Transmits aiming information to the turrets. The face can indicate “Zone 9” (or range 9 or bearing 9). If the internal communications go out, the gunners can sneak a glance up to the fire director to see what the heck is going on.
I have see similar things in old shore-defense sites.
That is a lot faster than a small full auto rifle like an m16 or such, which are around 500 -1000 rpm.
But each barrel only fires at 10 per second, it’s the multiple barrels that give it the high rate.
When I was in the Army stationed in Germany, we had some joint ops with not only our own fellow USA branches of service but with NATO as well (always had great names, too, like Caravan Guard and whatnot).
Anyway, we were at a tank range and there was an A-10 exercise going on nearby. I swear, that freaking gun sounds a LOT like a giant belching. It has such a low, fast, growling, deadly sound to it. No wonder tanks scurry in fear when one of those flying bathtubs is around. They are awesome.
So it can fire for approximately a minute and half total before it fails or jams? Not all that impressive.
This was the one I first thought of also.
It’s not just heat. (though that is certainly a factor) The design allows the various functions to happen in paralell, rather than sequentially…As an empty shell case is being extracted from one barrell, a fresh round is being inserted in another, and yet another being fired in a third barrell. If you are familiar with how fast computer processors pipeline instructions, there is an analogy to be drawn. In addition to the pipelining effect, seperating the functions in space helps avoid some types of jams…you don’t need to leave extra time for the ejected shell to fly clear of the reciever before trying to feed a fresh one thorough the same patch of space.
Actually, the range clocks (that’s what they’re called) weren’t developed for communication between the fire director and the turrets. The gunners are inside the main gun turrets, they nave no practical way to sneak a peak up at the foremast.
They were developed for ship-to-ship non-radio communication of range data. In the WWI, especially during the Battle of Jutland, the Royal Navy found that they missed opportunities to fire on German ships for lack of good aiming information. The cordite smoke and generally poor visibility conditions meant that often fire-control officers in the tops couldn’t make good range and bearing identifications. The visibilty was patchy, though, so there were situations where a ship that theoretically should have had a good shot on an opposing ship didn’t have a good view of it but another ship could see the enemy. The range clocks were means of sharing range information between ships.
When the US Navy sent a squadron of battleships to join the Grand Fleet a year later, the range clocks spread to the US fleet, and stayed through the 30’s when replaced by a reliable short-range radio system called TBS (Talk Between Ships).
You are right of course. It all came back to me as I read your excellent description. (WHat were the things in shore installations?)
Yeah, but this is what a burst about a second long can do. Here’s another clip with test range and a few field firings mixed in. The clips are slow motion, but I’ll bet none of the bursts that pounded the shattered fragments of what used to be a tank into the dirt was longer than 2 seconds.
Considering that the Vulcan was designed for aircraft that carry about 700-1000 rounds, it is not a problem.
Even the ship mounted Phalanx CIWS (built round a Vulcan 20mm cannon) only has a magazine of 1550 rounds.
So the in-use expectation is “short, controlled bursts” - you are filling quite a small space with high velocity metal and explosives, and want to be bang on target. But you will chew that target to bits if you hit.
Si
I know ! Ever since I learned that fact, I keep imagining Goose yelling in the intercom : “The airbrakes are not enough, we’re going too fast, Maverick ! We’re going to overshoot !” “Let’s fire that sucker.” :D.
And now, for a silly anecdote related to the OP :
Back when I started roleplaying (that would be when I was 12 years old. I know.) a friend and I got hold of the first edition of Shadowrun, a cyberpunk game. The French translation of that book was… sketchy, and the almighty minigun, one of the most powerful individual weapons one could get his hands on, got translated as “mini pistol”. Guess somebody didn’t do his research.
For years we thought it was a joke or reference to something else - how else could a Derringer do more damage than a heavy machine gun or a rocket launcher ? 
For aircraft guns the typical firing window on a target is a couple of seconds at most, hence the focus on high rate of fire so you can throw 100 rounds or more at the target in that time. If you ever need to fire at something for more than a minute and a half, you’re basically brought the wrong weapon to the fight. This is particularly the case if they’re shooting back with a gun capable of shredding your aircraft in a few seconds.
Could they be using metric time?
Maybe it’s metric. 
It’s a picture of an American battleship. Think it’s metric?
They’ve just prepared for a “Star Blazers” type of event. Iscandar rotates with a 20-hour day.
It doesn’t say if that’s a per barrel figure, or an overall figure. If you can put 10K rounds through a barrel before that barrel jams or fails, that’s a much higher number than simply putting 10K rounds through the weapon before it fails.
My understanding is that in the case of gatling gun weapons, they have a “quick change” feature, which allows the crew to swap the barrels out rapidly, so the downtime is relatively short.
What, was my post invisible? It’s not a timekeeping device of any sort, it is a display that indicates the range from the displaying ship to a target.
Maybe it’s metric.
