© Crown Copyright/MOD

Hull's Own Air Force Station

© Crown Copyright/MOD


The silver barrage balloons that flew over the Humber Area and elsewhere were a part of a highly visible defence and although they indicated an impending air raid they did provide some re-assurance to the civilian population.

However when seen close up by pilots of aircraft - be they friend or foe, they became Silver Monsters - majestic but deadly. Their function was to support the required length of steel cable below them, which was the form of defence.

The Barrage Balloons known as the LZ (Low Zone) Kite Balloon were developed at RAF Cardington in 1935 and initially had an upper limit of flight of 5,000 feet. Several modifications were made to the LZ but all had the approximate measurements of a length of 64 feet, a height of 31 feet, a diameter of 25 feet and a total weight of 600 pounds. The material used in the construction of them was a two-ply rubber-proofed Egyptian cotton finished with an aluminium powder - cut into 600 pieces with a total of over 1,000 square yards. This was coated with a "Dope" of black waterproof undercoat, an aluminium varnish topcoat, and finished off with the addition of the allocated Serial Number. The cost of each was over 500.

These Balloons were of the "ballonet" type with the main envelope divided into two compartments by a gas-tight fabric diaphragm. The upper part held 19,150 cubic feet of Hydrogen Gas and the lower compartment (or ballonet) contained at certain times air that would have entered through a wind scoop in the forward part, or Bow of the Balloon. The gas, which provided the lift of the balloon, was stored in high-pressure cylinders and for the initial filling 30 cylinders were needed at a cost of 50. To stabilise the balloon two fins were attached to the main envelope to minimise rolling and a rudder gave directional stability keeping the bow of the balloon into the wind. For their inflation wind entered into a scoop fitted on the rudder and together with the internal structure their shape was maintained.

Diagram naming parts of a balloon Air filled ballonet Inspection slevve Rip cord Inspection port Fin deflation sleeve Stabilizing fin Rudder fin Fin deflation sleeve Air scoop Gas deflation valve Hand line Handline Rip panel Inspection port Relief valve Diaphram Picketing guy rope Air filled ballonet Air scoop Gas topping-up trunk Steel cable atatchment

Attached to the main envelope fabric were hand lines and a harness of ropes (Flying Rigging) connected to a 0.31 inch flexible steel cable contained on the drum of a petrol engine operated winch on the 'prime mover' - the "Sussex" Winch Lorry vehicle.

The Fordson "Sussex" was a six-wheeled lorry fitted with an M B Wild & Company's Mark 6 winch with a drum capacity of 7,000 feet of 0.31-inch diameter flying cable. It had two Ford 30 bhp 3,500 cc V8 side valve petrol engines - one on the lorry and the other powering the winch. It had a length of 24 feet, a width 6 feet 6 inches, and a weight of 5 Tons. The paint work was in Air Force blue, with mudguards and running boards in black edged with white lining. (The latter was Black-out Regulations.) So as not to confuse anyone as to its owner, It was finished with the letters RAF in white on the panel of the cab doors!

Sussex winch lorry

Immediately behind the cab of the vehicle was the winch with associated petrol engine, then after that - the control compartment completely enclosed in steel mesh for the protection of the Balloon Operator - then a open area, on which a deflated and folded balloon could be stored. At the extreme end of the vehicle, an enclosed pulley wheel through which the winch cable passed to the balloon. This vehicle was capable of towing two trailers and was designed as a self-contained mobile balloon unit but they were used through out the war on permanent land remote sites. (The 'mobile' format was to come to the fore in the deployment of nearly 2,000 Mk X balloons in the fight against the V1 Bomb threat in 1944.)

Operation of the winch, powered through a five-speed gearbox was described as being the same as a car - but without a steering wheel! The foot pedals for clutch and accelerator were as normal, while the foot and hand brakes operated a Snatch Brake Unit that slowed or held the movement of the balloon cable. The gearbox had six selector positions. 'Neutral' and 'reverse' paid out the cable, while 'one' through to 'four' hauled it in at different speeds.

Another difference from a car was on the dashboard in front of the Operator's seat. The left-hand of the two dials displayed the speed and length of the cable in "Feet per minute", which was being let out or hauled in. It also gave an indication of the height at which the balloon was being flown. The right-hand dial, marked in "Tons" displayed the load or tension on the cable. Together, both dials were read to maintain the speed of the winch within the maximum laid down for the gear selected, so as to eliminate the strain on, or the breaking of, the balloon cable.

The cable was a good conductor of static electricity and lightning, and the winch drivers were very careful when climbing onto and off of the control position. The use of rubber sole shoes (not crepe) was recommended, but it is said that many wore Wellington boots, which provided some insulation from the metal parts of the operating vehicle. This was bonded to the ground by a copper earth pin that was examined every day as part of the winch Daily Inspection.

Having dealt with the EARTH PIN: which headed the list, the crew would check the engine for oil, petrol and water, and would lubricate four moving parts on the winch. Checks were then done of the hand and foot brakes, the clutch pedal and electrical equipment. On completion of all the checks, an entry was made on RAF form 1456.

The balloon was also subjected to a Daily Inspection, for which six instruments were available. This involved a test for leaks, the purity of the Hydrogen gas, and a "look" at the ballonet. The balloon fabric was examined internally and externally for any holes, and the ropes and wires connected to it were also checked. The balloons not only attracted bullets from passing enemy aircraft, many holes in the fabric were the result of birds pecking at them. (It's possible that the 'Silver Monsters' attracted insects!). Any necessary minor repairs were completed, and the required entry made on yet another RAF Form: No. 1332. If major repairs to the balloon were required it would be replaced and repairs of the damaged one would be undertaken at the Balloon Centre. RAF Motor Fitters were based at the Centre, where major repairs could be dealt with, though minor repairs and servicing of the winch lorry were done on Site.

The ordering of Hydrogen, fuel and all other equipment, was the responsibility of the Stores Department at the Balloon Centre, from where issues were made to the Squadrons when required.

Hydrogen is highly combustible and is said to be the lightest known gas that could not be seen, tasted or smelled. It is not poisonous, but will suffocate if inhaled, and when mixed with air the mixture would easily burn or explode if ignited by a spark. It was normally stored at the Centre and taken to the remote Sites when required, but because of logistics involved, some stock was held at Flight HQ's in North Lincolnshire.

This gas was produced at Air Ministry plant at Cardington in Bedfordshire and installations of the Imperial Chemical Industries at Runcorn, Cheshire and Billingham in Cleveland. The supply required for the Hull Barrage involved round trips of 200 to 300 miles by road for the refilling of cylinders. These were transported on "Eagle" four-wheeled trailers, each capable of carrying thirty cylinders on purpose-built metal frames. The towing vehicles carried a similar load.

Eagle hydrogen trailer

In addition to the prime mover - the "Sussex", two further Ford V8 powered vehicles were operated by the RAF on Balloon Barrages. A 3-ton model was used either as a covered personnel / equipment carrier, or by using the chassis only as a towing vehicle. For general duties a 15-Cwt totally enclosed Van was used, which was described as being 'streamlined, with a good turn of speed', possibly a forerunner of the "White vans" seen on the roads today!

All three vehicles were of American design and from 1937 onward built at the Fords of America plant in the United Kingdom. The Ford V8 engines were also used to power other War Office Transport, which included a 1942 version of the prime mover - a Balloon Winch Lorry.

The use of Hydrogen - a 'lighter than air' gas, to provide the 'lift' of the balloons, meant that they 'flew' themselves, but careful control with the use of clutch and brake was required by the Operator; even more so if the cable was fitted with DPL's - the Double Parachute Link.

This was a means of making balloon cables even more lethal to enemy aircraft and came into production late in 1939. The use of a single cable was maintained, but two cutting links operated by explosive charges had been added, one 150 feet below the balloon and another at the same distance above the ground. Attached to the cable between these links were two parachutes with the bags that contained them - one anchored to the cable below the link nearest the winch, the upper one connected to a ripcord attached to a patch on the balloon.

The impact of a aircraft striking the cable caused a tension wave to be sent along it in both directions which fired the explosive charges to sever the cable at both ends and as the aircraft flew on, taking the cable with it, which caused the two parachutes to open at the ends of the severed cable, creating a huge increase in drag, thus causing the aircraft to crash. When the top parachute was deployed, the pull on the bag would open the patch allowing the Hydrogen to escape, and in theory the balloon should then return to land. This system was later fitted at land sites in the Humber Area.

However, this modification caused more problems as miss-fires of the explosive charges often occurred, and gave the Crews' the dangerous task of recovering and making safe the devices. It also meant that more balloons became "rouges", which drifted off with full cable attached to them causing damage to buildings; even proving fatal to people on the ground, which happened at the Hull's Queens Garden Site, causing the death of a female pedestrian.

When the balloon was not being flown it was "bedded" over ground sheets to protect the fabric. It would remain connected to the steel cable but was kept down by canvas bags filled with sand that were hooked on to the ropes from the outer skin. This operation had to be done very carefully, and ideally there needed to be a few inches clearance between the balloon fabric and its bed, not allowing any movement.

Originally balloons were flown from the pulley fitted on the Winch Lorry, immediately over it and the operator. From experience gained, the Winch Lorry was moved to one side, a secondary pulley installed on an anchorage in the centre of the site through which the cable passed to the balloon, this became known as the 'Main Anchorage'. It could be said that this improved the safety of the Balloon Operators. Combined with this, another method for the bedding of the balloons at permanent sites came into being, known as the "Star-bed".

Hymers College balloon site Margaret Wood Hymers College Balloon tether

This innovation incorporated from the centre eight concrete blocks in the form of a star then eight screwed picket and finally at radius of 74 feet a further sixteen pickets; 33 sand bags were also used for the 'bedding' of the Balloon.

Land site anchorages eventually consisted of an eyebolt fitted in the top of a cubic yard of concrete weighing approximately 2 tons imbedded in the ground to form the Main Anchorage and surrounding it at a radius of 90 feet - 24 secondary anchorages. It is a fact that not all those of a lighter gauge were used but the metal eyebolts of them were highly polished by the WAAF Crews, they still preferred the use of sandbags!

On the first day of WW2, balloon manufacturers were unable to meet the demand, which - not including the London Barrage resulted in only 180 being available to the fourteen other barrages that were being created in the UK. By 1st October 1939, the Hull Barrage consisted of only 19 Balloons, which it will be seen was only about a quarter of those required.

During the first ten months of the war more than fifty Balloon Land Sites were created in the City of Hull and rural areas north and south of the River Humber. Open land was needed for the balloons to be safely flown and they had to fit into a plan - not only to defend strategic establishments, but also to form the perimeter of the proposed barrage area. Ordnance Survey Maps became very helpful in this task.

The area of land needed for the barrage extended from the village of Sutton in the North to Immingham Docks in the South, and from Paull Fort in the East to the Priory Railway Sidings at Hessle in the West. Within that boundary obvious sites were at the city's parks, recreation areas, school playing fields, a Convent and even the Hull's Municipal Airport. The remainder was on any open sizeable patch in the built up area and rural farmland.

Each of these Sites required accommodation for the crew. In the built-up area of Hull houses were commandeered, whilst elsewhere, initially bell-tents were used until replaced by either RAF's sectional Type B timber huts, or corrugated iron sheeted Nissen huts.

The 'Norman Wade' balloon barge. Air scoop (most of balloon is air, rather than gas filled after launch) Inspection port Inspection port Rudder fin (internal structure maintians fin's shape. Stabilising fin (inflated by air pressure after launch Air scoop (most of balloon is air, rather than gas filled after launch) Gas trunk Rip panel and cord Inspection port The 'Norman Wade'

The waterfront of the Port of Hull's Docks and Quays covered nearly eight miles of the River Humber that, and the adjacent built-up areas needed protection. Within the Hull Barrage, floating Balloon Sites on the River Humber were instituted using hired or commandeered river barges moored to buoys at strategic points, and crewed by RAF personnel to fly the balloons - they became known as the "Waterborne".

This 'fleet' increased with the addition of similarly obtained Fishing Drifters from which to operate Patrol Lines of balloons to deter the mining of the Estuary. These somewhat larger vessels known as "His Majesty's Drifters" were obviously under the command of the Royal Navy, no doubt crewed by members of the Royal Navy Volunteer Reserve, though the operation of the balloons remained the responsibility of the RAF personnel afloat.

All vessels were self-contained with space for the crew and equipment and the hold would contain, as well as cylinders of Hydrogen Gas, an aptly named Scammel Chassis-less Winch, bolted to a large block of concrete, which also provide ballast for the vessel. The DPL system was not used afloat and the balloons used had the addition of an internal structure of bamboo canes in the Stabilisers. To operate them from a floating site was somewhat restrictive, especially when the Daily Inspection was done! The Scammel Winches' had been dismounted from post war trailer units hence the title; later some were installed on permanent land Sites.

For use on merchant vessels in convoys, the Royal Navy used the smaller Mark 13 balloon, flown at 2,000 feet on piano wire to discourage low flying attack by enemy aircraft. In the Humber Estuary these inflated balloons were available from the paddle steamer HMS 'Killingholme' anchored in an area of the Estuary known as the 'Convoy Anchorage', situated between the Middle Light Vessel and Spurn Point. 25 Royal Navy personnel manned this supply vessel, while on board a similar number from 942/3 Balloon Squadron of the Royal Air Force serviced the balloons. The Grimsby tug 'John Mowlem' and two Belgian fishing boats complete with their crews were used to ferry the balloons to and from the merchant ships.

(Launched for the Humber Ferry services in 1912, the PS 'Killingholme' regularly operated until 1934. Retained as reserve ferry and used for river excursions, she was commissioned for her war service and eventually scrapped in 1945.)

PS Killingholme flying five balloons Mk 6 Balloon Mk 6 Balloon Mk 6 Balloon HMS Killingholme Mk 6 Balloon

There was an even smaller balloon made available in the Humber area from September 1941 and known as the Admiralty Type Mk VI. This spherical balloon only required 320 cubic feet of Hydrogen for its inflation. It was to be part of the Free Balloon Barrage under the code name of "Albino" which was hoped, would knock the enemy aircraft out of the skies as suspended below it was an explosive charge, The Air Mine!

Thunderstorms were always a great danger, and while flying, the balloons were regularly struck by lightning before they could be lowered, and were unfortunately destroyed by fire, so weather forecasting was vital. To that end, a Meteorological Section was set up at the Balloon Centre, which compiled reports that were then sent to the Squadrons and Flights by telephone and radio, if thunderstorms were taking place or imminent - balloons did not fly.

Eventually a more exact method of detecting the amount of, and any sudden increase in, static electricity in the atmosphere became available and certain positioned Barrage Balloons were fitted with the necessary equipment. This consisted of a 'sensor', fitted on the balloon and electrically connected via a single insulated copper wire embedded in the 'heart' of the steel balloon cable to terminate at apparatus on the ground. Based on an Electrostatic Volt Meter, this device continuously displayed the amount of static electricity and if a critical level were reached, alarm bells would ring at which point a member of the crew would immediately make a report by telephone and Balloon Control would take the necessary action.

This equipment would operate whether the balloon was flown at an operational height or bedded on the ground but ideally the Site from which it operated needed to be on spacious open land or hilltops while it still formed an operational unit within the Barrage.

One such site in the Hull Barrage was No. 63 Site on the then closed Hull Municipal Airfield in East Riding of Yorkshire some five miles east of the City of Hull. It was from there that the Meteorological Section regular sought readings of the level of static electricity.

This special type of balloon cable was first used on WW1 Observation Balloons and provided telephone communications between those in the suspended basket and the ground. It is a fact that the cable was updated, but indirectly it helped to prevent lightning damage to the WW2 balloons and maximised the safe flying duration.

The operation of the Hull Barrage was controlled by the local Barrage Control, who acted on orders from RAF Fighter Command at the Sector Operations Room based at the then RAF Station Kirton Lindsey in North Lincolnshire. It was there that all information of approaching enemy aircraft from RADAR Stations and the Observer Corp was received.

When enemy aircraft were detected Balloon Sites received a "Alert Yellow" signal and the balloons were made ready and flown, usually to a height of 100 feet. If the enemy was seen to be flying toward the Humber a "Alert Red" signal would follow with "FLY 4,000" the figures referring to the altitude to which the balloon was then raised. Eventually when enemy aircraft left the area an "Alert White" would be sent and the Balloon lowered and "Bedded".

Records show that during WW2, the City of Hull received 819 Alerts and more that 1,000 Hours under those Alerts.

In 1939/40 enormous supplies and services were needed by each Arm of defence so even the Hull Balloon Barrages took time, sweat, muscle and loss of life to materialise.





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