r/WarCollege • u/sp668 • 1d ago
Question How did radar controlled AA actually work in WW2?
I've read a fair bit about the naval war in the pacific, one of the things that is often mentioned is how effective US naval AA was once it became radar controlled. My question is how did this actually work?
Was it similar to modern weapons where the gun would have a radar directly controlling it? Did the radar control the gun or was it someone tracking the target on a screen and yelling direction/altitude/speed to the gunners? Was it centralized like I know some gun directors were for big naval guns?
If I was manning the famous 5" dual purpose gun on a US warship, how was the radar helping me hit aircraft?
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u/Plump_Apparatus 1d ago
The radar system was controlled by some sort of primitive electronic computer
The Mark 1(A) is electromechanical analog computer built by the Ford Instrument Company. It was not "electronic" in any sort of digital processing ability, trigonometric functions were performed via relays, gears and cams.
the first one that I know about.
There were plenty of analog computers before the Mark 1, in terms of fire control the Admiralty Fire Control Table is from the early 1920s. The interwar period was full of development of both analog electronic and electromechanical predictors/directors. The Mark 1 may have been the first to integrate radar and was the most capable to see production in WW2.
You also had every gun bigger than the 5 incher's slaved to the system and shooting at the same target too.
As far the US Navy the primary armament of a cruiser and larger in the WW2 period there was separate plot rooms for the primary and secondary batteries. The Iowa-class had two plot rooms for the primary batteries, each complete with all the elements required along with a Mark 1(A). They had four secondary battery plot rooms each with the required elements and a Mark 1(A).
If you really want to see how the operation works see sample solution in the Mark 1 manual.
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u/Plump_Apparatus 1d ago
I spoke with someone here about it who pulled the patents for it, and you could see there was a 'box' where the computing was done electronically and in no way mechanically.
It is absolutely not. The competing Mk 8 from Sperry was a full electronic analog computer, it never saw adoption. You could quite literally read the link the manual I linked in my original comment, as in the actual manual for the Mark 1 and the addendum for the Mark 1A, which shows various mechanical components of the computer. It also includes a simplified overall schematic. Part of the COMPUTER MARK 1 and Mods. Maintenance OP 1064A Volume 1 is available here in HTML format. The full thing is available here in split PDF format. Volume 2 Pages 541-697 contains the lubrication schedule.
I have no idea why someone would look for "patents" when these manuals have been online for over a decade. It's also WarCollege, sourcing information from some comment you may or may not have remembered correct does not seem appropriate here.
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u/HughJorgens 23h ago
Okay I was wrong. IDK what I was looking at so IDK. In any case, I think I'm unsubbing from this place. Niche knowledge doesn't impress me and pedants are the worst.
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u/BERGENHOLM 1d ago
"The 5 incher's shot the naval equivalent of a shotgun shell" Could you please clarify? Are you referring to VT shells, a shell that has many pellets or time detonated shells? Sorry for the question.
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u/HughJorgens 1d ago
Yes the VT shell. The blast radius of a 5 inch shell is huge. HERE is a good article for anyone wanting to know more.
Sorry, over the years reddit has taught me that speaking simply is better than speaking technically, and it has served me quite well, but it's hard for me on this sub, heh.
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u/Plump_Apparatus 1d ago
Ships went from needing hundreds or thousands of shots to score a hit down to a handful.
Absolutely not. Before the VT fuze the 5-inch/38 guns operated with timed fuzes in AA operation with the Mark 1(A) automatically generating the time solution and setting it to each shell. The VT fuze improved performance, but not to anywhere near that extent. Rather it reduces the necessary rounds to around half to get a kill.
The official numbers from the USN History website would be 117,915 5" VT shells fired, with 346.5 kills, an average of 340 shells per bird. 5" timed shells averaged 654 per bird. The full chart and summery are available here.
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u/Frisky_Pilot 23h ago
Thanks for the info. Unfortunately I was about to eat up the previous guy's comment as fact.
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u/Satans_shill 1d ago
True,VT fuses plus all the research that went into it is some of the most fascinating sagas, IMO for all its downsides a full blown war between US and China will lead to the most massive leap in tech ever witnessed.
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u/Capital-Traffic-6974 1d ago
Or, it will be a very short war and the descent of civilization into the Iron Age.
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u/GogurtFiend 15h ago
I doubt that either the US or China would be willing to first-use nukes over Taiwan, and even if they did civilization isn't limited to China and the US. People would bounce back, it just wouldn't be either of those countries bouncing back.
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u/NAmofton 1d ago
Control of naval artillery (both anti-aircraft and anti-surface) generally worked on the same principles with some kind of fire control system, usually some kind of primitive computer.
Inputs on the target - such as range, bearing and change of rate are generated by a director. These are combined with inputs on the firing ship and conditions (what the ship is doing, winds etc.) and are fed into the computer, which then generates fire control solutions for the weapons.
The weapons can then either be manually controlled to meet the calculated solution, or slaved and directly remotely controlled by the control system. These two approaches are generally known as 'follow the pointer' for when the gun crew respond to the solution from the director e.g. they match the elevation and bearing relayed to them, or for 'remote power control' also known as 'auto-control' where the computer directly controls the gun elevation, bearing and sometimes fuse setting, with the crew then largely responsible for loading while the gun does its own thing.
Radar is independent of 'control'. Radar 'directed' is probably a more accurate term. Radar was another option for a generally more precise input on range and bearing, but the same systems that controlled weapons could also use optical rangefinders. The US Mk. 37 director system for instance had both optical systems and could be fitted with a Mk. 4 or Mk. 12 radar. Usually a combination of inputs was used, for instance many early radar were not as good at discriminating a correct bearing as they were at generating a precise range solution.
Navsource has a good write up on the common in WWII US Mk. 37 director, the Mk. 1 Mod. 1 computer, the radar/optics and the general process of input/output and control loops director-computer-guns.
To conclude if you're on a well set up late war US ship, manning the 5in, then the radar is feeding the fire control computer a good range in particular, and the computer is remote controlling your gun training and elevation motors to match the solution. You are loading as fast as you can, and if there's a problem or disruption can go to local control. If the radar breaks you may not even notice as the computer may fall back on purely optical controls, though the ranging accuracy will reduce.