Courses
Rocket engineering, from the beginning.
Every lesson is written against a simulator that already implements it, so the equation, the code and the flight are the same thing. Start at the top if you are new.
Foundations
- 01The rocket equationWhy a rocket's reach depends on the ratio of its masses and not its size, and why that ratio is so punishing.
- 02Thrust, mass flow and specific impulseWhere thrust actually comes from, what specific impulse measures, and why a vacuum nozzle is shaped differently.
- 03Why rockets are built in stagesDead mass, the cost of carrying empty tanks, and how to split a vehicle so the sum beats the whole.
- 04Why a rocket turns instead of steeringGravity losses, drag losses, and the pitch programme that trades one against the other without bending the airframe.
Orbital mechanics
- 05Orbits as conic sectionsThe shape of every unpowered trajectory, the six numbers that name one, and what each of them moves.
- 06Transfers and the Oberth effectThe cheapest way between two orbits, why burning low is worth more than burning high, and when the rule breaks.
- 07Latitude, azimuth and the orbits you can reachWhy a launch site's latitude sets the lowest inclination it can fly, what the Earth's spin is worth, and the azimuth that hits a given plane.
- 08Spheres of influence and patched conicsWhere the Earth stops being in charge, how a trajectory is stitched from one conic to the next, and what arriving at another world costs.
Flight
- 09Dynamic pressure and max-QThe product of density and speed squared, why it peaks and then falls, and what the airframe feels at the peak.
- 10Attitude control in six degrees of freedomGimbal, fins and cold gas: three ways to produce a torque, and the control loop that decides how much.
- 11Coming back through the atmosphereBallistic coefficient, peak deceleration and peak heating, and why a returning booster lights its engines before it reaches the thick air.
- 12Bringing the booster homeBoostback, return to the launch site or a ship downrange, and the propellant a reusable stage has to hold back to do either.
Advanced
- 13Closed-loop ascent guidanceFrom a fixed pitch table to a guidance law that re-solves the rest of the climb every cycle and puts the vehicle into the orbit it was asked for.
- 14Lambert's problem and launch windowsGiven two positions and a flight time, find the orbit. The solver behind every interplanetary window.
- 15Powered descent guidanceSolving for a burn that arrives at zero velocity and zero altitude at once, with an engine that cannot throttle to nothing.
- 16Entry, descent and landing on MarsAn atmosphere too thin to stop you and too thick to ignore, and the sequence that threads it.
- 17How a simulator steps through timeEuler, Runge–Kutta and adaptive steps: how a differential equation becomes a flight, what the error costs, and how to know a result is converged.