Airfield Buildings and Site Info ( Part One )

 Policy and Procedures

In 1939 there was a policy of dispersing aircraft on and around and sometimes beyond the perimeter of the airfield, but his would make defence very difficult. Defence was confined to a limited number of light machine-gun posts for anti-aircraft use in protecting the airfield against enemy attack Certain operational stations would have additional guns of a higher caliber :- two pounders and three inch guns, but no further works were constructed for them.

In 1940 with the threat of invasion there was an initiation to construct pill-boxes, rifle pits and very extensive wire entanglements ( barbed wire on screw pickets ) as additional airfield defence. Some pill-boxes were constructed with anti-aircraft positions on the flat roof for twin Browning or Lewis machine-guns, thus giving an elevated all round view and protection of the surrounding area.

There was no laid down procedure or standard for the defence of an airfield due to the fact that owing to variations and topography it was impracticable.

A procedure that was adopted required the Local Military Authority, usually acting through the Local Defence Commander, who was the Defence Advisor to the Station Commander and would plan the defences and produce designs and drawings for the structural work. These were then sent to the Air Ministry Works Area Headquarters who prepared detailed drawings for contractors to work from.

In 1940  the R.A.F. Regiment had not been formed, but in the Autumn of 1940 there was created a new trade of " Ground Gunner " for airfield defence within the R.A.F.

Light anti-aircraft defence was the responsibility of the Royal Artillery with Bofors Guns. These were supported by the R.A.F. Gunners with light machine-guns.

In 1941 the location of defences of an airfield was considered a priority second only to the runway layout and above the requirements for accommodation. It was an important issue that the defence was completed in readiness of the opening of an airfield. There was also a requirement for inward facing defences in the event of the enemy landing on the airfield itself by parachute.

In August 1941 after R.A.F. Harrowbeer opened the Local Defence Advisor was Major Gaywood  MC.

As far as is known at present R.A.F. Harrowbeer defences consisted of :- 

                    Three Alan Williams Gun Turrets

                    Four anti-aircraft machine-gun posts on top of Dispersal Bays

                    One anti-aircraft machine-gun post on the flat roof of ' Ravenscroft '

                    One anti-aircraft machine-gun post on the ground close to the Leg

                                                                                         O'Mutton facing Princetown

                    Two pill-boxes, one definitely with provision for twin machine-guns

                    on top

                    Various slit trenches ( straight and half moon ) and fox-holes

                    A mobile Bofors Gun and Searchlight at the crossroads by Coombe 

                    Farm Fisheries and Buckland Abbey

Royal Engineers

With the evacuation of the British Forces from France in June 1940 a body of men became available who could maintain vital airfields under the worst conditions. This body of men were the Royal Engineer Units. Detachments of sixty six to one hundred men each were located on approximately one hundred and ten airfields. A total of seven thousand Royal Engineers were available during the Battle of Britain and carried out repair work of the utmost importance.

Gunnery School

Gunners trained at No.1 Ground Defence Gunnery School at North Coates, Lincolnshire in December 1939.

The Gunnery School moved to Ronaldsway on the Isle of Man during March 1940.

In March 1943 the School was absorbed by the R.A.F. Regiment.

The R.A.F. Regiment  

In November 1941 the Committee on Airfield Defence recommended that the R.A.F. should have it's own defence force under the Air Ministry control.

The ' R.A.F. Regiment ' was formed from all existing R.A.F. Ground Defence Squadrons and Flights on the 1st February 1942 and soon relieved the Army of it's unwanted responsibility for defending R.A.F. installations in the U.K.

The R.A.F. Regiment  ( the next stage )

On the 18th April 1944 Winston Churchill wrote :-

" I do not think we can afford to continue to maintain a special body of troops purely for the defence of aerodromes. The R.A.F. Regiment was established at a time when the invasion of this Country was likely, and when our life depended on the security of our Fighter Aerodromes. Since then it has been reduced, but the time has now come to consider whether the greater part of it should not be taken to reinforce the field formations of the Army. I consider that at least twenty five thousand men should be transferred. They will be much better employed there than loafing around overcrowded airfields warding off dangers which have ceased to threaten. "

The suggestion was taken up and two thousand men were transferred to the Guards in June 1944. In October 1944 all defence work was abandoned apart from half a dozen airfields in the South East of England and the Shetlands which kept limited anti-aircraft facilities.

The  Royal  Observer  Corps

Originally called ' The Observer Corps ' but later their job was recognised as being of national importance and they were renamed the ' Royal Observer Corps '. Their function was to plot aircraft movements both visually and by sound. All information was then passed on to their respective Group Operations Room by telephone where a complete picture was built up on an Operations Plotting Table of aircraft ( friendly and hostile ) in the area. This information was then forwarded onto Fighter and Bomber Command to be dealt with in the appropriate manner.

R.A.F. Harrowbeer in 1941 had a Royal Observer Post ( a wooden hut ) on the airfield in the area of the Leg O'Mutton. The personnel at that time had no official uniform, they wore an armband. It was not long before they received a uniform very similar to the Royal Air Force, a black beret was worn instead of the R.A.F. forage / side cap. After a short time the Observer Post was moved off the airfield site and set up in an area by the Walkhampton road junction ( Woodman's Corner storage unit site ) between the Princetown Road and the railway line.

Air Raid Sirens

Airfields were equipped with air raid sirens to give prior warning of an enemy attack.

The R.A.F. adopted the signals :-

          Alert                     =  A wailing, undulating tone

          Raiders passed   =  A steady, constant note ( also known as " the all clear " )

The sirens were usually activated from the Operation Block. Alternatively it was from the Guard Room after notification by telephone from the Operations Block.

There were two forms of siren. There was the large pole or on  top of a building electronically operated version or a small portable, mobile siren which was operated by cranking a handle. The audible tone could be altered by twisting the hand-hold on the top of the siren.

Air Raid Shelters

There were many forms of Air Raid Shelters. The early type being a crude covered slit trench. These were soon superseded by precast concrete shelters ( Stanton Type ) each holding twenty five to fifty people. Concrete precast sections were bolted together to form the required length, then covered with earth for bomb splinter protection. At one end was an entrance, shielded by a blast wall. At the other end was a wall mounted ladder leading up to an escape hatch.

 The Stanton Type shelter was often incorporated into some of the Dispersal Bay designs. Where the three earth banked sections joined together a shelter would be constructed which was capable of giving shelter to twenty five personnel. At the front of each of the aircraft bays there was an entrance into the shelter. Instead of a blast wall to protect the entrance you would enter a dog-legged passage, then through a door into the shelter. At the back of one of the short passages there was an emergency exit.

R.A.F. Harrowbeer had a large number of the Stanton Type air raid shelters close to the airfield defence accommodation huts and also on the Dispersed Sites for the airmen.

On the main airfield close to the ' two bay Bomb Store ' there are three underground re-enforced air raid shelters which are not shown on the official site plan.

Each of R.A.F. Harrowbeer's twelve Dispersal Bays had a Stanton Type shelter built into them.

Windows in buildings on an airfield were a great liability and kept to a minimum. The reason for this was that in the event of an enemy gas attack the windows could have the glass shattered or blown out therefore creating an opening for the gas to penetrate and render the occupants inoperative.

Battle  Headquarters

R.A.F. Harrowbeer was in a unique position of having two Battle Headquarters, it is not clearly understood as to why this was.

One was situated on the Technical Site in accordance with the official site plan of the Station Airfield Site. The second Battle Headquarters was built in 1942 and is not on the main airfield site. it is to the south and commands an excellent view of the airfield.

The defence of the airfield was co-ordinated from the Battle Headquarters. It was a purpose built stronghold which was standardized as drawing No.1108/41 for Operational Stations and usually built underground ( Harrowbeer's second one ). Another type of Battle Headquarters was to drawing No.3329/41 normally for R.A.F. Fighter Stations, Satellite Stations and Training Fields, ( Harrowbeer's original one ). This design again was normally built underground, but Harrowbeer's was above ground !

As with other defence work, the Battle Headquarters was not always included in the plans for an airfield but sited in agreement with the Local Authority, taking into account terrain and camouflage. The Battle Headquarters was normally built on high ground, in a hedge or close to farm buildings. A few were built close to the Watch Office.

The 1108/41 Battle Headquarters was recognized by a square observation block     ( six foot square and three feet high ) standing above ground with a three hundred and sixty degree viewing slit. The rest of the building was usually underground, if not a substantial earth bank was placed on all exterior sides. The sunken section was entered by a stairway at the opposite end to the observation block. The observation block had it's own emergency escape hatch. The building measured approximately twenty foot long by eight foot wide and comprised an office, sleeping accommodation and a latrine. A member of the personnel would act as a ' runner ' for use if the telephone communication system ceased to operate.

Once Harrowbeer's second Battle Headquarters was in use, the original one was used as either a store or a Tannoy announcements room for the airfield. 

Bellman  Hangar

R.A.F. Harrowbeer had two Bellman Hangars used for major repairs, servicing and overhauling the aircraft.

This design at one time the most common steel hangar of which approximately four hundred were located on British Airfields between 1938 and 1940. The Bellman Hangar became obsolete during the 1940's when superseded by the ' T ' series of Hangars.

Blister  Hangar

R.A.F. Harrowbeer had eight Over Blister Hangars used for servicing and minor repair work on aircraft.

Blister Hangars were produced by Messers C. Miskin and Sons in 1939. There were basically three designs :-

          ( 1 )  The ' Standard ' which was constructed of wooden arched ribs, clad 

                  with corrugated iron sheets and had a span of forty five feet.

          ( 2 )  The ' Over Blister ' constructed of steel arched ribs, clad with 

                   corrugated sheets with a span of sixty five feet.

          ( 3 )  The ' Extra Over Blister ' constructed as ( 2 ) but with a span of sixty 

                   nine feet.

All three styles were manufactured in forty five foot length sections making it possible to construct a ninety foot long building if required.

It was usual to have canvas curtains at each end for protection against the weather, sometimes the canvas curtain at one end would be substituted with a brick wall.

An advantage of the Blister Hangar was that they did not require foundations or hard standing, therefore being flexible enough to be constructed on fairly uneven ground.

Blast  Shelters

Within the Technical Area were constructed brick ' Blast Shelters ' which were traversed blast walls built above ground in a large rectangular shape with shielded entrances ( blast walls ). These shelters were for personnel to use at the last minute, minimizing the disruption of their duties.

There were three standard sizes giving effective protection for 10, 20 or 30 personnel.

Bomb  Dump / Store

On airfields in the early stages of the Second World War bomb storage was a simple and economical design. This consisted of open ' Bomb Dumps / Stores ', each around 200 tons capacity made up of four 50 ton bays separated by grass covered blast banks / walls. This was an easy way of manhandling and storing small capacity bombs, from unloading off delivery lorries to re-loading onto the Bombing-up Trolleys. Efficient movement of vehicles was ensured by circulating roads from the Bomb Storage area, Component Stores, Pyrotechnic Stores and other ancilliary Explosive Buildings in a hut construction, onto the Fusing Shed and onto Aircraft Dispersal Bays.

R.A.F. Harrowbeer had a two bay Bomb Dump / Store. The earth blast banks / walls and unloading ramps are still visible. The area where the bombs were stored is a little harder to identify, but they are there, as are the tarmac roads leading too and from the Bomb Dump / Store.

' Tannoy '  Broadcasting  System

This is probably better known as the ' Tannoy '.     It's general purpose was to enable operational instructions to be given clearly, rapidly and simultaneously to personnel at dispersal points and other distant parts of the airfield.

Microphones were placed in the main operational buildings, eg :- Operations Block, Watch Office and Battle Headquarters and connected to a Speech Broadcasting Building which housed the amplifying equipment. This small blast-proof building was normally found close to the Watch Office. Cables ran to an average of 150 loudspeakers spaced around the airfield.

It was often found that the early type of Battle Headquarters, on an airfield that was no longer required,  ( due to the building of a new design  Battle Headquarters ) was used for the Broadcasting and back-up System. It is not sure if Harrowbeer's original Battle Headquarters was used for this purpose. There are photographs that show loudspeakers on poles on the ends of the Dispersal Bay arms at Harrowbeer. 

Cannon  Test  Butt

This was constructed as a robust brick and concrete wall with returns and sand piled up against it. A red flag would have been flown when firing was taking place at the test butt.

Another feature at the test butt was usually a large grooved block which would contain a pulley wheel, this was used to enable the tail-wheel of an aeroplane to be raised in order that the aircraft's guns and cannon could be tested and re-aligned as required.

Compass  Base

The ' Compass Base ' at R.A.F. Harrowbeer consists of a round concrete base thirty feet in diameter with a central bronze pin level with the top of the base. There would have been a circular ring fixed in the ground at sixty feet diameter to the bronze pin which would of had the points of the compass marked on or fixed to it.

At R.A.F. Harrowbeer the thirty feet concrete base and pin are in situ but the outer ring can only be located by a slight ridge where it should be.

The Compass Base would have been used fairly frequently to check the accuracy of an aircraft's compass. This was done by positioning the center of gravity of the aircraft over the central bronze pin in the center of the concrete base. A trolley was normally placed under the tail wheel of the aeroplane so that it could be rotated easily. The aeroplane was moved in a circular movement to the main points of the compass on the fixed outer Compass Base ring and the aircraft's compass was checked for accuracy against this. There was also a field compass on a tripod close by that was used as a three way check for accuracy. If an inaccuracy was found it was marked on a variation card which was kept in the cockpit of the aeroplane alongside the compass.

Compass variations were often caused by an aircraft's armoury, the amount of ammunition on board, bomb loads and or other metallic additions to the aircraft's normal construction.

When an aircraft was in flight ( on an operation ) and the Flight Controller gave the pilot a course to fly the pilot would have to check the variation card against his compass and given course, make the necessary calculations ( in his head ) and fly in that direction. A miscalculation could result in the pilot missing the target or rendezvous point.

Dinghy  Drill

This would usually be carried out at a local swimming pool, pond or reservoir        ( for R.A.F. Harrowbeer they used the ' Moorland Links Hotel ' outside swimming pool ).

The procedure was that the aircrews were blindfolded ( to give the impression of night time conditions ) then thrown into the water. Each man had a whistle which he could blow, allowing them to come together as a group. An inflated dinghy was dropped upside down in the water and the aircrew had to locate it, right the dinghy and then climb on board. 

Direction  Finder

Also known as the ' Radar Directional Finder '. This was an octagonal building which contained instrumentation that could follow ( track ) aircraft by means of radio ' fixes '. these were obtained from the I.F.F. ( Identification Friend or Foe ) sometimes known as the ' pip squeak ' which was a small automatic transmitter fitted in the aircraft's cockpit.

The Direction Finder passed an aircraft's position onto the Station Operations Room. From here it was calculated the aircraft's interception course and the information given to the Flight Controller. He could then direct the friendly aircraft to intercept a hostile aeroplane.

A code was used between the Flight Controller and the pilot of an aeroplane :-

          Scramble  =  Take off immediately

          Angels  =  Height in thousands of feet ( eg. Angels ten = ten thousand feet )

          Orbit  =  Circle a given point

          Vector  =  Steer a course of . . . . degrees

          Buster  =  Use full throttle

          Tally Ho  =  Enemy sighted

          Pancake  =  Return to base and land

R.A.F. Harrowbeer's Direction Finder was in the vicinity of the junction of the Moorland Links Hotel on the A386 road. On one side of the main road was the transmitter and on the other side was the receiver. All that remains today are the concrete bases.

Dispersal  Bays / Pens

Dispersal Bays ( also known as Dispersal Pens, Blast Pens and ' E ' Pens ) were constructed as substantial earth banked areas with small retaining brick walls on the inner edges in the rough shape of a letter ' E '  if viewed from above.     

R.A.F. Harrowbeer's twelve Dispersal Bays were designed for Hurricane and Blenheim sized aircraft.

These bays would offer blast protection for two aircraft and their ground crew. At the intersection of the three banked fingers was housed a Stanton type Air Raid Shelter for up to twenty five personnel. This was entered from each aircraft standing area by an entrance with a short tunnel with a dog-leg built into the earth banking, next was a door into the pre-cast concrete shelter . Within the shelter was sometimes an emergency exit which consisted of a ladder fixed to a wall leading up to an escape hatch through the roof of the shelter. There was also an emergency exit built into the rear of the Dispersal Bay leading off one of the short entrance tunnels.

Some of the aircraft standing areas had concrete pads for the aircraft to be positioned on, this was because various types of aeroplanes ( the Typhoon in particular ) were notorious for leaking oil and fuel which broke up the tarmac standing area making it unstable. Around the edges and in the center of the concrete pads were metal loops set in the ground for securing the aircraft in strong windy and gale force conditions.

Another feature on some of the earth banked fingers of the Dispersal Bays was a defence, anti-aircraft gun position. R.A.F. Harrowbeer had twelve Dispersal Bays of which four had these gun positions for either Browning or Lewis guns.

On the central earth banked finger, towards the extremity on the ground in each of the aircraft standing areas is a small brick rectangle. Its purpose is not clear, but was possibly used for standing fire fighting equipment on ( fire buckets with sand / water and a fire extinguisher ).

Fencing

Barbed Wire :-     The best use of barbed wire as a means of defence during the Second World War was in rolls. This normally took the form of two rolls on the bottom layer stretched out and interlocking, with another roll balanced on the top stretched out. The barbed wire would have been held upright by the use of looped metal screw - picket stakes.

Basic  Picket / Perimeter  Fencing :-     Airfield perimeter fencing ( as in the type used at R.A.F. Harrowbeer ) and specific defence areas were often encompassed by a waist-high barbed wire fencing. This would usually comprise of several straight lines of barbed wire stretched taught and fastened to upright pre-drilled, metal angle iron posts. The bases of these posts were concreted into the ground for stability. 

After R.A.F. Harrowbeer was de-commissioned and the perimeter fence was taken down most of the angle iron fence posts were cut off at ground level and the posts sent for recycling. Remains can be found of the metal angle iron stubs protruding from the ground in certain areas. In the R.A.F. Harrowbeer Archive Museum are a couple of original perimeter posts and a small roll of original barbed wire from along the Crapstone Road section of fencing.