Hands-On Throttle and Stick
Other examples of easing a pilot’s workload include the essentials of weapons management and other requirements being incorporated on two controls so that combat pilots can keep their hands on the engine throttle control and the flight control stick. This arrangement of control buttons on the engine throttle and stick is known as HOTAS (see Figure 15.16). The essential control buttons are ergonomically located (Table 15.10). Most modern aircraft have buttons on the flight-control stick for communication, trimming, and so forth.
15.8.6 Voice-Operated Control
Voice-operated control (VOC) through voice recognition – still in the development stage – has been installed in advanced combat aircraft. All voice commands also are visually displayed and are very effective for a pilot operating under severe stress, especially if incapacitated by injury.
All of these advancements help a pilot but the systems still require the pilot’s familiarity. Pilots undergo extensive training and practice to gain familiarity with a mass of information in a rather claustrophobic presentation. A pilot’s workload is nearly an inhuman task. They are a special breed of personnel, rigorously trained for years to face the unknown in a life-or-death situation. It is the moral duty of any combat aircraft designer to enhance pilot survivability as best as possible in an integrated manner, embracing all types of technologies.
15.9 Aircraft Systems
Figure 2.1 shows the aircraft-design process in a systems approach. The definition of system is provided in Section 2.2. In that regard, an aircraft can be seen as a system composed of many subsystems. Chart 15.1 illustrates a typical top-level subsystem architecture of aircraft as a system. The subsystems can be designed in separate modules and then integrated with an aircraft.
Together, the system and subsystem mass is 10 to 12% of an aircraft’s MTOM. Typically, this amounts to nearly a quarter of the OEM. Practically all of the items in aircraft subsystems are bought-out. A better understanding of the subsystems improves weight and cost predictions. It is important for good information about subsystem items at the conceptual design stage for better weight and cost estimation. Designers are continually assessing cost versus performance of the subsystems to obtain the best value for the expense.
Aircraft as a System
Engine/Fuel Avionics Electrical Control Black Boxes Power Supply System Subsystems Subsystems
Chart 15.1. Aircraft as a system
Mechanical systems are connected by direct linkages and pneumatic and hydraulic means. Larger undercarriages are actuated hydraulically.