Z4

Preparations for Z2 commenced at 1120 and were completed at 1157.

Care was taken with the fixing of bungee cord to the lanyard pin to ensure that the same would not withdraw if the pin rotated.

After the launch it was noticed that the loop in the bungee cord had been broken. It is evident from the photo to the right that the loop in the bungee cord was not large enough to permit the lanyard pin to withdraw and the spring loaded barrel to withdraw before the rocket had moved sufficiently far forward for the loop to be broken.
A larger loop in the lanyard withdrawing bungee cord is needed if lanyard pin system used with Z2 is to be used again.

Z2 was launched at 1209:58. The wind observed at LA9 immediately prior to the launch was 5 to 10 knots from the south to south east.

A report described as a "pop" was heard by RB1 at approximately t+60s, which would have been the separation charge. Allowing 333 m/s as the speed of sound, this would suggest that the separation point was about 6,327 metres from RB1. This is consistent with the impact point.

The CLO observed a small amount of trailing white smoke characteristic of a tumbling payload module. There was no record of any sighting of the deployed ballute.

An impact was observed in the form of a specific white dust burst at t + 1m 20s and a bearing of 251 deg mag from the observation tower at LA9 and away from magnetic disturbances. This bearing was recorded through the ATM's range/bearing binoculars, which were later confirmed to require adjustment for magnetic anomalies of +7 degrees, plus a further 7 degrees to give a true bearing (ie +14 degs to true). Accordingly, the adjusted impact bearing was 265 degrees true.

Although no secondary impact was observed, the shape of the dust cloud observed by the ATM was consistent with a double impact. About a second or two after the dust cloud appeared it seemed to be speared through by a more dense central pillar of dust that rose more quickly. At the time this was thought to merely be something associated with a single impact, something like the central rising column of water after the initial splash when something is dropped from a height into water. However, on reflection, it is possible that a double impact was observed on the same bearing from LA9. The following sketch is a depiction of the phenomenon observed.

The impact site for Z2 motor was located on 7 June 1998 and the following GPS data was recorded (on 8 June 1998):

The motor impacted nose first and about one metre remained above the surface. All fins had sheared off and were laying nearby. The motor was 5 to 10 degrees from the vertical. A photograph appears below.

The motor was dug out on 8 June 1998. The first 50 cm of earth was reasonably soft but the remainder very hard. Even when there was only about 15 cm of the motor remaining in the ground, it took a lot of effort to remove it. No payload module was attached and the end cap was full of soil, so separation of the payload module was confirmed.

Approximately 70 cm below the surface there was a layer of white sedimentary or other strata, possibly limestone or gypsum. This had been penetrated by the motor, and explains the white dust cloud that was observed upon impact. There was no white material on the surface that might have assisted recovery operations.

Although an extensive search was conducted, the payload module from Z2 was not found. The search aircraft reported an unconfirmed sighting of something orange on the surface near where the Z3 payload was found, but it is possible that it was merely a reflection off a rock. The fact that the search aircraft did not find any ballute and the CLO's observation of the module tumbling would suggest that the ballute did not effectively deploy. If so, the module would have impacted heavily and now lie below the surface, probably close to the motor impact on a line between that point and LA9. It might be closer or further than the motor was found relative to LA9.

Addendum

The payload module from Z2 that was not able to be found during the
June 1998 Campaign was located and recovered during the October 1998 campaign. The rear of the payload casing was approximately 10 cm beneath the surface but the ballute lay on the surface. The position of Z2 payload module was:-

S 30 54 51.2

E 136 25 58.2