Lesson 7: Miscellaneous Components of an Aircraft

Miscellaneous Components of an Airplane


Miscellaneous Components of an Aircraft






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Click here for the previous lessons, to learn about: Principle of Airframe; Principles of Aerodynamics; Airfoil Characteristics; Primary Flight Control Surfaces; Description and Operation of Helicopter; Miscellaneous Components of an Aircraft…

 

Key points:

Miscellaneous Components, Nacelle Structural Components, Wing Structural Components, Types of Wing Construction, Semi-Cantilever wing, Cantilever wing,Structural members, Spars, Ribs, Stringers, Stiffeners.

Nacelle Structural Components,


Nacelle of aircraft


The nacelle is what houses or encloses the engine. This helps to streamline engines during flight. On most heavy aircraft the engines are located under the wings, therefore they need some form of streamlining. Most tactical aircraft usually have their engines enclosed in the fuselage.

Wing Structural Components,  

Wings of an aircraft are designed to produce a lifting force when moved through the air. The airflow must be directed over and under the wing to create lift. Due to the curved surface the velocity of the air moving over the top of the wing is much greater than the air moving along the bottom of the wing.

 Aircraft wing design depends on a number of factors: size, weight, use of the aircraft, desired landing speed, and rate of climb. Larger compartments of the wings may contain fuel tanks. Wings also have flight controls ailerons that are attached by hinges to the trailing edge to control the roll movement of the aircraft.

Types of Wing Construction,  

There are two basic types of wing construction found on today’s aircraft, semi cantilever and cantilever.


Semi-Cantilever wing


• Semi-Cantilever wing,  

A semi-cantilever wing is a type of construction that uses some type of external bracing usually a strut. This strut can be one piece or it may be of a triangular construction. The strut is usually attached to the underside of the wing and to a reinforced section of the fuselage. Some privately owned aircraft use this.

• Cantilever wing,

Cantilever wing construction is built in such a way that no external bracing is required. This means the wing is assembled so that it carries all the weight of the aircraft. The cantilever type construction is the most commonly used on today’s military aircraft.

 

STRUCTURAL MEMBERS.

As we stated earlier, the lifting force applied to the wings, and the load that is carried inside the wings, require the wing structure to be very strong. Wings are subjected to stress, such as twisting and bending. These stresses are resisted by a truss construction of the wing itself. Aircraft wings have structural members called spars, stringers, stiffeners and ribs.

SPARS.

SPARS structure


Spars are the main structural units of the wing.

They extend from the wing root to the wing tip. They must have the ability to resist twisting and bending. This is why there is no external bracing on the full cantilever constructed wing.

Spars are the longest and strongest members of the wing.


RIBS.

Notice how the ribs are fastened to the spars and stringers to give cross sectional strength and shape to the wing. They also transfer the wing load from the covering skin to the spar. To reduce the weight of a solid rib, lightening holes are punched or cut in areas of low stress.


Stringers Wing

 

Stringers Wing

The stringers may be as long as the spars and are installed parallel to the spars. They are lighter in weight than the spars. Stringers are used to add strength to the frame and for attaching the skin. See figure 1-35, stringers are colored blue for identification.

Stiffeners.

Stiffeners


 Stiffeners are used to give more support in critical areas such as between the ribs. Some stiffeners are made as a part of the rib while others can be removed so work can be done. Stiffeners are also used to support the skin and other units.

WING SKIN. Wing skin is either aluminum alloy covering or honeycomb construction. Some aircraft wings may be a combination of both. The aluminum alloy cover used on the wings is similar to that used on the fuselage.