Airfield Buildings and Site Info ( Part Two )

Flying  Control  Caravan

During the Summer of 1942 to reduce the number of accidents on the airfield, especially on the runways it was decided to position a caravan alongside the touchdown area. Where an airfield had a hard runway the caravan had it's own hard-standing and access track at each end of each runway. The caravan was managed by an Aerodrome Control Pilot who had an Aldis Signalling Lamp and a Very Pistol to warn pilots of danger.

An access track for a Flying Control Caravan can be found at R.A.F. Harrowbeer at the south eastern end of runway two not far from the large granite rock formation. 

Lighting / Signals / Emergency  Landing  Systems

Aldis  Lamp :-     This was a small moveable trolley which was pointed into the wind, on it were mounted four powerful Aldis Lamps. As the aircraft descended on landing the lamps were switched on, shining a beam of light over the runway surface it was to land on. The aircraft would land into the beam, the lamps being switched off after the aeroplane had touched down on the runway.

Aldis  Signalling  Lamp :-     The Aldis Signalling Lamp was a hand held lamp that was used for communicating messages by morse code. There was also provisions for changing filters from clear to red, yellow, blue, green etc. for use in transmitting the colours of the day when required.

The  Darky  System :-     If an aeroplane was in an emergency situation regarding it's condition and position to an airfield it is due to land at the pilot could use the basic life-saver ' Darky '. This was a system where the pilot could call for a ' Homing ' using the call-sign Darky. Most R.A.F. Stations operated on a permanent Darky Watch on a common frequency with a transmitter / receiver of limited range to avoid possible overlap with other Stations. By taking bearings and comparing them by telephone they could rapidly fix a lost aircraft's position and guide it to safety.

Where R.A.F. coverage was poor the Royal Observer Corps Posts could be contacted to assist as they were also equipped with the Darky sets. 

Gooseneck  Flares  :-     The Gooseneck Flare was so called because of the long-necked spout on the container that resembled a large watering can. The main body contained paraffin, or any other flammable liquid with a wick traveling up the spout and extending by a small amount. The Gooseneck Flare would be positioned with the spout pointing downwind to prevent flaring when it was alight. It produced a bright light that was extremely difficult to extinguish in the event of enemy aircraft approaching the airfield. The Gooseneck Flare would be positioned at intervals along both sides of the runway being used at night to assist the pilots in taking off and landing their aeroplane. On the end of the spout there was a metal hinged flap that could be used to cover the wick to extinguish the flame when no longer required. When not in use the Gooseneck Flare would be stored in the Night Flying Equipment Store.

R.A.F. Harrowbeer did not have any form of electrical runway lighting, it was dependent on the Gooseneck Flare system.

Landing  Floodlights  :-     These were improvised from floodlight units surplus to other services. The floodlights were mounted on three wheeled trolleys for ease of movement around the airfield. One floodlight unit would be placed on the left-hand side on the end of the runway edge and twenty five yards in from the G.P.I.'s so as to shine down the runway length in the same direction as the landing aircraft.

Pundit  Beacon :-     This was a mobile beacon which would flash the Airfield's Pundit Code ( identity call sign ) high into the sky at night using morse code by way of a red light.

R.A.F. Harrowbeer's Pundit Code was 'Q. B. '  =  Quebec Bravo.

Sandra  Lights :-     This system comprised three search-lights positioned around the airfield which could be directed skywards to form a cone. In the case of low cloud-base when the system was switched on a glow could be seen from above thereby guiding aircraft to the safety of an airfield.

Signals  Square

The Signals Square was a black area sixty feet by sixty feet edged with a white 4 inch border and situated fairly close to the Watch Office. On this square was marked the runways in the correct orientation to the main airfield which could be visible by overflying aircraft. The Flight Controller would be responsible for keeping the symbols on the Signals Square up to date at all times.

For instance :-     On an airfield, the runway in use for landing and take off was dependent on wind direction. For aircraft coming into land a white ' Landing Tee ' would be positioned on the touchdown end of the appropriate runway showing the direction the aircraft was to land in.  There would also be a second white         ' Tee ' positioned at the downwind end of the runway. The crossbar was always nearest to the approaching wind.  Other signs may include :- 

a white ' Dumb-bell '  =  airfield is unserviceable except for runways and taxiways, a red ' G ' on a triangular white background  =  airfield has been subjected to a gas attack, etc.

The Signals Square was of the utmost importance for the reason being that if a pilot was returning from an operation and had lost radio contact he could fly over the airfield and read the visual signs on the square.

R.A.F. Harrowbeer's Signal Square is still visible apart from its markings of the border and runways. It can be found on the southern side of where the main Watch Office was built.

Signal  Mortar

A Signal Mortar was a device built into the ground close to the Watch Office and controlled by the  Flight  Controller.  It was used when visibility was very poor      ( usually thick fog ) to guide aircraft safely to the airfield.

A very large pyrotechnic flare would be fired from the Signal Mortar vertically high into the air when the use of a very pistol would be useless. The flare would cut through the thick fog giving off a visual light which could assist the pilot of an aeroplane to either land or proceed to another airfield.

The Signal Mortar at R.A.F. Harrowbeer is still in its original position, adjacent to the Signals Square and close to the Watch Office. It is three inches in diameter and is stamped around the rim with a date of 1943. We know from the Station Operation Record Book that the Signal Mortar was used on several occasions.

Very  Pistol

The Very Pistol was a hand held device which fired flares of different colours, depending on the situation into the air as a signal to pilots and personnel. 

A flare was often fired to alert pilots, air crew and ground crew at dispersal of a scramble in the event of other methods failing, eg. :- Tannoy or Telephone. A green flare would be fired for aircraft to take off when on the end of a runway awaiting take off instructions. Flares were often used to warn air-borne pilots to fly round again if they were approaching with another aircraft in its blind spot or the aircraft was attempting to land with its undercarriage retracted.

There were occasions at R.A.F. Harrowbeer when a red flare would be fired into the air when a Squadron was about to return from an operation. This was to call all personnel to the airfield from Dispersed Sites ( around Crapstone ) to clear Dartmoor ponies from the runways and perimeter tracks so that the aircraft could land safely.

Link  Trainer

The Link Trainer was invented in 1920 by an American - Edward Albert Link, it was the first electro-mechanical Flight Simulator.

This was a machine housed in a building which was a very basic representation of an aeroplane with cockpit controls and flight instruments. A bellows arrangement at the base of the cockpit would give the impression of movement. A hood could be placed over the top of the cockpit to give the impression of night so that night flying practice could be carried out.

Operations  Block / Room

This was normally a windowless building. The usual design was for the main Operations Room to be constructed similar to a small theatre with a raised dias for the Controller. The rest of the building was a maze of rooms and corridors.

Pundit  Base / Code

During the Second World War the R.A.F. adopted a system of airfield recognition which was visible from the air.  In front of the Signals Square would have been two rectangles with a code letter marked on each  of them. In the case of R.A.F. Harrowbeer this was ' Q B ' ( Quebec Bravo ) which was known as the Pundit  or Airfield Code.

The Pundit Base Code was only visible from the air during certain times of the day. The enemy could very easily have made a record of every airfield by this code and marked them on their attack target maps. To keep secrecy to a minimum the Pundit Base was covered over with a tarpaulin sheet when not required. The only time it would be uncovered is when Squadrons were returning from operations, immediately the last aircraft was home the Pundit Base would be covered again.

Runways and Taxiways

Due to the large number of aircraft at an airfield and the increase in activity there had to be regulation of vehicle movement, the clearance of obstructions and the control of taxiing aircraft. Taxi routes were devised and white lines were painted on perimeter track bends, this proved effective especially at night.

Runways had numbers ( compass bearings ) allocated to their extremities.

R.A.F. Harrowbeer had three runways, therefore they required six numbers. The numbering started from the runway end nearest to north and continued in a clockwise direction. Harrowbeer's numbers were :-   05 / 23            11 / 29            17 / 35.  From March 1944 runways were referred to by their magnetic bearings.

On an all grass airfield it was possible for a Squadron of four aircraft to take off at the same time in a line abreast, this had the advantage of the Squadron to be in a fighting formation immediately after lift off. It was also possible for all the aircraft to land at the same time. Another advantage of grass airfields was that take offs and landings could be directly into the wind. The disadvantages that in continuous bad weather the airfield became waterlogged and therefore impossible for the aircraft to take off or land effectively, this made them vulnerable in the event of an enemy attack. Another factor was that as aircraft were becoming larger and heavier they required a firmer surface to stand on and operate from.

Hard runways ( asphalt, tarmac or concrete )  had a few restrictions, mainly that aircraft could only take off singly or in a staggered group of three down the runway. Landing had to be carried out one at a time with sufficient intervals between aircraft, a major danger being that if aircraft were landing too close together the following aeroplane ran the risk of being caught in a slipstream which caused it to be thrown out of control resulting in a crash.

The longest runway was normally in the direction of the prevailing wind, other runways used for landing due to unforseen circumstances could involve cross-wind landing which required expertise and handling skills which had to be learnt.

A Spitfire MKI required 230 yards to take off and 270 yards to land.

Sewage  System

To minimise the amount of drawings for types of buildings and other site layouts, the R.A.F. standardised as much as possible in order that units could be made en-masse. The Sewage System was one such area. By the end of 1939 most sewage layouts were the same comprising :- humus tanks and drying beds, sedimentation tanks and percolating filters.

R.A.F. Harrowbeer's Sewage Site was to the rear of the Station Sick Quarters and off Stokehill Lane ( Dispersed Site No.13 ), it is still in use today under the control of South West Water.

The Latrines on R.A.F. Harrowbeer were of the chemical toilet type ( commonly referred to as ' bucket and chuck it ' ). The waste material would be collected at regular intervals throughout the day and taken to the Sewage Site for processing. Dirty water and storm water was disposed of through a drainage network incorporated within the construction of the airfield.

Screw  Pickets

Short Screw Pickets were commonly used for tying down aircraft.

Long Screw Pickets were used for staking out barbed wire. Barbed wire fencing was used as a method of enclosing an airfield around its perimeter, airfield Dispersed Sites and also some anti-aircraft gun positions.

Smoke  Generators

This was a device that could indicate wind direction and if required lay a smoke screen. This usually consisted of a slotted metal cover over a pit, the smoke was produced by vaporizing oil or paraffin over a hot surface.

( It is not clear whether R.A.F. Harrowbeer had any on the airfield ).

Tactical  Units

A Tactical Unit ( Squadron ) of twelve aircraft would normally be divided into four sections of three aircraft as follows :-

          Red and Yellow Sections in " A " Flight

          Blue and Green Sections in " B " Flight

The pilots in each Flight were numbered 1, 2 and 3.

Red 1 would lead Red Section followed by Red 2 and Red 3.

Watch  Office     518 / 40

 Watch Office was an English term for the building used for controlling the movements of aircraft both on the ground and in the air on an airfield. Most people today refer to this building as ' The Control Tower / Room ', this is a word brought to England by the Americans and has now become the common terminology. 

The Watch Office was considered the nerve centre of a Second World War Airfield second to the Operation Block / Room.

The Watch Office was normally located on the ground floor of a two storey building constructed with a internal staircase to the rear. The building also housed a Control Room, Duty Pilot's Room, Meteorological Office and a Teleprinter Room.

The Duty Pilot's Room was situated on the ground floor and it was one of his functions to book the aircraft in and out. Every movement of an aeroplane had to be logged even if it was only from one side of the airfield to the other side.

In the Control Room which was situated on the first floor was a backless iron cabinet and used for storing Very Pistol Cartridges. The cabinet would be situated either in front of a window or an asbestos panel, the reason being that in the event of the contents being accidentally ignited ( during an attack on the airfield ) the contents would blow out into the open air.

R.A.F. Harrowbeer's original Watch Office was a three storey, square tower built onto the existing house ( known as ' Knightstone House ' ) and thought to have been built early in 1939. It was used for the duration of Harrowbeer's operational life and after the Second Watch Office ( a 518 / 40 ) was built and opened in early 1942 close to the Technical Site as a Plotting Room, Intelligence Office, Squadron Offices, etc.                    ( Confirmed by Mr. Colevill who was an Air Gunner / Observer on Fairey Swordfish aircraft with No.838 F.A.A. Squadron operating from R.A.F. Harrowbeer in 1944 ).

The ground floor of Knightstone House comprised five rooms and a staircase to the first floor.  The five rooms were :-  A Flight Office, two Crew Rooms and two Workshops ( one of which was used for repairing wireless transmitters and radios for the aircraft ).  On the first floor of Knightstone House were a number of rooms used by Squadron Officers and Intelligence Rooms ( used for de-briefing of pilots ) was carried out within the building.

It was in this building that on the 21st October 1941 No.276 Air Sea Rescue Squadron was formed and used part of it as their Squadron Headquarters until moving across the road into Ravenscroft in February 1943.