How did bombers in WWII survive being shot at with bullets and flak?



I see pictures and hear stories of aircraft struggling back to base with hundreds of bullet holes or missing engines/parts of wings or shrapnel inside the wings. How did they stay in the air after all that anti air fire and why are modern aircraft weaker than them (Iran shot down one easily)?

In: Engineering

Well, Iran shot down a plane with a surface to air missile. Which is 1000s of times more powerful than bullets and flak. (and im probably still off by a few orders of magnitude)

Bullet, unless they hit something super important just punch holes in stuff.

A missile explodes and destroys the craft.


Fun fact, there’s a lot of survivorship bias here. *A lot* of bombers *did* get shot down, and the ones that survived were the ones where important parts didn’t get hit. You really never saw a craft that hit the cockpit (which kills the pilot) or hit the engines return.


[Here is a great video about that by Eddie Woo.](

Bullets and flak can tear a plane up, but the plane can still be aerodynamic enough to fly to safety as long as its fuel lines or vital systems aren’t taking direct damage.

These days there are missiles with a lot more explosive power than bullets that are guaranteed to do more damage to planes if they land a direct hit.

I mean, over 12 thousand bombers were shot down during WWII, so I’d be hesitant to act like they were somehow resistant to anti-aircraft fire.

Some aircraft were hit less critically, and were able to limp home. But, like I said, 12,000+ were destroyed and hundreds of thousands of people were killed, so…

Firstly many bombers didn’t survive, you hear stories about ones that did but they were often shot down. Secondly is that they were built to take a few hits, they had armour in places and robust structures designed under the knowledge they would be under fire. A modern airliner has no armour and barely enough rigidity to be safe, they are built for fuel efficiency and not much else.

Flak also isn’t that effective compared to something like a modern surface to air missile, which is what shot down the plane over Iran. Even an airliner might survive being shot at briefly by flak, but if a plane gets hit by a missile it is almost impossible for it to survive,

WWII bombers making it back to base after massive damage are like the epitome of survivorship bias

You hear about the epic tales of the planes that took significant damage but got lucky with it missing the critical systems. What you don’t hear about are the ones that took a lucky single hit and went down. There’s a lot of redundancy in a plane, particularly a large one, and losing 40% of the wing area to 20mm AP rounds is bad but not plummet from the sky bad, but a single machine gun hit to the tail control linkage can be plummet from the sky bad because you can no longer control the plane despite the small hole in it.

Modern planes can still take pretty significant damage and make it back to base. There’s a case of an Israeli F15 that landed with a single wing after a training accident. But bear in mind that the weapons modern planes go up against are far superior to WWII AA Guns and AA Artillery and are often high speed missiles or radar targeted high velocity gun batteries. Late war Anti-Aircraft weaponry was absolutely devastating in the Pacific Theater with radar guided 5″ guns able to pick off planes from quite a distance away.

A lot didn’t. Ultimately, if nothing structural or critical to flight (fuel systems, cockpit, etc) is hit, a plane may or may not be able to stay in flight.

That begin said, aircraft design has changed in the recent past to favor multi-role aircraft that can engage both air and ground targets. Something like an A-10 Warthog/Thunderbolt II that was built specifically for a ground attack role will have way more suitability built into its core design, as it’s far more likely to expect ground-based fire. Something that’s designed to be able to attack ground targets, function as a fighter AND and interceptor needs to be able to be fast and nimble, and the focus is on never getting spotted or hit in the first place. Redundant systems, heavy armor around critical systems are not going to be implemented due to weight, cost, and practical considerations.

If you’re talking about UIA flight 752, that’s a passenger jet that’s not built to see combat. You can’t really compare that to a built-for-combat WWII bomber, which will necessarily be designed with additional redundancy and much more comprehensive crew training to survive damage.

Bombers are hard to shoot down because they’re designed to be. Their wings give them more lift than they need, so they can still fly with holes in their wings. Their engines give them more power than they need, so they can still fly with a destroyed engine. And so on.

The tradeoff is that they’re big, heavy, slow, and consume a lot of fuel.

Modern commercial airliners like the one Iran shot down aren’t built for durability. They’re built to use the least amount of fuel possible (to keep ticket prices low), so redundancies like having extra engine power would just be a waste.

There are modern aircraft that are just as hard or harder to shoot down than WWII bombers: things like attack helicopters or the A-10 Warthog are armored and extremely durable. But you’d never want to take a passenger flight in one of them.

You’re taking about [Survivorship Bias](, for which there is a noted example specifically related to this topic.

During WW2 they were examining the parts of the planes that most often got damaged to figure out where to put additional armor – initially planning to add it to the most damaged areas. Then someone pointed out they were only able to assess the damage from the planes that *returned* from missions, so the additional armor should instead go on locations where they rarely saw damage on returned planes – because damage to those areas meant a plane got shot down.

So – a plane can take a lot of damage to some parts, but almost no damage to others. The image linked above gives an idea of where the critical areas were – mostly in the cockpit, around the engines and between the pilot and the tail wings.

It’s not that the planes got worse, the guns got better.

You can put quite a few holes in something before it goes from operating optimally to not operating at all. The holes just make it operate a little bit worse. That is what machine guns do – they aim to put a bunch of small holes in the plane to cause enough damage to cause the plane to crash. Modern missiles only put one hole in the plane but it’s more likely than not going to be a big enough hole to make the plane inoperable.

You’re looking at things from a survivor’s bias. For every plane that returned to base all swiss-cheesed, there were plenty of planes that got swiss-cheesed and crashed.

In fact there’s an engineers’ parable from WWII about exactly this:
Mechanics were diligently upgrading the armor on parts of planes that got all shot up, and an astute engineer pointed out, “if they’re making it back to base just fine with that part all shot up, then clearly the original design is sturdy enough! If you’re going to add more armor, add it somewhere else!”

Just luck. Some of them had four engins and could make it home with just one engine still operational provided the electronics and hydraulics that allowed control over the engine and steering were still in tact and the structural integrity of the plane doesn’t fail.

Most aircraft are semi-monocoque, there’s still a truss or frame structure beneath the skin, so an aircraft missing skin panels is not airworthy, but it still has enough integrity to get back to base if flown carefully, a lot of these aircraft didn’t have a pressurized cabin as the crew wore oxygen masks, this meant that a damaged panel didn’t cause an explosive decompression that can collapse floors and cause worse structural damage as the air escaping is akin to a massive compressive force.