Chapter 6: Powerplants (Aircraft Engines)

A set of practice flashcards covering piston engines, jet engines, turbofan and turboprop concepts, turboshafts, engine layouts, and core thrust principles from the chapter.

What is the general purpose of an aircraft powerplant?

An engine that produces power to propel the aircraft by converting chemical energy (fuel) into mechanical energy to drive a propeller or create thrust.

What basic principle does a piston (reciprocating) engine operate on?

It converts chemical energy from fuel into mechanical energy through combustion in cylinders, driving pistons that turn a crankshaft to rotate the propeller.

In a piston engine, what component connects the piston to the propeller?

The crankshaft.

What is thrust in a piston-engine aircraft and how is it produced?

A forward force produced by the propeller as the crankshaft rotates, driven by the piston's back-and-forth motion.

How many cylinders do typical small aircraft piston engines have?

Usually four or six cylinders.

Name four common cylinder layouts used in aircraft piston engines.

Radial, inline upright, inline inverted, and horizontally-opposed.

What is a key cooling advantage of radial engine layouts?

Good cooling because each cylinder has access to the cooler outside air (air-cooling).

What is a major downside of radial cylinder arrangement?

Large frontal area, which increases drag and makes streamlining difficult.

What is the inline upright cylinder arrangement?

Cylinders arranged one behind the other above the crankshaft.

What is the inline inverted cylinder arrangement?

Cylinders arranged one behind the other below the crankshaft.

What is a characteristic of inline cylinder engines in terms of power-to-weight and cooling?

They tend to have a lower power-to-weight ratio, and the rear cylinders have poorer cooling due to limited access to outside air.

What is a horizontally-opposed (boxer) engine?

An engine with an even number of cylinders arranged opposite each other around the crankshaft, offering a small frontal area and good air cooling.

Which engine type has powered aircraft for over 100 years and remains the main power source for many today?

The piston (reciprocating) engine.

Which engine type is typically used on large aircraft and can produce enormous power?

Jet engine (gas turbine).

What are the basic components of a turbojet engine?

Intake, compressor, combustion chamber, turbine, and exhaust.

How does a jet engine produce thrust?

By expelling high-velocity exhaust rearward; Newton’s third law states action equals reaction, producing forward thrust.

What distinguishes a turbofan from a turbojet?

Turbofan has a large front fan with bypass air that flows around the core, increasing thrust and reducing noise.

What is bypass air in a turbofan engine?

Air that passes around the engine core rather than through it, contributing to thrust and noise reduction.

What is a turboprop engine and how does it move the aircraft?

A turbine drives a propeller via a gearbox; propulsion comes mainly from the propeller, not the exhaust.

What is a back-to-front turboprop configuration and its advantage?

Air is directed to the back of the engine and then forward to the propeller, resulting in a compact engine and short shaft.

What is a turboshaft engine and where is it mainly used?

A turbine engine that powers helicopter rotors via a shaft (turboshaft).

Why is reliability emphasized for aircraft powerplants?

Modern powerplants are highly reliable, but engine failure in flight can have very serious consequences.

Which type of engine is noted as still being the main power source for many aircraft today?

The piston (reciprocating) engine.

What is the relationship between power requirements and aircraft size?

Power requirements increase with aircraft size; larger or heavier aircraft require larger engines or multiple engines.