COMBAT AND COMPETITION.pdf - Lakes Gliding Club

CHAPTER ELEVEN A TESTING TIME
to its designers, who were now operating from Twinwood Farm, and
Horace put them under great pressure. He was most unhappy about the
rumours which had originated from Camphill and wanted confirmation
of the performance as soon as possible.
Stable conditions were essential and it took almost eight months to
complete the tests - just five days being suitable during the whole of
that time. One flight was typical of the problems which they faced.
Starting even earlier than usual - out of bed at 3 am - to be
confronted with an unbroken layer of stratus 200 feet thick, base 800
feet above the ground. The plan - for Roger Austin to find the airfield
after the tow and mark it by circling in the tug, while Harry made his
partial glides - misfired completely. After release they never saw each
other again. Harry broke cloud some miles away and had to land out.
A new technique was used to record the raw data. On each partial
glide, the pilot reported his height by radio at 50 foot intervals. Ralph
Maltby and his two assistants, one armed with a stopwatch, plotted time
against height straight onto a chart. The effect of any disturbance was
instantly apparent and the pilot could be instructed to continue his run
over a further thousand feet.
The maximum gliding angle of 1 in 33.5 compared with the original
design at I in 26.5, was a total vindication of their efforts. But the
minimum sink was slightly greater than expected and it occurred at 44
knots.
When I joined Harry's test group, after the 1955 Nationals, we
carried out pilot rake and china clay/paraffin tests on an inboard
section of mainplane. But they showed no evidence of premature
laminar separation.
Before the aircraft left Twinwood, Ralph managed to organise wind
tunnel tests on one wing, using the aileron as a flap. Intended to
confirm their extrapolation of relevant NACA 4 information, to glider
Reynolds numbers, this may well have been the origin of the 'no
substitute for span' philosphy of the later developments.
The 402 arrived at Twinwood two weekends before Easter. Barely
time to sort out any problems and obtain a temporary C of A for an
entry in the first contest of the year, the Long Mynd Easter Rally. If
it proved good enough there was just a possibility that it might be
flown by the British team in the World Championships now only
months away.
We got there, but only just. To avoid altering the aileron hinge
line, the tip chord on the extended wing had become almost 80%
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