Scharnhorst w/ 38cm's and other improvements

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Alberto Virtuani
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Re: Scharnhorst w/ 38cm's and other improvements

Post by Alberto Virtuani » Thu Jan 31, 2019 2:24 pm

Thanks, therefore:

285 is a gunnery radar able to direct blind fire effectively, but we don't know up to which range it was usable.

281 and 273 are air and surface warning that can give the range (but not the bearing) that can be spotted from the flashes with witch "tolerance" ? 2 to 3 degrees I guess for instant flashes in the night.... not really an effective blind fire capability, I would say, just a help.


In any case, none of these above sets can be compared to FuMO26 blind fire capabilities in terms of combined max range, range accuracy, bearing accuracy and FoS spotting precision. Only the single Type 284 can (I understand however not very favorably, in its 1943 version).


Bye, Alberto
"It takes three years to build a ship; it takes three centuries to build a tradition" (Adm.A.B.Cunningham)

"There's always a danger running in the enemy at close range" (Adm.W.F.Wake-Walker)

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Re: Scharnhorst w/ 38cm's and other improvements

Post by dunmunro » Thu Jan 31, 2019 3:35 pm

Alberto Virtuani wrote:
Thu Jan 31, 2019 2:24 pm
Thanks, therefore:

285 is a gunnery radar able to direct blind fire effectively, but we don't know up to which range it was usable.

281 and 273 are air and surface warning that can give the range (but not the bearing) that can be spotted from the flashes with witch "tolerance" ? 2 to 3 degrees I guess for instant flashes in the night.... not really an effective blind fire capability, I would say, just a help.


In any case, none of these above sets can be compared to FuMO26 blind fire capabilities in terms of combined max range, range accuracy, bearing accuracy and FoS spotting precision. Only the single Type 284 can (I understand however not very favorably, in its 1943 version).


Bye, Alberto
Type 281 was expressly designed for gunnery, both surface and air along with air warning capability. It had bearing accuracy of .5 degrees (30 arc minutes) which was sufficient to put the director's optics onto the target.
TYPE 281 SEA TRIALS
The first sea trials of the new 3.5m air warning set in the new cruiser Dido
in September/October 1940, conducted by S.E.A. Landale and D.S.
Watson from Signal School, were an outstanding success, qualified only
by difficulties with the mechanical system for controlling and rotating the
aerials. (It was so noisy, many operators called it the 'mangle'.) A Hudson
aircraft at 25,000ft was detected at over 100 miles, one at 1,OOOft at 25
miles; Dido's sister-ship Phoebe was detected at 9.5 miles and a trimmeddown
submarine at 2.75 miles. (During Dido's passage from Liverpool to
Scapa, Watson, operating the type 281, detected a ship at around 7 miles
and it remained on a constant bearing until Dido, on radar information
alone, altered course to avoid. Was this the first example of radar collision
avoidance?)
But there were two other aspects which particularly interested the
Naval Staff when the trial results were circulated round the Admiralty.
First, the flight of 5.25in projectiles had been followed and splashes seen
out to 5,000 yards, making blind spotting for range quite possible which,
with a bearing accuracy of ±.5deg, could have a significant effect on night
fighting even though it could not give an elevation datum for the director
layer. Secondly, the characteristics of the type 281 aerial gave a wel ldefined
first minimum, making the method of height estimation
described in Appendix C much easier than with type 279.
It has to be said that in the event the gunnery capabilities of types 279
and 281 were seldom used at sea - with the honourable exception of the
Battle of Cape Matapan in March 1941 - first because of commanding
officers' reluctance to abandon all-round warning, secondly because,
even by mid-1941, a high proportion of big ships were already fitted with
additional radar sets dedicated to gunnery. Indeed, by the end of 1942 no
new type 279s were fitted with the ranging panel and many were
removed from existing sets. It could not be removed immediately from
type 281, being an integral part of the set.
Radar at Sea, Howse



I don't understand why you feel that FuMO26 was so good as Scharnhorst's gunnery was not very effective especially as DoY was trying to steer as steady course as possible to aid her own gunnery.

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Alberto Virtuani
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Re: Scharnhorst w/ 38cm's and other improvements

Post by Alberto Virtuani » Thu Jan 31, 2019 4:32 pm

Hello everybody,
"Type 281 was expressly designed for gunnery, both surface and air along with air warning capability. It had bearing accuracy of .5 degrees (30 arc minutes) which was sufficient to put the director's optics onto the target. "
Sufficient to train optic, not to direct blind fire in the dark, when optics are unusable anyway.

I base my judgement on FuMO26 upon Dave Saxton authoritative data (viewtopic.php?f=36&t=1724&hilit=FuMO26&start=30#p63707).

Why Scharnhorst fired badly not scoring more hits is due to: 1) 66% of her main armament put out of action early in the battle, 2) her own avoiding maneuvers (impacting gunnery more than enemy maneuver IMO), 3) sea state.
We don't know how long could the aft set be kept in action under the deluge of fire Scharnhorst was receiving from all British ships. DoY was not firing very well too...


Bye, Alberto
"It takes three years to build a ship; it takes three centuries to build a tradition" (Adm.A.B.Cunningham)

"There's always a danger running in the enemy at close range" (Adm.W.F.Wake-Walker)

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Re: Scharnhorst w/ 38cm's and other improvements

Post by dunmunro » Thu Jan 31, 2019 9:11 pm

Alberto Virtuani wrote:
Thu Jan 31, 2019 4:32 pm
Hello everybody,
"Type 281 was expressly designed for gunnery, both surface and air along with air warning capability. It had bearing accuracy of .5 degrees (30 arc minutes) which was sufficient to put the director's optics onto the target. "
Sufficient to train optic, not to direct blind fire in the dark, when optics are unusable anyway.

I base my judgement on FuMO26 upon Dave Saxton authoritative data (viewtopic.php?f=36&t=1724&hilit=FuMO26&start=30#p63707).

Why Scharnhorst fired badly not scoring more hits is due to: 1) 66% of her main armament put out of action early in the battle, 2) her own avoiding maneuvers (impacting gunnery more than enemy maneuver IMO), 3) sea state.
We don't know how long could the aft set be kept in action under the deluge of fire Scharnhorst was receiving from all British ships. DoY was not firing very well too...


Bye, Alberto
It's hard to hit a high speed target that is salvo chasing, even in daylight.

Optics are not unusable at night (why would you think that?) and optics played a large role in the destruction of Scharnhorst.

The AFCT would use the range and bearing data provided by Type 281 to create a range and bearing plot and from that an extremely accurate bearing could be determined. Additionally .5 degrees was sufficient to nearly centre the target in the director's optics and thence it would be simple to precisely centre them on the gunflashes (or via star shell illumination)

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Re: Scharnhorst w/ 38cm's and other improvements

Post by Alberto Virtuani » Thu Jan 31, 2019 11:25 pm

Hello everybody,
"Optics are not unusable at night...it would be simple to precisely centre them on the gunflashes"
sure, star shells and projectors can play a role for the "optics". Here we (hypothetically) speak about a true blind firing in a duel between DoY and SH alone, with SH that is not "illuminated" by the other British ships that were surrounding her.

I don't know how optics can be helped by flashes at night: the day movie of Bismarck at Denmark Strait shows a camera "flashed" by the "flash"....even when looking at PoW salvo from 15 km in full daylight, the "bearing" of the flash is "covering" something like 5°, and the exact position of the ship inside the flash is very uncertain.

PoW_flashes.jpg
PoW_flashes.jpg (78.94 KiB) Viewed 1713 times

At night, the flash is blinding everything: I don't think the enemy gun flashes can help gunnery a lot (of course it tells that a ship is there, but it doesn't give a "bearing" usable to calculate a firing solution or the train the rangefinder exactly, it looks to me more a problem instead.


Bye, Alberto
"It takes three years to build a ship; it takes three centuries to build a tradition" (Adm.A.B.Cunningham)

"There's always a danger running in the enemy at close range" (Adm.W.F.Wake-Walker)

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Re: Scharnhorst w/ 38cm's and other improvements

Post by Dave Saxton » Fri Feb 01, 2019 4:20 pm

Duke of York did not use any other radar type to direct fire at Scharnhorst after the 284 went down. Neither did it use 273 to assist in spotting after the 284 was unable to spot the fall of shot. Instead it asked any other British ship via voice radio that could spot the fall of shot to forward their observations to DoY.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Scharnhorst w/ 38cm's and other improvements

Post by dunmunro » Fri Feb 01, 2019 4:37 pm

You've proven that the IJN couldn't fight at night...and that the RN wasted all those interwar years training to use optical FC at night.
This from the Baron:
... I could see through my director our shadowy attackers
coming nearer and nearer, twisting to attack—each time, I thought, "Now the torpedoes are
hissing out of the tubes"—then drawing off. They dared not stay near us for long because of the
speed with which our gunnery found its targets. This, in spite of the fact that our fire control had
to contend with occasional heavy rolling of the ship caused by seas coming in off our beam and
with the even greater disadvantage of our inability to maneuver.
So the Baron could put his director onto the target and track it optically.

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Re: Scharnhorst w/ 38cm's and other improvements

Post by dunmunro » Fri Feb 01, 2019 4:46 pm

Dave Saxton wrote:
Fri Feb 01, 2019 4:20 pm
Duke of York did not use any other radar type to direct fire at Scharnhorst after the 284 went down. Neither did it use 273 to assist in spotting after the 284 was unable to spot the fall of shot. Instead it asked any other British ship via voice radio that could spot the fall of shot to forward their observations to DoY.
Type 281 was tracking and ranging on Scharnhorst throughout (when ranges were less than 12.75 nm) while DoY's 273Q was used for all round warning via it's PPI display but that was Fraser's decision, not a limitation of the radar. Type 285 was used continually as well for 5.25in ranging.

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