main purpose of this proving flight was to test a part called a 'thrust
interrupter unit' or 'motor cut-down' device, designed to disable the
motor by blowing out a sealing plug at the opposite end of the motor to
the exhaust throat.
Preparation: This was originally intended to be the last of the
proving flights, but as SL05 had been delayed, and the preparations for
SL06 had proceeded without problem, it was launched beforehand.
Flight: Wednesday 2nd
April 1958 dawned fine and cloudless, with visibility at 15 miles (24 km),
and launch occurred at 8.02 am. The Raven 1A motor powered SL06 for just
26 seconds, and then the motor thrust was interrupted as planned.
Recovery: The head was
separated from the motor by the cut-off operation and fell to the ground 3
miles (4.8 km) downrange, although unexpectedly the residual thrust from
the motor meant the case travelled much further, to 35 miles (56 km)
Although the thrust interrupter worked well on this
occasion, it was not long before it caused the first Skylark failure, when
in June 1958 SL18 crashed after launch, and the interrupter had to be