Hello Frank,
I'm happy to accept these designations. However, H.von Kroge seems to point to GEMA shipborne sets installed on board of large ships (detection at 60 km for enemy ships would be only possible from very high position, like foretops of battleships and heavy cruisers).
I don't know which large ships actually received TS60 for GEMA equipment: according to Mr. Saxton, Tirpitz detected Lancaster at 150 km distance, therefore she should have had a high power equipment, but he is uncertain if it was a FuMO34 (or Berlin or Sophie, both installed on Tirpitz) detecting airplanes.
As you say, Tirpitz could have retained TS6 equipment FuMO26 for fire direction, but could have received a set with TS60 for long range warning.
hans
Gun precision / dispersion
Moderator: Bill Jurens
-
hans zurbriggen
- Senior Member
- Posts: 425
- Joined: Sat Dec 21, 2019 8:15 am
Re: Gun precision / dispersion
Hallo Hans,
that sounds reasonable.
Frank
that sounds reasonable.
Frank
Re: Gun precision / dispersion
Hallo Hans,
60km sounds a bit too far when considering the curvature of the earth even for a 30m radar height.
45 km is probaly the realistic maximum for a 30m radar vs. a 30m tall target. Detection of only the target's mast beeing above the horizon would require a high power radar.
The optical limit i.e. line of sight would even be less, at 39km.
So 60km must be from a coastal station at 80m above the sea.
Best regards
Frank
60km sounds a bit too far when considering the curvature of the earth even for a 30m radar height.
45 km is probaly the realistic maximum for a 30m radar vs. a 30m tall target. Detection of only the target's mast beeing above the horizon would require a high power radar.
The optical limit i.e. line of sight would even be less, at 39km.
So 60km must be from a coastal station at 80m above the sea.
Best regards
Frank
-
hans zurbriggen
- Senior Member
- Posts: 425
- Joined: Sat Dec 21, 2019 8:15 am
Re: Gun precision / dispersion
Hello Frank,
of course theoretical and practical range are different, depending on earth curvature but also on weather conditions (allowing or not allowing microwaves refraction) and materials reflection properties).
However, Tirpitz main director rangefinder was at 40.5 meters height and radar antenna was at around 43 meters. I guess GEMA tested possibility to detect a similar ship (battleship size, 40+ meters high) because H.von Kroge (see full paragraph I have posted above) is clear that this TS60 powerful equipment in combination with large antennas "...led to ranges with ship-borne sets of up to 60 km, according to the size of the target ship" (my underlined). Possibly this limit was achieved under special weather conditions, detecting just target foretop director.
hans
of course theoretical and practical range are different, depending on earth curvature but also on weather conditions (allowing or not allowing microwaves refraction) and materials reflection properties).
However, Tirpitz main director rangefinder was at 40.5 meters height and radar antenna was at around 43 meters. I guess GEMA tested possibility to detect a similar ship (battleship size, 40+ meters high) because H.von Kroge (see full paragraph I have posted above) is clear that this TS60 powerful equipment in combination with large antennas "...led to ranges with ship-borne sets of up to 60 km, according to the size of the target ship" (my underlined). Possibly this limit was achieved under special weather conditions, detecting just target foretop director.
hans
Re: Gun precision / dispersion
Thank you Hans.
I can see this as possible, when special atmospheric conditions exist.
Frank
I can see this as possible, when special atmospheric conditions exist.
Frank
Re: Gun precision / dispersion
I have to apologize. I made some mistakes in the designations. I slipped in rows. Here are the correctet dsignations:
1000 / 2000Hz:
FuMG 39 G (gL): FuMO 21 Zerstörersäule; Destroyer
FuMG 39 G (gO): FuMO 22 aufgesetzte Drehhaube, Heavy Cruiser, Battleships
FuMG 39 G (gP): FuMO 23 kombinierte Drehhaube, Heavy Cruiser, Battleships
500Hz:
FuMG 40 G (gL): FuMO 24 Zerstörersäule; Destroyer, Light Cruiser
FuMG 40 G (gM): FuMO 25 abgesetzte Drehsäule an Mast, T-Boats, Destroyer, Light and Heavy Cruiser
FuMG 40 G (gO): FuMO 26 aufgesetzte Drehhaube, Heavy Cruiser, Battleships
FuMG 40 G (gP): FuMO 27 kombinierte Drehhaube, Heavy Cruiser, Battleships
FuMG 40 G (gS): FuMO 28 T-Boote 37
FuMG 41 G (gU): FuMO 29 U-Boote Tower mounted panels, electronically scanned
FuMG 42 G (gU): FuMO 30 U-Boote Drehsäule
FuMO 31 "Sophie" with 400kW was cancelled in favor of "Hohentwiel" radar
TS60 with 125kW:
FuMO 24 => FuMO 32
FuMO 25 => FuMO 33
FuMO 26 => FuMO 34
1000 / 2000Hz:
FuMG 39 G (gL): FuMO 21 Zerstörersäule; Destroyer
FuMG 39 G (gO): FuMO 22 aufgesetzte Drehhaube, Heavy Cruiser, Battleships
FuMG 39 G (gP): FuMO 23 kombinierte Drehhaube, Heavy Cruiser, Battleships
500Hz:
FuMG 40 G (gL): FuMO 24 Zerstörersäule; Destroyer, Light Cruiser
FuMG 40 G (gM): FuMO 25 abgesetzte Drehsäule an Mast, T-Boats, Destroyer, Light and Heavy Cruiser
FuMG 40 G (gO): FuMO 26 aufgesetzte Drehhaube, Heavy Cruiser, Battleships
FuMG 40 G (gP): FuMO 27 kombinierte Drehhaube, Heavy Cruiser, Battleships
FuMG 40 G (gS): FuMO 28 T-Boote 37
FuMG 41 G (gU): FuMO 29 U-Boote Tower mounted panels, electronically scanned
FuMG 42 G (gU): FuMO 30 U-Boote Drehsäule
FuMO 31 "Sophie" with 400kW was cancelled in favor of "Hohentwiel" radar
TS60 with 125kW:
FuMO 24 => FuMO 32
FuMO 25 => FuMO 33
FuMO 26 => FuMO 34
-
Byron Angel
- Senior Member
- Posts: 1658
- Joined: Sun Mar 06, 2011 1:06 am
Re: Gun precision / dispersion
McMullen's (Gunnery Officer - HMS Prince of Wales) letter to Ludovik Kennedy re Denmark Strait -
Note - One can also access an IWM oral document featuring McMullen here: https://www.iwm.org.uk/collections/item/object/80010751
McMullen’s Letter
The following text is an extract from a letter written by the late Colin McMullen (Gunnery Officer of H.M.S. Prince of Wales during the Battle of the Denmark Strait) to author Ludovic Kennedy in the early 1970s. Apparently, this was for Kennedy's excellent book, "Pursuit." Special thanks to Bruce Taylor for sharing this with us.
"Bismarck Battle
Arthur Skipwith has forwarded on your letter dated 7th November and the following main points may be of interest. I am afraid I cannot now remember some of the details, but briefly "Prince of Wales" had two radar sets capable of feeding range into the 14 inch gunnery system. The main set purely designed to feed into the 14 inch system, had an aerial which was attached to the main Director Control Tower; as a result it was trained directly on to the target by the Main Director Trainer. Unfortunately the limiting range on the "Tube" was 24,000 yards.
The second set was the air warning system, the aerial of which was situated on top of the mainmast. Although primarily an air warning set, it was possible to feed ranges from a surface target into the 14 inch Transmitting Station.
This set had a more or less unlimited range.
"Prince of Wales" had the following optical range finders feeding range directly into the 14 inch Transmitting Station:- Two very large range finders, (about 45 feet I think) one at the back of A Turret and one at the back of Y Turret. One "Duplex" range finder (about 35 feet I think) at the back of B Turret (2 separate range finders inside one instrument). One "Duplex' range finder (15 feet) under my feet in the 14 inch Director Control Tower. (Total 6 range finders). These fed automatically into the range "Plot" in the Transmitting Station a small letter being automatically typed showing the range of the range finder concerned, whenever a "cut" was obtained.
I think the ranges from the radar sets were not plotted automatically but were plotted by pencil under the direction of the T. S. Officer, Mr. Murphy, Commissioned Dagger Gunner, from range repeaters.
The ship, although suffering from teething troubles in her 14 inch mountings, had done several shoots and fire control exercises including opening fire runs firing one gun "thrown-off" at a target ship to exercise the open fire procedure.
It was therefore sad that only the scantiest information was available on this particular occasion to obtain an accurate open fire range.
The story as far as I can remember is as follows.
Y Turret was "wooded" as "A " arcs were not open. A rough sea and strong wind on the starboard bow together with our high speed resulted in a continuous stream of spray and water over A and B Turrets, and in spite of their window washing gear neither obtained any ranges before opening fire.
Both radar sets had been switched off to maintain Radar Silence and were switched on at the order "enemy in sight".
The main gunnery set due to its technical limitation was unable to pass ranges until the range was reduced to 24,000 yards.
As far as I can remember the range on opening fire was about 26, 000 yards.
No range was obtained before opening fire from the air warning radar set; I think (but am not certain} due to having been switched-off and slowness in becoming operational after being switched-on again. (Blutarski Note – see Paddon on this for another p.o.v.)
That left the 15 foot 14 inch Director Control Tower Duplex Range finders which were high up and clear of spray but the range was very extreme for such small range finders.
"Hood and "Prince of Wales" fired in their own time sectors, each controlling their own gunfire.
This procedure although independent, laid down that gun ranges be interchanged between ships before opening fire but we received no gun ranges from Hood and I was unable to pass any to her, so I expect she suffered the same trouble, being also a "wet" ship with her main optical range finders low down on the back of the Turrets.
We actually opened fire with a gull range obtained from one range from the 15 foot Director Control Tower Duplex range finders "meaned" with my estimated range. This latter was done, if you remember, with "Block Sketch Cards" where the height of the enemy's upper deck is observed relative to the horizon.
Once the range was down to about 20,000 yards the T. S. had a good Range Plot including radar ranges from the 14 inch Director Tower set and continual optical range finder ranges, certainly from "B" Turret.
It is of interest that having the "windward berth" was even in comparatively modern days an advantage where spray was concerned.
I also remember noticing the large range finders "high-up" in Bismarck (as they were in all large German ships}.
The procedure at that time was for the "Spotting Officer" (Lt. Cdr . Skipwith, R.N. ) (on my right} to give the routine orders, "enemy in sight" etc., "bearing and description"; for the "Rate Officer" Lieut. Buxton RNVR (on my left), to give Enemy's Inclination and speed while the G.O. in the middle, communicated with the Captain, kept an overall view and then, being in direct touch with the T.S. Officer (Mr. Murphy) discussed the range plot and arising therefrom the open fire range.
Thus on this occasion I remember almost "imploring" Mr. Murphy for ranges and his reply "No Ranges".
I can also remember asking the W/T operator (by my left foot) for ranges from Hood, also negative. Then Mr. Murphy's report of one range from D. C. T. and my "estimation by card"; then Hood opening fire and we following as per drill in our "time sector" on a mean of two ranges. (One from a 15 foot range finder and one estimated).
I hope this gives a picture of the opening range picture; a sorry story in the vital "opening fire" stage but a good range plot as the range was reduced.
What was "dramatic" at the start was the speed with which everything happened, with both squadrons steaming at about 27 knots and a very-high closing rate.
I remember Skipwith and I discussing the leading ship, and either he or I said "Looks like Strasburg" in other word"Prince Eugen" looked like a "big ship" but "Bismarck" even at that range looked much bigger, hence our disregard of Hood's original concentration signal to engage the "left hand ship".
On this point, Hood had an old fashioned open spotting top with the wind probably roaring through it whereas we had a modern enclosed Director Control Tower with the most modern large optical instruments."
- - -
Page 572; Note 27 - “Battleship Bismarck: A Design and Operational History”, Garzke, Dulin, Jurens -
“Captain Colin McMullen was critical of the design of the King George V class. He considered them to be wet ships because of their lack of flare at the bow. At full speed or in heavy sea, their bows dug in and caused much spray formation that hampered the rangefinders in two forward turrets from finding their targets. This criticism, along with others concerning the lack of bow freeboard in these battleships, was instrumental in the bow design of HMS Vanguard, the last battleship delivered to the Royal Navy.
- - -
The authors of “Battleship Bismarck: A Design and Operational History”, Garzke, Dulin, and Jurens, had this to say about Lt-Cmdr McMullen’s contributions to their research (provided several decades after McMullen’s earlier correspondence with Ludovic Kennedy) –
“The authors especially want to acknowledge the assistance of Captain Colin McMullen who, despite a debilitating illness, provided valuable insights to the gunnery of Prince of Wales and Hood during the Denmark Strait battle of 24 May 1941.”
Were they just being kind? Readers may judge for themselves.
Pg 220 – “Once Prince of Wales came within 21,500 meters of Bismarck, Commander McMullen had the Type 284 radar turned on, as spray and water were masking his 4.75-meter (15-ft) rangefinder on the forward control tower, With this radar, he could check on the ranges being taken from his rangefinder and his rough approximations using a block check card. The closing rate to his target was increasing, and the lenses of the rangefinders in the two forward turrets were covered with spray for a short time before a course change was made. Conditions for ranging on the enemy’s masts were also not easy. As a result it took two down-ladders to find the target. The Type 284 radar did not have a calibration scale for ranges of more than 22,000 meters (~24,000 yards), and some malfunctions and interference made this radar difficult to use; it later failed from gun blast damage. The Type 281 radar was switched on too late, and it later failed from battle damage.
(Byron note – The course change mentioned above almost certainly refers to “Prince of Wales’” alteration of course to port at ~0555. It is interesting to note that, after this turn, target bearing for all intents and purposes remained constant at 330deg (true) from ~0555 through ~0600 hrs. McMullen’s salvo plot suggests as well that the shooting of Prince of Wales improved from ~0556, when range had gotten down to ~20,000 yards - maximum effective range (IMO) for the 15-ft aloft range-finder. The record appears to be silent regarding any range cuts provided by any of the turret rangefinders; if anyone has any data on this, I’d be thrilled to see it.)
Byron
Note - One can also access an IWM oral document featuring McMullen here: https://www.iwm.org.uk/collections/item/object/80010751
McMullen’s Letter
The following text is an extract from a letter written by the late Colin McMullen (Gunnery Officer of H.M.S. Prince of Wales during the Battle of the Denmark Strait) to author Ludovic Kennedy in the early 1970s. Apparently, this was for Kennedy's excellent book, "Pursuit." Special thanks to Bruce Taylor for sharing this with us.
"Bismarck Battle
Arthur Skipwith has forwarded on your letter dated 7th November and the following main points may be of interest. I am afraid I cannot now remember some of the details, but briefly "Prince of Wales" had two radar sets capable of feeding range into the 14 inch gunnery system. The main set purely designed to feed into the 14 inch system, had an aerial which was attached to the main Director Control Tower; as a result it was trained directly on to the target by the Main Director Trainer. Unfortunately the limiting range on the "Tube" was 24,000 yards.
The second set was the air warning system, the aerial of which was situated on top of the mainmast. Although primarily an air warning set, it was possible to feed ranges from a surface target into the 14 inch Transmitting Station.
This set had a more or less unlimited range.
"Prince of Wales" had the following optical range finders feeding range directly into the 14 inch Transmitting Station:- Two very large range finders, (about 45 feet I think) one at the back of A Turret and one at the back of Y Turret. One "Duplex" range finder (about 35 feet I think) at the back of B Turret (2 separate range finders inside one instrument). One "Duplex' range finder (15 feet) under my feet in the 14 inch Director Control Tower. (Total 6 range finders). These fed automatically into the range "Plot" in the Transmitting Station a small letter being automatically typed showing the range of the range finder concerned, whenever a "cut" was obtained.
I think the ranges from the radar sets were not plotted automatically but were plotted by pencil under the direction of the T. S. Officer, Mr. Murphy, Commissioned Dagger Gunner, from range repeaters.
The ship, although suffering from teething troubles in her 14 inch mountings, had done several shoots and fire control exercises including opening fire runs firing one gun "thrown-off" at a target ship to exercise the open fire procedure.
It was therefore sad that only the scantiest information was available on this particular occasion to obtain an accurate open fire range.
The story as far as I can remember is as follows.
Y Turret was "wooded" as "A " arcs were not open. A rough sea and strong wind on the starboard bow together with our high speed resulted in a continuous stream of spray and water over A and B Turrets, and in spite of their window washing gear neither obtained any ranges before opening fire.
Both radar sets had been switched off to maintain Radar Silence and were switched on at the order "enemy in sight".
The main gunnery set due to its technical limitation was unable to pass ranges until the range was reduced to 24,000 yards.
As far as I can remember the range on opening fire was about 26, 000 yards.
No range was obtained before opening fire from the air warning radar set; I think (but am not certain} due to having been switched-off and slowness in becoming operational after being switched-on again. (Blutarski Note – see Paddon on this for another p.o.v.)
That left the 15 foot 14 inch Director Control Tower Duplex Range finders which were high up and clear of spray but the range was very extreme for such small range finders.
"Hood and "Prince of Wales" fired in their own time sectors, each controlling their own gunfire.
This procedure although independent, laid down that gun ranges be interchanged between ships before opening fire but we received no gun ranges from Hood and I was unable to pass any to her, so I expect she suffered the same trouble, being also a "wet" ship with her main optical range finders low down on the back of the Turrets.
We actually opened fire with a gull range obtained from one range from the 15 foot Director Control Tower Duplex range finders "meaned" with my estimated range. This latter was done, if you remember, with "Block Sketch Cards" where the height of the enemy's upper deck is observed relative to the horizon.
Once the range was down to about 20,000 yards the T. S. had a good Range Plot including radar ranges from the 14 inch Director Tower set and continual optical range finder ranges, certainly from "B" Turret.
It is of interest that having the "windward berth" was even in comparatively modern days an advantage where spray was concerned.
I also remember noticing the large range finders "high-up" in Bismarck (as they were in all large German ships}.
The procedure at that time was for the "Spotting Officer" (Lt. Cdr . Skipwith, R.N. ) (on my right} to give the routine orders, "enemy in sight" etc., "bearing and description"; for the "Rate Officer" Lieut. Buxton RNVR (on my left), to give Enemy's Inclination and speed while the G.O. in the middle, communicated with the Captain, kept an overall view and then, being in direct touch with the T.S. Officer (Mr. Murphy) discussed the range plot and arising therefrom the open fire range.
Thus on this occasion I remember almost "imploring" Mr. Murphy for ranges and his reply "No Ranges".
I can also remember asking the W/T operator (by my left foot) for ranges from Hood, also negative. Then Mr. Murphy's report of one range from D. C. T. and my "estimation by card"; then Hood opening fire and we following as per drill in our "time sector" on a mean of two ranges. (One from a 15 foot range finder and one estimated).
I hope this gives a picture of the opening range picture; a sorry story in the vital "opening fire" stage but a good range plot as the range was reduced.
What was "dramatic" at the start was the speed with which everything happened, with both squadrons steaming at about 27 knots and a very-high closing rate.
I remember Skipwith and I discussing the leading ship, and either he or I said "Looks like Strasburg" in other word"Prince Eugen" looked like a "big ship" but "Bismarck" even at that range looked much bigger, hence our disregard of Hood's original concentration signal to engage the "left hand ship".
On this point, Hood had an old fashioned open spotting top with the wind probably roaring through it whereas we had a modern enclosed Director Control Tower with the most modern large optical instruments."
- - -
Page 572; Note 27 - “Battleship Bismarck: A Design and Operational History”, Garzke, Dulin, Jurens -
“Captain Colin McMullen was critical of the design of the King George V class. He considered them to be wet ships because of their lack of flare at the bow. At full speed or in heavy sea, their bows dug in and caused much spray formation that hampered the rangefinders in two forward turrets from finding their targets. This criticism, along with others concerning the lack of bow freeboard in these battleships, was instrumental in the bow design of HMS Vanguard, the last battleship delivered to the Royal Navy.
- - -
The authors of “Battleship Bismarck: A Design and Operational History”, Garzke, Dulin, and Jurens, had this to say about Lt-Cmdr McMullen’s contributions to their research (provided several decades after McMullen’s earlier correspondence with Ludovic Kennedy) –
“The authors especially want to acknowledge the assistance of Captain Colin McMullen who, despite a debilitating illness, provided valuable insights to the gunnery of Prince of Wales and Hood during the Denmark Strait battle of 24 May 1941.”
Were they just being kind? Readers may judge for themselves.
Pg 220 – “Once Prince of Wales came within 21,500 meters of Bismarck, Commander McMullen had the Type 284 radar turned on, as spray and water were masking his 4.75-meter (15-ft) rangefinder on the forward control tower, With this radar, he could check on the ranges being taken from his rangefinder and his rough approximations using a block check card. The closing rate to his target was increasing, and the lenses of the rangefinders in the two forward turrets were covered with spray for a short time before a course change was made. Conditions for ranging on the enemy’s masts were also not easy. As a result it took two down-ladders to find the target. The Type 284 radar did not have a calibration scale for ranges of more than 22,000 meters (~24,000 yards), and some malfunctions and interference made this radar difficult to use; it later failed from gun blast damage. The Type 281 radar was switched on too late, and it later failed from battle damage.
(Byron note – The course change mentioned above almost certainly refers to “Prince of Wales’” alteration of course to port at ~0555. It is interesting to note that, after this turn, target bearing for all intents and purposes remained constant at 330deg (true) from ~0555 through ~0600 hrs. McMullen’s salvo plot suggests as well that the shooting of Prince of Wales improved from ~0556, when range had gotten down to ~20,000 yards - maximum effective range (IMO) for the 15-ft aloft range-finder. The record appears to be silent regarding any range cuts provided by any of the turret rangefinders; if anyone has any data on this, I’d be thrilled to see it.)
Byron
Re: Gun precision / dispersion
Hallo Byron,
thank you. So it could actually be, that PoW never got any range other than from the small 15ft device and the estimation via block check cards. And still did PoW show the best long range hit rate of any Royal Navy battleship in a high speed naval battle in ww2.
thank you. So it could actually be, that PoW never got any range other than from the small 15ft device and the estimation via block check cards. And still did PoW show the best long range hit rate of any Royal Navy battleship in a high speed naval battle in ww2.
Re: Gun precision / dispersion
Hans, or atually anybody, can you provide the height of other directors, range finders and fire control radars as well?
43m for Tirpitz is a number I was wanting. I would be glad to see numbers of other ships to get a comparison.
Best regards
Frank
43m for Tirpitz is a number I was wanting. I would be glad to see numbers of other ships to get a comparison.
Best regards
Frank
-
Byron Angel
- Senior Member
- Posts: 1658
- Joined: Sun Mar 06, 2011 1:06 am
Re: Gun precision / dispersion
>>>>> If I'm interpreting McMullen's letter properly, he seems to say that even ranging by the 15-ft duplex rangefinder was intermittent. McMullen probably deserves the lion's share of credit for whatever hits were scored upon Bismarck that day.
>>>>> Re longest distance hit by a British battleship in WW2, I believe that WARSPITE was credited with a hit at ~26,000 yds.And still did PoW show the best long range hit rate of any Royal Navy battleship in a high speed naval battle in ww2?
Byron
-
hans zurbriggen
- Senior Member
- Posts: 425
- Joined: Sat Dec 21, 2019 8:15 am
Re: Gun precision / dispersion
Hello Frank,
I'm afraid I don't have any info re. other battleship height.
I know just that Richelieu had to remove part of her foretop to pass under Brooklyn Bridge when entering New York yards for refit.
A well known photo (see link) shows the ship just after bridge, under tugs, without her 2 top directors: a 380 mm and a 150 mm director. Brooklyn Bridge passage height is 41 meters, but I don't know how much tolerance they wanted, difficult to judge also from a film scene (see link)
hans
https://www.reddit.com/media?url=https% ... xydz71.jpg
https://www.google.it/search?q=+battles ... y9fek,st:0
I'm afraid I don't have any info re. other battleship height.
I know just that Richelieu had to remove part of her foretop to pass under Brooklyn Bridge when entering New York yards for refit.
A well known photo (see link) shows the ship just after bridge, under tugs, without her 2 top directors: a 380 mm and a 150 mm director. Brooklyn Bridge passage height is 41 meters, but I don't know how much tolerance they wanted, difficult to judge also from a film scene (see link)
hans
https://www.reddit.com/media?url=https% ... xydz71.jpg
https://www.google.it/search?q=+battles ... y9fek,st:0
-
José M. Rico
- Administrator
- Posts: 1008
- Joined: Sat Oct 16, 2004 10:23 am
- Location: Madrid, Spain
- Contact:
Re: Gun precision / dispersion
That must be the total height from the keel I guess.hans zurbriggen wrote: ↑Mon Sep 11, 2023 4:50 pmHowever, Tirpitz main director rangefinder was at 40.5 meters height and radar antenna was at around 43 meters.
The height from the waterline should be something around 32 meters depending on the ship's draft.
Re: Gun precision / dispersion
We've discussed this in the past. Mcmullen's memory is faulty and he's confused events that happened in the hours/days after the Denmark Straits battle with the events that happened on the morning of 24 May 1941. PoW engaged Bismarck 25 May and was able to obtain radar ranges on that occasion:Byron Angel wrote: ↑Mon Sep 11, 2023 6:25 pm McMullen's (Gunnery Officer - HMS Prince of Wales) letter to Ludovik Kennedy re Denmark Strait -
Note - One can also access an IWM oral document featuring McMullen here: https://www.iwm.org.uk/collections/item/object/80010751
McMullen’s Letter
The following text is an extract from a letter written by the late Colin McMullen (Gunnery Officer of H.M.S. Prince of Wales during the Battle of the Denmark Strait) to author Ludovic Kennedy in the early 1970s. Apparently, this was for Kennedy's excellent book, "Pursuit." Special thanks to Bruce Taylor for sharing this with us.
"Bismarck Battle
Arthur Skipwith has forwarded on your letter dated 7th November and the following main points may be of interest. I am afraid I cannot now remember some of the details, but briefly "Prince of Wales" had two radar sets capable of feeding range into the 14 inch gunnery system. The main set purely designed to feed into the 14 inch system, had an aerial which was attached to the main Director Control Tower; as a result it was trained directly on to the target by the Main Director Trainer. Unfortunately the limiting range on the "Tube" was 24,000 yards.
The second set was the air warning system, the aerial of which was situated on top of the mainmast. Although primarily an air warning set, it was possible to feed ranges from a surface target into the 14 inch Transmitting Station.
This set had a more or less unlimited range.
"Prince of Wales" had the following optical range finders feeding range directly into the 14 inch Transmitting Station:- Two very large range finders, (about 45 feet I think) one at the back of A Turret and one at the back of Y Turret. One "Duplex" range finder (about 35 feet I think) at the back of B Turret (2 separate range finders inside one instrument). One "Duplex' range finder (15 feet) under my feet in the 14 inch Director Control Tower. (Total 6 range finders). These fed automatically into the range "Plot" in the Transmitting Station a small letter being automatically typed showing the range of the range finder concerned, whenever a "cut" was obtained.
I think the ranges from the radar sets were not plotted automatically but were plotted by pencil under the direction of the T. S. Officer, Mr. Murphy, Commissioned Dagger Gunner, from range repeaters.
The ship, although suffering from teething troubles in her 14 inch mountings, had done several shoots and fire control exercises including opening fire runs firing one gun "thrown-off" at a target ship to exercise the open fire procedure.
It was therefore sad that only the scantiest information was available on this particular occasion to obtain an accurate open fire range.
The story as far as I can remember is as follows.
Y Turret was "wooded" as "A " arcs were not open. A rough sea and strong wind on the starboard bow together with our high speed resulted in a continuous stream of spray and water over A and B Turrets, and in spite of their window washing gear neither obtained any ranges before opening fire.
Both radar sets had been switched off to maintain Radar Silence and were switched on at the order "enemy in sight".
The main gunnery set due to its technical limitation was unable to pass ranges until the range was reduced to 24,000 yards.
As far as I can remember the range on opening fire was about 26, 000 yards.
No range was obtained before opening fire from the air warning radar set; I think (but am not certain} due to having been switched-off and slowness in becoming operational after being switched-on again. (Blutarski Note – see Paddon on this for another p.o.v.)
That left the 15 foot 14 inch Director Control Tower Duplex Range finders which were high up and clear of spray but the range was very extreme for such small range finders.
"Hood and "Prince of Wales" fired in their own time sectors, each controlling their own gunfire.
This procedure although independent, laid down that gun ranges be interchanged between ships before opening fire but we received no gun ranges from Hood and I was unable to pass any to her, so I expect she suffered the same trouble, being also a "wet" ship with her main optical range finders low down on the back of the Turrets.
We actually opened fire with a gull range obtained from one range from the 15 foot Director Control Tower Duplex range finders "meaned" with my estimated range. This latter was done, if you remember, with "Block Sketch Cards" where the height of the enemy's upper deck is observed relative to the horizon.
Once the range was down to about 20,000 yards the T. S. had a good Range Plot including radar ranges from the 14 inch Director Tower set and continual optical range finder ranges, certainly from "B" Turret.
It is of interest that having the "windward berth" was even in comparatively modern days an advantage where spray was concerned.
I also remember noticing the large range finders "high-up" in Bismarck (as they were in all large German ships}.
The procedure at that time was for the "Spotting Officer" (Lt. Cdr . Skipwith, R.N. ) (on my right} to give the routine orders, "enemy in sight" etc., "bearing and description"; for the "Rate Officer" Lieut. Buxton RNVR (on my left), to give Enemy's Inclination and speed while the G.O. in the middle, communicated with the Captain, kept an overall view and then, being in direct touch with the T.S. Officer (Mr. Murphy) discussed the range plot and arising therefrom the open fire range.
Thus on this occasion I remember almost "imploring" Mr. Murphy for ranges and his reply "No Ranges".
I can also remember asking the W/T operator (by my left foot) for ranges from Hood, also negative. Then Mr. Murphy's report of one range from D. C. T. and my "estimation by card"; then Hood opening fire and we following as per drill in our "time sector" on a mean of two ranges. (One from a 15 foot range finder and one estimated).
I hope this gives a picture of the opening range picture; a sorry story in the vital "opening fire" stage but a good range plot as the range was reduced.
What was "dramatic" at the start was the speed with which everything happened, with both squadrons steaming at about 27 knots and a very-high closing rate.
I remember Skipwith and I discussing the leading ship, and either he or I said "Looks like Strasburg" in other word"Prince Eugen" looked like a "big ship" but "Bismarck" even at that range looked much bigger, hence our disregard of Hood's original concentration signal to engage the "left hand ship".
On this point, Hood had an old fashioned open spotting top with the wind probably roaring through it whereas we had a modern enclosed Director Control Tower with the most modern large optical instruments."
- - -
Page 572; Note 27 - “Battleship Bismarck: A Design and Operational History”, Garzke, Dulin, Jurens -
“Captain Colin McMullen was critical of the design of the King George V class. He considered them to be wet ships because of their lack of flare at the bow. At full speed or in heavy sea, their bows dug in and caused much spray formation that hampered the rangefinders in two forward turrets from finding their targets. This criticism, along with others concerning the lack of bow freeboard in these battleships, was instrumental in the bow design of HMS Vanguard, the last battleship delivered to the Royal Navy.
- - -
The authors of “Battleship Bismarck: A Design and Operational History”, Garzke, Dulin, and Jurens, had this to say about Lt-Cmdr McMullen’s contributions to their research (provided several decades after McMullen’s earlier correspondence with Ludovic Kennedy) –
“The authors especially want to acknowledge the assistance of Captain Colin McMullen who, despite a debilitating illness, provided valuable insights to the gunnery of Prince of Wales and Hood during the Denmark Strait battle of 24 May 1941.”
Were they just being kind? Readers may judge for themselves.
Pg 220 – “Once Prince of Wales came within 21,500 meters of Bismarck, Commander McMullen had the Type 284 radar turned on, as spray and water were masking his 4.75-meter (15-ft) rangefinder on the forward control tower, With this radar, he could check on the ranges being taken from his rangefinder and his rough approximations using a block check card. The closing rate to his target was increasing, and the lenses of the rangefinders in the two forward turrets were covered with spray for a short time before a course change was made. Conditions for ranging on the enemy’s masts were also not easy. As a result it took two down-ladders to find the target. The Type 284 radar did not have a calibration scale for ranges of more than 22,000 meters (~24,000 yards), and some malfunctions and interference made this radar difficult to use; it later failed from gun blast damage. The Type 281 radar was switched on too late, and it later failed from battle damage.
(Byron note – The course change mentioned above almost certainly refers to “Prince of Wales’” alteration of course to port at ~0555. It is interesting to note that, after this turn, target bearing for all intents and purposes remained constant at 330deg (true) from ~0555 through ~0600 hrs. McMullen’s salvo plot suggests as well that the shooting of Prince of Wales improved from ~0556, when range had gotten down to ~20,000 yards - maximum effective range (IMO) for the 15-ft aloft range-finder. The record appears to be silent regarding any range cuts provided by any of the turret rangefinders; if anyone has any data on this, I’d be thrilled to see it.)
Byron
This is from Roskill's history, The War at Sea, Volume 1:B - Events during First Action
24th May. - Enemy was sighted at 0537, range about 38,000 yards. The similarity between the two enemy ships was amazing and with the smaller ship "nearer", it was difficult at first to distinguish which was Bismarck.
2. This difficulty was evidently experienced in Hood as B.C.1 signalled GSB/337/L1 at 0549 (engage left-hand ship bearing 337° ), followed by GOB1 (shift target one ship right) just before opening fire.
The ships were at an inclination of about 130° and Gunnery and Spotting Officers in the fore D.C.T. both agreed at the time that at long range Prinz Eugene (sic) looked exactly like Dunkerque when "X" and "Y" turrets were "merged" into the after superstructure.
3. The rangefinders failed to develop a satisfactory range plot before opening fire; the fore D.C.T. 15-ft rangefinder was the only rangefinder which had a reasonable chance; the closing rate was very high and "A" and "B" rangefinders were able to see the enemy's superstructure for a short time only before "table turning." Conditions for ranging on the enemy's masts were not easy. As a result it required two down ladders to find the target.
4. No results were obtained from either Type 281 or 284 R.D.F.; it is understood that Signal School Officers are now of the opinion that Type 281 suffered interference and Type 284 was defective, although it appeared at the time that 284 was also suffering from interference....
...D - Events during the Third Action
25th May. - One double salvo was fired at 0131 at a range of 20,000 yards at an enemy ship which might have been Bismarck or Prinz Eugen. A good R.D.F. range was obtained but the target was then lost in funnel smoke and mist and fire could not be continued.
http://www.hmshood.org.uk/reference/off ... 09guns.htm
It's a historical fact that in May 1941 that Type 284 could range accurately beyond 24000 yds.As regards radar, the British ships had both been recently fitted with new sets specially designed to obtain ranges for their main armaments and capable of producing results on a battleship target out to a range of ten or eleven miles. The Prince of Wales' modem search radar set could also transmit ranges to the main armament. It must, however, be remembered that radar was at this time still in its infancy and that many ships were experiencing difficulty in obtaining the designed performance from their sets, owing, in no small measure, to inexperience of the operators in their maintenance and use. The Admiralty, fully alive to the great potentialities of this new development, had sent an officer to check both ships' sets at Scapa (16) —by chance on the day before they sailed on this operation—and they had then produced the designed performance. Both ships twice exercised with their sets during the westward passage and reported them correct. The radar policy ordered by Admiral Holland during the approach had, probably for reasons already suggested, forbidden the use of any set unless and until action became imminent, and it seems certain that transmission was not started until very shortly before fire was opened. In the Prince of Wales no results were obtained from either of her sets throughout the action. Yet the Suffolk, using a set identical to that fitted to the battleship’s main armament, was successful in holding the Bismarck out to ten miles range. Whether the failure to obtain good ranging results was avoidable or not must remain a matter for conjecture...
(16) The officer in question was the author of this history.
KGV's GAR of 27 May 1941 states
The enemy was sighted at 0842 on a bearing of Green 7°. The range-takers
were unable to obtain ranges owing to the visibility so that an estimated range
of 24,000 yards was ordered preparatory to opening fire. Almost immediately
afterwards Type 284 obtained a cut of 25,100 yards and this was tuned to...
Here RA Burt (British Battleships) quotes from a report (probably written by Stephen Roskill) after Type 284 was installed on HMS Hood:
Hood was fitted with Types 282, 284 and 285 in
Scapa Flow, but in such haste that many of the installations were incorrectly wired.
Tests were carried out ranging on King George V with the following results:
Outward Run. 11,000 yards … saturation of target; 14,000 yards … 10 times the
signal; 16,000 yards … 6 to 8 times the signal; 27,000 yards … VA times the
signal; 27,300 yards … the signal was lost. The echo was very spasmodic from
25,000 yards, but the plot of the run taken from RDF ranges and bearings was a
very good one. Inward run. King George V came in on an unknown bearing and
was picked up at 24,700 yards; it was thought that it would have been possible
to pick up the target earlier but for the fact that she came in on the same bearing
as land echoes. The destroyers escorting King George V were picked up at
16,300 yards.
-
Byron Angel
- Senior Member
- Posts: 1658
- Joined: Sun Mar 06, 2011 1:06 am
Re: Gun precision / dispersion
This is the document I prefer to go by -
CB 4112 (4) (1942)
HANDBOOK ON THE USE OF R.D.F. FOR GUNNERY PURPOSES
TYPE 284
Admiralty Gunnery Branch, SW1 – Dated 19th July 1942.
quote -
RANGING CAPABILITIES
4. The results tabulated below show the average maximum usable ranges reported by the Commander-in-Chief, Home Fleet, from experience gained in the first five ships fitted with Type 284.
Target - - - - - - - - - - - - - - - Average Maximum Usable Range
Land Echoes - - - - - - - - - - - 50,000 yards
Battleship - - - - - - - - - - - - - 18,000 “
Large Cruiser - - - - - - - - - - - 15,000 “
Small Cruiser - - - - - - - - - - - 12,000 “
Destroyer - - - - - - - - - - - - - 8,000 “
Submarine on Surface - - - - - 5,000 “
Greater ranges can at times be obtained: for instance, ranges of an “Aurora” class cruiser have been taken at 28,000 yards when the Director Trainer could see the target and was keeping the aerials accurately trained, but the echoes in these cases are weak and fluctuating and cannot be relied upon in practice.
These ranges are somewhat less than were expected from the results obtained in the first sea trial referred to in Paragraph 1, and the possibilities of improving on them are still under investigation.
- unquote
Some other items of interest -
> In general, it was recommended that the range accuracy of the early Type 284 not be considered any better than +/- 150 yards.
> A range adjustment of 400 yards, on average, would be required to obtain a straddle.
> Transmission of range data was not automatically fed into the AFCT. Range was manually read/interpreted from the cathode ray trace by the "range reader" (radar operator) in the Type 284 office; he would pass the range reading to a companion sitting adjacent, who would pass it to the T.S. via electro-mechanical drum counter (see Paddon's account). Once it reached the T.S, the data would be input into the AFCT.
As far as the overall accuracy and value of Mr McMullen's recollections of 24 May 1941 are concerned, perhaps Mr Jurens can comment; he and his co-authors (Dulin and Garzke) interviewed Mr McMullen shortly before his passing for their recent book on BISMARCK.
,
Byron
CB 4112 (4) (1942)
HANDBOOK ON THE USE OF R.D.F. FOR GUNNERY PURPOSES
TYPE 284
Admiralty Gunnery Branch, SW1 – Dated 19th July 1942.
quote -
RANGING CAPABILITIES
4. The results tabulated below show the average maximum usable ranges reported by the Commander-in-Chief, Home Fleet, from experience gained in the first five ships fitted with Type 284.
Target - - - - - - - - - - - - - - - Average Maximum Usable Range
Land Echoes - - - - - - - - - - - 50,000 yards
Battleship - - - - - - - - - - - - - 18,000 “
Large Cruiser - - - - - - - - - - - 15,000 “
Small Cruiser - - - - - - - - - - - 12,000 “
Destroyer - - - - - - - - - - - - - 8,000 “
Submarine on Surface - - - - - 5,000 “
Greater ranges can at times be obtained: for instance, ranges of an “Aurora” class cruiser have been taken at 28,000 yards when the Director Trainer could see the target and was keeping the aerials accurately trained, but the echoes in these cases are weak and fluctuating and cannot be relied upon in practice.
These ranges are somewhat less than were expected from the results obtained in the first sea trial referred to in Paragraph 1, and the possibilities of improving on them are still under investigation.
- unquote
Some other items of interest -
> In general, it was recommended that the range accuracy of the early Type 284 not be considered any better than +/- 150 yards.
> A range adjustment of 400 yards, on average, would be required to obtain a straddle.
> Transmission of range data was not automatically fed into the AFCT. Range was manually read/interpreted from the cathode ray trace by the "range reader" (radar operator) in the Type 284 office; he would pass the range reading to a companion sitting adjacent, who would pass it to the T.S. via electro-mechanical drum counter (see Paddon's account). Once it reached the T.S, the data would be input into the AFCT.
As far as the overall accuracy and value of Mr McMullen's recollections of 24 May 1941 are concerned, perhaps Mr Jurens can comment; he and his co-authors (Dulin and Garzke) interviewed Mr McMullen shortly before his passing for their recent book on BISMARCK.
,
Byron
Re: Gun precision / dispersion
Respectfully, the above info regarding average Type 284 ranges is quite useless and likely to be misleading. What matters is the performance of a particular radar , on a particular ship, at a particular moment in time, and we get that info from the ship's GAR or Report of Proceedings and/or from test reports.Byron Angel wrote: ↑Tue Sep 12, 2023 4:05 am This is the document I prefer to go by -
CB 4112 (4) (1942)
HANDBOOK ON THE USE OF R.D.F. FOR GUNNERY PURPOSES
TYPE 284
Admiralty Gunnery Branch, SW1 – Dated 19th July 1942.
quote -
RANGING CAPABILITIES
4. The results tabulated below show the average maximum usable ranges reported by the Commander-in-Chief, Home Fleet, from experience gained in the first five ships fitted with Type 284.
Target - - - - - - - - - - - - - - - Average Maximum Usable Range
Land Echoes - - - - - - - - - - - 50,000 yards
Battleship - - - - - - - - - - - - - 18,000 “
Large Cruiser - - - - - - - - - - - 15,000 “
Small Cruiser - - - - - - - - - - - 12,000 “
Destroyer - - - - - - - - - - - - - 8,000 “
Submarine on Surface - - - - - 5,000 “
Greater ranges can at times be obtained: for instance, ranges of an “Aurora” class cruiser have been taken at 28,000 yards when the Director Trainer could see the target and was keeping the aerials accurately trained, but the echoes in these cases are weak and fluctuating and cannot be relied upon in practice.
These ranges are somewhat less than were expected from the results obtained in the first sea trial referred to in Paragraph 1, and the possibilities of improving on them are still under investigation.
- unquote
Some other items of interest -
> In general, it was recommended that the range accuracy of the early Type 284 not be considered any better than +/- 150 yards.
> A range adjustment of 400 yards, on average, would be required to obtain a straddle.
> Transmission of range data was not automatically fed into the AFCT. Range was manually read/interpreted from the cathode ray trace by the "range reader" (radar operator) in the Type 284 office; he would pass the range reading to a companion sitting adjacent, who would pass it to the T.S. via electro-mechanical drum counter (see Paddon's account). Once it reached the T.S, the data would be input into the AFCT.
As far as the overall accuracy and value of Mr McMullen's recollections of 24 May 1941 are concerned, perhaps Mr Jurens can comment; he and his co-authors (Dulin and Garzke) interviewed Mr McMullen shortly before his passing for their recent book on BISMARCK.
,
Byron
The first 5 ships to be fitted with Type 284 were a mix of cruisers and battleships, so average ranges were likely to be worse than that fitted to a KGV class battleship, if only because of the lower height of the radar antennae on Aurora but it does show that at a particular moment in time ranges at 28K yds could be obtained.
Mcmullen was human and memories fade! There's nothing more to said about that. Even Mcmullen's letter to Ludovic Kennedy was written 30+ years after the fact.