
Bouncing bomb - grzm
https://en.wikipedia.org/wiki/Bouncing_bomb
======
arprocter
They came up with an ingeniously simple way to tell if the plane was at the
correct altitude over the water

[http://www.thedambusters.org.uk/height.html](http://www.thedambusters.org.uk/height.html)

~~~
cyberferret
This is what surprised me about the Wikipedia article - you would think they
would have mentioned the simple yet clever way that the crew could ensure that
they were at the correct release height over the water using spotlight beams.

~~~
moioci
From the article: "Height was checked by a pair of intersecting spotlight
beams, which, when converging on the surface of the water, indicated the
correct height for the aircraft - a method devised for the raid by Benjamin
Lockspeiser of MAP," I didn't look to see when this was added.

~~~
cyberferret
I searched for the phrase 'light' on the article when I looked at it, but
didn't see this. Someone may have seen this thread and added it perhaps?
Useful addition in any case, and I hope it stays.

EDIT: Actually I may have searched for 'lights', which would have returned no
results, so perhaps my bad after all.

~~~
cooper12
If you look at the page history,
[https://en.wikipedia.org/w/index.php?title=Bouncing_bomb&act...](https://en.wikipedia.org/w/index.php?title=Bouncing_bomb&action=history),
the last edit was on November 6.

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Tepix
German Wikipedia has a long, quite dramatic page about the bombing of the
Möhnetalsperre using these bombs in May 1943 at
[https://de.wikipedia.org/wiki/M%C3%B6hnekatastrophe](https://de.wikipedia.org/wiki/M%C3%B6hnekatastrophe)

According to the page, the attack did not achieve its goal of interrupting the
arms production in the Ruhrgebiet area, however a lot of people were killed,
including many female forced laborers.

~~~
ygra
Well, killing the workers is also a way of disrupting arms production. In my
hometown the allies didn't so much bomb the shipyard or airplane factories,
but rather the part of the city where workers lived. Not sure how effective it
was, though.

~~~
cyberferret
The same happened where my parents grew up in WWII. When the Japanese forces
came in, they mainly took out strategic points such as railway bridges,
command centres etc. When the allied forces counter attacked later, they
mainly bombed the railway yards killing almost all of the civilian labourers
living there.

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JackFr
One of the coolest unit patches of all time:
[https://en.wikipedia.org/wiki/File:617sqn-600.jpg](https://en.wikipedia.org/wiki/File:617sqn-600.jpg)

'Apres moi le deluge'

~~~
cyberferret
Which is all very gung-ho and all that, until you consider the thousands
[edited - hundreds] of German civilian men, women and children who drowned in
the valley after the dam breach. [0]

[0] - [http://www.abroadintheyard.com/german-survivors-of-
dambuster...](http://www.abroadintheyard.com/german-survivors-of-dambusters-
raid-remember-human-cost/)

~~~
sujayakar
It's one of those moments in war where technology leaps ahead of international
law. Additional Protocol I to the Geneva Conventions in 1977 outlawed the
attack of "works or installations containing dangerous forces" to the civilian
population [1]. You'd be very hard-pressed to argue it was illegal at the
time. Whether it was immoral is, of course, up for debate!

[1] [https://ihl-
databases.icrc.org/ihl/WebART/470-750071?OpenDoc...](https://ihl-
databases.icrc.org/ihl/WebART/470-750071?OpenDocument)

~~~
cyberferret
Oh I agree with you. It is just that the dam busters raid was such a powerful
propaganda piece - "English ingenuity over the Evil Empire" type thing, and I
truly do admire the technical skills and bravery involved in the whole raid.

But the downvotes that my comment above (and no doubt this one) gets just
exacerbates the whitewashing of Allied atrocities during WWII. Case in point:

"Bomber command lost nearly 50% of their crew during WWII" \- "Oh dear that is
terrible tragedy - upvotes for you, my friend for pointing out this invaluable
fact."

"Lots of German civilians were killed in the floods after the Dambuster raid"
\- "Meh, who cares? Cost of war. Downvoted. NEXT!"

~~~
sujayakar
Yeah, I think it's pretty interesting to compare Germany with Japan in that
case. Japanese cultural memory and historiography intensely remembers the
suffering of civilians from famine, firebombing, and nuclear weapons [1] (but
rarely from the military itself [2]), but even suggesting that German
civilians suffered unnecessarily from strategic bombing in Der Brand (2002)
earned Jörg Friedrich, a German historian of Nazi war crimes, widespread
censure.

[1] Grave of the Fireflies is a gorgeous, heartbreaking film. Highly
recommended!

[2] See the discussion of Okinawa in [http://apjjf.org/-Mark-
Selden/3173/article.html](http://apjjf.org/-Mark-Selden/3173/article.html)

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SixSigma
Barnes Wallace had previously designed the R100 [1] airship for Vickers - the
one that _didn 't_ crash. The one that did crash was an RAF project. The govt.
was having a competition to see which design would be best.

The R100 flew to Canada and back without incident, setting various records on
the way.

The fatal R101 flight to India was insisted on by the Air Ministry in
response. A deadly effect of "ship it when we say" rather than "ship it when
it's ready"

One interesting fact from the R100 story : the stress calculations of their
airframe were obviously done by hand and took 3 months to complete, something
one could do in Excel nowadays, even without CAD.

The figures are almost unimaginable :

Wallis finally settled on the use of six reconditioned Rolls-Royce Condor
petrol engines for propulsion. [2] Each of which generated 500 hp (373 Kw) and
weighed 1,504 lbs (682 kg).

From wikipedia :

Nevil Shute later suggested in Slide Rule: Autobiography of an Engineer that
the success of R100's Canadian flight indirectly led to the R101 disaster.
Prior to the transatlantic flight, the Cardington team could suggest that
neither airship was ready for a performance of such duration. However, when
R100 returned in triumph they had to either make the flight to India or admit
defeat – which would have meant discredit with the consequent danger of losing
their jobs.

[1] [https://en.wikipedia.org/wiki/R100](https://en.wikipedia.org/wiki/R100)

[2] [https://en.wikipedia.org/wiki/Rolls-
Royce_Condor](https://en.wikipedia.org/wiki/Rolls-Royce_Condor)

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tnorthcutt
I really enjoyed watching _The Dam Busters_ [0] as a kid. Pretty amazing
technical feat, given the circumstances.

[0]:
[http://www.imdb.com/title/tt0046889/](http://www.imdb.com/title/tt0046889/)

~~~
greedo
Lucas used a lot of footage from The Dam Busters for storyboarding the Death
Star trench run in Star Wars. Some of the dialogue is lifted as well.

~~~
zazen
Do you mean 633 Squadron, rather than the Dam Busters? The fjord attack seems
like a more obvious parallel to the trench run.

~~~
greedo
Nope.

[http://www.starwars.com/news/the-cinema-behind-star-wars-
the...](http://www.starwars.com/news/the-cinema-behind-star-wars-the-dam-
busters)

[https://www.youtube.com/watch?v=lNdb03Hw18M](https://www.youtube.com/watch?v=lNdb03Hw18M)

~~~
zazen
Your first link is to one of a series of articles linking Star Wars to:
Lawrence of Arabia; E.T.; the Seventh Voyage of Sinbad; The Good, The Bad, and
the Ugly; Empire of the Sun; and possibly others. They can't all be major
influences!

The start of the YouTube video puts the exposition of the attack from one film
next to the exposition of the attack from the other. Is that really such a
strong similarity? I'd guess a lot of war/action movies have a here's-how-
it's-going-to-go-down scene. Some of the other pairings are closer - I think I
buy the one with the line about the number of guns.

So, I see a Dam Busters reference, and that's interesting! But I'd need more
convincing that it's used for storyboarding.

~~~
greedo
Did you read the first article? It's pretty clear in spelling out the
heritage:

"As the British pilots approach the superstructure, one asks, “How many guns
do you think, Trevor?”

To which Trevor replies, “I’d say there’s about ten guns. Some in the field,
some on the tower!”

The similarities go even further… A tense countdown leads to the first bombing
of the German dam, just like the trench run. After the first bomb attack
against the German dam is away, one of the pilots exclaims, “It’s gone! We’ve
done it!”

To which he’s told, “We haven’t! It’s still there!”

That bomber tells his other pilots to set up for their attack run, eventually
taking three bomb runs to destroy the target."

That's almost verbatim what Lucas used for dialogue (something he always
admitted he struggled with writing).

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unicornporn
Here's a fantastic video showing a bouncing bomb in action:
[https://www.youtube.com/watch?v=Ik9vCg-
xRr4#t=0m47s](https://www.youtube.com/watch?v=Ik9vCg-xRr4#t=0m47s)

~~~
cyberferret
That's a great video. Extremely low release. The splash from the drop actually
smacked into the rear fuselage. I bet in the actual mission the tail gunner
would have had wet feet, but a great view of the bomb skipping across the
water...

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biofox
There was a Channel 4 documentary a few years ago where they made and tested
one of these. I didn't see it, but there are clips online:

[https://www.youtube.com/watch?v=8IeGYkwVIWw](https://www.youtube.com/watch?v=8IeGYkwVIWw)

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paulajohnson
Growing up, Barnes Wallis was my hero. Paul Brickhill's book describes how he
had to battle unimaginative Whitehall bureaucrats one day, and cutting edge
engineering problems the next, to get the thing built.

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trhway
Similar technique using regular bombs

[https://en.wikipedia.org/wiki/Skip_bombing](https://en.wikipedia.org/wiki/Skip_bombing)

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bgentry
The PBS show Nova attempted to recreate this bomb on an episode called Bombing
Hitler's Dams: [http://www.pbs.org/wgbh/nova/military/bombing-hitler-
dams.ht...](http://www.pbs.org/wgbh/nova/military/bombing-hitler-dams.html)

They dug a giant hole to build a test dam for this project. Fun to watch.

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mLuby
Apparently these were the inspiration for the Death Star trench run (because
why else would you fly into that trench?)

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leonix
This reminds me of an old russian anecdote of the cold war period.

USA dropped a nuclear bomb on the USSR. 5 million people died, panic in the
media, outcry from the whole world community, etc.

Couple days later another sensation: USSR dropped a rubber bomb on the USA. 50
million people died, counting: the bomb continues to bounce!

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sndean
There's a decent video by Veritasium about the Magnus Effect, where the bomb
is essentially given lift by its backspin:

[https://www.youtube.com/watch?v=2OSrvzNW9FE](https://www.youtube.com/watch?v=2OSrvzNW9FE)

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ada1981
We are going to have such great bouncing bombs. The best.

