ADA-Jack Woodman:Flying the Arrow Pg.4
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Jack
Woodman:
Flying the Arrow.
Pg.4
continued
from page 3,
Systems
   The aircraft systems (the fuel system, hydraulic
system, electrical system, pneumatic system, etc.)
were all relatively conventional except, perhaps,
for the landing gear and the flying controls system.
   The tricycle landing gear consisted of a forward
retracting nose gear with dual wheels, and main
gear with two­wheeled bogies, which retracted
in­board and forward into the wing.
   Cockpit control was by means of a lever in the
shape of a wheel, located on the left-hand forward
panel, and it was operated by a simple up or down
motion.
   Emergency lowering of the landing gear was by
a 5,000-psi nitrogen bottle, which, when activated,
released the door and gear uplocks, and the gear
then fell in a normal manner by gravity, aided
by air loads.
   The problem with the CF-105 landing gear was
one of stowage. Because of the high, thin wing
the gear was relatively long. In order to
stow the gear, it had to be shortened and twisted
as it retracted. On June 11, on the 11 th flight
of the first airplane, the gear failed to extend
completely, even though cockpit indicators showed
it down and locked. The landing was made with the
left main gear cocked approximately 30° to
one side. In other words, it had not fully untwisted.
The landing roll was about 4,000 ft., and, of course,
with the port leg twisted it pulled the aircraft
to one side. As the aircraft left the runway and
came in contact with soft ground, the undercarriage
snapped. The aircraft came to rest on its
right gear and left wingtip.
   Because of the excellent photographic coverage,
the cause of the accident was quickly determined.
Avro had the airplane flying again approximately
four months later, and flight procedure from that
time was to have a chase-plane check gear extension
prior to landing. Zurakowski was the pilot,
and I know that if he had only had some indication
of a problem, the accident would never have
occurred.
   The CF-105 flying control system was a fully
powered, irreversible, artificial feel control
system. There were three modes of operation: a
normal mode, an automatic mode, and an emergency
mode. The automatic mode was not installed in the
early aircraft.
   Two independent hydraulic systems provided the
muscle, each with two engine driven pumps.
The supply was 4,000 psi. Also, a ram air turbine
was to have been installed on later aircraft for
use in the event of a two-engine flameout.
   In the normal mode, a damping system provided
stability augmentation for all three axes, and
co-ordinated rudder movement with movement of the
ailerons and elevators. Artificial feel was
provided by an electrical system in such a way
that stick force required was made to feel proportional
to the amount of g's
pulled. Stick force per g was constant, irrespective
of speed or altitude.
   When the pilot exerted a -force on the control
column to move the elevators, a force transducer
on the control column transmitted electrical signals
to a series of servos, which converted the electrical
signals into mechanical movement by means of hydraulic
pressure. The electrical output at the transducer
was directly proportional to the force exerted
at the grip. The control column would move as the
force was exerted, as with a conventional flying
control system, but it was not moved directly by
the pilot. Movement of the control column
followed the positioning of the elevators. The
response of the system was instantaneous, and it
therefore appeared as if the control column
were moved by the pilot.
   In the emergency mode, the force transducer was
taken out of the loop. The control column was linked
by cable directly to the hydraulic actuators, which
controlled the elevators. Artificial feel was provided
by a spring-loaded assembly along with a bob-weight,
which induced loads on the control col­umn
and made control column move­ment progressively
heavy as g's were applied.
   Operation of the ailerons and
the rudder by means of electrical signals, or by
cables, was very similar to operation of the elevators.
Components in the systems differed slightly, but
from the pilot's point of view, the systems operated
in a similar manner. The damping system was duplicated
in yaw, however, as this was the critical axis
and of major importance to the safety of the airplane
in the high-speed range. The airplane in the lateral-directional
axis was naturally unstable. It was de­signed
that way, by necessity, to meet performance guarantees
specified by the RCAF.
   The flying control system
was anything but developed at the time the program
was cancelled, and if I remember correctly, it had
No. 1 priority in the flight test program. The airplane,
at certain
speeds and altitudes, flew as well as any airplane
I've ever flown; at other points control was very
sensitive and the airplane difficult to fly accurately.
However, I know it was just a matter of optimizing
the controls, the damping system, and the feel throughout
the complete flight envelope. And it would have been
accomplished.
   I know the control system sounds sophisticated
and perhaps overly complicated, and maybe it
was for its time. But the Arrow flight control system
was very similar to the systems being used now in
today's most advanced aircraft. If the automatic
mode had been installed, we would have had what
is known today as Control Wheel Steering (CWS), i.e.,
flying the airplane through an autopilot. The Arrow
control system was the same as a "fly-by-wire" system
except for the mechanical linkage provided in
the emergency mode.
   I can't help but feel that if Avro had been permitted
to develop the Arrow, both Avro and Canada would
have been recognized
as leaders in the field of high-performance
airplanes.
Cockpit
   The cockpit was generally comfortable and
well arranged. It was a bit small, and with a pressure
suit some of the controls and switches on the side
consoles were difficult to see or operate. There
was only 2 or 3 ins. of clearance between the
canopy and the pilot's helmet, and I remember
hitting the canopy with my helmet on several occasions
with normal head movement and look-around.
   Entry and exit to the cockpit was by means of a
vertical ladder, nine or 10 steps high, hooked over
the engine intake ramp. From the ladder, you
stepped to the top of the engine intake, over the
canopy, and down into the cockpit. This was a little
awkward. Also, I think it would have been a source
of trouble in squadron servjce, with people stepping
on the side railing and air-conditioning ducts with
dirty or snow-covered boots. Generally, however,
I think the cockpit was quite comfortable.
   The parachute harness and the seat harness were
combined, and strapping in was relatively simple.
Leg restraints were used to pull and hold pilots'
legs back against the front of the seat pan during
emergency ejection.
   A Martin-Baker C.5 automatic ejection seat
was used, which provided an escape envelope from
ground level up.
   The Arrow had a V-shaped wind­shield and vision
splitter. This is not, in my opinion, the best kind
of windshield to fly behind, but it was obviously
satisfactory, and Avro did a good job with forward
visibility.
Flight test program
   The flight test program was scheduled as an
eight-phase program. Basically, the first series
of tests were to evaluate the general handling qualities
of the aircraft, to evaluate the flying control system
and damping system, to check instrumentation and
telemetry techniques, and to check safety under adverse
conditions.
   The initial series of flights entailed pre-production
testing and development, using the first five
aircraft with the J.75 engines. This was the Arrow
Mk. I.
   The Arrow Mk. II started with the 6th airplane,
with production Orenda engines. Phases I through
III were to have involved contractor testing and
development, and phases IV through Vlll were
slated for Air Force testing and evaluation.
   Obviously, only a portion of the initial Phase
I pre-production testing was accomplished; however,
some significant milestones were reached:
First two flights were familiarization
flights.
On the third flight, the aircraft
flew supersonically (M 1.1-M 1.2).
On the seventh flight, the aircraft flew to Mach
1.5 (1,000 mph) at 50,000 ft.
Maximum speed attained was Mach 1.97-1.98.
Four pilots were checked out. According
to my records, the five aircraft flew 64 flights
for a total of 68 hours and 45 minutes.
CONVERTED TO HTML,
AND HYPERLINKS ADDED, OCTOBER 1, 2004.
Scott McArthur.
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