Concrete blocks that once protected Britain

Re:Concrete blocks that once protected Britain by benj111 on Monday January 07, 2019 @05:28AM (#18844140)

I'm somewhat surprised these weren't constructed as decoys even after their usefulness had passed.

The second to final one looks very much like an early radar station (or was that the point?).

Would it not have been preferable for enemies to believe all our radar stations were acoustic mirrors?

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Re:Concrete blocks that once protected Britain by londons_explore on Monday January 07, 2019 @05:37AM (#18844186)

Accoustic mirrors could actually be rather effective - a large mirror could perhaps hear a plane in good conditions up to 75 miles away, well over the horizon.

Early radar only had about the same range, but the advantage was it could work in nearly all conditions, rather than just windless sunny days.

They also weren't used by the Germans, so perhaps the accoustic mirrors were as much of a secret as radar.

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