|Avro's Computer Capacity
was greatly increased with the addition, this year,
of the IBM 704 electronic data processing machine
shown above. Latest and most powerful digital computer
available to industry, Avro's 704 is the only one
outside the U.S.
From Concept To Completion
In Record Four Years
from Page 3, Col. 4)
ground support equipment mock-ups were also built
for design appraisal. The CF-105 was officially
designated the Avro Arrow in early 1957, and the
two versions of the aircraft were designated Arrow
1 and Arrow 2.
Aerodynamically, the Arrow was entertaining a new realm
of science. Performance, stability and control problems were difficult to evaluate,
and data had to be obtained to establish air loads on the wing, fin, canopy and
control surfaces. In this respect, wind tunnel results proved and supplemented
theories in over- coming some of these problems. Im- provements in longitudinal
stability, buffet characteristics, subsonic drag and directional stability for
example were a direct result of wind tunnel testing.
Analog computing equipment was installed to
accelerate the solution of dynamic and stress problems. The company also obtained
a new electronic digital computer of great speed and capacity to accommodate
its accelerated research and development program in supersonic aircraft. This
was the IBM 704 electronic data processing machine the latest and most powerful
digital computer designed for scientific applications, now available to industry.
The giant computer is equivalent in calculating and problem solving power to
3000 tireless, perfectly organized and trained engineers. A staff of thirty mathematicians,
technicians and operators is involved at the present time in feeding problems
to the 704, analyzing results, and keeping the machine in operation. Avro's 704
is the only one installed outside the United States.
| The Arrow structure
is designed to provide a high wing, delta planform,
all metal aircraft. Although the air loads had been
determined by the Aerodynamics Department, it was impossible
to know at that time what effect manoeuvrability would
have on the structure. For this reason a large number
of stressing cases had to be investigated. Supersonic
aircraft are virtually flying pressure vessels, and
the problem was further complicated by the need to
keep weight to a minimum. Supersonic aircraft also
involve problems which previously could be ignored.
Two such problems which required extensive investigation
by the Stress Department were structure weakening caused
by heat and sound.
In simple terms the heat problem is caused by friction
between the air and the aircraft skin. Temperatures attained while flying at
supersonic speeds are high enough to weaken structure-the higher the speed, the
more the heat, bigger the problem.
There are two main types of detrimental sound-jet engine
and aero dynamic. These can cause skin panels to fracture and rivets to loosen,
again weakening structure. Sonic structural tests are being car- ried out constantly,
and will con tinue, until they have run Ion enough to indicate satisfactory pane
Proper ground support equipment plays an important role
in the operational effectiveness of any modern military aircraft. Since most
existing equipment could not be used for Arrow servicing requirements it was
essential to ensure adequate main- tenance facilities were available.
A joint Avro-RCAF Maintenance Engineering Group
was formed, and to date has designed some 200 pieces of equipment. Problems to
be overcome in this field were as great in their own way as those in the aircraft
itself. This is self-evident when one realizes for example that the engine starter
truck is a jeep- mounted gas turbine, and the power- and-air-conditioning truck
m u s t maintain
|a constant air flow at 55°F to the
weapons, electronic and other sensitive equipment,
under all ground temperature conditions. Arrow development
presented some problems that were not even dreamed
of when the CF-100 was designed. At supersonic speeds,
for instance, air loads on the control surfaces are
extremely high, and the pilot must be provided with
considerable amplification of his physical strength.
In fact, control mechanisms are installed on the Arrow
wliieh are sufficiently powerful to lift the equivalent
of six elephants standing on the elevators.
Modern military aircraft require elaborate
electrical and electronic systems. In the Arrow there are some eleven miles of
wiring and enough vacuum tubes to equip about two hundred television sets except
for picture tubes.
Tremendous power is needed to fly an aircraft at supersonic
speeds, and the Arrow uses about twice as much power as that required to drive
the Queen Mary. To develop this power, the engines consume fuel at the rate of
more than a quarter of a ton per minute. Much of this power is dissipated in
air friction at these very high speeds, and air friction raises the aircraft
temperature to such a degree that the air conditioning required to protect the
crew and the vital equipment is sufficient to produce 23 tons of ice a day.
The complex structural requirements, and the desire
to keep construction as simple as possible made extensive research necessary
in this field. A vast amount of development has been done in the field of metal-
to-metal bonding which ehninates much of the time-consuming and difficult processes
of conventional riveting and fastening. In order that metal bonding can be used
successfully, it must be sufficiently strong, reasonably easy to use, and must
have sufficient heat resistance to be unaffected at temperateres experienced
by an aircraft flying at supersonic speeds.
Static testing of wing structure
being conducted by the Structural Test department.
Dial test indicators are being used, along with
strain gauges, to measure deflection.
While bonding of aluminum alloys imposed no great
problem, considerable experimental work was required with magnesium alloys. A
process has been developed by Avro metallurgists which has proven very satisfactory
under tests, and is used in many parts of the aircraft.
Until recently, high-performance aircraft were not committed
to production until after flight testing of one or more prototypes. Normally
quite a number of changes are necessary before the aircraft can go into production.
The Arrow program is unusual in Canada in that even the first flying model has
been built on production tooling. This time-saving approach made it essential
to prove the basic soundness of the structural and system concepts by exhaustive
testing prior to the actual build of the aircraft. This procedure subjects nearly
all components to test
|equivalent to the most severe and varied
All the aircraft systems, too, must undergo the most
rigorous tests to ensure the high safety standard and efficient component operation
demanded of the Arrow.
The fuel system for instance, has been set up in every
detail on an elaborate test rig which simulates its operation and allows it to
be tested in any position that the aircraft may assume. Fuel system test program
includes investigations of the pressure system, refueling and de-fueling, simulated
flight sequences and emergency operation,
The difficult task of analyzing the structure
of the Arrow imposed many unique problems on the stress engineers. The complexity
of the Arrow's structure demanded the use of the most advanced analysis methods
and techniques available.
A novel technique used in the stress analysis program
involved the use of plastic models. These models had to be constructed with great
care so that the structure would have the required degree of similarity to the
actual aircraft. They were then placed in test rigs which were capable of producing
loads on the models comparable to the predicted flight loads. After intensive
testing, the deflections and stresses which were produced showed that the methods
being used for analytical studies were valid.
The hundreds of items of mechanical, hydraulic,
electrical and electronic equipment in the Arrow are all required to operate
in a severe high temperature, high-altitude environment with the utmost reliability.
Equipment which would perform under these conditions simply did not exist when
the Arrow design got under way. It was therefore necessary for Avro to specify
the special performance necessary for each one of these devices to do its job,
and to assess the proposals of equipment manufacturers throughout the continent
to determine their capability to develop the items. Avro then maintained close
engineering contact with all these sources while the units which had to meet
the Arrow's stringent requirements were being designed, built, tested and delivered.
| In modern military
terms, an aircraft like the Arrow becomes the central
component of a "Weapon System". Besides the
basic aircraft, this Weapon System must include a complete,
compatible air and ground environment, starting with
the support and maintenance equipment at RCAF bases,
through the ground radar and communication facilities,
up to and including the airborne electronic system
and weapons. All this is essential for a supersonic
interceptor to perform its specified task.
As the Arrow program progressed, it soon became evident
that no existing combination of electronic equipment met the RCAF's operational
requirements and the Arrow's environmental needs. After evaluating several proposals,
the RCAF selected RCA as the electronic system contractor, with the task of developing
this most essential component of the Arrow weapon system.
RCA and RCA's associate contractor, Minneapolis-Honeywell,
along with their Canadian affiliates, plunged into the task of creating the advanced
specialized electronic system for automatic flight, weapon fire control, communication
and navigation which has been designated the "Astra I" system.
To date, approximately 17,000 different
dawings have been released for the Arrow 1 and Engineering has formed a liaison
team, which is on call twenty-four bours a day, to ensure that any drawing geery
or problem which may arise is immediately dealt with.
It is now four years since the design started. This
is considered better than average for the time required to design and build present
day high performance aircraft.
The Arrow is a fighter aircraft, yet its armament bay
is as large as the bomb bay of some World War II bombers and the power of its
two Iroquois engines is almost sufficient to lift the aircraft vertically off
With the Arrow 1 engineering complete, the Engineering
Division is looking toward future development of the aircraft; It. is a flexable,
versatile, aircraft and with development it can have a greatly extended future.
The present Arrow is on the threshold of the heat barrier, popularly called the
Thermal Thicket, and studies are now under way as to how to adapt the aircraft
for even higher speeds
|Pilots' view from the
cockpit of the Arrow shows excellent visibility despite
slight nose-up attitude while taxiing. Photo was
taken from mobile cockpit mock-up.
Test Pilots Aid Program
|(Continued from Page 9, Col. 4)
by General Joseph Caldara, of the
Office of the Director of Flight Safety, U.S.A.F.,
following an official visit to the plant, ater which
he stated that the Arrow's cockpit layout is the
best he had seen.
Members of Avro's Experimental Test Pilot staff have,
as part of their preparations for preliminary flight tests of the Arrow, spent
some time at the Convair test facility at Palmdale, California. There they have
flown experimental and production version of the F-12 single-engine, delta-wing
interceptor now being
|produced for the U.S. Air Force. Now
that the Arrow is completed and is unveiled for the
first time, it will be moved from the production
bays to the flight test hangar in preparation for
its initial flight. The test pilots experience a
strong feeling of pride in the achievement of the
Engineering and Manufacturing divisions, and of anticipation
for the opportunity to launch the Arrow on its flight
program. They are eager to commence that portion
of the development which is implied by the professional
title: Experimental Test Pilot.