5.1.1 Craft should be provided with means for
directional control of adequate strength and suitable design to enable
the craft's heading and direction of travel to be effectively controlled
without undue physical effort at all speeds and in all conditions
for which the craft is to be certificated.
5.1.2 Directional control may be achieved by means
of air or water rudders, foils, flaps, steerable propellers or jets,
yaw control ports or side thrusters, differential propulsive thrust,
variable geometry of the craft or its lift system components or by
a combination of these devices.
5.1.3 For the purpose of this chapter, a directional
control system includes any steering device or devices, any mechanical
linkages and all power or manual devices, controls and actuating systems.
5.1.4 Attention is drawn to the possibility of
interaction between directional control systems and stabilization
systems. Where such interaction occurs or where dual purpose components
are fitted, the requirements of Chapters 15 and 16 are also to be complied with as applicable.
5.1.5 For the purposes of this and other chapters,
unless expressly provided otherwise the following definitions apply:
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(a) "Foil" means a profiled plate at which lift
is generated when the craft is under way.
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(b) "Flap" means an element of the trailing edge
of the foil with the help of which foil lift is controlled.
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(c) "Side thrusting ports" are discrete controllable
apertures in the cushion supply ducting or skirt system which enable
jet reaction forces to be generated, to assist in controlling an air-cushion
vehicle.