Anti-Aircraft Guns WWII


Been watching Catch-22 on Hulu, and I’m seeing all kinds of AA fire going off all over the place. I know the show is based on the book and somewhat of a satire, but even in Band of Brothers, the AA seemed to have a somewhat low success rate. I know these are television/movies, but was there any accuracy to the amount of AA fire shown in the films? I’m not sure how exactly how they worked. I guess the true question is, “How did these work? Why didn’t they try to fly above it? Was flying above an option? What kind of success rate did they provide? How have they improved over the years?

In: Engineering

The success rates of AA for most of the second world war for most of the combatants were spectacularly low.
I can look up some exact numbers if you want but it’s a lot of work.
Something in the order of 12,000 rounds spent per aircraft downed iirc.
There was light, medium and heavy AA (short, medium and long range). Above those the defence would often have fighters.
The fighters would attack the bombers and try to push them down into the AA. The higher the bombers stayed the lower their accuracy was (which was already terrible in WW II), but the lower they went the more AA they would be exposed to. There were also batteries of large searchlights, AA-balloons, early radar systems, and ground observers involved.

There were great improvements made during the war, on all sides, and since.
Two of the biggest in WW II would be the improved radar systems, and the Variable Time fuse, in my opinion.

And with ubiquitous guided rocketry AA has become far more deadly since.

You could fly above the flak curtains, but that made aiming your bombs less accurate (they had further to fall and get knocked off course by winds). That’s why dive bombing techniques were developed. You could fly in above the flak, dive in and bomb your target, but then you had to pray you could get out of the way of the low level fire before someone hit you.

The flak curtains of WWII were pretty much “Lets throw a shit load of stuff into the air and hope it hits something”.

They’re essentially area denial. The point of flak guns isn’t hitting the enemy, it’s building a huge aerial danger mushroom meadow. Those danger mushrooms are relatively dense so by sheer chance they *will* hit at least some of the approaching bombers, if only with dropping shrapnel rather than the actual blast. In a way, they aren’t supposed to hit, just scare and confuse the enemy into missing.

This one is conjecture but I assume they also made for aerial depth charges. The explosions of those shells create pockets of vastly different air pressure which destabilizes the planes in their vicinity.

Flying above wasn’t viable for several reasons, first of which would be the depth charge effect. Airplanes also have a limited climbing height, especially heavy strategic bombers. It takes a lot of gas to climb and at some point will simply stall. Flak grenades were actually calibrated for the estimated stalling altitude of then-current bombers. Another point is that aiming becomes increasingly difficult due to target lag (as opposed to target lead, this is when you’re aiming at a stationary target from a moving platform) and differences in wind speed and direction throughout the troposphere. The last reason is that bomber cabins weren’t pressurized until very late in the war. That’s why they’re wearing breathing masks and those heavy flight suits. It’s cold and there’s barely any oxygen up there and you can only get so high before it damages whatever skin you have exposes.

I would say that the AA fire is depicted fairly accurate. Flying above AA fire wasn’t possible for heavy AA guns as they could reach 30,000 ft altitude relatively easy though with a roughly 30 second delay/flight time of the shells. As it wasn’t really possible to get accurate hits at that altitude AA batteries would mostly just saturate the air space ahead of the bomber formations with well timed explosive shells that would go off all around the planes as you see it in those shows. Even though direct hits were relatively unlikely the shrapnel could still damage planes and wound/kill flight personnel, and a direct hit would most likely end in the plane going down. On a bombing run anywhere between 10-20% of planes would be shot down during the mission by AA fire and interceptor aircraft, and probably a similar percentage would be able to fly home with some damage. [This 1943 instructional video explains it quite well.](

This might seem like a cop-out, but the best source on this is probably the [Army Air Force’s training video on the subject](

The short of it is that most contemporary flack was designed to detonate at a particular altitude, and gunners and pilots were in a cat-and-mouse game of maneuvering vs aiming that involved a lot of guesswork and randomness.

The actual effectiveness of flack was also questionable, with some estimates putting the rounds-per-kill at above 3,000. This was due to all of the limitations of hitting something moving a couple hundred miles per hour at thousands of feet of altitude.

Bomber strategy and AA capabilities changed over the years.

By WW2 flak guns could shoot high enough that bombers couldn’t avoid them but flying high kept them safe from fighters. By the middle of the war they were vulnerable to both fighters and AAA(Anti Aircraft Artillery)

On of the most common Anti Aircraft guns of WW2 was the German 88mm Flak which could hit targets 32,500 feet up. Later models like the 105mm Flak could hit bombers 37,400 feet up. Both these could easily get to even the late war B-29 Superfortress with it’s <32,000 feet max altitude.

Propeller driven aircraft with rotary engines need a fair amount of air to work. Large heavy bombers also need either thick air or large wings to stay in the sky. Both these factors kept Allied bombers within the effective range of Axis AA guns.

The AAA also fired flak rounds. These are shells which would explode into tiny fragments after X seconds or at a set height. This made it much easier to hit planes as you just needed the shell to detonate near them not actually hit the plane with the small shell.

So essentially, they’re just high flying grenade shotgun shells?

AA in ww2 was not an exact science. The gunners would calculate the altitude and speed of the aircraft and fire ahead of the planes with a timed fuze. If they got it right the shell would explode in the proximity of the aircraft and hopefully the flak would damage the aircraft. It took a lot of shells to down an american B17. The death rate was high but planes often came back with huge chunks missing. Due to winds or the aircraft moving in zig zags (a common tactic) the accuracy often went way down. A small change in aim on the ground could mean a huge change when fired in the air at 25,000 feet.

Flying above the AA was not a real option. If the guns were too far away then yes they could fly over the arch of the projectile. The cannons were designed so this couldn’t happen often. Another option was to fly low so that the gunners had much less time to track the planes and fire at them. This made the planes more susceptible to ground fire and enemy aircraft though.

AA started to get really good towards the end of the war. The US developed radar fuses for AA guns. The bullet had a radar on the tip of the round and would detonate itself when it detected something near it (at first an enemy plane but they were also used on enemy bunkers). These radar fuses are what helped the US pacific fleet to protect itself much much better against Japanese torpedo bombers and kamikaze. The success rate went way up but they weren’t used everywhere at first, the US made it a priority to keep such a good technology a secret.

You have some good answers on how they worked in WWII, so I’ll answer you last question, How have they improved over the years?

They used to use timed fuses, so the shell would explode at a certain height, which meant that almost all of them missed. Later in the war, the British and US cooperated to invent a proximity fuse, so the shell wouldn’t explode until it was near an airplane. That’s what AA shells use today.

Most ground-based air defense today, though, uses guided missiles that use either radar or heat sensors to steer the missile toward a specific aircraft. They’re much more expensive than AA shells, but you can use a lot fewer shots to take down attacking aircraft.

That’s a big part of why the US has invested so much in “stealth” aircraft, which are hard to see with either radar or heat sensors. Those can attack the air defenses of an enemy and then the regular planes can come in afterward.

Well, it worked fairly well in some naval operations when you see AA shooting down many of the Kamikaze attacks, but the amount of shells fired per hit was big. Defending cities and using the flak guns as a battery centrally controlled could make bombing runs dangerous and less than ideal for good bomb aiming. So it was mass area fire and not all that effective.

Just like the number of infantry bullets it takes to cause a single wound among the enemy is in the thousands, the same was for AA defenses..

Until radar directed and servo controlled guns firing thousands of rounds per minute can now shoot down a very fast moving small target almost all the time at close range.