MEGA int. Study Set

Why SpaceX?

Because of its mission to make humanity multi-planetary, focus on innovation, rapid iteration, and pushing aerospace boundaries.

Do you have any questions for us?

Ask about team structure, specific projects, company culture, or challenges you might face in the role.

How would you try to solve a problem in an area you had never worked in?

Break problem into fundamentals, research analogous systems, consult experts, hypothesize solutions, test iteratively.

Tell me how you got interested in space?

Share personal story about curiosity, projects, research, or early experiences that sparked interest in aerospace.

Do you know SpaceX’s stated Mission?

To make humanity multi-planetary and enable life on Mars.

Tell me about your experience?

Walk through relevant projects, internships, technical achievements, and skills pertinent to the role.

What are you looking forward to learning at SpaceX?

Exposure to cutting-edge engineering, high-performance systems, and new problem-solving techniques.

What are your greatest strengths and weaknesses?

Strengths: teamwork, problem-solving, initiative. Weaknesses: acknowledge honestly and show steps to improve.

What is your work style?

Collaborative, hands-on, data-driven, adaptable, and proactive.

There are many other new startups. Why SpaceX?

Focus on mission, engineering challenge, culture of rapid iteration, and opportunity to contribute to high-impact aerospace projects.

Run me through your resume.

Brief, chronological walkthrough highlighting relevant projects, achievements, and skills.

Describe the most impressive technical project you've accomplished.

Explain the project context, your role, challenges, results, and lessons learned.

One problem or challenge you faced.

Describe the challenge, your approach, and how you resolved it.

Describe an experience that shows how you’ve overcome an obstacle.

Show problem-solving, persistence, and learning from difficulties.

Choose one thing on your resume to talk about.

Explain the project, your contribution, results, and technical insights.

What qualities do you have that make you helpful to this job?

Reliability, collaboration, initiative, technical expertise, communication, adaptability.

Explain a technical problem you’ve solved.

Provide context, method, analysis, solution, and impact.

What is your proudest achievement?

Highlight a technically significant accomplishment demonstrating skill, leadership, or problem-solving.

What sort of requirements did you follow or create?

Explain engineering standards, design requirements, or testing protocols used in a project.

What problems did you face in a project?

Describe technical, logistical, or team-related challenges and how they were handled.

What is your biggest mistake?

Briefly describe, focus on lessons learned and corrective actions.

Explain UNC vs. UNF Threads.

UNC = coarse thread, UNF = fine thread; used for different load and fit requirements.

Which way does a hotdog split?

Along the seam, following the weakest path.

Tape measure question.

Depends on specifics; usually tests reasoning about units and accuracy.

Bowling ball/rock on lake.

Analyzes center of mass, friction, and torque effects on rolling/sliding objects.

If you were in a desert in a car would you drive at night or in the morning?

Drive during cooler times (morning/night) to avoid overheating and reduce fuel consumption.

Steel vs. Aluminum.

Steel: stronger, heavier, more ductile; Aluminum: lighter, lower density, less strong.

What are the forces on a box traveling through the air?

Drag, lift (if shaped to generate), weight, inertial forces, and moments if rotating.

How would you design a hammock?

Consider load distribution, attachment points, material strength, and safety factor.

If you had to get over from one tall building to another carrying equipment, what would you bring and how would you set it up?

Plan pulley/rope systems, harness, anchor points, and ensure safe load transfer.

How would you determine the force caused by flow through a control volume?

Use momentum balance, control volume analysis, and sum of forces = rate of change of momentum.

What is the lift equation?

L = 0.5 * ρ * V^2 * S * CL.

Hoop stress and its derivation?

σθ = P * r / t; derived from equilibrium of a thin-walled pressure vessel cylinder.

Design three systems to lift a horizontal rocket to vertical.

Cradle with winch, tilting gantry, hydraulic lift arms; each supports weight and maintains stability.

Tip load on cantilever beam: where does it break?

If welded: max stress at fixed end; depends on weld type and stress concentration.

Three parameters to analyze a column under buckling load?

Length, cross-sectional moment of inertia, material modulus of elasticity.

Design for electrical harness protection from falling objects.

Use shielding, conduit, clamps, impact-absorbing covers.

Cantilever beam with mass m and uniform load w: moment at L/4?

M(L/4) = wL^2(1/8) + mgL/4 (superposition principle).

What is Reynolds number?

Re = ρ V L / μ, determines laminar or turbulent flow.

If a heavy object moves fast how do you slow it safely?

Use gradual deceleration, damping, energy-absorbing structures, or friction control.

Spot welding nickel touching copper: what happens?

High current causes rapid heating; dissimilar metals may form intermetallics, high localized stress.

Beam attached to wall, other end free, force applied: where breaks?

Max bending moment at fixed end; stress depends on load and geometry.

How do you size a relief valve?

Based on maximum expected flow, system pressure, and safety factor.

How do you size a main valve?

Match max flow requirements, consider pressure drop, valve characteristics, and safety margins.

Rank gate, needle, and butterfly valves in flow resistance.

Gate < Butterfly < Needle (low to high).

Analog clock at 3:15: difference between hour and minute hands?

7.5 hours or 97.5 degrees; use relative angle formula.

Water flow along 100 ft pipe: how to analyze pressure drop?

Apply Darcy-Weisbach, friction factor, pipe length/diameter, flow rate, fluid properties.

Difference between compressible and incompressible flow?

Compressible: density varies with pressure/temp; incompressible: density constant.

Half the temperature and double the volume of ideal gas: what happens to pressure?

Pressure halves (PV=nRT), P ∝ T/V.

Three modes of heat transfer?

Conduction, convection, radiation.

Find heat transfer coefficient in pipe with forced convection?

Use Nusselt number correlations based on geometry and Re, Nu = h L / k.

Explain CdA equation.

If you double mdot, ΔP quadruples (ΔP ∝ (mdot / CdA)^2).

Bernoulli’s equation?

P + 0.5 ρ V^2 + ρ g h = constant along a streamline.

Shock wave effects: total/static pressure, density, temperature?

Static pressure, density, temperature increase; total pressure decreases; flow decelerates.

Pressure ratio upstream/downstream for choked flow?

For γ=1.4, P2/P1 ≈ 0.528.

Incompressible flow: double mass flow rate, what happens to pressure drop?

ΔP quadruples (ΔP ∝ mdot^2) assuming same pipe geometry.

Type of heat transfer in liquid engine?

Convection from fluid, conduction in walls, some radiation in combustion chamber.

Specific impulse?

Thrust per unit weight flow of propellant, Isp = F / (mdot * g0).

C-star?

Characteristic exhaust velocity, relates chamber conditions to throat flow(c* = Pc*At/m shows the chamber velocity based on throat Area independent of the exit nozzle)

C-star efficiency?

Actual C-star / ideal C-star.

Fill time requirement for LOX tank: where to start?

Check lines, valves, pump capacities, and flow restrictions.

Fill time too high, hardware built: how to lower?

Increase pressure, change flow path, use parallel lines, minimize restrictions.

Pros and cons of helium vs nitrogen for tank pressurization?

Helium: inert, low density, expensive. Nitrogen: cheap, denser, less compressible, can freeze.(helium = less mass for same presure)

Process for sizing vehicle plumbing?

Determine flow rates, pressures, line lengths, valve sizing, pump requirements, safety margins.

Water tank with pipe and valve: what affects mass flow rate?

Pressure, pipe diameter, fluid properties, valve opening, friction losses.

Two tanks with same volume, exit pipe different diameter: compare mass flow rates?

Smaller diameter: higher velocity, higher friction; depends on downstream constraints.(DA is greater for a bigger change)

Single tank not backfilled: flowrate over time?

Flow decreases as head decreases.

Ways to increase mass flow rate in a system?

Larger diameter, higher pressure, shorter pipes, reduce friction, parallel lines.

Choked flow: difference in flow rate between two plumbing sets?

Limited by sonic velocity at throat; upstream pressure and area dominate.

Cantilever beam fail if loaded one end and simply supported other end?

Max bending at fixed end; failure depends on material and cross-section.

Ways a bolt can fail?

Tensile, shear, fatigue, thread stripping, bending.

First thing to consider when designing for manufacturability?

Minimize complexity, tolerances, cost, ease of assembly, standard parts.

Analyze bridge for sturdiness?

Calculate max load, bending moments, deflection, material strength, safety factor.

Bike chain vs ground speed?

Bike chain moves faster than ground due to gear ratios.

Walk 1 mile north, 1 mile east, 1 mile south, back to start: where?

North pole or specific south pole circle.

Hot coffee, room temp air, small creamer: when to add creamer to cool fastest?

Immediately, to increase heat transfer rate.

Considerations for shipping a rocket across country?

Weight, size, center of mass, support, vibration, regulations.

Center of pressure on a rocket: where and why?

Below center of gravity for stability.

Design system to deliver propellant to rocket on pad?

Pumps, valves, lines, sensors, safety reliefs, support structure.

Determine thrust from spherical pressure vessel with circular exhaust hole?

Momentum balance, pressure*area, consider gas expansion.

What type of beam to carry load and why?

Choose based on bending, shear, weight, and stiffness requirements.

Beam material choice?

Depends on strength, weight, cost, corrosion, manufacturability.

Flagpost with vertical load: expected failure mode?

Compression, buckling, or bending depending on cross-section.

Beam attached to wall on two ends: failure mode?

Max bending at midspan.

Beam attached to wall on one end: failure mode?

Max bending at fixed end.

Beam with rollers instead of fixed: failure mode change?

Yes, boundary condition changes: 0 if one or both end rollers; if at center max bending at center

Radiation most effective?

High temperature, vacuum, or line-of-sight applications.

How are beams manufactured?

Casting, extrusion, rolling, machining, welding.

Bolt torque spec: what info needed?

Material, size, grade, lubrication, desired preload.

Relation between stress and strain?

Stress = E * strain in elastic region; slope of linear portion of stress-strain curve.

Difference between strength and toughness?

Strength = max stress; toughness = energy absorbed before fracture.

Select material for rectangular simply-supported beam: cost vs strength?

Choose balance of strength, stiffness, weight, and cost (aluminum or steel often).

How does a can opener work?

Mechanical leverage to pierce and rotate lid; cutting edge shears metal.

What makes metal oxidize and how to prevent?

Exposure to oxygen/water; prevent with coatings, anodizing, painting.

Forces on simplified stationary rocket model before launch?

Weight, support reactions, aerodynamic loads (if wind), and structural reactions.

Manufacture X in factory?

Consider materials, machining, tooling, assembly, quality control.

Design rocket landing system and legs?

Absorb impact energy, distribute load, use crushable structures or dampers.

Beam attached to wall on one side, force applied: where would it break?

Max stress at fixed end; depends on load and cross-section.

Pull rug from beneath cylinder: which way does it roll?

Depends on friction and rotation; FBD analysis needed.

Most clever design seen?

Personal answer highlighting ingenuity, efficiency, or simplicity.