The Directorate of Technical Development (DTD) was established by the UK Air Ministry in 1924 with a focus on research and application of emerging materials, technologies and processes for the Royal Air Force. It issued a series of DTD Standards until its functions were reorganised and absorbed after WW2 into Britain’s continuing defence research effort. DTD Standards persisted until being officially deemed obsolete in 1999. Many interwar, WW2 and early jet age aircraft and engines use DTD specifications. Where a DTD Standard grew into extensive use, it was often promulgated as a British Standard. In general, new DTD Standards described newly invented and sometimes secret materials, while those that persisted in the DTD format in later years described rarely used but nevertheless important materials.
Where DTD Standards are revised, the later version will contain a sequential letter at the end of title, eg DTD36, DTD36B, DTD36C. On this page the year of publication is also listed to place a revision into a time context. This page incorporates a listing of DTD standards from 1999 as well as earlier revisions from the 1930’s through to the 1960’s.
There are several ranges of numbers used to indicate different types of specifications :
DTD1-DTD899 cover aircraft materials or parts. Indexes for DTD specifications at various periods are listed here to provide a time context and record of DTD specifications that may have become obsolete and disappeared from later records. These indexes also record the promulgation or substitution of a DTD Standard for an equivalent British Standard, or, after 1999, current DStan specifications.
DTD900-DTD999 cover protective treatments such as anodising.
DTD1000 onwards cover materials or parts of a Confidential nature not available for general issue. The author has never sighted a DTD1000 series Standard but has seen reference to them on certain historical aircraft parts, eg DTD 1047 and DTD 1042 self sealing fuel tanks used on deHavilland Mosquitos and Vampires. It is inferred that these specifications relate to Secret materials or proprietory processes offering trade or defence advantage. For the restorer of historic WW2 or Cold war aircraft components often a little research around the context of the product will reveal industrial processes now well established in the public domain that can resolve restoration issues.
INST are DTD specifications for Instrument Fittings. A small number have been found and are incorporated here.
GE are wartime DTD specifications for General Equipment, eg ‘GE125 Bonding and Screening Systems’ To date, no GE specifications have been located.
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