Norman Long
recalls his time in the Research and Development Department...
I joined Hawker Aircraft at Kingston in 1962 as a sixteen year old
Engineering Apprentice. One highlight of my first year in the
Apprentice Training School was a talk on structural testing by Derek
Thomas from Rochefort's then R&D department. This was followed
by an exciting tour round the huge airframe test frame and the labs. in
the Experimental building. I remember being introduced to Derek's
'boys' - probably Richard Cannon, Colin Flint, Brian Indge and others -
in the main control room and being fascinated by all the sophisticated
electronic control equipment and the rigs they had developed.
I had an
interest in making radios and other electronic devices and after seeing
what they did, their enthusiasm, the stimulating work, and the general
camaraderie of the team, I was determined that this was where I wanted
to work when I finished my apprenticeship.
The
R&D Department In The Sixties And Seventies
In the years that followed I
made frequent visits to the lab., usually on the scrounge for the odd
transistor or other electronic component from the scrap box to use in
my own projects at home. As a result I got to know Richard Cannon and
the other boys in the lab. really well.
Derek Thomas, later Head of Ground Test Services, was one of the
most charismatic engineering group managers I have ever known. He had a
way with words which would make his engineers feel ten feet tall,
invincible and prepared to take on anything! Once when I was in the
lab. during one of his weekly tours he said to me, "Oh, you'll have
them eating their own young next", likening the electronic equipment I
was developing to an animal creation. Such interest and encouragement
was really motivating for the young engineer. Derek had a good
awareness of the skills and attributes of the people in his group and
was always finding new ways of raising the bar and challenging the
team. As a result he was adept at selling ideas to the directors and
other senior management to fund new and exciting projects and equipment
which encouraged success in the group.
One of Derek's 'hot
buttons' circa 1966 was an idea to replace the g meter fitted to
aircraft to assess structural fatigue. The g meter counted the g
excursions encountered during flight and Derek wanted to substitute a
meter that counted load excursions measured by strain gauges mounted at
key points of the structure. He believed that this would give a far
more realistic picture of actual airframe fatigue. Subsequently when I
passed through R&D on my apprenticeship tour of departments I
got
the job, under Richard Cannon's magical mentoring, of doing a design
study to investigate the feasibility of this idea. The study started
with the writing of a computer programme, for the early Ferranti
Pegasus valve computer using the Autocode programming language, to
simulate a fatigue counter with, say, twenty or more key load points
each with ten or more load excursion counters. Periodically the load
excursion spectrum of counts for each point would be dumped and
subsequently analysed for cumulative fatigue damage. The study then
went on to investigate the viability of producing a prototype based on
the Ferranti FM1600 airborne computer that fitted in a standard ATR
airborne equipment box.
Once
the study was complete I went
with Derek and Richard to the RAE Structures Department at Farnborough
to discuss the idea with them. While we were there we were invited to
go down to the structures lab. to see the Concorde fatigue test which
was controlled by a Digital Equipment PDP10 computer. The whole thing
was quite something, particularly the way the airframe skin temperature
had to be heat cycled, to simulate supersonic flight, in addition to
the normal load cycling with which we were familiar.
During the
last six months of my apprenticeship and when it was completed I
finally joined Richard Cannon's Control Engineering section working
initially on signal conditioning and electronic control equipment for
the Kestrel static strength test. It was now circa 1969 and there was
some concern over the fatigue life of the Folland Gnats used for
training at RAF Valley and by the Red Arrows. Given Derek's earlier
load excursion fatigue counter interest I assume he used his influence
to utilise this Gnat problem as a means of initiating a project to
develop a prototype fatigue counter or meter. The scheme consisted of
instrumenting with strain gauges the tailplane or fin of one Red Arrow
Gnat and one from Training Command . An electronic unit then evaluated
any changes in load relative to four pre-set levels and recorded them
on eight numeric counters, four up and four down. I did the electronic
and printed circuit board design and Alan Abbot, originally from the
lofting department, did the mechanical packaging design and the changes
necessary to fit it all into the aircraft. The main unit with counter
display was fitted in the cockpit and a small strain gauge preamplifier
was fitinatalled in the fin through a small access panel.
For
convenience the equipment was fitted first to one of the Red Arrows
which at the time was on summer detachment at RAF Kemble. Over the
summer we went to Kemble a number of times but could not get access to
the aircraft until after flying had finished for the day. Therefore
during these airfield visits the drill was that Alan would pick me up
at about 11.30 am and we would drive to Kemble, stopping off at the
Star Inn in Kingsclere for a nice carvery lunch. Then on to Kemble
arriving at the airfield at about 3.00 pm to start work in the hangar
as soon as the aircraft was available, working until late evening.
Unfortunately, during the initial commissioning trials we had lots of
problems with spurious counts. After discussion with the RAF it was
decided, that to start with, a pilot would taxy the aircraft round the
airfield and along the runway with Alan in the back seat observing any
problems. Subsequently we discovered that when the pilot transmitted on
UHF, radio frequency interference was induced in the signal cable
linking the preamplifier in the fin, from the adjacent UHF aerial
feeder in the spine. Given the power this was a difficult problem to
solve but after involving virtually all the electronic knowledge in the
Control Engineering Section. the preamplifier and screening was
hardened sufficiently for the system to work satisfactorily in this
harsh EMC environment.
Later
the 'Reds' moved down the road to
RAF Fairford where Concorde was on flight trials. During our visits we
felt privileged in being able to observe some of the Concorde work. One
day a very bad thunderstorm broke out while we were working in the
hangar and even with all the noise of the torrential rain on the roof
we could still hear the Concorde at the end of the runway. Everybody,
including ourselves and all the RAF 'erks', rushed to the doors to see
what all the commotion was about, only to get nearly drowned in the
water gushing off the roof. There she was, in all her power and beauty
straining on her brakes with full reheat, then accelerating flat out
down the runway for a maximum braking test just before taking off. Of
course we realised that the Concorde flight test engineers were using
the opportunity to complete some wet runway braking test; but what a
sight!
The
prototype fatigue counter was subsequently also
fitted to the training Gnat and produced some interesting results.
Contrary to what one might think, it was observed that the generally
higher g flight profile of the Red Arrows was often causing far less
fatigue damage than that of training flights. As a result of the
fatigue programme, the extrapolated remaining fatigue life,
particularly of the training aircraft, was reduced significantly
resulting in the Gnat being retired earlier than planned. This put more
pressure on getting the Hawks, which would replace them, into service.
The project was a tribute to Derek Thomas who had always been there as
the visionary behind real-time airborne fatigue load monitoring. In
modern times with fly-by-wire and computerised stress analysis and
simulation there is more known data and the problems are better
understood. It was with great shock and sadness that I learnt of
Derek's premature death in the 1980s after I had left Hawkers to join
Digital Equipment Corporation in 1977.