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Author Topic: Langdon Structures  (Read 20530 times)

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Offline cliveh

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Re: Langdon Structures
« Reply #33 on: August 24, 2015, 16:29:53 »
I have been having a discussion on a Facebook Group regarding the later flat concrete holdfast. Someone is insisting its for a 40mm Bofors AA gun. I know there were two at Langdon but do we know if this was the site for one of them or are we still convinced the mount is for the 100ft Barr & Stroud?

cliveh


Offline Far away

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Re: Langdon structures
« Reply #32 on: January 19, 2012, 13:52:49 »
There appears to be a similar 100 ft type of range finder base on the Great Lines: http://www.kenthistoryforum.co.uk/index.php?topic=12747.0


Offline JohnG

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Re: Langdon structures
« Reply #31 on: April 28, 2011, 22:46:15 »
In the report I have it says the 30ft came first and then the 100ft.  I have not seen the primary documents myself but hope to soon.  I attach a drawing of a 30ft range finder for those interested.


30ft Range finder.
JohnG

Offline cliveh

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Re: Langdon structures
« Reply #30 on: April 28, 2011, 08:48:49 »
I would agree with you regarding the bolt mountings JohnG but the one thing that raises a slight doubt in my mind is the close proximity of the raised mounting to the flat one. Would the raised mounting not be likely to foul the operation of anything of a substantial size, such as the 100ft rangefinder, mounted on the on the flat one?

cliveh

Offline JohnG

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Re: Langdon structures
« Reply #29 on: April 27, 2011, 23:14:24 »
Hi cliveh,  I would think the raised mounting is the 30ft and the one level with the ground is the 100ft.  The one level with the ground is the hievier one.  In this case the rail may not have been 360 degees but just enough to cover the arc required.  I would like to see the TNA plans and I hope to soon. The fact that the remains of the rail can not be seen does not mean it was not there.  JohnG

Offline cliveh

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Re: Langdon structures
« Reply #28 on: April 27, 2011, 22:57:03 »
helcion - that shows a great view of the two bolt mountings side by side. So which one is for the 100 ft rangefinder do you think JohnG?

cliveh

Offline helcion

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Re: Langdon structures
« Reply #27 on: April 27, 2011, 22:40:17 »
That's my photo that has gone missing in post # 12

I've tried re-posting the photo without success in the original post, the image code is there OK after my text but it still comes up as 'Image Deleted' in the preview.

So lets try it again.

A Belgian Sea King by the way, the UK had run out of choppers that day.







Offline cliveh

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Re: Langdon structures
« Reply #26 on: April 27, 2011, 21:56:55 »
JohnG - I didn't notice any signs of any remains of the circular rail - that's not to say there isn't any there. I may try and get down again on Monday and look - if I can get the time away from the garden! :)

cliveh

Offline cliveh

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Re: Langdon structures
« Reply #25 on: April 27, 2011, 21:09:30 »
JohnG I can still see them in reply#13!

That's a great pic of the rangefinder - thanks!

cliveh

Offline JohnG

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Re: Langdon structures
« Reply #24 on: April 27, 2011, 20:27:58 »
cliveh.  Where have your photos gone, the ones of the LAA position?  I have aquired this picture of a 100ft Range Finder.  I wonder if there is any sign of the circular rail.


100ft Range Finder.
JohnG

seafordpete

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Re: Langdon structures
« Reply #23 on: April 27, 2011, 12:38:58 »
Yup sounds right-difficult to imagine a beast 100ft long, but then why would it have so chunky bases if it was 100 & 30 inches. The only ones I could find on line were infantry type which are about 30". thanks

Offline cliveh

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Re: Langdon structures
« Reply #22 on: April 27, 2011, 12:34:37 »
No seafordpete I think they are feet not inches. just found this article on the web which explains:

"The Barr and Stroud 100 ft. self-contained base rangefinder


Depression, two-position, and more recently self-contained types of rangefinder have been employed for coast defence purposes. The first two types are subject to several disadvantages which have led to the introduction of the 100 ft. base self-contained instrument. The rangefinder has a new type of triple field. It is carried upon a mounting comprising two trucks running upon a roller path of 50 ft. diameter, the trucks being connected by a rigid horizontal framework. Upon the trucks are carried cantilevers from the ends of which are suspended cradles having special bearings within which the rangefinder rests. Training is done by power or by hand. During extensive tests the uncertainty of observation at a range of 31,000 metres did not exceed 20 metres."

Link below
http://iopscience.iop.org/1475-4878/23/3/304

cliveh

seafordpete

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Re: Langdon structures
« Reply #21 on: April 27, 2011, 12:17:20 »
Should 100ft & 30 ft be inches not feet?

Offline cliveh

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Re: Langdon structures
« Reply #20 on: April 27, 2011, 10:42:12 »
JohnG would I be correct in assuming that the larger, flatter bolt mount would be for the 100ft B & S and the smaller, raised one for the 30ft?

Don't suppose any photographs exist of these in place anywhere?

cliveh

Offline LenP

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Re: Langdon structures
« Reply #19 on: April 26, 2011, 20:56:56 »
Those two tunnels are linked in a horseshoe shape. There is another tunnel further to the west but it appears to have been filled in apart from the entrance. Is it known if this was this associated with the position?

 

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