Fan Bay Deep Shelter & the Sound Mirrors

[tonyc206]

Hi Chaps

No this is not about a new band!

On Saturday, as a shiny new member of the Kent Archaeology Society, I was invited to a guided tour of the Fan Bay coastal defence site that has recently been excavated and I thought you might like to see some of the photo's? The site was first used in WW1 when two 'sound mirrors' were constructed to detect and locate German Zeppelins and Gotha bombers (later Giant bombers). In WW2 it became a coastal defence site, with multiple guns of varying calibres and a deep underground shelter for the gun crews, directly in front of the 'Chain Home' radar facility. It's primary 'declared' purpose was the defence of Dover harbour and invasion protection for the coastline from Dungeness (almost) to Margate.


A copy of the original architectural drawing for the shelter (this was built in just 100 days)


A copy of a painting done in 1940 at the base of the entrance stairs.


The IWM have this listed as 'in the tunnels under Dover Castle' but it is quite clear when you see it in the shelter that it matches the architecture exactly.



A 'Gun Trace' map showing the different calibres and their relative arcs of fire. You can see that the 15inch guns could reach the French coast and the 9 inch guns were for the anti-invasion support of the coastline


Record Plan for the 3x 6inch guns






The mounting for one of the two 15inch guns (Jane)


The northernmost 'Sound Mirror'. Also where the deep shelter tunnels were started from. One entrance/exit from each sound mirror


This shows how the sound mirrors were used. The 'sound cone' was directed at the mirror until the aircraft noise was the loudest an then the 'stick' would point to the location of the sound source. The operator would then read azimuth and elevation off the scales and using the two mirrors at the same time allowed for triangulation to give range and height. This particular sound mirror is the one a the above ground construction at Abbot's Cliff.

In WW2 the site also had two fixed mount 3.7inch AA guns and the Chain Home station behind had 3 40mm Bofors guns.

I hope you find this interesting and useful

[flash]

Seen acoustic mirrors at Denge before, Ian, not seen these before or about the gun positions.
This site has links to all sound mirrors in the country: http://www.andrewgrantham.co.uk/soundmirrors/

(PS I slipped the spurious pic into the text where I thought it might be logical !)

[tonyc206]

Seen acoustic mirrors at Denge before, Tony, not seen these before or about the gun positions.
This site has links to all sound mirrors in the country: http://www.andrewgrantham.co.uk/soundmirrors/

(PS I slipped the spurious pic into the text where I thought it might be logical !)

Thanks Dave

These have only been excavated recently and are only 10 miles from me. I've also joined the Kent Defense Research Group and the Kent underground Research Group. So should get to see lots more interesting stuff as we find it.

That picture thing happens when I insert one in the wrong place and then try to delete it. The text disappears but the pic just gets attached somehow.

BTW who's Ian?

[flash]

Dunno what you mean... ?

[CrashCraig]

Very clever these sound mirrors

[zenlizard]

Another great bit of history!

[David Manley]

Last time I saw the Denge mirrors they looked pretty at risk from erosion and subsidence. Are they still there? We couldn't visit the site in your pictures as it was at the height of foot and mouth disease

As an aside, after I visited them I wrote an article adding rules for them to Aeronef, after which Brigade Models released a set in (I think) 6mm

[Windy Jack]

Thanks for sharing the pictures.
I think I have seen these sound mirrors or others like them on a Michael Portillo television programme. We learn a lot about the UK from him and his rail journeys.

[tonyc206]

Last time I saw the Denge mirrors they looked pretty at risk from erosion and subsidence. Are they still there? We couldn't visit the site in your pictures as it was at the height of foot and mouth disease

As an aside, after I visited them I wrote an article adding rules for them to Aeronef, after which Brigade Models released a set in (I think) 6mm

Yes I believe that the Denge mirrors are still there and in much the same condition. Most if not all now have been taken over by the National Trust as important historical sites. Much of the site at Fan Bay is still being uncovered and no firm decisions have been made about what the final outcome will be. Stanmding in front of them on the platform at the right spot is amazing as your voice reverberates directly back to uou.

Love the thought of adding rules for them to WW1 games. Well done David

[malachi]

Thanks for sharing, Tony! Very cool.