Details
346/0/10009
01-DEC-05
HENLOW
Buildings 186, 187, 188 and 189 (aircraft hangars), RAF Henlow
GV
II
Group of four paired aircraft hangars in line. 1918, by the War Office's Directorate of Fortifications and Works. Walls, buttresses, central piers and door 'pylons' in brick, curtain walls half-brick thickness in cheaper bricks, softwood 'Belfast' roof trusses, corrugated steel door cladding and later profiled steel roofing, including lean-to units.
PLAN: Each of the buildings is a double-span shed, with a central row of brick piers, some with later brick or block partitions. Otherwise a single large working space; on each of the longer sides is a low single-storey set of stores or offices, occupying the central bays, set outside the main volume. Buildings 186, 187 and 188 are in 16 bays each, and 52 m long overall, with two clear spans, each of 24.3; Building 189 is in 15 bays, and with two clear spans, each of 30.5m, otherwise the designs are identical. The sheds are aligned to the access road, with a larger interval between 188 and 189 than that between the first three.
EXTERIOR: The general design of all the sheds is similar, with minor differences in the scope of the attached out-buildings. A series of raking buttresses in dark red brick frames the intermediate panels which are in half-brick thickness in lighter colour, with broad 3-light casements at a high level, and smaller lights at low level; the end bays on each side are without windows, and usually have a small door. Openings have flush concrete lintels. The low lean-to ranges in 6 or 7 bays, with small casements to most bays; on the airfield side some small sections of lean-to are in 2 storeys. The ends have full-width groups of 6-leaf sliding doors, with corrugated cladding, below a continuous overhead box containing gear, and above each span a low segmental tympanum with profiled sheeting. Originally the doors opened to brick 'pylons' outside the outer bays, but one only of these now remains, on the outer end, right, to shed 189; this is in red brick, with three sets of paired piers carrying thin brick stiffening diaphragms with straight top but segmental lower edge - similar to the internal construction. Between the groups of doors to each span a large down-pipe is carried in a recess to brick piers. Building 189 differs only in having wider main spans.
INTERIOR: Main spaces have plain concrete floors, except where modified for eg a gymnasium. Some later small office units have been inserted to the main spaces, which otherwise are clear, but with a central row of paired brick columns; these carry a longitudinal thin brick stiffening diaphragm in brick on a segmental arch, are 2 bricks square, with a clear gap, and the outer faces carry a concrete spreader on brick corbelled in 3 courses to carry a strut in 3 small scantling timbers spliced into the doubled bottom chord of Belfast trusses. These trusses, commonly used from 1916 for aircraft hangars, have their bearing ends plated in diagonal boarding to the point where the strut is taken in, then a close-set diagonal grid of small struts. The doubled upper chord, in a flat segment, carried close-set purlins, and the lined profiled roof sheeting. There is vertical X-bracing between bays, and horizontal bracing in the bays adjoining the main doors.
HISTORY: RAF Henlow was established in 1917 as the Eastern Command Repair Depot, raised to Group status in 1965 and still in RAF hands. The War Office had issued instructions for the construction of repair depots for each RFC Command, further to heightened awareness of the need to train more men in the rapid repair of aircraft and aero engines in order to sustain the war effort. Construction at Henlow - conveniently served by the Midland Railway - was begun in 1917, and some of the more substantial structures including the hangars date from this time; the last of the huts dating from this period were demolished in the 1970s. The first service personnel arrived (from Farnborough) in May 1918, and a limited output of Bristol fighters and Haviland aircraft was achieved by the Armistice. An extra area was added in early 1920, and in March of that year Henlow became the Inland Area Aircraft Depot; it was thus one of a very small number of airfields retained for use after November 1918, in its role as the RAF's flight test and maintenance centre forming a vital element within Sir Hugh Trenchard's newly-independent air force. By 1924, when it was selected as the permanent home of the School of Aeronautical Engineering, Henlow was producing 35 engines and 15 aircraft each month. In its role as a training base for skilled engineers and equipping operational stations with the latest aircraft it became, with Cranwell, Halton and Uxbridge, one of the RAF's largest bases, accommodating some 7000 of various nationalities in 1940. Basic engineering theory and management were taught at the Officers' Engineering School (formerly at Farnborough), one of the 1932 pupils being Frank Whittle. The Aircraft Riggers' School was brought in after 1935, and during the Second World War it performed a vital function as one of the RAF's largest Maintenance Units, overhauling, repairing and modifying a wide range of fighters and bombers, from Spitfires and Typhoons to Lancasters. A significant period was during the Battle of Britain in 1940: Hurricanes manufactured in Canada were crated in, assembled at Henlow and flown onto front-line bases. At one stage in 1941, in Operation Quickforce, about 100 Henlow fitters were trained for the assembly of Hurricanes on carriers en route for Malta, to which the completed planes were flown off deck. The Control Tower was at this time manufactured from packing case material, and still remains. Parachute training, including SOE officers, was another key function of the base. In 1947 the School of Aeronautical Engineering became the RAF Technical College, moving to Cranwell in 1965.
The most complete group of early buildings at Henlow comprises the five General Service Sheds which, although subjected to some external alteration, comprise the most complete ensemble of hangar buildings on any British site for the period up to 1923. The flying field has been partly developed by a golf course. The domestic site, which was subjected to an extensive rebuilding programme concentrated in the first half of the 1930s, is situated across the A6001 to the south of the technical group. This has retained an extensive group of married quarters, executed in the Garden City tradition, and barracks and office buildings dated 1933-5 which display unique architectural treatment for a military air base: the most consistently well-handled of these buildings is the officers' mess.
(Air Ministry Drawing 1528/18, RAF Museum Hendon; The History of RAF Henlow, RAF Henlow, 1998)
