ADA-Arrow Pilots:Jan Zurakowski
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Arrow Pilots:Jan
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Jan
Zurakowski:
Test Flying the Arrow. pg5
And Other High Speed Jet Aircraft.
This
republication has been made possible thanks to
the assistance of
The Canadian Aviation
Historical Society.
We hope you enjoy this piece of aviation history.
Scott McArthur. Webmaster, Arrow Recovery
Canada.
TEST FLYING THE ARROW
and
other high speed jet aircraft.
Jan
Zurakowski
continued
from page 4,
An engineer was instructed to write the specification
for wheel brakes for the Arrow. The standard specification
at the time, if I remember correctly, required
brake capacity to have kinetic energy absorption
equal to 1.2 times stalling speed squared, multiplied
by the aircraft landing weight. Checking by phone,
he got his figures, but the stalling speed quoted
was completely unrealistic for use in estimating
landing speed. Wings of 60deg delta reach stalling
speed at an angle of attack of about 45 deg; during
landing the geometry of the undercarriage does
not allow the use of more than about 15deg.
     The specification went to the subcontractor and
after the necessary design, development and proving
time, the brakes were found to be completely inadequate
for the aircraft when the wheels arrived, specially
since in the meantime the aircraft weight was increased.
A crash programme to develop new brakes was required
to prevent delay in the flight testing.
     The Flight Test
Instrument Section was developing a system known
as telemetry, which would provide in-flight information
consisting of a large number of parameters transmitted
automatically to the ground. This system increased
safety of the flight, helped to warn the pilot
if he was approaching a limiting stress or other
limiting conditions, and could be of high value
if an aircraft crashed or disintegrated in
unknown circumstances.
     With the help of
an IBM 704 computer, a flight simulator was created
using as many parts and systems from the aircraft
as possible. Designers were very optimistic, promising
to teach the pilots to fly the Arrow. Unfortunately
the simulated
aircraft was very difficult to fly; I lost control
of it in three seconds; Spud Potocki, who was much
better on instrument flying, managed to fly eleven
seconds before crashing.
     I was completing
taxiing tests in preparation for the first flight
on an actual Arrow Mk. I. An unpleasant situation
was created: if the simulator is unflyable, is
the aircraft safe for flight? A specialist from
the U. S. was called to assess the situation, but
was not very optimistic.
     What next? To develop this simulator to flyable
condition, or to fly the actual aircraft? I recommended
disregarding the simulator for the time being and
going ahead with the first flight. It turned out
later that there was much more to the art of simulating
flight than just feeding parameters into a computer
and transmitting the results into cockpit instruments.
     The first flight
of the Arrow on 25 March 1958 was very simple.
Just check the response of controls, engines, under­carriage
and air brakes, handling at speeds up to 400 knots,
and low speed in a landing configuration. There
certainly was more excitement for the several thousand
Avro employees watching my first flight than for
myself seated in the cockpit trying to remember
hundreds of do's and don'ts.
     The aircraft flying
characteristics were similar to that of other delta
wing aircraft like the Javelin or Convair F-102,
but the Arrow had a more positive response to control
movement. The unpleasant part of my first flight
was the feeling of responsibility, combined with
the realization that the success of this aircraft
depended on thousands of components, especially
electronic and hydraulic, with only a small percentage
under my direct control. But total responsibility
for the flight was mine.
     Flight by flight,
with ground monitoring based on telemetry results,
I was going a bit faster and a bit higher. On flight
No. 7, climbing at 50,000 feet, I exceeded 1000
MPH, and that was the only performance released
at that time by Air Force headquarters.
     Phase One of the Arrow flight test programme was
successfully completed, and F/L Jack Woodman made
a familiarization and initial assessment flight.
In August of the same year I started tests on a
second prototype (No. 202) and in September on
the first flight of the third prototype (No. 203),
1 exceeded the speed of sound.
     Shortly after, Prime Minister John Diefenbaker
in a statement released to the press declared that
two Canadian bases for U. S. Bomarc missiles would
be established and the current development programme
of the Arrow and Orenda Iroquois engines would
continue, but would be reviewed in the next March.
     Development flying was speeded up when Spud Potocki
and Peter Cope joined in testing. For me, the time
to retire from testing had arrived. Normal retirement
age from high speed flying was 40, and I was already
44. 1 was leaving experimental flying in good hands.
Spud Potocki, Peter Cope, and F/L Jack Woodman were
all excellent pilots, already with some experience
on the Arrow. I moved to Engineering Division as
staff engineer. Spud Potocki did the first flights
on two more Arrows (No. 204 and 205), increasing
the number of test aircraft to five. Testing was
progressing well, but was slowed down by two accidents.
     I was involved in
the first one. During a landing run on 201 I suddenly
realized that the aircraft was pulling to the left
and I could not maintain direction. Suspecting
that the braking parachute had not opened evenly,
I jettisoned it: there was no improvement, and
at about 30 MPH the aircraft left the runway and
the undercarriage collapsed in the soft ground.
     On investigation it was established that the
left under­carriage leg had not completed the
lowering cycle and during the landing run the wheels
were at about a 450 angle to the direction of travel,
producing a higher drag than the brakes on the
right side could compensate for. With decrease
of speed, rudder effectiveness decreased and the
aircraft could not be prevented from changing direction.
     This accident probably
could have been avoided if the warning light had
indicated that the undercarriage had not locked
properly, or if the chase plane pilot had watched
me during landing and reported the trouble by radio.
Unfortunately, he was short of fuel and landed
first. If I had known of the fault, I could have
landed slightly across the runway, making correction
for the expected turning moment.
     The second accident took place on aircraft No.
202, flown by Spud Potocki. During a landing roll
all four wheels skidded and the tires burst. The
pilot lost directional control and the aircraft
ran off the runway, damaging the right undercarriage
leg. The initial impression was that it was pilot
error. The pilot was thought to have applied too
much braking pressure too early and locked the
wheels.
     As I mentioned before, we had the telemetry system
recording basic parameters of flight. It was recorded
that during touchdown the elevators suddenly moved
full 300 down.
     Spud was sure that
he did not move the controls. Instrumentation experts
suspected an error in recordings. Fortunately,
a photograph of this landing run was discovered
in the possession of a suspected spy, showing the
elevators fully down. Now the cause of the accident
was clear. The Arrow's elevators were large and
when deflected fully down, acted as powerful flaps,
increasing wing lift so much that only 20% of the
aircraft weight was on the main wheels. The pilot
was not aware of this and normal application of
brakes locked the wheels.
     During this landing, a small aircraft vibration
as the wheels touched the ground had resulted in
a wrong electrical signal to the stability augmentation
system, calling for full elevator down.
     The pilot was lucky; if the elevator had moved
fully down in flight at any speed faster than 300
knots, disintegration of the aircraft was likely
in a fraction of a second.
     Performance results
collected on flights of five Arrow Mk. I aircraft
fitted with Pratt & Whitney
J-75 engines were used to estimate the performance
of Mk. 11 Arrow fitted with Iroquois engines. The
Arrow with J-75 engines was heavier than with Iroquois
and had to be ballasted for a correct centre of
gravity position, Mk. II with Iroquois engines
did not need ballast and was about 5000 lbs lighter,
and had 40 to 50% more thrust. It was estimated
that we had a high chance of beating the world
speed and altitude records held at that time by
the United States.
     The first Mk. II (No. 206) was expected to fly
at the end of February 1959.
     On 20 February 1959, the President of the Avro
Company informed all working personnel over the
public address system that the Prime Minister had
just announced the termination of the Arrow and
Iroquois programmes.
     A telegram received later in the day by the company
instructed:
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Scott McArthur.
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