Thoughts on US Navy Anti-Aircraft Gunfire in World War II

@GuadaBattle remarked last night on the incredible losses of the Japanese air fleet during the Battle of Santa Cruz. I offered him a few thoughts on the subject off the top of my head, and since I’m lazy, I thought I’d share them with you here.

First, the obvious- radar. The early warning radar provided cut down on the numbers of surprise attacks. If incoming raids were atrited by the CAP, even better, as it tended to break up attacks, reducing the chance of saturation.

Second, fire control, both as methodology and as a technical matter. The Navy quickly devised doctrine with regard to which ships covered which sectors of a task force or group, and had officers specifically tasked to this control measure, not just gunnery officers doubling duty.

On the technical side, the Japanese had good fire control, but the US Mk37 fire control system (and variants of it) was the outstanding anti-air gunfire director system of the war. 5″/38 operating in total director control was quite deadly. Couple this with the Mk51 director control of the 40mm batteries. A separate pedestal director control station, away from the blast of the guns, featuring a gyrostabilized optical fire director controlled each 40mm mount.

Japanese ships had director controlled 5″ guns, but they never seemed to be nearly as effective as ours. They lacked a weapon in the 40mm range, using instead triple, twin, and single 25mm cannon, all of which lacked director control.

Add in the scads of relatively ineffective, but quite visible 20mm Oerlikons all over US ships, and there were a lot of tracers flying around!

Typically, a Fletcher class DD of the Guada period would mount two twin 40mm forward of the bridge, and a twin mount aft. By the end of the war, they would often have the twins forward, a quad replacing one set of torpedo tubes, two twins in the waist.

One of @GuadaBattle’s twitter respondents also mentioned another fairly obvious point- Japanese aircraft were lightly built, in a structural sense, and lacked armor and self sealing fuel tanks. That was a tradeoff that boosted their range and performance, but made them much more vulnerable to weapons effects.

The battle of Santa Cruz was where the VT proximity fuze made its Pacific debut. We’ll discuss the history of that a bit more later, but I wanted to share a picture a reader sent a couple months ago. During the Okinawa campaign, the seaplane tender USS St. George came under kamikaze attack, and engaged with VT fuzed 5”/38.

St George crop

Here’s a cropped version:

St George fuze

With an effective kill radius of about 50 feet, that’s a deadly shot and a prime example of the effectiveness of the VT proximity fuze.