

WW2: If planes are back with no damages on the tails, add armor on the tails...  [pdf] - napolux
http://cna.org/sites/default/files/research/0204320000.pdf

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gk1
Where do you see such a conclusion in this document?

From Page 88 (emphasis added):

> "This analysis of the hypothetical data would lead to the conclusion that
> the plane is _most vulnerable to a hit on the engine area if the type of
> bullet is not specified_ , and is most vulnerable to a hit by a 20-mm cannon
> shell if the part hit is not specified. The greatest probability of being
> destroyed is .534, and occurs when a plane is hit by a 20-mm cannon shell
> _on the engine area_. The next most vulnerable event is a hit by a 7.9-mm
> machine gun bullet _on the cockpit_..."

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stan_rogers
The received wisdom here is that if an aircraft is capable of returning from a
mission with heavy damage in a particular area, that area probably has enough
strength/redundant structure already, and adding armour isn't going to
accomplish much beyond adding weight.

If, however, aircraft rarely or never return from a mission with significant
damage to a particular area, it's probably a good indication that damage to
that area is not survivable (which is why the aircraft are not returning).

One needs to pay attention to the data that aren't present, or at least wonder
_why_ they aren't present.

~~~
gk1
I understand... the survivor bias... Just couldn't understand what the OP was
trying to say with the title.

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bluedino
Previous discussion:
[https://news.ycombinator.com/item?id=1748979](https://news.ycombinator.com/item?id=1748979)

But I swear I saw it a week or two ago as well.

~~~
Zancarius
You did:

[https://news.ycombinator.com/item?id=7851927](https://news.ycombinator.com/item?id=7851927)

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adolgert
This is an interesting application, and dogged mathematical derivation, of
survival analysis. We would do the same calculations today with standard
Kaplan-Meier curves. Do you see the survival functions, S=1-F, in the first
few pages? They also state a hazard rate, all without reference to stochastic
variables. It's like seeing the mathematical version of a 1943 automobile.

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mcfunley
Two weeks ago I tried to explain this idea to an ex-Air Force tour guide as we
were standing next to the waist guns in a B17. He said I was full of shit and
that the planes flew with basically no reinforcing armor. It was kind of
embarrassing.

~~~
nether
> It was kind of embarrassing.

I would be cringing at this scene, mostly at you.

~~~
mcfunley
Me too.

