instrument needed being displayed automatically as a colour picture on the screen.The crew will be able to operate every control in the cockpit just by clicking a fewbuttons on his control column, never needing to take his hands off the controlcolumn and throttles.12.Helmet-mounted sights are already being used, especially in helicopters.The pilot looks through a special visor goggles, which have a weapon sight projectedon them. The weapon can be aimed at the target just by the pilot turning his headso that the sight points at the target. This system is likely to be used more andmore, because it is fast and easy to operate.13.The biggest problem in building an aircraft which can turn very tightly in adogfight is the ability of the pilot to withstand the g-loads. Tilting the seat back andraising the pilot’s legs make him or her much more able to fly in high-g turns withoutblacking out, but the seat needs to be brought back upright if the crew need toeject. This can be done very quickly, in the time that is needed to jettison the canopy.This illustrates the limiting effects the human body and mind have on futuredevelopment of aircraft.33.4.12-8CHAPTER 12Helmet mounted sightG-loads
THE COCKPIT33.4.12-9Self Assessment Questions1. What is an attitude indicator?2. What is an altimeter used for?3. What is a Vertical Speed Indicator used for?Do not mark the paper inany way - write youranswers on a separatepiece of paper, in the formof a sentence.
33.4.1a NOTESCHAPTER 1CHAPTER 1AIRFRAME DESIGN FEATURES1.The change in aircraft design from biplanes to monolane has been brought about by theever-increasing need to fly at higher speeds. During the biplane age, only low powered aero-engines were built, and as the biplane could not fly much beyond w50 mph, a light-weight structure,braced externally with struts and wires, was suitable. As the action of the airflow (air loads) on theaircraft was low, doped fabric was satisfactory for covering the wings, fuselage, etc. The internalstrength members (spars) of the biplane wing are maintained parallel to one another and are ofconstant thickness throughout their length. Owing to the external bracing, which takes most of thelift forces, the spars are subject to reduced bending loads and great depth in this is not necessary.2.The braced monoplane design is used mainly for small high wing aircraft. The bracingstruts relieve the spars of much of the life forces and a form of wing construction similar to thebiplane is used. To resist the greater bending loads, the spars are deeper than those of thebiplane. In this type of design, frontal area and relative drag are much less than the biplane ofcorresponding span.3.Most modern aircraft are cantilever monoplanes ie the wings are supported at one end onlyand decrease in thickness both in plan and elevation towards the wing tip. Air loads increase withthe square of the airspeed and at 615 mph are six times as great as at the 250 mph achieved bythe fastest biplane. A fabric wing covering is therefore no longer suitable and a heavier and morerigid material, such as plywood or thin metal must be used ie high speed cantilever monoplanesare of stressed skin construction.
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- Summer '18