alecsandros wrote:Lutzow's main battery firings against Obdurate at Barents Sea, at 15km, through dense fog, seems to indicate the use of a very precise tracking and spotting system, with no visibility. .
The Luetzow's shooting at Barents Sea is instructive about Seetakt's capabilities for blind firecontrol circa 1942. When Luetzow finally opened fire at 11:38 hours it did so using an optical firing solution initially. But spotting the fall of shot was soon impossible optically, because after the first salvo the target was soon hidden by a heavy snow squal, and splashes from shots of the secondary battery falling short also obscured the target. The range was ~16,000 meters and increasing. The Luetzow then went over to full radar direction. We know that radar was being used to spot the fall of shot, because it was stated that the radar operator had some difficulty spotting, caused by the shock of each 28cm salvo making the indicator "jump". After six minutes they shut down the radar, serviced it, and brought it back into the battle in five minutes. There after it performed well; allowing Luetzow to accurately target the Obdurate.
Seetakt was well set up for spotting the fall of shot using the fine range CRT. The target pip was positioned right in the middle of fine range CRT screen. The amount of range could be zoomed in or out so that there was say 150 meters presented short or long of the target and the splashes short and long of target easily observed.
Spotting for bearing could be done on the fine bearing indicator. The target pip was also positioned in the middle of screen. If the bearing track was off line to the left or the right then the target pip was presented off line to the left or to the right of the center line. Accuracy was within 0.1*. Shell splashes off line could be presented the same way. The bearing resolution would be that of the ½ power beam width, however. (Luetzow’s Seetakt antenna was 16 wavelengths wide)
Spotting the fall of shot for the British Type 284 was problematic because of the nature of the instrumentation. It was a simple A-scope which presented no bearing data. The aim of the antenna was known to be on line or off line by if the target trace flickered or held steady. Obviously spotting for bearing using the radar alone was not possible. Spotting for range was only possible if the shots fell outside of the range resolution window of 150 meters.
Also, from what I understand from Bill Jurens and Garzke's analysis of the NOwaki chase, fall of shot was plotted on the radar screens throughout the engagement, so at ranges in excess of 32km.
As I understand it the shooting at Nowaki was initially done with optical firing solutions (probably radar ranged). But once the range increased to extreme it was switched over to full radar control.
American Mk8 radar was well set up for spotting the fall of shot on its B-scope. Here the target pip was held in the middle of the screen for both range and bearing. Splashes picked up relative to the target were presented for both range and bearing relative to the target. MPI was easily seen. MK8 had only a 2* wide beam. The transmitted beam was panned back and forth through a wide arc and so targets could be discriminated for bearing to a resolution of 2*. The discrimination for range was about 65 meters. MK8mod2 gave a repeater B-scope to the firecontrol computer room. (Mk8mod3 was a Mk8 converted to Mk13)
The British 10cm firecontrol, Type 274, introduced in May 1944 could not spot the fall of shot. The British were more concerned about jamming and other counter measures than the Americans. Type 274 didn’t pan the transmitted beam like Mk8 and Mk13, so that the lobing frequency could not be picked up by the enemy and easily jammed. Only the receiving antenna was lobe switched. But this meant it could not see splashes of shots falling outside the very narrow transmitted beam.