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Put armor where there aren't bullet holes

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Re: Put armor where there aren't bullet holes

#71
post #9

Survivorship bias: http://en.wikipedia.org/wiki/Survivorship_bias

Would you mind fleshing that out? Just posting two words and linking to wikipedia doesn't add much to the conversation, and people who care about maintaining the level of discourse on HN might heavily downvote you.

I think there's value in pointing out a specific topic that might otherwise be difficult to discover. Sure, it would be even better to summarize it a bit, but it's still valuable enough.

Re: Put armor where there aren't bullet holes

#72
post #60

You must be careful when applying this sort of logic because it assumes that what happens to a plane after its shot is entirely deterministic, ie. if it gets shot in the tail fin it crashes, if it gets shot in the wing it doesn't. That may or may be accurate for planes (I really don't know) but may not for other things. Suppose anywhere the plane was shot led to a 1/5 chance of the plane crashing, meaning that all pl…

Suppose anywhere the plane was shot led to a 1/5 chance of the plane crashing, meaning that all places are equally deserving of armor. Suppose also that the wings comprised about 75% of the surface area of the plane. You'd see 3 planes returning with bullet holes in a wing for every 1 with a bullet hole somewhere else. So do your study with the plane divided up into equal-sized sections. Or look for clustering and di…

Yea. The key assumption for the "put the armor where the bullets aren't" is that the initial bullets are spread evenly over the surface area (or, rather, that the bullets are spread evenly over the cross-section, which you then average over the typical orientation of the plane as it takes enemy fire). This turns out to be a good assumption because planes typically take highly dispersed enemy fire compared to the size of the plane.

On the other hand, if the enemy had extremely accurate guns and (say, for visibility reasons) always shot at and hit particular parts of the plane (say, the parts of the wings next to the necessarily shiny propellers) then the naive reasoning would be correct: the areas that were bullet-ridden on returning planes would be the ones that should be armored.

Re: Put armor where there aren't bullet holes

#73
post #14
post #2

> count up all the bullet holes in various places, and then put extra armor in the areas that attracted the most fire. > > Obvious but wrong Please tell me I'm not the only one who instantly thought, obviously wrong. And thought the obvious solution is look at what got shot down (or similar such as the article listed) Really? Are most people this illogical?

It's not completely illogical to want to protect the places with holes, because the distribution of where bullets hit isn't random. Fighter pilots aimed at specific parts of planes they were attacking. And some surfaces would have been protected either by other surfaces or by having a nearly flat angle of incidence to probable incoming fire.

Well, the article is specifically about ack-ack fire. I guess from a statistical perspective, adding enough armour to prevent fighter bullets from killing you would be a bad trade-off.

Re: Put armor where there aren't bullet holes

#74
post #48

Reminds me of common belief that dolphins push drowning people to the shore. It's hard to check if it's actually true, after all, most people pushed in opposite direction are most likely dead.

There was an article about this in the paper recently, specifically about dolphins protecting swimmers from sharks. The scientist said, dolphins are curious about you because you're warm-blooded like they are. They usually have their kids with them, so they will make sure the area is shark-free for that reason. If you don't get rescued before the dolphins get bored, they'll leave you to the sharks without a second's thought...

Re: Put armor where there aren't bullet holes

#75
post #23

Earlier quoted context omitted.

WW II fighter pilots were very rational about what they aimed at. (I happen to have read a lot about this.)

Was this because of their incredibly short ammunition reserves? I heard something recently about spitfires having only having about 20s worth of machine gun fire.

Partly, and in the case of Spitfires and Hurricanes (never forget the Hurricanes -- they weren't nearly as pretty, but they were every bit as effective) partly because of the limited structural damage that the .303 round could do. Later variants were more heavily armed, but the Battle of Britain was fought primarily with Brownings chambered for the .303 British. That pretty much left pilots, the cylinders of radial engines and pressurized fuel and oil systems as the vulnerable points. (Those with .50 Brownings and 20mm auto cannon could afford to shoot at other things, but a fuselage hit still rarely did more than add ventilation.)

Re: Put armor where there aren't bullet holes

#76
post #10

http://en.wikipedia.org/wiki/Black_swan_theory

The only black swan connection I see is Taleb's point about "the graveyard of silent evidence". Absence of evidence is not evidence of absence. We didn't see all the planes returning that had catastrophic failures in the known bullet-holed areas and never returned.

"Absence of evidence is not evidence of absence"

I think Eliezer Yudkowsky strongly disagrees - http://lesswrong.com/lw/ih/absence_of_evidence_is_evidence_o...

Re: Put armor where there aren't bullet holes

#77

Earlier quoted context omitted.

According to John Forester, being struck by an overtaking car is among the least likely bicycle accidents, even though it is the rationale used to justify mandatory bike lane usage. http://www.johnforester.com/ His book, Effective Cycling is a great way to improve bicycle safety.

His book is a mixed bag. His thoughts about how to ride are good, but his conclusion in favor of wide curbside lanes and against bike lanes did lots of damage, as many locales/planners used his book as justification for not putting in bike lanes. This thinking was difficult to unwind. Of course bike lane use shouldn't be mandatory, as they aren't in California at least. I don't know any cyclists here who aren't grate…

The closest I've ever been to being killed on a bicycle was in a traffic configuration where the presence of a bike lane completely upset the rules of the road. It was in Gainesville, Florida which has bike lanes everywhere and where drivers are familiar with people using them.

While I appreciate that some people favor bike lanes, in my experience riding in the traffic lane as a vehicle is safer than accepting secondary status in a separate lane. And the technique is not dependent on infrastructure...and saying, "But California does it," won't help the cause in most places. [I bought the book about 20 years ago, recently returned to it now that I'm teaching my son to ride]

Re: Put armor where there aren't bullet holes

#78
post #33

Earlier quoted context omitted.

Do you have any citations for that? I'm not doubting you, but genuinely curious (and ambivalent about helmets). There seems to be a pervasive attitude in the US that if you're a cyclist hit by a car when you're not wearing a helmet, you're automatically at fault, because you're not being responsible. Which is weird, because the risk isn't coming from the bikes...and there's a good chance that it makes cycling seem mo…

Can't remember the name but an experiment by a prof from UCL showed that cars approached him more closely when he was wearing a helmet - but they gave him more space when he was wearing a long blonde wig. So the safest solution is a transvestite without a helmet.

This is why I hate people quoting sociology studies. A comparison between wearing helmets and wearing long blonde wigs gets summarized as:

> research has shown that cars drive closer to people with helmets than they do to people without them

I've taken to just assuming any surprising result from sociology is bullshit unless I really trust the source or have thoroughly investigated the methodology.

Re: Put armor where there aren't bullet holes

#79
post #34

Earlier quoted context omitted.

For bombers thats the main cause of aircraft losses, fighters of WWII were pretty ineffective, especially at night. It's difficult to believe a WWII era fighter diving into a stream of bombers, at night, while the multiple gun turrets on 100s of bombers were returning fire - were making precise tactical decision about which part of the airframe to target. The nice thing (statistically) about AA fire is that it's rath…

The RAF didn't fly in formation during night bombing attacks, rather they flew in "streams" often hundreds of miles long. So there wouldn't have been hundreds of turrets to bring to bear on a single fighter. I think you're also overestimating how easy it would be to spot a blacked out fighter at night. A popular german night fighter tactic was often to sneak up beneath a bomber and then pitch the nose of the fighter…

I think that was the result of Dyson's study - a gunner never saw a fighter so they could just as effectively be removed or repalced with fixed guns.

And in Wald's research a night fighter still had some difficulty finding and approaching abomber even with ground radar - so they fired at it (using proximty fuses or upward firing guns) essentially at random points - there was no statsistical bias of the fighter pilot targetting specific systems

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