philosophy of proceeding immediately with, production
type build which we adopted on the CF-105, and which
I will discuss later, obviously involves greater
technical risks than the prototype/pre-production/production
technique and, to protect as much of our engineering
investment as possible, the decision was made early
in the programme to carry out what was considered
at the time to be an extraordinary amount of structural
and systems testing.
A large proportion of this testing was used for development purposes,
for instance, the basic development of the control system and damping system
was done on the control system rig.
Many of the major structural tests, however, could not be considered
in the development category, since production components were required from Manufacturing,
and these components were not, in many cases, ready until the first aircraft
was about to fly. In these cases, the test became more of a check on the completed
A large number of critical components were checked prior to flight.
This included the checking of fatigue of typical joints and structures, elevated
temperature testing, panel and torsion box testing, and so on.
16. Structural static test rig.
next step in the structural programme was to test
the complete aircraft in the large static test rig
(Fig. 16). These tests began in early 1958, the objective
being to confirm the calculated internal load distribution
in the complete aircraft structure from the applied
,external loads, and to confirm the calculated stiffness
and deflections of the structure under load, in addition
to establishing the overall structural strength of
the airframe under limit load conditions for various
flight and landing cases.
In the major cases, up to 30 hydraulic systems are used to apply
the loads, via a multiple beam system, to some 1,100 points on the aircraft.
This has led to the use of an automatic load control system which allows control
to be maintained by a single operator through regulating valves.
The load in each hydraulic jack is sensed by a strain gauge system
to ensure that the overall load is compatible with the percentage of limit load
to be applied. More than 3,000 strain gauge recording stations are used on the
structure, and 300 deflection gauge stations. The central strain gauge recording
unit is capable of reading out close to 800 stations in 25 minutes. The results
are simultaneously typewritten and punched on to IBM cards for ease of processing
by the Technical Office.
heating tests were made on representative sections
of the fuselage and wing using radiant heat lamps
powered by a variable voltage supply controlled by
a simple analogue computer.
FIGURE 20. Static testing of crew escape systern.
Control System Rig
Since this rig was used for basic development of the flying control
system, it was a fairly sophisticated rig, containing a dummy cockpit, a complete
control system, closely controlled electric motor drives to simulate various
engine conditions, all control surfaces and adjacent structure, and the synthetic
stability system. (Fig. 17).
For the aerodynamic response tests, surface loading was provided
by large leaf springs attached to the surfaces, and the tests simulated correct
inertial conditions at the same time maintaining structural stiffness.
A large amount of instrumentation was provided to record motions
of the actuators, valves, servos, and so on, together with hydraulic system pressure
at critical points in the system. On this rig we were able to make complete evaluation
of the flying control system from the cockpit to the control surfaces. The rig
was also used during simulation tests on the complete aircraft. This
particular rig is tied in with a co-axial cable to the Analogue Computer Room,
some distance away. Output from potentiometers mounted at the control surfaces
were transmitted to the computers, which in turn fed in derivatives obtained
from wind tunnel testing. Landing, take-off and manoeuvring under gust conditions
were simulated to give the pilot some feel of aircraft problems, including break-out
A flight simulator was set up with visual representation of aircraft
attitude, rate of climb, stability, and so on, and included engine noise inputs.
A considerable amount of " flying" was done on this rig by the test
pilots, before actual flight.
A full scale rig representing half the complete aircraft fuel system
was built and mounted on a special gantry on which the specimen is pitched and
rolled to simulate all attitudes of the aircraft in flight. All components of
the fuel system were installed so that their function would be similar to that
experienced in flight. Vacuum pumps were available on the rig to simulate altitude
conditions. Tank pressurisation was provided, and a large heater to elevate the
fuel temperature, to check flows under hot fuel conditions. This rig was also
used for qualification testing of the various items in the fuel system (Fig.
Conditioning System Rig
This rig was provided to check systems functioning and the mass flow distribution
throughout the system. The rig represents the complete air conditioning system,
the cockpit being represented by an air tank of equivalent volume.
The rig had to be totally enclosed because of the high noise level. Air
temperatures at 30 locations in the rig were recorded by thermocouples, and the
air turbine speed was obtained from a magnetic pick-up, which in turn was recorded
on special instrumentation. Fig. 19 shows the rig before completion.
A number of other tests involving the complete aircraft electrical
system, the complete landing gear, the utility hydraulic system, and so on, were
made. A system of insulating panels can be placed around most of the test rigs,
and air is supplied through heat exchangers to raise the temperature to 250'F.,
or reduce it down to -65', by reversing the process. It was possible by this
method to test the control system, structure, and so on, at the temperature conditions
which apply throughout the flight envelope.
The complete aircraft armament has also been the subject of an intensive
test and development programme, and has involved considerable flight time on
the CF-100's, which have been used as test vehicles for the Sparrow weapon programme
at Malton, and at the U.S. Naval missile test centre at Point Mugu, California.