RAAF 220 Radar Station, Bones Knob
- Radar/signal station
- Atherton Tablelands
Bones Knob, Bowcock Road, Tolga 4882
RAAF 220 Radar Station at Bones Knob became operational in 1943, and was one of five British-designed Advanced Chain Overseas (ACO) radar stations constructed in Queensland during World War II: four being completed (Benowa, Toorbul, Charlie’s Hill [Queensland Heritage Register 601716] and Bones Knob) with a fifth not completed (Paluma). The former WWII RAAF 220 Radar Station stands at the summit of a timbered hill called Bones Knob, located about 3km west of Tolga.
Surviving elements at Bones Knob comprise two concrete igloo buildings, a smaller concrete igloo, and concrete and steel footings of one radar tower. The two main semi-circular reinforced concrete igloos are 11.20 metres long by 7 metres wide, and are spaced 55 metres apart in parallel alignment. Attached to one is a small lean-to. Entrances to both igloos are sheltered under recent bow-roof verandahs. A smaller reinforced concrete igloo, probably for a generator, is located about 250 metres south of the transmitter and receiver igloos.
A timber tower over 40m high was originally located alongside each igloo. Only the base of the northern tower was visible in 2007. The tower footings comprise four 1 metre square concrete foundations, each containing two steel members about 1.5 metres in height.
Royal Australian Air Force (RAAF) 220 Radar Station, a unit of RAAF 42 Radar Wing, was located at Bones Knob near Tolga on the Atherton Tableland. It became operational in September 1943 and played a role in the protection of the large concentration of ammunition, ordnance and stores depots established on the Atherton Tableland as part of the assembly and training of Australian troops for the final phase of the New Guinea and island campaigns. Operation of the Radar Station at Bones Knob ceased in December 1944 as the South West Pacific frontline moved further north.
The delays that Australia experienced in acquiring British radar equipment spurred an innovative period of radar development by Australian scientists from late 1941. By the time the British Advanced Chain Overseas (ACO) radar system was installed at Bones Knob, features of its design, especially its two conspicuous timber towers, had already been superseded by the Australian designed Light Weight Air Warning (LW/AW) radar.
One tower in ACO stations was for transmitting and the other was for receiving radar signals. The towers were spaced about 100 metres apart to ensure that radio pulses were received as echoes and not confused with transmissions. The towers did not rotate like those commonly used in other radar models. The ACO radar installation consisted of 14 switches on the receiver tower and more on the transmitter. These had to be constantly relayed from on to off, lower to higher, and between different directions.
The igloos were built to house the radar electronics and two tonne consoles for the transmitter and receiver. The reinforced concrete igloos could be covered with earth, and were designed with a small tower at one end which was equipped with a ladder and served as a ventilator and escape passage. However, the ACO igloos used in Australia were not buried. Entrance doorways at the other end were large enough to accommodate the radar consoles.
The ACO electronics were the second generation of the British CH (Chain Home) type of radar, a 'floodlit' system operating on the VHF band. The transmitter was a British MB3 model which put out 250 Kw of power at 42.5 MHz. The transmitter aerial system was in two parts set at different heights (at 37.2 and 14.3 metres high) to enable height finding using the floodlit system. Each part had four elements to cover four sectors of 120 degrees.
The receiver was a British RF7 (receiver fixed location) built in four vertical racks held in a frame of 2 x 2 x 0.6 metres. The receiver detected radio echoes from all directions simultaneously, and compared the strength of an echo from within a radius to identify the direction from which the signal was originating. The receiver had two parts on the tower (at 40.2 and 14.3 metres high) plus crossed dipoles used for the height finding of an aircraft by comparing the echoes from the higher and lower sections of the tower.
Nine British ACO radar stations were completed in Australia by the end of 1943, (while others were built but were never made operational). Four were completed in Queensland. As well as Bones Knob, there were ACO stations at RAAF 209 at Benowa (since demolished); RAAF 210 at Toorbul; and RAAF 211 at Charlie’s Hill (near Home Hill). An ACO station was started at Paluma, and concrete igloos were built that still exist on Lennox Crescent, but the towers were never built as the ACO program was cancelled in late 1943.
RAAF 220 Radar Station was formed at Camden, New South Wales, on 7 July 1943. The unit arrived at Tolga on 23 September, moving to Bones Knob the following day. The initial strength of the radar station was two officers and 34 airmen. A site plan for the installation at Bones Knob had been prepared by the Department of the Interior, Townsville, on 2 September 1942. Therefore, work may have already begun on construction of two concrete transmitter/receiver igloos, a smaller concrete igloo power house and two transmitter/receiver towers, together with a camp area and water storage tanks. The timber towers for 220 Radar Station were prefabricated by the Civil Construction Corps in Sydney from Australian oak.
During the early months of 1943 the headquarters of the Australian Army in north Queensland was transferred from Townsville to the Atherton Tableland. Units of the 6, 7 and 9 Divisions, AIF, were encamped on the Atherton Tableland at various times between early 1943 and 1944, at locations such as Kairi, Tinaroo, Danbulla, Wongabel, Wondecla, Ravenshoe and Millstream. The radar station at Bones Knob could detect hostile aircraft approaching from the north towards the Atherton district.
War-time radar operators played a significant role in saving the lives of airmen, but manning a remote radar station in northern Queensland was a routine and mostly uneventful task. To alleviate the boredom, the men of 220 Radar Station regularly travelled to Tolga, Atherton and Mareeba to the picture shows. A tennis court was constructed at the station during 1944 and cricket matches and table tennis tournaments between RAAF and Army units also helped to pass the time.
Operation of 220 Radar Station ceased on 7 December 1944 and the unit completed the move to Townsville on 18 January 1945, being disbanded on 13 February 1945.
WWII RAAF 220 Radar Station. Queensland Heritage Register 602741
Radar Station, Charlie’s Hill. Queensland Heritage Register 601716
Smith, N and Simmonds, E, (eds), 2007. Radar Yarns. Radar Returns, Hampton, Victoria.
Pearce, Howard. January 2009. WWII-NQ: A cultural heritage overview of significant places in the defence of north Queensland during World War II. EPA, Brisbane.
"No 202 Radar Station, Victor Harbour", Twentieth Century Heritage Survey, Stage Two (1928-1945)
WWII RAAF Radar Station 208 (former), NSW Heritage Register