Aerospace Engineering Mock Interview Questions & Practice

What is drag, and what are its two main components in aerodynamics?

Key points to cover:

• The aerodynamic force acting opposite to the direction of motion
• Parasitic drag: from friction and form, largely independent of lift
• Induced drag: a byproduct of generating lift

What is the Bernoulli principle-based explanation of lift generation, and what is one limitation of relying on it alone?

Key points to cover:

• Air flows faster over the curved upper surface (lower pressure)
• Than the flatter lower surface (higher pressure), creating net upward force
• Doesn't fully explain symmetric airfoils or inverted flight alone

What is the rudder, and what axis of rotation does it primarily control?

Key points to cover:

• A control surface on the vertical tail (fin)
• Primarily controls yaw about the aircraft's vertical axis
• Also used to coordinate turns and counteract adverse yaw

What is the basic function of the turbine section in a jet engine, and what powers it?

Key points to cover:

• Extracts energy from hot, high-pressure combustion gases
• To drive the compressor (and possibly a fan/propeller)
• Powered by the expanding combustion gases passing through it

What is specific impulse, and what does it indicate about a rocket engine's efficiency?

Key points to cover:

• A measure of how effectively a rocket engine uses its propellant
• Higher specific impulse indicates a more efficient engine
• Requires less propellant for a given thrust/velocity change

What is a shock wave, and under what flow condition does it typically form?

Key points to cover:

• An abrupt, nearly discontinuous change in flow properties
• Pressure, density, temperature, velocity
• Typically forms around objects moving at supersonic speeds

State the Second Law of Thermodynamics and explain its significance.

Key points to cover:

• Heat cannot spontaneously flow from a colder to a hotter body
• Or: entropy of an isolated system never decreases
• Establishes the direction of natural processes

What is the Otto cycle, and what type of engine does it model?

Key points to cover:

• Two isentropic and two constant-volume processes
• Models a spark-ignition (petrol) internal combustion engine
• Notes the idealized nature of the cycle

What is thermal conductivity, and what does it indicate about a material?

Key points to cover:

• A material property indicating how well it conducts heat
• Heat flux per unit temperature gradient
• Higher value means the material transfers heat more readily

What is hydrostatic pressure, and how does it vary with depth in a fluid?

Key points to cover:

• Pressure exerted by a fluid at rest due to the weight of fluid above
• Increases linearly with depth
• Proportional to fluid density, gravitational acceleration, and depth

What is the Reynolds number, and what does it indicate about a flow?

Key points to cover:

• A dimensionless ratio of inertial forces to viscous forces
• Used to predict whether a flow will be laminar or turbulent
• With a critical value marking the transition

What is cavitation in a centrifugal pump, and what conditions promote it?

Key points to cover:

• Local pressure inside the pump drops below the fluid's vapor pressure
• Vapor bubbles form and then collapse violently
• Promoted by insufficient suction head or excessive pump speed

What is Hooke's Law, and within what range of deformation does it apply?

Key points to cover:

• Stress is directly proportional to strain
• Proportionality constant is the material's modulus of elasticity
• Applies only within the elastic limit

What is a bending moment diagram, and what information does it provide?

Key points to cover:

• A graphical representation of bending moment along a beam
• Provides the location and magnitude of maximum bending stress
• Essential for beam design

What is stress concentration, and what commonly causes it in a machine component?

Key points to cover:

• A localized increase in stress at a geometric discontinuity
• Well above the average stress in the surrounding material
• Commonly caused by abrupt changes in cross-section or geometry

What is the difference between hot working and cold working in metal forming processes?

Key points to cover:

• Hot working: above the material's recrystallization temperature
• Allows significant deformation without work hardening
• Cold working: below recrystallization, results in work hardening

What is cutting speed in machining, and how does it affect tool life and surface finish?

Key points to cover:

• The relative velocity between cutting tool and workpiece surface
• Higher speeds increase material removal rate
• Can reduce tool life due to increased heat generation

What is the difference between MIG (GMAW) and TIG (GTAW) welding?

Key points to cover:

• MIG uses a continuously fed consumable wire electrode
• Plus a shielding gas
• TIG uses a non-consumable tungsten electrode with a separate filler rod