R0 – 28 June 1968
R0 was launched on a trajectory to the north west, towards Talgarno in Western Australia. The first two stages were live; the third stage was inert.
The launch procedure was that the vehicle was held down on the launch pad by a ball and claw mechanism, the engines were started, and when full thrust was reached, which took around 4 seconds, the vehicle was released. But as soon as it cleared the pad, the vehicle immediately developed a large rolling oscillation. The cause of the fault was an open circuit in the feedback loop that controlled one of the pairs of motors: a wire had probably broken.
At about 64 seconds into the flight, the control system could not cope and the vehicle tumbled. One of the payload fairings broke away, followed by the payload, then the Gamma 8 first stage motor stopped working. The vehicle was destroyed by ground command when it was at an altitude of 9,000 ft on its descent.
The response of the motor pair concerned was normal up to about 4.1 seconds after opening the first stage engine start valve, 0.5 seconds before the release jack was opened. Loss of the signal meant that the pair of motors concerned would swing to their full extent and back again on receiving a correction, instead of the small deflection needed to put the vehicle back on to its correct course.
This can be seen quite clearly in the film of the launch, where one of the set of rocket exhausts can be seen swinging from side to side. Figure 115 shows the vehicle a few seconds after lift-off, and one of the sets of exhausts can be clearly seen pointing to one side.
Eyewitness statements were taken from those who had been watching the flight.
One, by Ken Smith of RAE, reads as follows:
Ignition was seen to occur just after zero time, and the vehicle lifted off as expected a few seconds later. The ascent appeared normal, and the downrange pitch programme was clearly occurring. Just after the time count of 60 seconds, two or three glowing fragments were detached and fell away from the ascending vehicle.
Immediately afterwards, the clean flame pattern changed to an intense white smoky trail. The vehicle pitched violently, then appeared to recover to its original path, but the rate of ascent diminished. Then tumbling began; the vehicle turning slowly nose over tail several times and beginning to descend. The intercom call was made ‘vehicle descending’. The FSO announced that break-up would be initiate when the vehicle reached 9,000 ft on the descent. After a short interval, the vehicle still falling and tumbling, he announced break-up ‘NOW’. An instant later the vehicle disintegrated in a bright luminescent explosion. The loud sharp detonation was hard several seconds later.17