Aircraft Engines Flashcards
What are the three important differences between aircraft piston and automobile engines?
Air cooling
Dual Ignition
Fuel/Air Miture Control
What are the ‘Four Strokes’ of a piston engine?
Induction
Compression
Power
Exhaust
What are the ‘Five Events’ associated with a Piston Engine?
Induction
Compression
Ignition
Power
Exhaust
What is the Carburetor?
A device which provides a suitable mixture of fuel and air to the cylinder for ignition.
How does air draw fuel through the carburetor?
Air flowing through the carburetor draws fuel from a reservoir through a ‘Venturi’ Tube.
What three things happen when air passes through a Venturi in a piston engine?
The Air Accelerates
There is a drop in pressure
This causes fuel to be drawn through the main jet, allowing it to mix with the air in the Venturi
What is a problem with Venturi type carburetors?
They are prone to Icing.
Outline two reasons for Carb Icing.
The pressure drop in the Venturi is accompanied by an instant drop in temperature.
When fuel changes state from liquid to vapour, latent head is absorbed, cooling the air further.
How much can the temperature in a carburetor drop?
As a result of the ‘double cooling’ effect, the air temperature in the carburetor may drop by as much as 20 degrees.
If there is more water vapour present in the air, will the risk of carb icing be greater or lesser?
Greater
How can pilots avoid carb heating?
Avoid areas where moisture is present and icing likely.
Regular application of carb heat.
What system is used to overcome problems associated with carb icing?
Fuel Injection Systems
Why are most aircraft piston engines air cooled?
Lighter and Safer
What is the difference between geometric and effective pitch known as?
Slip
Define blade pitch
The angle made by the chord of the blade and its plane of rotation
What is the difference between Coarse pitch and Fine pitch?
A coarse pitch will take a bigger bite of air and move the aircraft farther forward in one rotation than a fine pitch.
Which propeller pitch do you want at takeoff and cruise?
Takeoff - Fine
Cruise - Coarse
What are the three types of fixed pitch propeller?
Coarse
Fine
Standard
What pitch propeller do most light aircraft use?
Standard pitch propeller
How is a variable pitch propeller useful if the engine shuts down?
Variable pitch propellers can be rotated to be parallel to the airflow and reduce drag. This is known as Feathering.
What is another name for variable pitch propeller?
Constant Speed Propeller
What are the advantages of a piston/propeller?
Simpler design reducing costs
More efficient at low speeds and low altitudes
Faster initial acceleration than jet engine
Immediate reaction to pilot input
Propwash over wings generates lift and aids controllability
What is a disadvantage of a piston/propeller?
As the propeller tips approach supersonic speeds, their aerodynamic efficiency decreases.
What is Newtons 2nd Law?
F = MA
What are the basic parts of the jet engine?
Air Intake
Compressor
Combustion
Turbine
Exhaust
What are some different types of Jet Engine?
Turbojet
High/Low Bypass Turbofan
Turboprop
Ramjet
Scramjet
Turboshaft (Helicopters)
What are the two types of basic jet engine?
Centrifugal Compressor
Axial Compressor
