After considering the architecture of Britain’s airfields in Part 5, we turn to the hard surfaces, primarily the runways. Developed out of necessity, they created a steep learning curve for those involved in their construction. Many problems were found, many materials were tried, but ultimately they were built and even after their removal for hardcore, many have left scars in the tissue of the earth that remind us of their once massive presence.
Runways, Perimeter Tracks and Hardstands
In the pre-war years, the development of hard runways and large airfields was a new phenomena, hard surfaces being a new aspect still very much a topic of considerable controversy. In the First World War, water logging and mud was an issue even for the small biplanes that filled the skies over Britain and France. To overcome this, ash was spread over landing surfaces and to some degree successfully, but even though many local remedies were tried, it wouldn’t be taken seriously until the Second World War loomed.
At this point the typical airfield layout included up to four grass runways, one of 1,300 x 400 yards and three of 1,000 x 200 yards, many were even smaller. Bomber and Fighter Command, realising that not only would the new era of aircraft call for longer, hard runways on its airfields, but the need to maintain year round activity was essential if Britain was to defeat the Luftwaffe.
Both Fighter and Bomber Command pushed the Government to allow these to be developed, on the one hand Sir Hugh Dowding, fighting the corner for Fighter Command, pressed home the need for hard surfaces on his fighter airfields, whilst Sir Arthur Harris on the other, pushed for hard surfaces on his bomber airfields.
The entire process was lengthy and complex, and lacked in-depth, professional knowledge. The first hard ‘pavements’ later runways and taxi ways, being constructed based on road building techniques and knowledge. So before any firm decisions could be made, trials would need to be carried out to determine not only whether or not they were indeed needed, but if so, how they should be best constructed.
Initial steps in runway construction was started as early as 1937, where ‘flexible’ runways were constructed comprising layers of brick or stone covered with two further layers of tarmac and a coat of asphalt to seal the structure in. Concrete pavements, which proved to be much stronger were either 150 mm or 200 mm thick slabs laid directly onto the ground after the topsoil had been removed by heavy machinery. As would be expected, these early designs failed quite quickly under the heavy loads of the fighters and bombers that were coming into service. Rapid repairs were carried by adding a further layer of tarmac (6.5cm) and another layer (2cm) of sealant.
These early flexible constructions continued to fail whereas the concrete designs stood up to much more wear and tear and proved longer lasting. However, time was short and the learning curve would be steep.
The test to determine these needs was to take a Whitley bomber, laden to equal its full operational weight, and taxi it across a grassed surface. A rather primitive assessment, it was intended to ascertain the effects of the aircraft on the ground beneath. Trials were first carried out at Farnborough and then Odiham, and these were generally successful, the Whitley only bogging down on recently disturbed soils. Further trials were then carried out at RAF Stradishall in March 1938, and the results were a little more mixed. Whilst no take offs or landings took place during these trials, the general agreement was that more powerful bombers would have no problems using grassed surfaces, as long as the ground was properly prepared and well maintained. All well and good when the soils were dry and well-drained.
By April 1939, the Air Ministry conceded, and agreed to lay runways at a small number of fighter and bomber airfields, of which Kenley, Biggin Hill, Debden and Stradishall were identified. Whilst construction was slow, only two fighters airfields being completed by the outbreak of war, progress was finally being made.
These initial runways were only 800 yards long and 50 yards wide, but were extended later that year to 1,000 yards long, as aircraft were repeatedly running off the ends on to the grassed areas. Over the years Stradishall in particular, would be further developed, its longest runway eventually extending to 2,000 yards.
During the early war years, the demand for airfields grew. By early 1940 the requirement was for three runways as close as possible at 60o to each other, and of a minimum length of 1,000 yards with room for extension up to 1,400 yards. This then became the norm by late 1940 especially at bomber airfields, with the main runway being 1,400 yards and subsidiaries at 1,100 yards. A month later, this increased by another 200 yards with a requirement to be able to extend to 2,000 and 1,400 yards respectively.
However, these short piecemeal responses were not sufficient and it was both a continual problem and a thorn in the side for the Air Ministry. Sir Arthur Harris, in raising his concerns for airfields belonging to Bomber Command, also pushed the need to develop good, long and reliable surfaces. He voiced his frustration in a vehement letter*6 to Lord Beaverbrook in 1941, In which he states:
“For twenty years everybody on the stations and the squadrons has been screaming for runways without avail.”
and he continues stressing the need for hard surfaces particularly in winter as:
“Through not having runways our effort will be seriously detracted from in normal winter conditions and reduced very probably to zero in abnormal winter conditions.”
He then goes on to state that Britain’s views were ‘blinkered’ saying that:
“Every other nation throughout the world has long been convinced of the necessity for runways…”
By the summer of 1941, the length of runways had again increased, all stations would now have a main runway of 2,000 yards and two subsidiaries of 1,400 yards and where this was not possible, then a minimum of 1,600 and 1,100 yards (fighter and night fighter stations being shorter at 1,300 and 1,400 yards respectively).
The harsh winters were less than ideal for laying concrete (by far the best material for the job) but any delay could mean the difference between success and failure. Elaborate testing was therefore passed over, materials were laid and experience led the way. This method of trail and error, led to many instances of runways having to be dug up and relaid, this in itself led to problems as aircraft, men and machinery had to then be moved and housed elsewhere. The American Eighth Air Force suffered greatly with these problem, fully laden bombers repeatedly breaking through the surface or falling off the edges as it gave way.
Another consideration was that of training and satellite airfields. As the need for new pilots increased, the training of new recruits intensified. The harsh winters were causing major headaches for these airfields as mud, stones and other winter debris was causing continuous problems for flying. With both man power and materials being in short supply, suitable alternatives were sought. A number of solutions were offered all very similar in their design and material.
The answer it seemed lay in steel matting – of which twelve different types were used – the more common being : Sommerfeld Track, Pierced Steel Planking (PSP – also called Marston Mat), or Square Mesh Track (SMT).
Sommerfeld track was a steel mat designed by Austrian Kurt Sommerfeld. The tracking was adapted from a First World War idea, and was a steel mat that when arrived, was rolled up in rolls 3.25 m (10 ft 8 in) wide by 23 m (75 ft 6 in) long. It was so well designed that a full track could be laid, by an unskilled force, in a matter of hours. Each section could be replaced easily if damaged, and the entire track could be lifted and transported by lorry, aeroplane or boat to another location and then reused.
Sommerfeld track (along with these other track types) were not only used commonly on training and satellite airfields, but also on Advanced and Forward Landing Grounds in Kent and later France after the Allied invasion of Normandy. In the build up to D-Day, 24 Advanced Landing Grounds in southern England were created using this form of Steel Matting,
Tracking had to be robust, it had to be able to withstand heavy landings and be non-conspicuous from the air. Sommerfeld track met both of these, and other stringent criteria very well, although it wasn’t without its problems. Crews often complained of a build up of mud after heavy rain, and concerns over both tyre and undercarriage damage were also extensively voiced; several records reporting tail wheels being ripped off after catching in the track lattice.
Because of the poor state and short length of runways, bombers were still regularly running off the ends, especially at night, or being unable to fly because the surfaces were poor or even unusable. A number of ideas were tested out to alleviate the problem, one such idea led to twenty sites testing arrester hook facilities. Several heavy bombers: Halifax, Manchester, Stirlings and later the Lancaster, were all modified to undertake these trials, with Woodhall Spa becoming the first airfield to have the full complement of six arrester sets.
The idea was met with scepticism, but trials went ahead and in January 1942, a list of priority airfields was sent out to the Headquarters of No. 1,3,4, and 5 Groups RAF detailing those twenty sites selected for the equipment. At the top of the list was RAF Woodhall Spa in Lincolnshire, followed by Bottesford, Swinderby, Ossington, Syerston, Middleton St. George, Linton, and ending with Waterbeach and Stradishall. By late 1942 Woodhall Spa was ready and in October, five landings were made by an Avro Manchester. A month later the decision was made to install units at all major operational airfields, but this never came to fruition and the idea was soon mothballed. By 1943, it had been forgotten about and the 120 or so units built were scrapped (many being left buried where they were laid).
It was finally during early 1942 that a standard design airfield would be put in place. Known as the Class ‘A’, it would be the standard to which all new airfields and updated older sites would be made.
A Class A airfield would be designed around three hard concrete runways, shaped like an ‘A’ with each runway at 60o to each other where possible. The main runway would be aligned with the prevailing wind again were possible to allow aircraft to take off/land into the wind as often as possible (north-east, south-west). In several cases, due to land features and local restrictions, this was not always possible, and so many permutations of design were seen as a result.
Rapidly becoming the largest part of the airfield layout, the runways and other paved areas – perimeters tracks, aprons and hardstands – were now given high priority. The standard now called for a main runway of 2,000 yards with two subsidiaries of 1,400 yards. Each of these would be 50 yards wide whilst the connecting perimeter tracks would be 50 feet wide. Along side these runways would be an emergency landing strip, a grassed area given a landing surface of 400 and 200 yards respectively.
Dues to the high numbers of bombers returning badly damaged and unable to make safe and proper landings, a small number of emergency strips were created by extending the main runways to 4,000 yards long and 400 yards wide. One such airfield was RAF Manston in Kent. Being on of the closest airfields to the continent, it was often the first place a stricken aircraft, especially a bomber, would seek out.
Whilst the general layout of airfields did not change for the remainder of the war, some further runways were extended to 3,000 yards, one such example being RAF Sculthorpe in Norfolk which was prepared to take the heavy B29 ‘Superfortress’ and post war, the B-36 ‘Peacemaker’.
A further point worth mentioning here is that of dispersals, not required pre-war, they were also an aspect of airfield architecture that were born out of the Second World War. In the inter-war years, aircraft were housed either on a central pan (apron or ramp) or within hangars. These collections of aircraft were easy targets and even a small amount of munitions could cause huge damage. In 1939 the need for dispersals was therefore recognised and so to address the issue, hedges were removed and tracks created that took aircraft away from the main runway but kept them within easy reach of the airfield site. The initial design was that of the ‘frying pan’ a 150 ft circle connected to the perimeter track by a small concrete track.
However, by 1942, it was found that aircraft were clogging up these tracks, some even ‘falling off’ the concrete onto soft soil and so blocking following aircraft in their tracks. The answer was the ‘spectacle’ or ‘loop’ hardstand, so-called by their oval shape, generally in pairs, that allow aircraft in and out without the need to turn or block access tracks. From 1942 onward, this model became the standard hardstand for all Class A airfields, and the aim was to have 50 such hardstands placed strategically around the perimeter, with 25 at satellite airfields. As the threat of attack diminished toward the end of the war, ‘finger’ or ‘star’ dispersals began to appear, much less effective than the predecessors, they were however cheaper and easier to construct.
In addition to hardstands, pens were built on fighter stations. The first, an experimental pit, was dug at Feltwell, whilst overly expensive and obtrusive, it did lead the way to aircraft pens later on, pens that were developed as either type ‘B’ or ‘E’ on these fighter airfields. The main difference here is that the early type ‘B’ had cranked side walls whereas the ‘E’ had walls that were straight. The former requiring more space, was later phased out in favour of the ‘E’, named so by its shape, using side and back walls to protect the fighter or small bomber located within.
Examples of these pens were located at Matlaske (type ‘B’ – built to design 7151/41) whilst the type ‘E’ were found on airfields especially those around London that included Biggin HiIl, Kenley and North Weald.
These pens were designed to specific dimensions and were designed as either a ‘Hurricane’ or ‘Blenheim’ to accommodate either a single engined or twin-engined aircraft. Within the back wall of these pens was a shelter for up to 25 personnel, and in some cases, they had Stanton Shelters built-in to the structures. Some, for example, at Kings Cliffe in Northampton, remain with rifle slits for additional protection from ground forces.
Whilst the majority of these shelters were manufactured using banks of soil, sandbags, brick or concrete, there was a least one example at RAF Drem, in Scotland which used logs cut to size and shape and built in the style of a Scandinavian house. It is these various designs of aircraft pen that paved the way to modern hardened aircraft shelters (HAS) seen on military airfields today.
From the early days of grass runways to the massive lengths of concrete that were created up to and after the mid 1940s, runways and hardstands have become a defining factor in airfield design. The sole purpose of an airfield – to get aircraft off the ground as quickly as possible, get them to their target and them get them home again – led to the development of both runway lengths and construction materials, much of which has paved the way for modern airfields today. These early leaps into runway designs have enabled larger and heavier aircraft to make those important journeys that we very much take for granted in this the modern world of air travel and general aviation.
In the next section we look at one of the buildings most associated with the airfield. An early form of aircraft storage, its role changed as it was soon realised that aircraft needed to be dispersed and not grouped together on large aprons as they were in the prewar era. Aesthetics and neatly lined up aircraft were no longer an important factor in front line flying, but safety and the ability to repair aircraft quickly and efficiently were. Here we introduce the hangar, a huge building often of a temporary or transportable nature, that became one of the more longer lasting structures of airfield architecture.
Sources and further reading.
*6 Letter from Arthur Harris to Lord Beaverbrook, February 1941 – AIR 19/492 – National Archives