AdvancedTopic 81 of 102Manufacturing, Robotics & Systems
Aircraft structures and propulsion
Light airframes and jet or propeller engines.
In depth
Airframes use semi-monocoque structures: skin, stringers, frames and ribs, spars; materials: aluminium alloys, titanium, composites. Design for strength, stiffness, fatigue and damage tolerance with high safety factors of 1.5. Propulsion: piston, turboprop, turbofan (bypass ratio), turbojet, ramjet; thrust T=ṁ(V_e-V₀).
Key points
- Wing box
- Fatigue and inspection
- Engine cycles (Brayton)
ExampleTurbofans with high bypass ratios give lower noise and fuel use.
What is Aircraft structures and propulsion?
Light airframes and jet or propeller engines.
Why is it important to understand aircraft structures and propulsion?
Aircraft structures must be light yet strong, and the choice of engine sets the efficiency and noise of the whole aircraft.
What is a turbofan?
A jet engine with a large fan that moves a large mass of air at low speed, which is quieter and more efficient than a simple turbojet.
Why is weight so important for aircraft?
Extra weight needs more lift and thrust and more fuel, so every kilogram saved reduces the fuel burned over the life of the aircraft.
How is Aircraft structures and propulsion used in practice?
Typical applications include designing a wing box to carry bending loads with minimal weight, selecting a turbofan engine for a short-haul airliner and choosing composite materials for a fuselage to reduce fuel use.
What should I learn before Aircraft structures and propulsion?
Study "Aerodynamics for aircraft" first (topic 80 of 102 in Manufacturing, Robotics & Systems). It covers the groundwork this topic builds on.
What are the key points of Aircraft structures and propulsion?
Wing box. Fatigue and inspection. Engine cycles (Brayton).
Can you give an example of Aircraft structures and propulsion?
Turbofans with high bypass ratios give lower noise and fuel use.
What comes after Aircraft structures and propulsion?
The next topic is "Flight stability and control", which builds directly on this one.
How difficult is Aircraft structures and propulsion?
It is classed as Advanced in Manufacturing, Robotics & Systems (topic 81 of 102). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Manufacturing, Robotics & Systems.