OHAKEA AIR BASE

Evening Post, Volume CXXVII, Issue 90, 18 April 1939, Page 12

OHAKEA AIR BASE

HUGE MILITARY HANGARS

RUNWAYS A MILE LONG

New Zealand has been told, plainly and definitely, as have other Dominions, that the responsibility for defence today rests directly upon her own shoulders. The Government, advised by the ) mP c"al authorities, has raised the air, which for so long lagged behind as a mere side issue, to rank as an essential long-range defensive arm. The programme of expansion was drawn up two years ago. The translation of that programme into fact has been, and still is, a tremendous task. The former Air Force offered no more than a. slight foundation, and the Royal New Zealand Air Jjorce that is now coming into being has in fact been built up during the past two years—training of flying, wireless, and maintenance personnel, the provision of aircraft and equipment, the tar wider and more intricate system of control and co-ordinated effort, and the modernising of the former bases at Wigram and Hobsonville. and the building of two new main bases at Ohakea and Whenuapai. A third base is to be formed in Marlborough.

The organisation has been threefold, the Regular section of the Air Force, the Territorial squadrons, and the Reserves, each of which has today increased many times its original strength. The three lines of development were planned to a time-table of converging lines of advance—training (in part in New Zealand, and in part in Britain, under the exchange system with the R.A.F.'), arrival of equipment adequate to the expanded and effective Air Force, and the completion of bases. Today thosn lines are converging rapidly.

By courtesy of the Air Office and the Public Works Department, a "Post" reporter last weekend visited Ohakea, 12 miles from Palmerstun North. A year ago this was farm land; today there is a single field of 500 acres, of which 350 acres are levelled and elaborately drained, waiting for the first rains for seeding. Ohakea will give mile-long runways, for the conception of air defence of the Dominion and the Pacific is that any threat of aggression shall be met while it is still far distant, and the extreme range of the aircraft with which the main bases will be equipped will require great lengths of runway for full-load take-off. Nearer patrol and service will be performed by machines of lesser, range, but still capable of operating to distances of some hundreds of miles from their bases. HOUSING FOR BIG BOMBERS. Ohakea will be ready for the first batch of bombers, to be flown from England by New Zealand pilots and airmen, trained to high efficiency in the operation of modern craft with the Royal Air Force; Whenuapai, near Auckland* will receive the squadrons to arrive later. At both air bases work on the landing fields goes on round the clock, 24 hours a day; a 10-hour Jday is worked on the hangar, quarters, stores, and workshop construction at Ohakea. Thirty long-range bombers have been ordered for the Regular Air Force, of which half will be stationed at Ohakea. They are big machines, with wing-spans of over 80ft; the hangars are huge, and are unique in design. They are visible for miles above the tableland before one reaches the northern boundary of the landing field, near Sanson; near at hand the great arches are impressive in the extreme. Because supplies of structural steel were practically unprocurable when Ohakea was commenced, standard types of construction were not feasible, and the Public Works Department evolved a new plan of reinforced arch construction, in which the arch strength was given by ten main members, reinforced with steel rods, of which supplies- were available. So successful has been the unusual design that it is to be used at Whenuapai also. » Each, hangar covers a greater area than a Rugby ground. A Rugby field is 330 ft long and 165 ft wide; the arches of the Air Force base hangars at Ohakea touch down 300 ft between footings, and from front to back the hangars measure 210 ft. The arch sweeps overhead, 66ft high in the centre and 30ft at the side walls. No other building in New Zealand or Australia compares, with these great arch construction hangars in clear floor area. Not all the area within the arch members is hangarage, for on either side of the hangar proper are annexes, 26ft wide, and at the rear are workshops, stores, and offices, 40ft deep, across the full width. The space available for aircraft, clear of pillars or obstructions, is 220 ft between side walls and 170 ft deep. TAKING UP A BIG STRAIN. The weight of this great arch of concrete is enormous, and though the river flat on which the base is situated offers excellent foundation, special means had to be applied to anchor the footings of the ten main members against the spreading thrust of the arch. This was done by pre-stressing the footings, so that as the thrust came upon them the whole would be in balance. j In trenches below floor level heavy rolled steel sections, tied to the footings on either side, were laid so as almost to meet along the middle line; the ends of each pair of beams were an inch and a half short of locking. Oil-burners were played along their lengths until expansion closed the gap and they could be locked together as single beams. As they cooled contraction stressed the footings to an estimated tension of 150 tons to counter the thrust of the arch. So great are the height and the span of the arch that normal boxing and concrete placing methods were ruled out and a false work, which ate up 140,000 ft of timber and a great quantity of steel, and which weighs 240 tons, was built to support the mazes of steel rodding and the fresh-poured concrete. The false work is the full width of the hangar floor, 220 ft, and is one-third of the depth of the arch. As one section was completed the upper boxing was stripped . away, the false work lowered and cleared, and winched forward for the fabrication of the steel net and the pouring of the succeeding section. , Now it is clear of the first hangar and is sliding, an inch at a time over a four-track rail bed v to be slewed between the side walls of the second hangar. CONCRETE DOORS. The hangar openings are the full width of the building and will be closed by ten reinforced concrete panels, running on rails to pack away in square towers on either side of the 200 ft doorway. The hangar floor will be a clear concrete .slab, and outside the hangar an "apron" will stretch away, 600 ft long and 100 ft wide. The first of the two hangars at Ohakea has passed the main construction stage and detailed work and the installation of lighting and power, water and drainage and other services has been commenced. The footings, the massive abutments, and the side walls of the second hangar are prac-

The Royal New Zealand Air Force is moving far and fast from the air force of two cor three years ago, when a handful of officers and men, operating with out-of-date aircraft arid inadequae equipment, upheld the name and face, but not the fact, of a New Zealand air arm, capable of standing alone or of co-operating with other arms. The lines of development and advance —enlistment of larger personnel,. training to efficiency in modern aircraft, and completion of new operational bases —are timed to meet when the first long-range bombers land in New Zealand in October.

tically completed, and the building of the intricate steel rod reinforcing of the second great arch will be commenced when the false work is in place between the side walls. Under the terms of the contract the two hangars are to be completed in July. This is not necessarily the end of development at Ohakea, for the ground plan provides for a further and greater expansion in the future if still greater concentration is to be made in the air arm of defence. Simultaneously with progress upon the hangers, the administration block —the heart of the station—the officers' and airmen's quarters, stores and workshops, bomb stores, the radio direction and the general wireless communication station, and various offices and stores are taking rapid shape. Ohakea will be a town in itself," covering 60 acres, with 30 dwellings for married officers and men apart from the main quarters. The base and village will have several miles of streets and service roads, their own water supply and drainage systems, a fire station, a standby power plant, and sports ground for summer and winter sports. The base personnel will be something over 300. NEARLY DEAD-LEVEL. The flying field at Ohakea made a straight-away start from a naturally level expanse of solidly compacted ancient river flat. Generally the foundation is of clay, with patches of packed gravel; the natural drainage is good and the sub-soil is a guarantee against bogging after heavy rain. At Whenuapai greater problems have to be met in levelling the landing field, and enormous quantities of spoil are being transported from "highs" to "lows" to obtain the aerodrome levels. It has been calculated by the Public Works Department that under former methods of handling spoil the levelling.of Whenuapai would have taken eight years. The contract time, using heavily powered machinery, is twelve months, working round the clock, and the finished cost will be far below estimates for any other method of working. The landing field specifications are rigid. The finished surf ace must: be within one and half inches of true levels—over all-way runways one mile long! That is bowling green, accuracy, except that the surface is not dead level, but slopes away on fixed grades to ensure run-off of surface water. Up and down and across the landing field at Ohakea has been laid a system of drains connected by herring-bone side drains; altogether there are 24 miles of these open-joint drains to keep the surface clear of storm water, no matter how grejat the downpour. Diesel tractors handle all the soil shifting, levelling, and surface planing, and. the ditching of the field for the miles of drain and minor surface drains is also a power job. There are two ditching machines, carving out trenches at the rate of a mile a day, to spirit level accuracy.