MECHANICAL Flashcards
What is a Monocoque Principle?
Strong but light structure
If equal pressure is applied to both ends, it’s quite difficult to break, however if the pressure is applied to the side, it is easier to break.
It relies entirely on the skin to resist the loads.
What is a semi monocoque principle?
It gives added strength to the airframe by constructing a skeletal framework, most especially to doors and windows.
A framework is used to support the skin
Describe Frames
Frames are the main structural components, which form the cross sectional shape of the airframe.
Used as mounting points for components.
In areas where the loads are high (engine & undercarriage), they are especially strengthened.
Describe Longerons
Longerons are the main longitudinal members of the airframe structure.
Used to tie frames together.
They form the basic shape of the airframe.
Also use as attachment pounts for components
Describe stringers
Stringers are added between frames where additional strength is required.
They are shorter than longerons, therefore they are lighter in weight.
Describe Bulkheads
They are frames that have been filled in with either a single or double sheet metal.
They provide protection for the aircrew by isolating equipment, e.g fireproof bulkhead between engine compartment and the cockpit.
Also provide strong attachment points for various types of equipment.
Describe skin
Skin is used to cover the semi monocoque construction which gives it added rigidity and a streamline shape.
Provides protection for aircrew, components and equipment.
Im areas of high loads, the skin may be made out of metal or composite materials
In areas of low load or no load, the skin may be made out of GRP (glass reinforced glass).
Describe stiffeners
Found in areas of the skin where its not supported by frames, longerons and stringers.
Angled in shape and made of metal.
Prevents the area of the skin panting (wobbling) during flight.
What is a gas turbine engine and its operating cycle?
It’s essentially an engine which forces air rearwards to produce thrust.the efficient operating cycle of a gas turbine is a smooth and continous rotational.
1) Induction
2) Compression
3) Combustion
4) Exhaust
What happens to the gas turbine engine’s components when it rotates at high speeds?
It generates a great deal of heat and so it expands.
What is the purpose of the engine lubricarion system?
1) dissipate heat
2) minimise wear
3) reduce friction
4) prevent seizing
What is the main rotor head?
The rotor head is attached to the main rotor drive shaft.
Supports the main rotor blades.
Transmits the control movements to the blades.
What are the 2 types of aircraft fuel system?
1) Airframe fuel system - store and deliver fuel to the aircraft engines.
2) Enginer fuel system - supply fuel to the combustion chamber.
What is the purpose of the fuel content system?
To continously indicate to the pilot the fuel state of the aircraft.
Fuel is normally carried in various tanks around the aircraft in groups, each group will have its own fuel content gauge.
The fuel is measured by weight not volume so that the pilot can figure out the amount of stores and armament that can be carried and also the endurance of the flight.
How do you transmit movements from the pilots control to the flight controls?
A control run is used which can be completely mechanical and uses pulleys, cables and push rods.
Or it can be electrical or hydraulics.
