How did soldiers control the altitude at which anti-aircraft ammunition (flak) detonated? How could they know if the flak rounds would go off at 5000 feet, 10,000 feet etc? Were they magnetized somehow to detonate near aircraft? First post. Please be kind. Lol.
In: Engineering
Early shells had timed fuses. Artillerymen were trained on how to estimate the height of aircraft and how to adjust the timer so that the shell would detonate at *around* that same height, depending on the type of shell and the firing angle. That’s fairly simple math: shell goes at X feet per second, you need it to explode at Y feet, so you set the fuse to Z seconds.
Of course, it’s *not* that simple since the shells aren’t going straight up, they’re fired at an angle. So there’s some trigonometry in there if you were to sit down and do it “right”. They didn’t have that kind of time so they just made estimates, fired a shell, paid attention to where it went off (and how close it was to the altitude of the planes they were shooting at) and adjusted the timer on the next shell accordingly. For the most part, though, the strategy was to fire an ass-ton of flak shells and hope that at least a few of them exploded at the right altitude and close enough to a plane for the shrapnel to be dangerous, and then hope that some of that dangerous shrapnel did its job.
The other problem was that those timers weren’t super reliable. WWI timing fuses were made from something that burned at a fairly predictable rate, like [a stereotypical string fuse](https://www.youtube.com/watch?v=oq8jzn2sd-g). The problem is that those don’t always burn at exactly the same rate, especially at different altitudes. By WWII most shells were using clockwork fuses, which greatly increased the accuracy.
In 1942 British engineers figured out how to use reflected radio waves in the shell to create proximity fuses that would explode when the *shell* knew it was close enough to a plane. They still weren’t perfect and sometimes exploded early or late, but they were leaps and bounds better than timed fuses. The British military actually restricted their use to the navy for a long time so that if a shell failed to explode it would disappear into the ocean where the Germans couldn’t find it to figure out how exactly the British were suddenly way better at shooting down planes.
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