Aerospace Studies with a focus on Rocket Propulsion
Thrust, Isp, the rocket equation, nozzles and engine cycles, then today’s engines, 30 years of launch footage, and where to study.
⚙️ The fundamentals
- 🚀 Thrust
Throw mass backward fast and the rocket is pushed forward (Newton’s third law). It works in vacuum.
F = ṁ·vₑ + (pₑ − pₐ)·AₑCourse unit 7 · 🧮 Calculator - ⏱️ Specific impulse (Isp)
Thrust per unit of propellant weight burned each second. Higher Isp = more push from the same fuel.
Isp = F / (ṁ·g₀)Course unit 7 - 📈 The rocket equation
How much speed change (Δv) you get from exhaust speed and the ratio of full to empty mass. It is why rockets stage.
Δv = vₑ · ln(m₀ / m_f)Course unit 9 · 🧮 Calculator - 🔔 Nozzles
A converging-diverging bell turns hot, high-pressure gas into a supersonic jet. Bigger bells suit vacuum; shorter ones sea level.
Course unit 8
Engine cycles: how the pumps are powered
- Gas generator
A small burner drives the turbine; its exhaust is dumped overboard. Simple. Example: Merlin (SpaceX).
- Staged combustion
Preburner gas goes on into the main chamber, so nothing is wasted. Example: RS-25 (Shuttle, SLS).
- Full-flow staged combustion
Two preburners, one fuel-rich and one oxygen-rich, so all propellant flows through the turbines. Raptor was the first to fly (Starhopper, July 2019).
- Expander
Fuel warmed in the cooling jacket drives the turbine. Clean and reliable for upper stages. Example: RL10.
- Electric (ion, Hall)
Electric fields accelerate ions. Tiny thrust, very high Isp, for months-long burns in space.
Course unit 8 · AIAA Aerospace America, 2020 year in review · Spaceflight Now, Jul 26, 2019 (Starhopper hop)
🔥 Latest and greatest: SpaceX Raptor
Raptor burns liquid methane and liquid oxygen (methalox) in a full-flow staged combustion cycle. Numbers below are SpaceX’s, with the date each was published.
| Version | Thrust, sea level | Thrust, vacuum version | Engine mass | Status | Source |
|---|---|---|---|---|---|
| Raptor 1 | 185 tf | — | 2,080 kg | Flown | Teslarati, Oct 26, 2026 (quotes Elon Musk on X, Oct 26, 2026) |
| Raptor 2 | 230 tf (507,000 lbf) | 258 tf (568,000 lbf) | 1,630 kg | Flown | SpaceX, “Introducing Starship V3”, May 12, 2026 |
| Raptor 3 | 250 tf (551,000 lbf) | 275 tf (606,000 lbf) | 1,525 kg | Flying (Starship V3) | SpaceX, “Introducing Starship V3”, May 12, 2026 · SpaceX, Starship / Raptor page (read Oct 28, 2026) |
| Raptor 4 | 300 tf | — | “hopefully about the same mass” as Raptor 3 | Announced / planned | Teslarati, Oct 26, 2026 (quotes Elon Musk on X, Oct 26, 2026) |
What changed, and what is still a plan
- Raptor 3 integrates sensors and controllers inside the engine under its thermal protection, so the engine shrouds are gone; all variants get a redesigned ignition system; SpaceX says simplification saves about 1 ton per engine at vehicle level (May 12, 2026). SpaceX, “Introducing Starship V3”, May 12, 2026
- Sources differ on Raptor 3 thrust: SpaceX’s 2024 target was 280 tf; its newest official figure for flight engines is 250 tf (May 12, 2026), used here. On Oct 26, 2026 Elon Musk wrote that SpaceX can “only reliably get to around 230 t-F with Raptor 3”. SpaceX, “Introducing Starship V3”, May 12, 2026 · Teslarati, Oct 26, 2026 (quotes Elon Musk on X, Oct 26, 2026)
- Raptor 4 is announced, not built or shown: on Oct 26, 2026 Elon Musk wrote “Raptor 4 will be 300 tons of thrust at sea level and hopefully about the same mass.” SpaceX has published no Raptor 4 spec sheet, date, chamber pressure or Isp. Teslarati, Oct 26, 2026 (quotes Elon Musk on X, Oct 26, 2026)
📽️ 30 Years of Raw Power
Real launch and test-fire footage, oldest to newest. Videos load only when you press play.
Space Shuttle Discovery, STS-133 (last launch)
2011-02-24images.nasa.gov · Video: NASA (public domain)Falcon Heavy test flight (27 Merlin engines)
2018-02-06YouTube · SpaceX · Video: SpaceXFalcon 9, NASA’s SpaceX Crew-1 (9 Merlin engines)
2020-11-15images.nasa.gov · Video: NASA (public domain)SLS, Artemis I (4 RS-25 + 2 solid boosters)
2022-11-16images.nasa.gov · Video: NASA (public domain)Starship Flight 5, first booster catch (33 Raptor 2)
2024-10-13YouTube · SpaceX · Video: SpaceXRS-25 engine No. 2063 hot fire, NASA Stennis
2026-01-22images.nasa.gov · Video: NASA (public domain)Starship Flight 12, first flight of Starship V3 and Raptor 3
2026-05-22Watch on SpaceX.com ↗ · Video: SpaceX
| Vehicle / test | Date | Engine | Thrust per engine | Total liftoff thrust | Chamber pressure | Isp | Propellant | Source |
|---|---|---|---|---|---|---|---|---|
| Space Shuttle (STS-133) | 2011-02-24 | RS-25 ×3 | ≈491,000 lbf (104.5%, vac) | — | — | — | LH₂ / LOX | NASA, SLS RS-25 Core Stage Engine fact sheet (MSFC, Dec 2025) |
| Falcon Heavy | 2018-02-06 | Merlin ×27 | 845 kN / 190,000 lbf | > 5 million lbf | — | — | LOX / RP-1 | SpaceX, Falcon Heavy page (read Oct 28, 2026) |
| Falcon 9 (Crew-1) | 2020-11-15 | Merlin ×9 | 845 kN / 190,000 lbf | — | — | — | LOX / RP-1 | SpaceX, Falcon Heavy page (read Oct 28, 2026) |
| SLS (Artemis I) | 2022-11-16 | RS-25 ×4 + 2 SRB | ≈512,000 lbf (109%, vac) | 8.8 million lbf | — | — | LH₂ / LOX + solid | NASA, SLS RS-25 Core Stage Engine fact sheet (MSFC, Dec 2025) · NASA Image and Video Library, Artemis I launch recap, Nov 16, 2022 |
| Starship V3 Super Heavy | 2026-05-22 | Raptor 3 ×33 | 250 tf / 551,000 lbf | 8,240 tf / 18.1 million lbf | 350 bar (test, 2023) | — | CH₄ / LOX (subcooled) | SpaceX, “Introducing Starship V3”, May 12, 2026 · SpaceX, Starship / Raptor page (read Oct 28, 2026) · Elon Musk on X, May 13, 2023 (archived) |
Chamber pressure and Isp are left blank where the maker has not published a current figure. The one sourced Raptor value: 350 bar reached in a Raptor 3 ground test (Elon Musk, May 13, 2023), a test result, not a rating.
Thrust per engine over time (kN)
Sea-level thrust unless marked “vac” (NASA quotes RS-25 in vacuum). Dashed bar = announced target, not flown. Conversions: 1 tf = 9.80665 kN, 1 lbf = 4.448 N.
🏆 Learn from the best
Free courses, top programs and real career paths. No affiliation or endorsement; links checked Oct 28, 2026.
Free courses
- MIT OpenCourseWare 16.512 Rocket Propulsion ↗MIT’s graduate rocket propulsion course, free: lecture notes and problem sets.
- MIT OpenCourseWare 16.50 Introduction to Propulsion Systems ↗MIT’s undergraduate course on both jet and rocket engines, free.
- edX: Aerospace engineering courses ↗University aerospace courses online; many can be audited for free.
University programs and labs
- MIT AeroAstro ↗MIT’s Department of Aeronautics and Astronautics (Course 16), home of the courses above.
- Purdue University, Maurice J. Zucrow Laboratories ↗Purdue’s propulsion research labs, founded in 1948, which describe themselves as the largest academic propulsion lab in the world.
- Caltech GALCIT (Graduate Aerospace Laboratories) ↗Caltech’s aerospace labs, the group whose early rocket work led to NASA’s Jet Propulsion Laboratory.
- Georgia Tech, Daniel Guggenheim School of Aerospace Engineering ↗Georgia Tech’s aerospace school, with propulsion and combustion research.
- Stanford Aeronautics & Astronautics ↗Stanford’s aero/astro department, including space propulsion and combustion research.
- University of Michigan Aerospace Engineering ↗Michigan’s aerospace department, home of the Plasmadynamics and Electric Propulsion Laboratory.
NASA
- NASA Glenn: Beginner’s Guide to Rockets ↗NASA’s own plain-language pages on rocket thrust, nozzles and flight, with interactive simulators.
- NASA Glenn Research Center ↗NASA’s center for propulsion research, including electric propulsion.
- NASA STEM learning resources ↗NASA’s free lessons and activities for students and teachers.
Careers and internships
- NASA Internships ↗Paid NASA internships for students.
- NASA Pathways ↗NASA’s student program that can lead to a full-time NASA job.
- SpaceX Careers ↗Jobs and internships at the maker of Merlin and Raptor.
- Blue Origin Careers ↗Jobs at the maker of the BE-4 engine.
- L3Harris Careers (Aerojet Rocketdyne) ↗Aerojet Rocketdyne, maker of RS-25 and RL10, is part of L3Harris.
🌍 How this path helps the planet
Every Saving Planets solution helps both people and nature. Efficient engines cut fuel use and emissions; launch vehicles carry the satellites that watch oceans, forests and ice.
- Year 1: Chemistry and calculus are the language of combustion and of the air itself: the base for judging cleaner fuels later. See Sustainable Aviation.
- Year 2: Thermodynamics and fluids decide how much fuel an engine burns for each unit of thrust, so this year is where efficiency, and lower emissions, begin.
- Year 3: Propulsion and orbits are how Earth-observation satellites reach orbit to watch oceans, forests and ice. See Earth Observation and Upcoming Launches.
- Year 4: Senior work turns this into design: quieter, lower-emission engines and alternative fuels (Sustainable Aviation), spacecraft for space solutions and missions for planetary defense.
🧮 Built-in calculator
Subject
Calculator
- Lift Equation Calculator
- Stall Speed Calculator (with Bank Angle and Altitude)
- Mach Number & Speed of Sound Calculator (Standard Atmosphere)
- Thrust-to-Weight Ratio Calculator
- Rotor Hover Power Calculator (Momentum Theory)
- Orbital Period Calculator
- Orbital Velocity & Escape Velocity Calculator
- Hohmann Transfer Calculator
- Delta-v Calculator (Tsiolkovsky Rocket Equation)
- Projectile Motion Calculator with Air Resistance
- Pendulum Period Calculator (Small and Large Angles)
🔥 Prefer jet engines? See the Jet Propulsion track · Propulsion · 🔎
Choose a topic
- ✈️ Aeronautical Engineering
- 🛰️ Orbits & Orbital Elements
- ⚛️ Physics
- ∑ Mathematics
- 🛠️ Engineering Core
- 🧪 Chemistry
Specs from SpaceX, NASA and the outlets cited, as of Oct 28, 2026. Videos: NASA (public domain) and SpaceX (official players). Independent study guide: no affiliation, credit or endorsement.