A proper law

[Brian Morrison]

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On Thu, 06 Mar 2003 14:39:05 -0000 in 3E675D89.22586.17CFF9D@localhost
"David Hansen" <davidh@spidacom.co.uk> wrote:

> True story. The only thing to properly penetrate German U-Boat pens 
> was a rocket propelled bomb devised by the Royal Navy, which was only 
> used a handful of times. The RAF were very unhappy at the RN 
> designing anything to do with aeroplanes and one of their objections 
> was that the bomb would have to travel faster than the speed of sound 
> to penetrate and this was hard/impossible. To this the RN replied 
> that they had many years of dealing with supersonic projectiles, so 
> the speed was no problem for their people. IIRC the RAF (well Barnes 
> Wallace actually) did eventually come up with a bomb that travelled 
> at around/possibly just above the speed of sound, though not as fast 
> as the RN bomb.

The Barnes Wallis-designed Tallboy and Grand Slam bombs were designed to
be dropped from 40,000 feet, but in fact were only dropped from about
half that height. In the early tests the bombs wobbled as they went
supersonic (even from 20,000 feet) and upset the accuracy of their fall
(617 Squadron used the Stabilised Automatic Bomb Sight which corrected
for air temperature, pressure, air speed etc). Hence the fins were
slightly twisted to cause the bomb to spin and impart gyroscopic
stability. It worked.

Some of the Tallboys were able to penetrate 40 feet or more of
reinforced concrete in the U-Boat pens at Brest. Their effect as they
burst inside was much enhanced of course because of the enclosed nature
of the pen.

- -- 

Brian Morrison

bdm at fenrir dot org dot uk
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