5"/38 engagement envelope

[Northstar98]

Hi everyone,

The 5" mounts on the Essex appear to track aircraft but, in the majority of tests I've run, only actually engage below 2500 ft.

In the tracks below I have a single Ju 88 A-4 at various altitudes that should be well within the engagement envelope of the guns. The only track where the guns engage reliably is the 2.4k ft track.

The other thing is the range at which the guns start firing - according to the linked trajectory chart, the upper-limit of the range should be around 15000 yards (~13.7 km) for a target flying at 10,000 ft and around 16000-17000 yards (~14.5-15.5 km) maximum for a target at 2500 ft. In DCS however, the guns first start firing at around 1.5 nautical miles (or about 3000 yards or about 2.8 km) and only get a single salvo off (and even then, not all the mounts engage) before the carrier is overflown. Each gun should be able to fire at a rate of 15-22 rounds per minute (or 30-44 rounds per Mk 32 mount, as used on the Essex).

Part of the range issue may be down to the directors (Mk 37 GFCS), whose radar ranges (for the Mark 12) are half of what they should be (they also are defined with the wrong frequency range). In Essex_Class_Carrier_1944.lua, the director's "distanceMax" is set to 25 km. The Mark 12 radar (the rectangular antenna on top of the director, mark 22 is the elliptical antenna beside it) should be able to track bomber-sized targets out to ~41 km [source]

Suffice to say, these issues drastically limit the effectiveness of these guns.

Essex_5-inch38_Engage_2.4kft.trk Essex_5-inch38_NoEngage_2.5kft.trk Essex_5-inch38_NoEngage_5kft.trk Essex_5-inch38_NoEngage_10kft.trk

Edited June 19 by Northstar98

[Northstar98]

Just as an addendum, behaviour seems really inconsistent and appears to affect nearly all large-calibre WWII AAA I’ve tested (the Samuel Chase seems to be the exception but more testing required), in some form, not just the Essex (though Magnitude 3s assets are affected the most). 

Edited June 23 by Northstar98
Added link, bug affects all WWII, land-based, large calibre AAA to some degree

[Silver_Dragon]

More data about that system:
http://pwencycl.kgbudge.com/F/d/FD_fire_control_radar.htm

https://www.ibiblio.org/hyperwar/NHC/NewPDFs/USN/USN Manuals and Reports/USN.Characteristics.Naval.Fire.Control.Radar.1954-11-12.pdf

https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/u/operational-characteristics-of-radar-classified-by-tactical-application.html