basic flying control system of the CF-105 is fully
powered. The surfaces are operated by dual hydraulic
jacks, each side of which is supplied by an independent
hydraulic system, so that in the event of an engine
failure, or the failure of one hydraulic power supply,
full control can be maintained.
There are three modes of control., manual, automatic, and emergency.
The manual and automatic modes are shown in Figs. 11(a) and 11(b). The pilot's
effort is converted into an electric signal by a stick force transducer at the
top of the control column. This signal is fed to the command servo through a
magnetic amplifier circuit. The command servo is an electro- hydraulic mechanism
which converts the amplified signal into movement of the linkage leading to the
control valves on the elevator jacks. The stick is mechanically connected to
the command servo output.
To provide some feel for the pilot on pulling " g," which
has to be artifically created with a fully powered system, a suitable signal
is channelled into the command servo from the aircraft performance sensors, the
signal being picked up electrically by the sensors and fed into an electronic
In the automatic mode the command servos are operated by signals
from the electronic black boxes of the integrated fire control and combat system.
Displacement of the stick takes place under these conditions, but can be over-ridden
if the pilot applies sufficient force.
Artificial stability augmentation is fed into the system in the following
manner. Unstable tendencies are picked up by sensors and adjustments are made
to the control system deflections by an independent servo, without reaction by
the command servo, so that the pilot is unaware of this correction.
problem of obtaining adequate natural aerodynamic
stability for an aircraft with the altitude and speed
range of the CF-105 was extremely difficult especially
in view of the low aspect ratio, and direction stability
in particular was a problem.
With the very thin fin required with a supersonic aircraft there
is a large reduction in fin effectiveness high indicated air speed, and the fin
lift falls off considerably, due to the lift slope curve decreasing with Mach
To achieve adequate directional stability over the complete flight
envelope we resorted to a synthetic "damping " system.
Longitudinal dynamic stability is satisfactory at low altitude, but
deteriorates with altitude in the normal way, and above 40,000 ft. the natural
damping required augmentation to make the aircraft an effective weapon launching
platform. The periods of oscillation are too short at high speeds for the pilot
to be able to control adequately the response to a gust.
We were left then with a necessity to augment longitudinal dynamic
stability at high altitudes for weapon launching, and to augment lateral static
and dynamic stability at a combination of high altitude and high speed to obtain
adequate controllability. We did consider very carefully ways and means to produce
better natural directional stability by, say, increasing the fin area some 50
to 60 per cent or putting underslung dorsal fins, i.e. dorsal fins, under the
fuselage, but the performance penalties of doing this were considered to be unacceptable.
For instance, if we increased the size the fin, it would geometrically reduce
the fin arm. It would also increase the fin weight and move the c.g. aft, which
again reduces the directional stability, and so we would be getting into an area
of diminishing returns.
It was therefore decided to obtain the required stability on all
axes by artificial means, and since failure of the artificial damping system
could be a problem in some areas of the flight envelope, it was also decided
that the system must be made with either the same or better reliability than
a standard power-operated system.
The highest possible degree of reliability and safety has been built
in to the damping system. For instantance on the yaw axis, which is the most
critical, there is complete duplication, including sensors, computers, and hydraulic
servos. The duplicate yaw axis system called the " emergency damping system." The
switch over from " normal " to " emergency " in case of a
detected malfunction is automatic. The main sensing element is an accelerometer
and, at low speed, a side-slip vane. It is therefore necessary for a double failure
to occur before the pilot is left without damping.
The damping system has proved to be quite a development problem,
and much of our flight testing so far has been concerned with sorting out the
system. However, we were quite aware at the outset that this would be the case
and, on the other side of the ledger, the flight testing has shown that our directional
stability is better than expected.
The system is designed to operate in conjunction with the automatic
flight control system, which in turn is integrated with, and is an essential
part of, the integrated interceptor electronic system. The main function of the
damping system is to dampen the short period oscillations about all three axes,
and to dampen the longitudinal long period oscillations.
The system provides turn co-ordination and side-slip minimisation
in operational manoeuvres up to 6g positive in pull-outs, and 4g positive in
turns. This protects the fin structure from excessive loading. The damping system
also provides for uncoordinated manoeuvres at the option of the pilot, which
is carried out by a cut-off switch on the rudder bar, and provides a means of
The emergency damping system, which is on the yaw axis only, provides
stability and damping of the Dutch Roll mode, and limits the side-slip to well
within the structural integrity limit on the fin, in pull-outs or 2g turn manoeuvres.
it is not possible, for security reasons, to describe
the integrated electronic system which is the brain
and nerve centre of the Arrow weapon system, I can
say that it is a very sophisticated system and provides
automatic flight control, airborne radar, telecommunications
and navigation, and special instrumentation and pilot
displays, and can operate in either fully automatic,
semiautomatic, or manual environment.
The system is carried mainly in the radar nose, with missile auxiliaries
housed in the armament bay.