Aircraft Engines Flashcards
3 differences of Piston engines to automobile engines? (3)
Air cooled
Dual Ignition System
Fuel / Air mix
How many operations take place in the **4-stroke engine? (1)
5
The 5 operations of the 4-stroke engine? (5)
Intake
Compression
Power - Controlled explosion
Power - Burns & Expands
Exhaust
What is a Carburetor? (1)
Provides a suitable mixture of fuel / air to the cylinder for ignition
Where does fuel flow from during air flow? (1)
Venturi tube
What three processes happen through the Venturi section when air passes? (3)
Air accelerates
Drop in pressure (Benoulli’s principle)
Fuel draws through the main jet where it mixes with air in the Venturi
What problem are Carburetors prone to? (1)
Icing
What causes Icing with Carburetors? (2)
Venturi > Air accelerates > Pressure drops from an instant drop in air Temperature
Fuel changes from liquid to vapour > Latent heat is required > energy taken from air and metal of the Carburetor > Cools air further
How much can double cooling effect the air temperature to drop by? (1)
20° C
Two preventions of Carburetor icing? (2)
Avoiding areas with moisture present & likely icing
Regular application of Carburetor heat
What system is installed to overcome Carburetor icing? (1)
Fuel injection systems > Atomised fuel delivery to the cylinders
What is propeller ‘pitch’?
The difference between ** geometric** pitch of the prop AND its effective pitch
Geometric pitch: theoretical distance of a prop should advance in 1 revolution at given blade angle
Effective pitch: distance it actually advances
Name three fixed pitch propeller types and their uses (3)
Fine pitch - More power available on take-off
Coarse pitch - For speed cruising altitude
Standard pitch - Gives efficiency over a range of power settings
What is reverse pitch and what does it do? (2)
Reverses the direction of thrust
reduces the landing run & saves wear on tyre / brakes
What is another name for a variable pitch ‘prop’ ? (1)
Feathering - reduces drag if engine fails / shut down
