Trevor Davies recounts a unique experience at Dunsfol
One of my roles while working in the Flight Test
department at
Dunsfold was that of Flight Test Observer. This involved both
development and production test flying. Some time after I started
flying I was preparing for a flight with test pilot Jim Hawkins. After
we had sorted our test schedule for the flight Jim, a Qualified Flying
Instructor (QFI), informed me that as I was occupying the back seat of
Hawks quite frequently it had been decided that, should the pilot
become incapacitated (for instance by a bird-strike), it would be to
the advantage of all concerned if I was capable of getting the aircraft
back on the ground in one piece. There was no question of a dedicated
training programme but opportunity would be taken of any time that
presented itself once the purpose of any flights had been achieved; for
instance during transit to / from the test area. The training would
therefore be rather sporadic. We started with individual skills which
would subsequently be combined into the whole sequence.
Not
Your Usual Way To Learn To Fly
On the ground this involved taxying the aircraft. Aircraft are
controlled in yaw by using the rudder, this being connected to foot
pedals on a rudder bar in the cockpit. By pressing on the appropriate
foot pedal the pilot can yaw the aircraft; press the left pedal and the
aircraft yaws left, press the right pedal and it yaws right. However,
at low speeds the rudder is ineffective so each pedal has a toe
operated section which applies the brake on the corresponding main
wheel. Unlike a car brake pedal the toe pedals had hardly any travel
and required a much harder press. They each acted independently so that
you could steer but that meant that balancing them out to slow the
aircraft was also the pilot’s job.
For my first attempt at taxying I wasn’t given
control until we were in the wide expanse of the main runway - which
very quickly didn’t seem that wide anymore! We progressed along the
runway in a series of erratic zig-zags as I strove to keep the jet away
from the grass and as near to the centreline of the concrete as I
could. These excursions gradually became smoother and more controlled
as I got used to the feel of the brakes. Once at the end of the runway
the jet needed to be turned through 180 degrees, adding judicious use
of the throttle in order to make the tight turn. Once I had the jet
lined up pointing (sort of) along the centreline of the runway Jim took
back control so that we could get on with the job in hand. Subsequent
attempts improved the precision of control until I was taxying the jet
from, and back to, its parking spot on the flight line, managing to
keep the wing tips a safe distance from the expensive hardware parked
in the adjacent spots.
In the air the first skill to master was getting the
jet trimmed in straight and level flight. As the Hawk has hydraulically
powered pitch (tailplane) and roll (aileron) controls the pilot does
not feel the aerodynamic force on the control surfaces through the
stick. Without any ‘feel’ control of the aircraft would be very
difficult. In order to provide an artificial ‘feel’ a spring system is
incorporated which biases the stick to the central position. The spring
system provides a force which increases as the stick is deflected away
from the central (zero force) position. This enables the pilot to
‘feel’ the deflection of the stick (and therefore control surface
movement) that is being demanded for manoeuvre. Feeling zero force
indicates that the stick has been returned to its initial, stable
flight, position. The tailplane angle required for stable flight
however varies depending upon the speed / height / aircraft
configuration combination at the time. The system therefore also
incorporates a mechanism by which the zero force point can be adjusted
to ‘trim’ out the force across the range of stable flight conditions.
It was therefore necessary for me to get used to keeping the jet in
trim as flight conditions changed, practise making it progressively
become more intuitive and automatic. Straight and level flight quickly
gave way to holding speed in a climb or descent and to more dynamic
manoeuvres such as turns, initially level but then also during climbs
and descents.
It was not long before I had to start putting some
of these skills together and so one day Jim announced “You can do the
take-off today”, and then proceeded to brief me through all the
sequence. Once in the jet with the engine fired up and all the systems
checked Jim got taxi clearance from Air Traffic Control and then handed
control of the Hawk to me. The taxi out I’d done a few times but once I
had the jet lined up pointing down the runway I was entering new
territory. With the ‘voice up front’ talking me through the procedure I
checked from left to right across the cockpit that all the systems and
settings were as they should be. With take-off clearance obtained, and
a reminder to keep my feet on the brakes, I opened the throttle and
checked that the engine rpm and turbine gas temperature (TGT) rose
normally and that the engine control amplifier (ECA) held them to their
limiting values. Then I released the brakes. And we were off ….
accelerating down the runway at a rate that suddenly seemed a lot more
rapid than when someone else was in control! First job keep the jet
pointing down the runway, initially using the brakes but, as soon as
there was enough draught over the rudder for it to be effective (about
40 knots), using that alone. In no time at all (or so it seemed) the
speed was approaching 90 knots and it was time to gently move the stick
slightly back to raise the nose wheel clear of the ground so that at
around 130 knots only a very gentle further pressure was needed for the
jet to get airborne.
Once I had established the briefed pitch attitude
and a positive climb rate a quick dab on the brakes stopped the wheels
rotating so that the undercarriage could then be retracted, along with
the flaps, before reaching their limiting speed of 200 knots. By this
time the jet was heading upwards quite rapidly so I needed to level off
before we blundered into controlled airspace above us, turn slightly
right onto a westerly heading for the transit to the test area and
allow the airspeed to build to around 350 knots, then throttle back to
hold that speed.……. Oh yes, and breathe! That first take-off all seemed
to come in something of a rush but, after further take-offs, I
progressively started to feel that I was gaining control and no longer
just desperately trying to keep up with the jet.
So much for getting off the ground; the next, more
delicate, challenge was to get the jet back on it. On a suitable
flight, following completion of our test schedule and heading back to
Dunsfold, I was given control at a safe height to practice decelerating
the jet to circuit speed, trimming the jet as the undercarriage and
take-off flap were lowered (hardly any change) and then again as full
flap was lowered (quite a significant change). I also had to practise
the recovery action if I let the landing approach speed get too slow.
It was then a question of repeating these when we returned to Dunsfold
(but not, intentionally, the ‘too slow’ bit!), only this time doing so
at the appropriate points in the circuit. We entered the downwind leg,
parallel to the main runway, and once the speed was below 200 knots the
undercarriage and take-off flap were lowered and the speed allowed to
decrease to around 160 knots. Then, with the downwind end of the runway
behind the left wingtip, a left turn was commenced during which full
flap was lowered, the extra drag starting the descent towards the
runway. The aim was to roll out of the turn lined up into wind and
pointing along the line of the runway at a speed of 130 knots and
adjusting the throttle to give a rate of descent that would see us
reach the runway before we contacted the ground. Sounds simple written
like that, but felt more like a one-armed paper-hanger job at the time!
As we crossed the runway threshold I raised the nose slightly to reduce
the rate of descent and bleed off a bit more speed and then pulled the
power back a bit to allow the jet to settle onto the runway. Once I
felt the bump of the main wheels touching down I lowered the nose wheel
onto the runway and started braking. It was just starting to sink in
that I’d actually managed to land the jet when I began to get the
feeling that all was not quite as it should be – we didn’t seem to be
slowing down quickly enough. Co-incidentally the ‘voice up front’ said
“It’s all right Trevor, we’re on the runway, you can close the throttle
now”.……… B****r!!
More take-offs and landings followed as opportunity
allowed, all building towards the original objective of this training,
a check of which was not long in coming. Again flying with Jim Hawkins,
as we finished that particular test schedule at 2000 feet just off the
south coast, Jim announced that he had just gone unconscious and that I
would have to get us home. After which he went silent. Not just a
landing then, first get back to Dunsfold. As this was an area we
commonly used for test flying I was quite familiar with it. Selsey Bill
was just north of and behind us, so I headed east along the coast past
Bognor Regis to Littlehampton. Having double-checked that it really was
Littlehampton I then turned north to cross the South Downs above the
‘Arundel Gap’. While keeping a wary eye out for light aircraft from
Goodwood I called Dunsfold air traffic to tell them that we were
returning to the field and where we were. Then, with Pulborough below
us and Cranleigh up ahead, I was able to identify Dunsfold aerodrome. I
prepared to join the circuit for landing remembering to tell Dunsfold
Tower when we were positioned downwind to land and again when on final
approach (and with a gentle reminder from air traffic) to confirm
‘three greens’ i.e. the undercarriage was down and locked. I managed
not to make too much of a meal of the landing and then taxied in and
parked the jet on the flight line where, as I shut the engine down, Jim
made a miraculous recovery!
Having confirmed that all the training had achieved
its objective I continued to be given opportunities to fly the Hawk, as
circumstances allowed, to keep the skills I had learned practised and
also to expand on them. During the time I spent flying at Dunsfold I
got to fly the Hawk through most of its flight envelope: take-offs,
landings, stalling, spinning, supersonic dives, aerobatics, formation
flying. Apart from achieving the original objective of the
training, from a professional perspective the practical insights that I
gained from this training were of great benefit to the ground-based
elements of my work planning flight tests and analysing the data from
them. From a personal perspective it was an incredibly satisfying
experience and I will be forever grateful to Jim Hawkins and all the
other Dunsfold pilots involved for having had this opportunity.