 339 x 14in shells and 660 x 5.25in shells. Gunnery performance was below the expected standard because of design deficiencies in the interlock system to protect against explosions during loading of the 14in guns. For 7 minutes she was firing at only 80% efficiency and at 40% for 23 minutes. Only B-Turret, the twin, was 100% trouble free. In addition the low freeboard forward caused significant flooding of shell rooms in the heavy weather.
At 1023 hours a Swordfish approached KING GEORGE V to request her to cease fire so that the Swordfish could make another torpedo attack on BISMARCK, but the Swordfish was fired at by the flagship's AA battery.

(As he withdrew the CinC made a signal to ships in company; 'Any ship with torpedoes to close the BISMARCK and torpedo her'. The only ship in contact with torpedoes was the DORSETSHIRE, whose CO, Captain Martin had already anticipated the order. Closing to 2600 yards on BISMARCK's starboard beam, she fired two torpedoes, both of which hit. She then went round the other side, and from 2000 yards fired another, which also hit)

At 1035 hours the BISMARCK sank in approximate position 48-10N, 16-12W.
.At 1039 hours Tovey signalled the Admiralty, 'BISMARCK has sunk'.


Very interesting exercise.

Byron

So you take a brief summary of the action, that obviously has errors, and use it as a source! The open fire range according to the GAR was 24600yds, not 25500 yds. How could Mason come up with 25500yds when the initial Type 284 range, prior to opening fire was 25100 yds?


This is from John Roberts article in Warship 28, and is based upon a close reading of Rodney and KGV's GARs:

The two British battleships were steering 110° with
Rodney 1600yds off the flagship's port quarter when, at
0842, Bismarck was sighted from King George V bear-
ing green (starboard) 7°. One minute later the Air
Defence Officer aboard Rodney also sighted the Ger-
man battleship, 25,000yds away (12.3nm), steering
directly towards the British ships and listing 3° to 5° to
port. For both British ships range-taking conditions
were poor, due to the long range and funnel haze, and
fire control tables were initially set to estimated ranges
(25,000yds in Rodney and 24000 yds in King George
V). However, the flagship's Type 284 gunnery radar
obtained a momentary echo at 25,100yds and her table -
was returned to this range; the Type 284 continued to
obtain short echoes until the range dropped below
21,100yds (10.4nm) when they became continuous.

At 0847 Rodney opened fire with A and B turrets at
a gun range of 23,500yds, followed by King George V
one minute later at 24,600yds. Bismarck replied at
0849,

One effect of a 14 or 16in salvo splash might be to block the radar return signal from the target ship. and this might cause intermittent echos at ranges when they might have been continuous otherwise.

[dunmunro]

Hi Hans,
A couple of offhand thoughts .....

Radar - Reading the original “user manuals”, I noted with interest the emphasis placed upon:

> careful calibration of the radar device itself.

> further calibration of the radar in connection with the gun battery itself.

> the skill, training and experience required of the radar operator to correctly interpret what he was viewing on the screen.

However scientific radar was, there was clearly an “art” component involved as well in obtaining best results. This first generation electronic technology was new and unfamiliar. It was arguably not like a vending machine, where one drops in a coin and out pops a nicely wrapped candy bar.

- - -

Fuel state of the British BBs .....

I knew from reading Wellings that RODNEY had been desperately low on fuel. I did not appreciate that KGV was as well. If that Swordfish torpedo had not crippled Bismarck’s steering, does she outrun her pursuers and safely reach Brest?

Byron

From KGV's GAR:

From KGV's GAR:

1, Narrative. On the morning of the action the ranging set, Type 284, is
considered to have been in first' class working order: Final tuning adjustments
had been made on the previous afternoon; Rodney being used as target. Before
the adjustment Rodney had been detected at 23,800 yards, which showed that
good tuning had been maintained since the ship teft harbour on the 22nd May.

We've discussed fuel and how KGV and Rodney had opportunities to fuel in Eire, Northern Ireland and declined to do so. KGV had some reserve even when she broke off action on 27 May. The other factor is that Bismarck also slowed prior to the fatal torpedo hit and also reported, via radio, that she was in a critical fuel state.

[Byron Angel]

Hi Byron,
thanks again for your new info and reference !

I find a sentence from G. Mason quite interesting. He obviously analysed KGV GAR (as we are doing here; https://www.kbismarck.org/forum/viewtop ... 787#p91787 and in earlier posts) to summarize what happened during the engagement on May 27 and re. first minutes battle he says:

"At 0853 hours the operator of the Type 284 radar finally obtained an accurate range of 20,500 yards and KING GEORGE V obtained her first straddle."

I'm happy to see he is interpreting KGV GAR exactly in same way as we are: "...finally obtained..." means he is reading KGV GAR exactly as we have done: before this time, KGV range plot was unreliable (despite Bismarck ranges were intermittently, later constantly, obtained by 284 set, but apparently "ignored" by 284 operator and/or AFCT personnel). Only at 08:53, TS finally got and accepted a first "correct" range.

He also says "... obtained first straddle..." (while KGV GAR indicates that this "lucky" salvo, finally fired with correct range data, obtained both a straddle and a hit), as he agrees that first hits against Bismarck happened much later (as per Norfolk official report and as per Bismarck survivors accounts). Even a straddle at very first salvo fired "correctly" is anyway a very good achievement, under those bad weather conditions.

hans

Hi Hans,
Found this in my files and thought it might be useful/interesting -



The following comes from Duke of York’s 1943 engagement with Scharnhorst, but will shed a bit of perspective on use of radar in connection with surface gunnery under action conditions.


APPENDIX V – Gunnery Ranging and Spotting

A. DUKE OF YORK
( i ) Satisfactory “Ranging” echoes from 30,000 yards, and “Bearing echoes from 25,000 yards were obtained by Type 284(M)3, using L.18 Ranging Panel. Despite a rough sea giving pronounced “Sea returns”, and a wind of Force 5, splash spotting of the main armament was possible up to 20,000 yards. Bearing accuracy appears to have been adequate, although made difficult by the yaw of the ship and the time lag caused by control being operated from the T.S.

Byron note – Type 284(M)3 featured beam switching capability and a power of 150Mhz (compared to 25Mhz of the original RDF Type 284).

( ii ) Splash spotting was done principally from the L.12 panel in the Radar office where the Second Radar Officer had more space than in the T.S. and the advantage of a linear scan from which to estimate the M.P.I.

( iii ) The fault in Type 284 caused by gun blast was diagnosed and adequate “First aid” measures taken with commendable rapidity. This enabled fire to be re-opened using radar range as soon as the range closed again.


B. JAMAICA
Good results were obtained from Type 284.


C. Force 1

( i ) SHEFFIELD’s Type 284 went out of action through an electrical defect. In the amplifier M.56, making it necessary for her to use the T.S. radar for ranging. But thereby enabling her to spot fall of shot. That were out of range of the gunnery radar sets. After two years at sea gunnery radar has become much more reliable, but occasional breakdowns are inevitable and in ships with only one radar officer there will seldom be time for him to diagnose and repair faults during an engagement.

( ii ) In BELFAST unexpected interference from the convoy R/T wave (a frequency seldom used in the Home Fleet) rendered spotting useless and ranging difficult. The decision to retain an all round lookout with WS radar at the expense of the gunnery plot was entirely correct, particularly as BELFAST was the only ship of this force who was able to do it.

( iii ) NORFOLK’s GS radar was put to good use in blind firing which appears to have been accurate.


D. Destroyers
Type 285 in the destroyers gave very satisfactory results, the greatest picking up range being 22,000 yards. As no ship other than MUSKETEER has reported experiencing any interference to their gunnery radar, I consider the signals received in that ship to have been caused internally, possibly as a result of the faulty insulation of the main W/T aerial.


E. General
In all ships gunnery radar produced the results expected of them, but it should be remembered that apart from conditions of sea and wind, the situation was an ideal one for British ships. There was but one enemy ship so that the bugbear of beam-switch echo confusion, often so misleading with two or more targets at close range, did not arise.


Byron

[Steve Crandell]

Power is not measured in MHz. I'm guessing Kw?

[hans zurbriggen]

Hi Byron,
1943 284M was clearly superior to 1941 284.

Your point about early war radar "art" is very interesting and may explain problems on board KGV on May 27, despite a well tuned radar. Germans too had severe shortages of personnel training in usage of radar equipment. I feel British got more and more better during war, while Germans always lacked an effective dedicated tactical training, especially for officers, during war.

Re. fuel shortage, Bismarck too was low and could only get Brest at low speed (around 20 knots?), but without fatal torpedo, no British BB could have intercepted her in time, at least not without taking severe risk to pursue her well into Luftwaffe range and possibly no fuel enough to get back home.

hans

[Byron Angel]

Power is not measured in MHz. I'm guessing Kw?

Thank you, Steve. My bad.

Byron

[dunmunro]

Hi Byron,
1943 284M was clearly superior to 1941 284.

Your point about early war radar "art" is very interesting and may explain problems on board KGV on May 27, despite a well tuned radar. Germans too had severe shortages of personnel training in usage of radar equipment. I feel British got more and more better during war, while Germans always lacked an effective dedicated tactical training, especially for officers, during war.

Re. fuel shortage, Bismarck too was low and could only get Brest at low speed (around 20 knots?), but without fatal torpedo, no British BB could have intercepted her in time, at least not without taking severe risk to pursue her well into Luftwaffe range and possibly no fuel enough to get back home.

hans

There were no problems with Type 284 on KGV and it performed exactly as expected until damaged by shock. There were no problems with radar personnel training either; they were dealing with a novel situation and they handled it well. If they had to repeat the engagement, they would have been well prepared via 'on the job training' via lessons learned, which were undoubtedly promulgated throughout the fleet.

[hans zurbriggen]

Hello all,
no comment would be needed to above post.

KGV Gunnery Control.jpg (56.42 KiB) Viewed 227994 times

KGV Enclosure N.3_Section II_3.jpg (20.21 KiB) Viewed 227994 times

Willingness to read and understand what is written in KGV GAR should be enough to judge whether there were problems or not with 284 personnel training (interpretation of echoes) and cooperation with Gunnery Control / TS (acceptance of radar ranges into AFCT).

KGV 284 set was technically perfect (even superior to its specifications/expectations at that time) but its valuable outcome was only fully exploited after 08:53, due to radar "art" not being fully understood yet. KGV gunnery clearly suffered in very first minutes engagement, due to this 'problem'.

hans