The building of a modern aerodrome involves the cooperation of many widely different industries
A SECTION OF CROYDON AIRPORT being levelled by hand. The modern method with new aerodromes, where considerable levelling has to be carried out, is to use special tractor-drawn implements. The number of men required is thus greatly reduced and much time is saved. The aircraft in this illustration is a Handley Page H.P.42 type of air liner.
MILLIONS of pounds are being spent throughout the world on building new and improving existing aerodromes. The aerodrome constructor has to cope with a constant increase in the size, weight, power and numbers of aircraft, as well as providing equipment for aids to navigation. In Great Britain the number of licensed municipal aerodromes increased in the four years 1935-38 from sixteen to thirty-five. In 1938 another ten were being built and about fifty private aerodromes were in use. In addition, big developments were planned for the airports owned by the Air Ministry and new aerodromes were being built for the Royal Air Force.
A serious complication is the difficulty of providing for expansion; another is that of allowing for the increasing use of flying boats. These difficulties are exemplified in the problems with which London has to contend. An allowance of about three-quarters of an hour or more has to be made for a passenger’s transfer from the centre of London to the cabin of an aeroplane at Croydon Airport, twelve miles away. Croydon Airport is not adequate for the existing traffic. Further, London has at present within its boundaries no provisions for flying boats.
When the authorities are considering sites for airports to accommodate land-planes or flying boats there is often some conflict of opinion. The arguments for and against these sites reflect the complexity of the problems that accompany aerodrome construction. One problem in Great Britain is that aerodromes do not make profits. In spite of this, public-spirited authorities are providing aerodromes for civil aviation. The building of aerodromes has become a special branch of construction involving the cooperation of a number of sciences and trades ranging from meteorology to the making of fire extinguishers. In all parts of the world forests are cleared, sites blasted out of rock or swamps drained to become aerodromes for present and future air traffic. In the British Isles one of the most interesting new aerodromes is that opened at Belfast Harbour, Northern Ireland, by Mrs. Neville Chamberlain on March 16, 1938. The establishment of this airport on a formerly unprepossessing site shows how enterprise and applied science are serving the needs of the present and providing for the future. The airport, which is owned by the Belfast Harbour Commissioners, is situated partly on reclaimed land bordering the Musgrave Channel and is intended for the use of landplanes and flying boats.
Years ago the site was water; then the harbour channels were deepened, the mud was deposited and a retaining wall was built. In time an area of several hundred acres was reclaimed. When an aerodrome was decided upon, the instability of the soil and the lack of drainage were two disadvantages. The engineers installed a drainage system which has made the site one of the driest in the locality. To consolidate the surface, rubbish was spread over it, and then cinders and sand were spread over the rubbish After that the surface was sown with coarse grasses selected because they were able to grow in such soil.
The runways in any direction are from 800 to 900 yards long and the bad-weather approaches provide a run of 1,400 yards. At present the area is 365 acres, but this can be increased to about 800 acres by further reclamation. A temporary control building and a large hangar have been built. Permanent buildings are under construction. Floodlights and boundary lights, a wind T (see the chapter “Lighting the Modern Airport”) and smoke wind indicator are to be supplemented by direction finding and blind approach equipment. Weather reports are received by teleprinter and telephone from Newtownards Aerodrome, Co. Down, about eleven miles east of Belfast.
The permanent buildings which are being erected on the side of the aerodrome near the Musgrave Channel are planned to serve flying boats. For their accommodation there is water of sufficient depth clear of the channel used by ships. Adjoining the aerodrome and connected with it by a bridge that crosses an intervening width of water is the recently completed aircraft factory of Short and Harland, the company formed by the aircraft firm of Short Bros. (Rochester and Bedford), Ltd., and the shipbuilding firm of Harland and Wolff Ltd. This factory is built on piles over the water. Landplanes can be taken over the bridge to the aerodrome and flying boats can go by water to the waterfront of the airport.
The establishment of this airport on reclaimed land within the city of Belfast illustrates the new tendency to bring airports nearer to the centres of the cities.
Birmingham is building an airport at Elmdon (Warwickshire), seven miles south-east of the city. Elmdon Airport is planned to expand with the growth of traffic. The municipal authorities acquired a site much larger than was needed at first, so that the landing area could be extended and the buildings could be supplemented when necessary. Outside the boundary of the aerodrome is an area free from obstructions, surrounding this is another ring in which no obstruction exceeds a maximum height of 75 feet. Manchester’s new airport at Ringway, about eight miles south of the city, is another instance of the new developments in industrial centres. New buildings, including a control tower, have been erected at Liverpool Airport, at Speke, six miles south-east of the city. Speke is in a controlled zone in the special communication area for dealing with traffic over the Irish Sea region, the centre of which is the zone controlled by the airport at Ronaldsway, in the south of the Isle of Man.
Originally there was only one special communication area in the British Isles; this was based on Croydon Airport. Now there are four. They are Croydon, Ronaldsway (Isle of Man), Portsmouth (Hampshire) and Heston (Middlesex). The Portsmouth area covers part of the Channel west of the Croydon area, the controlled zone being at Southampton. The Heston area embraces a strip between the Croydon and Portsmouth areas and covers a region north and west of London extending as far as Holbeach (Lincolnshire), Leicester, Alcester (Warwickshire) and Andover (Hampshire).
THE HANGARS are among the more important structures of an aerodrome. This illustration shows the foundations for the hangars at Shoreham Airport, which serves Brighton, Hove and Worthing. All buildings at aerodromes have to be low-built to avoid obstruction to aircraft as much as possible; the skill of modern architects, however, prevents the buildings from having too squat an appearance.
Outside these communication areas there is a controlled zone at Doncaster (Yorkshire) and another at Yeadon, the airport for Leeds and Bradford. The growth of air traffic depends partly upon the adequacy of these British aerodromes outside the London area. Some of them are connected with the Continent. Newcastle-on-Tyne is on the English side of the route to Stavanger, in Norway, and Doncaster is linked with Amsterdam. Other airports, such as Shoreham (Sussex), began in the early days of aviation and have kept pace with its progress. Others again are comparatively new and have been built mainly to serve holiday traffic; an example is Jersey Airport.
In addition to the aerodromes built near the large cities, there are those in Scotland from which services operate to northern Scotland, the Orkneys and the Shetlands. Nearer to London, Leicester Municipal Airport is an example of an aerodrome serving a city; Sywell Aerodrome (Northamptonshire), which is six miles from Northampton, seven from Kettering and five from Wellingborough, is an example of an aerodrome serving several towns.
The building of these aerodromes has created a new section of industries. In Great Britain various firms are engaged in the construction and maintenance of the landing areas. Other companies construct hangars and buildings; some specialize in lighting equipment and wind indicators, others in radio and traffic control apparatus, others in fuelling and attending aircraft, and yet others in fire-fighting and first-aid equipment. Numerous firms supply the various requirements of aerodrome workshops; other firms supply miscellaneous electrical equipment, furnish building materials, paint or construction and operation equipment.
From Makeshift Shed to Airport
The ground organizations at large airports often include hotels and restaurants, with their staffs, as well as linguists, booking staffs, porters, post offices, customs and surface transport services.
The progress of aviation is indicated by the development from the days when an aerodrome was a field, with a wooden shed in which aircraft owners housed their aeroplanes, to the stage when the construction of an airport involves the collaboration of Government officials, civil engineers, architects, public authorities and technical experts.
Most of the airports in civilized countries grew from small beginnings on makeshift sites. As every penny that could be spared by the countries impoverished by the war of 1914-18 was required to enable civil aviation to fly, there was no money available for the construction of aerodromes capable of dealing with a traffic whose future was problematical.
The surfaces of some aerodromes subjected machines to undue strain and caused minor mishaps. Extemporized buildings chilled the enthusiasm of travellers making their first journey by air. Badly sited aerodromes were waterlogged in winter because of lack of drainage. When larger and heavier machines were produced some aerodromes were too small to provide the required length of run and their environs prevented extensions. The only remedy in some areas has been to abandon the original aerodrome and to build a larger one.
AN AERODROME SITE may require clearing before levelling operations can be begun. An implement called a Bulldozer fitted to a crawler tractor may be used for clearing the ground. Rocks and small trees are not obstacles to the Bulldozer, the sharp lower edge of which has a shearing action when the machine is raised above ground level. The Bulldozer can be used also for clearing away tree stumps after they have been blasted out of the ground This photograph was taken during the building of an important aerodrome in Kent.
Experience has shown the wisdom of devoting early attention to the site of an aerodrome and to the preparation of plans. Every aspect, from the local weather to the architecture of the buildings, is considered. The architectural aspect is not being confined to utility. New aerodromes, primarily designed for efficiency and convenience, are generally pleasing to the eye. The efforts of the architect are not spoiled by smoke and grime, nor by the proximity of mean dwellings. Moreover, although the height of buildings is necessarily moderate, a stunted appearance has been avoided.
The mechanical engineer has provided a battery of machines to clear the sites, to fell trees, to remove boulders, to level hillocks, to fill hollows and to maintain the landing areas. Shovels, wheelbarrows and armies of manual labourers are not necessary. The tractor supplies the power to the travelling excavator.
One type in use in Great Britain and many parts of the world is an American machine, the Le Tourneau Carryall Scraper. It is drawn by a tractor and operated by the tractor driver. At the bottom of the open body of the vehicle is a steel plate. The operator moves the control lever which tilts the blade so that it cuts the soil, the forward movement of the vehicle forcing the soil into the body.
When the body is full, the operator lifts the blade and closes the gap so that the earth cannot fall out, and then he drives to a hollow which needs filling or to a place where the earth is to be stored. He opens the gap, allowing the earth to be discharged in an even flow by the mechanism which expels it, while the pneumatic tyres on the back wheels act as rollers and compress the soil. The mechanism is designed so that two machines can be drawn in tandem by one powerful tractor and can be operated by the tractor driver.
As these machines remove the soil in layers, the aerodrome constructor turns this to advantage when dealing with hollows that have to be filled. The top soil, which is stripped first, is placed into a pile. When the lower, unfertile soil has been reached, this is carried to the hollow and spread. Then the top soil is taken from the stock-pile and spread; it is later sown with grass-seed. Although few people would connect such machines with aeroplanes, these excavators fulfil a vital function in aerodrome construction. To make some new airports they have cut, carried, filled and rolled huge quantities of soil, amounting to hundreds of thousands of cubic yards for individual aerodromes.
Even more remote from an aeroplane may seem a drain, but drainage is one of the essentials of an aerodrome, particularly in Great Britain, where the amount of grass-covered surface is relatively high. Some slow-draining soils tend to become waterlogged when the surface is flat. To overcome this defect, the height of the middle of the area is slightly raised. What is termed “mole drainage” has been successfully applied to a number of aerodromes. A hollow is made and a channel is cut leading to it from the waterlogged area. A special machine is used for cutting plugs out of the ground to a depth of nine inches; holes thus formed are filled with sand or ashes. This method has been used to drain a number of aerodromes.
Seedsmen sow aerodromes with seed suitable for the type of soil to provide turf to withstand the wear and tear. Manufacturers of mowers have produced machines for use on aerodromes; the largest of these machines will mow nearly a hundred acres in a day. Other firms specialize in artificial paving for aprons and runways. The provision of a firm and resilient surface to bear the weight of large aircraft is a study in itself.
Structural steelwork engineers provide hangars and buildings which are easily erected and dismantled. Hangars and workshops have to be designed to accommodate aircraft of the largest dimensions, and floor space unobstructed by pillars is essential. As some of the larger commercial aircraft have a wing span of more than a hundred feet, hangars and workshops have to be wide.
AMPLE FLOOR SPACE, unobstructed by pillars, is necessary in hangars so that the largest aircraft may be accommodated. Some modern air liners have wing spans of about 100 feet. This photograph shows one of the hangars being built in 1937 at the Manchester Airport at Ringway, Cheshire. A workshop hangar at Heston Airport, Middlesex, has a main doorway 200 feet wide ; the floor space is clear of all obstruction.
A workshop hangar built at Heston Airport, Middlesex, has a main girder of 200 feet span, the floor area of 32,450 square feet being completely free of supports. The main doorway is 200 feet wide and 30 feet high; the opening is closed by eight steel-framed doors mounted on roller bearing wheels so that each can be operated by one man.
One company concentrating on doors has made several which are in one piece and are 150 feet wide; a single door 300 feet wide has been designed. Meteorological and radio towers of structural steelwork are assembled on the ground and hauled upright by derricks. Structural steelwork buildings erected near the sea are coated with compounds and paints which protect them from the corrosive action of sea-winds.
Lightning and wind indicators are made by electrical firms. One type of steel T wind indicator is 50 feet long and has a span of 30 feet. It revolves on roller bearings and will react to a wind of only five miles an hour. It is lighted at night and is visible from 6,000 feet by night or by day. A type of smoke-trail wind indicator produces smoke from oil. The container holds a supply of oil which lasts for 180 hours (seven and a half days); the container is heated by electricity so that the oil is vaporized to provide the smoke, and the current is automatically switched off when the oil is exhausted. The apparatus is sunk level with the surface of the aerodrome and the lid is strong enough to take a load of 10 tons passing over it. Radio equipment at an airport is described in the chapter “Air Traffic Control”. Visual signals are provided by day and night signal lamps, searchlights, Very lights, rockets, smoke, flares, and symbols which inform pilots of the weather on the routes.
Fire-fighting equipment is devised to extinguish fires caused by petrol, in addition to including water-pumping engines. One aerodrome tender, powered by a 30-100 horse-power motor, is fitted with a 50-gallons foam solution tank and a 500-gaIlons water tank. The pump can deliver more than 1,500 gallons of foam a minute. The vehicle can take a crew of six with rescue equipment over rough ground in any emergency. Other equipment includes asbestos suits for rescuers, asbestos shields and screens which can be wheeled into position to isolate a fire in a hangar, trailer pumps and a range of hand extinguishers which spray chemicals on flames.
The problem of providing aircraft with fuel and lubricating oil has brought into being some interesting vehicles. The mobile tankers of one fuel company carry 800 gallons of fuel. Electric pumps can deliver this fuel to a height of 35 feet and the flow is registered on a meter.
Another type of fuel tender delivers at the rate of 150 gallons a minute; it is fitted with separate tanks for fuel of different octane values (see the chapter “Modern Aero Engines”) and the petrol is deprived of air, closely filtered and measured as it is pumped. Motor tankers of this size are used to tend large machines; smaller tankers tend smaller aircraft. A handy tender is capable of filling the tanks of twenty machines in forty-five minutes. Fuel hoses have been studied to prevent petrol from being spilled. When the tank of a machine is full the nozzle of one type of hose is closed automatically. A valve in the hose prevents inflammable vapour from escaping.
The workshops, with their machinery, tools and equipment for overhauls and repairs, are an essential part of an aerodrome. Clubs, flying schools and schools of aeronautical engineering and a host of ancillary services and interests gravitate to it. In civilized countries the aerodrome is the centre of a fascinating phase of modern life: in uncivilized countries it is the nucleus from which new ways of living are spreading to primeval peoples.
A LEVELLING IMPLEMENT suitable for use on the most uneven aerodrome sites. The vehicle pulled by the tractor slices soil off the high parts of the ground and is then used to carry the soil to hollows which require filling in. Here the soil is evenly distributed by the mechanism which expels the earth from the vehicle.