Aircraft Powerplant Outer Structures

 Aircraft Powerplant Outer Structures

               Aircraft powerplants produces the source of thrust to move the aircraft through the air, at the same time they are also the source of vibration, heat and drag forces. Powerplant Structures includes both the propeller and Engine work in combination to produce thrust. Engine provides the source of power to rotate the propeller.  Propeller is mounted at the front of the engine converts the rotatory force into Thrust in the engine.

Powerplant Outer Structures components

Nacelles

Nacelles encloses the engine provide the streamline flow (uniform flow) of air over the outer surface of the engine to improve the aerodynamics of the aircraft. Protect the engine and its components during flight. Allow the proper flow air to engine for cooling and combustion.

   

Fire walls

Firewalls are normally located near to the engine compartment. Engine, Auxiliary power units, combustion chamber and turbine produces tremendous amount of heat which affect other aircraft component and it functionality, to protect other aircraft component from this heat effect sections of the turbine engine must be isolated from the remainder of the aircraft by means of firewalls. Firewall is used to protect the nacelle strut and systems from the exposure.

Engine Mount

Engine mount is frame structures that support the engine and connect it to the fuselage. Which are designed to distribute the weight of the engine and distribute torque and vibration generate from the engine.

Cowlings and Fairings

Cowlings and Fairings both are similar, which are removable covering for covering the portions of the airplane (Engine, Mounts and other engine components). Design to provide uniform flow of air over the engine surface improve the aerodynamics of the aircraft.

 

 

 

Aircraft engine Firewalls

                      Firewalls are normally located near to the engine compartment.Engine, Auxiliary power units, combustion chamber and turbine produces tremendous amount of heat which affect other aircraft component and it functionality, to protect other aircraft component from this heat effect sections of the turbine engine must be isolated from the remainder of the aircraft by means of firewalls. Firewall is used to protect the nacelle strut and systems from the exposure.

Design

Firewall should design in such a manner that no hazardous quality of air, fluids, or flame can pass from the compartment to other portions of the aircraft.

To be easy access to repair and installation because they normally located in the engine compartment, later there may be need to remove and replace the engine or other components.

 

Material

Material used should provide protection against both heat and corrosion, Base on which following materials been used

• Stainless steel
• Titanium
• Copper or steel based alloy
• Terne plate

Engine Mounts

        Engine mount is frame structures that support the engine and connect it to the fuselage. Which are designed to distribute the weight of the engine and distribute torque and vibration generated by the engine, Vibration that originated in the reciprocating engine are transmitted through the engine mount to the airplane structure for such mounts engine must be attached with some sort of rubber bushing between the engine and mount attachment to control these vibration. 

Maximum vibration from the engines are controlled when tightened so that the engines move slightly with respect to the rubber bushing which limits in a torsion during operating condition, But at the same time if the bolt are too tight the mount structure will tend to vibrate along engine which would transmitted to Airplane wing and fuselage structure which would be undesirable. To avoid over tighten of bolts the technicians should always refer to the manufacture’s service before tightening such bolts.

Material Used

Engine Mount should withstand waste heat released from the engine and ability to carry heavy engines at temperature of up to 500 ⁰ C base on the requirement three alloys types are used

Nickel-Based alloys: Can withstand high extreme temperature

Titanium alloys:  half the weight of steel, used in the place where the light weight material is needed

Steel alloys: Use at the place where high strength needed at very low temperature.

Based On Aircraft

Light Aircraft - Engine mounts made of welded-steel tubing or aluminium alloy sheet metal.

Turbine powered Aircraft - Engine mounts made of forged metal bolted to airframe.

Design and Types

Engine mounts vary widely in appearance and Construction, but basic features of construction are same. Each aircraft differs from other, heat released from the engine differs base on this criteria each new engine mount should also be unique and to be designed that engine and its accessories should be easy for inspection and maintenance.

Most aircraft which exactly from same manufacturer of the engine shall uses the same mount.

Types

Dynafocal engine mount

Protects the vibration and motion from the engine to be transmitted to aircraft structure, Fixing is based on the centre of gravity of the engine.

Shape: Ring-like

Bolt Point: Usually Four points

 

Conical mount

Conical mount are attached parallel to the firewalls, easy for installation simple and easy to fix to aircraft.

Bolt Point: Usually Four points

Drawbacks: Vibration and Torque are transmitted through the Frames

 

Bed mount

Bed mount are attached under the crankcase, which totally differs from the other type of mount (Conical mount and Dynafocal engine mount), Designed for perfect fitting of the engine avoid transmit vibration to the structure

Bolt Point: Usually Four points in modern aircraft

Vibration is more Danger to Aircraft leads to failure, Engine Mount Helps to avoid some sort of Vibration to be transmitted to Aircraft Structure.

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Introduction to Helicopter

Introduction to Helicopter

                 Helicopter is a type of Rotary wing Aircraft that uses rotating wings to provide lift. Rotor blades rotate about a vertical axis generating lift to move the Helicopter upward along with the help of controls and propulsion. Lift is generated by the relative motion of wing surface with respect to the air.

The helicopter can do vertical flight (vertical take-off and landing) where rotor must efficiently supply thrust force to support to support helicopter weight.

Helicopter has two Rotor Blades

Main Rotor Blade

Main rotor is mounted on a vertical mast head over the top of the helicopter connected with a driven shaft and gear box (to control the speed of the rotating blade).

Tail Rotor Blade

Tail rotor is a small rotor mounted at the tail of the helicopter, position and distance from the center of gravity of helicopter to generate needed thrust in same direction with respect to the main rotor rotates. Connected with the shaft powered from main transmission and has gearbox.

Main use of the tail rotor is to counter the torque, In simple words when the main rotor rotates in clockwise direction the helicopter fuselage structure will rotate in anticlockwise direction if the tail rotor is not mounted, So tail rotor is to counter the torque, and maintain the helicopter fuselage structure stable according to the direction it moves or fly.

Single main rotor and tail rotor configuration combating used to provide the torque balance (yaw control) to the helicopter.

 

Use of helicopters

Helicopters are used for both military and civil purpose:

Military

Search and Rescue Operations

Anti-submarine activity

Air observation

Direct support of infantry, These Helicopters are provided with armaments such as missiles machine guns etc.

Civil

Emergency rescue and medical aid purpose

Agricultural operations

Forest patrolling, forest fire extinguishing

Patrolling of highways, oil pipes lines, Electrical supply lines

Commercial use