DESCRIPTION
A search and destroy operation by 7RAR in an area 13km NE from Nui Dat. 106 Fd Bty would be in direct support from an isolated FSB 8km NE of Nui Dat. The FSB YS 500715 was a clearing in a heavily timbered area.
131 SURVEY
Pre Op Trial of balloon observation on 31A. Gnr Endicott spotting, Gnr Brooker observing, Gnr McFadden sigging. Photo courtesy B Follington.
Conventional survey through traverses was impossible. Protection could not be afforded through the isolated countryside. The FSB was deep in timber, line of sight was not possible. Lt Yerbury had foreseen this problem and had been advised of a unique and challenging solution. It seemed feasible, at this “hidden” FSB, with the aid of tethered Met balloons hovering above the timber and visible from 2 known points, triangulation could fix the FSB.
Survey Control
9. Various other geometrical principles have been given consideration, and one advanced by WO2 D Christie sounds promising. Using 2 known stations to fix the position of the air station and a short base principle at the unknown station with an observed sun azimuth to carry the coordinates from the known stations to the air station and from the air station to the unknown station. The air station may consist of a meteorological balloon anchored to the ground by a long cord and positioned by helicopter or APC. This principle will be tested in the near future.
Det 1 Topo Svy Tp Op Report No 12 (April 67)
Survey Section was divided into 3 groups. 2 control groups would be stationed at the 2 “known” points. One on top of Nui Dat, the other at the Horseshoe. Lt Yerbury and the 3rd “balloon” group were air lifted with 106 Bty by Chinooks out to the FSB.
Bdr Hopper (balloon), Lt Yerbury, Gnr Boutlis and Gnr Endicott rasing the Met balloons at 106 Bty FSB. Photo courtesy P Hopper.
Gnr Endicott and Gnr Boutlis inflated the Met balloons and while sited directly over the Bty centre position, they were allowed to rise till they were clear of the timber and observable by both control points.
Method of Fixation
To eliminate as many unforseen vagaries inherent in such unconventional approaches, a simple straightforward procedure was adopted to effect triangulation.
By means of radio contact, the observers of the balloon from Nui Dat and the Horseshoe, would simultaneously observe the left face of the balloon and radio through their readings. This was then repeated simultaneously observing the right face. Again the readings were radioed through. This then gave enough information to compute the coordinates of the head of 2 triangles. These 2 positions were then meaned so as to give the coords of the centre of the balloon and hence the Bty Centre.
above: Method of balloon triangulation.
Of course the reality was far from this easy! Once above the trees the balloon was subject to any breeze and drifted off position directly over Bty Centre. To give a more stable and stronger balloon pull, 2 met balloons were used. The balloon party followed the wavering movement of the balloons and when it was reasonably directly over Bty Centre, would radio, “observe now”. Theodolite observing was extremely challenging for you were required to follow the moving face of the balloon whilst listening for that radio call to “observe now”.
It was achieved and coordinates given to 106 Bty Centre. The same procedure was carried out giving coordinates to Bty Director position. A sunshot was taken over the centre and bearing given to Bty Director position.
Orientation was provided to the battery by sun azimuth observation and fixation by the previously untried method of observing to a pair of tethered meteorological balloons. The technique is essentially just a variation on the synchronized helicopter observations described earlier at p. A better-than-expected closure of the scheme was achieved and the computed orientation differed by only 1mil from the orientation observed by sun azimuth.
PS Sadler Doc. 7 Ch 4 Survey Sect Pt C
I remember doing the sunshot at Bty centre. There was a fortunate break in the clouds at the time enabling sufficient time to track the sun to allow calculations to be made.
Bdr Hopper June 1967
The Horseshoe Battery in support of 7RAR, Cooparoo. Photo courtesy B Follington.
Bearing was also calculated from the “balloon” coordinates of the 2 positions. It compared most favourably with the sunshot bearing. 106 Bty was placed on provisional theatre grid!
above: Triangulation for operation Cooparoo
"Last week took us on another operation. This one was 'Cooparoo', (the last one was "Broken Hill" that the other chaps were on) and I spent 3 days at Horseshoe again. I took charge of a party there while another party manned Nui Dat and a third party were out in the bush. We had to fix the position of Party 3, and it was pretty hard as they were in a thick forest area. We could see the choppers dropping below the trees but couldn't see the ground. The choppers were completely disappearing and their total height was over 30' as they had 105mm guns strung beneath. They were "Shenook" choppers and the set up looked like this (small drawing of a chinook carrying a 105mm in a sling - inserted below). We finally got survey to them by putting a weather balloon up attached to a line and we lay on that. It's the first time we'd tried this and it was very successful.”
L/Bdr Irvine Horseshoe observer June 1967
Mortars were fired towards our FSB during the night. Surveyors were fortunate FSB perimeter defence was carried out by elements of 7RAR.
Bdr Hopper June 1967
I liked the Maths of the whole concept and I enjoyed the challenge of being as accurate as I could be despite the finicky conditions.
Gnr McFadden Nui Dat observer June 1967
17. The next task allocated to the survey section was to provide survey for 106 Bty who were to occupy a FSB at YS 500715, about 10,000 m NE of Nui Dat for Op “Cooparoo”. To accomplish this one survey party, incl Sect Comd, went with 106 Bty to the FSB, another party to the Horseshoe and a third party to the top of Nui Dat. The main problem to be overcome was that the FSB could NOT be seen from Nui Dat or the Horseshoe as it was a small clearing in the jungle, with trees of 10 – 20m ht.
19. Additional tasks performed during the period were ;
a) The providing at the request of the OC, a BP at D Coy 2 RAR.
b) The surveying for the 8” guns when they moved to a new position near LUSCOMBE airfield YS 436679 during Op “Cooparoo”.
131 Bty Reports, Survey Section June ‘67
SECONDARY ROLES
1/83rd Bty US moved to a position just off Luscombe for this operation. 131 Surveyors supplied theatre grid to their new position.
A bearing picket grid coordinates were also transferred to D Coy 2 RAR position in Nui Dat.
I did not go out on Cooparoo. Instead I was left to organise a survey job up at D Coy 2 RAR.
Bdr Poustie June 1967
above and below: Part of Gnr Follington's survey notes dealing with establishing coordinates for 2RAR, D Coy's platoon positions in Nui Dat. Bdr Poustie and Gnr Follington were responsible for the transfer. Notes courtesy B Follington.
