Or more specifically flak guns. How do they set those things for height? I mean, they are supposed to explode in the vicinity of the aircraft. But aircraft can fly at any height. If the aircraft fly 100 feet higher or lower than the shells are exploding at they won’t do much damage. Are there different shells set for different heights and the gunners select the apropriate brand from the shelf? Are the shells capable of being programmed?
And if they are set for a specific height how do the gunners know what height the aircraft are at? A rangefinder wouldn’t work I assume, since you don’t know how far away the planes are in addition to the vertical component.
There have been various schemes thru the years. My memory isn’t exact so others will fill in the details I’m sure.
AA shells have fuses that can be set before firing. They burn for a set time (translating to a particular altitude) and then explode. You have to estimate the heights of the bombers, which were often pretty steady.
Are you talking about the WWII-esque big black balls of flak guns? From the ones I’ve seen and played with, there are crank things that move the barrels up and down and side to side. I think they just guessed at the altitude, though I’ve seen some primitive rangefinder thingies.
Setting fuzes in cannon projectiles has been going on since just before the U.S. Civil War. By 1914 it was a fairly scientific discipline.
Before the gun officer has the gun loaded, he determines the range, figures the distance and the time the shell will travel to get to that range, then sets the fuze to explode in the midst of the troops at whom he is aiming. The fuze for each shell is set separately before firing.
When aircraft entered the picture, the armories simply did trials to discover how long it took shells to reach particular altitudes at various angles and wrote up tables that could be quickly read. The gun officers simply did what they had always done, except, instead of figuring for range, they figured for altitude. Since bombers tend to travel (relatively) slowly at a particular altitude (so as to maintain defensive formation against fighters and to allow the bombardier to select and aim at targets), once the altitude of a specific flight of bombers was determined, someone could be set the job of setting all the fuzes for the appropriate altitude for that flight. Even if bombers were coming in at different altitudes, each artillery battalion was likely to be firing at only one flight at a time.
(The preceding is for guns of 75 mm/3 in. or larger. For smaller weapons, they tried to make direct hits on the plane and use percussion fuzes for detonation.)
In WWII, the Allies came up with a nifty improvement. They placed a miniature radar unit in the nose of the shell. They set the timed fuze as always, but as the shell went up, if a target tripped the radar, it began to track the closing range to the target. If the target began to get farther away (or disappeared from the radar) the shell was triggered to explode, immediately, on the grounds that the shell was as close as it was going to get to that target.
I’m pretty sure there is a fire control radar associated with each anti aircraft battery. It makes the computations needed for setting the fuze timing on the shells.
The radar measures the slant range to the target as well as the azimuth and elevation angles. From these data and the ballistic characteristics of the shells, the proper gun aiming angles and time of flight can be computed.
Actually, binocular range finders with a good degree of accuracy were in production before 1900. Having several scattered spotters triangulate on the aircraft allowed a pretty good detection of altitude.
The British night system, with each plane flying separately, allowed more leeway in changing altitude, but you still don’t throw a Lancaster with five or six tons of bombs all over the sky. (It took a full minute to climb only 250 of altitude.) The formations used by all other air forces kept the altitudes steady.
OK, so I assume the fuses in individual shells could be set, rather than different shells being manufactured with different fuses. So how does one set a fuse in a shell? Is there a dial on the top or something?
Minor nitpick. They were setting fuzes in cannon projectiles during the Napoleonic wars, which I’m not sure qualify as “just before” the US Civil War. I’m not sure when the first use of this technology was.
I’ve been reading Stephen Ambrose’s The Wild Blue on and off lately.
Not only did the Germans set their shells to explode at a specific altitude, they set all of their AAA to explode at that altitude within a specific area. Once heavy bombers were lined up on the target, they more or less had to fly parade-like over it. The Germans had a central AAA controller, who would assign the altitude at which the flak was to detonate, and he would also assign all available artillery to fire into a “box,” or theoretical grid area in front of the approaching bombers. The bombers would then be forced to fly through the box. If they were particularly unlucky, the German AAA might be able to target the formation with a series of flak boxes before they reached the target. The concentration of fire was almost guaranteed to pick off a certain percentage of the bombers, every time.
Once the bombs were dropped the heavies could take some evasive action, and the flak became much less of a problem.
They did if there was a night fighter on their tail.
Most British bombers flew a long S pattern to give the tail gunner a better field of view.
When a night fighter was spotted, the tail gunner warned the pilot to turn left or right and the pilot would throw the bomber into a corkscrew turn losing hundreds of feet in altitude. Being ‘coned’ by searchlights also provoked violent evasive maneuvers.