Cornishbloke Posted December 3, 2020 Share Posted December 3, 2020 A friend has bought this on the basis that it looks interesting. However we don't have a clue what it is. It looks like some form of sighting equipment, but for what or attached to what is a mystery. There are some markings on it which are copied below. Any ideas? Richard Quote Link to comment Share on other sites More sharing options...
fv1609 Posted December 3, 2020 Share Posted December 3, 2020 In the early 1920s the Air Ministry Director of Technical Development produced standards in the DTD series to cover aeronautical requirements not already covered by an existing British Standard. The earliest reference I can find to DTD 133 is Sept 1930 when it was split to form DTD 133A. As yet I have not found a reference of this time to DTD 133B. No doubt it is related to the parent specification that covers aluminium not suitable for pistons. So if the frame is of aluminium rather than steel it suggests it is for airborne use to enhance sighting in perhaps dim light? I assume the lever in front of the brow rest allows the green or red filter to be flipped between the sight frames? 1 Quote Link to comment Share on other sites More sharing options...
Cornishbloke Posted December 3, 2020 Author Share Posted December 3, 2020 We think that the HDA stands for High Duty Alloys and the RR50 for Hiduminium the alloy developed by Rolls Royce Richard Quote Link to comment Share on other sites More sharing options...
fv1609 Posted December 3, 2020 Share Posted December 3, 2020 In with these other specifications, I suspect DG 4 is Defence Guide DG-4. I believe that Defence Guides were introduced in the 1960s. Many Defence Guides when updated appeared as Defence Standards from 1976 onwards. For example: DG-12 first issued in Jan 1969 after several issues, when in 1976 morphed into Def Stan 01-5 Quote Link to comment Share on other sites More sharing options...
jenkinov Posted December 3, 2020 Share Posted December 3, 2020 Hi . I believe it's a AA site for gunnery training .you have the traditional gunfire in the centre . The red and green lenses create a basic 3 d effect. So you could project a film of aircraft in 2d on a screen or some and the lenses would create a depth effect useful for AA gunnery .. It's missing the telescopic sights which would look a bit like trench sights but you can see the headrest and a side pad for the head ..the right hand side is likely to have a Audible ear piece for effects and instructions... Jenkinov Quote Link to comment Share on other sites More sharing options...
fv1609 Posted December 3, 2020 Share Posted December 3, 2020 Ah 3D ! I can remember those red & green lensed spectacles for looking at blurry off-set images to get a crude 3D effect. Quote Link to comment Share on other sites More sharing options...
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