20,000,000 lbf! Elon Musk Revealed New Raptor 3.X Broke Physics Limit!

The roar of the sky as the starship ascends, the ground vibrating with power beneath your feet. Every time the starship launches, shockwaves ripple through the entire starbase. Those standing in its wake can feel the thrill with their whole body. Well, this immense force is generated by 33 Raptor engines, each one an engineering marvel, continually evolving with every new iteration, from Raptor 1 to Raptor 3. And now, SpaceX is preparing to launch Raptor 4. Just how powerful will Raptor 4 be? Let's find out. We all know Starship, SpaceX's giant rocket whose mission will take us to explore Mars and further space in the future. In a speech at Starbase, Texas, Elon Musk presented a blueprint of Starship. This blueprint included three versions. The most recently flown version was V1, which performed the legendary booster capture on its fifth test flight, and was voted one of the top science highlights of 2024 by BBC World News. This version and the upcoming V2 version in early 2025 use the Raptor 2 engine. This is the second version of the Raptor series. In the further future, Starship Phi-2 is planned to be equipped with the latest Raptor 3 version, being developed by SpaceX. This raises an intriguing question. If Starship 2 will be powered by the latest version of the Raptor engine, what engine will power the final version of Starship? Will it still be the Raptor 3, or could SpaceX be developing a completely new, secret engine? While SpaceX has yet to make an official announcement, the answers often reveal themselves to those who are proactive in piecing together the clues. Let's take another look at the plan. Starship V2 has a diameter of 9 meters and a height of 124 meters. With this size, the super-heavy booster will be equipped with 33 Raptor engines providing more than 8,200 tons of thrust at sea level, allowing this ship to carry up to 100 tons of cargo to orbit. Starship V3 will be much larger than V2. At 150 meters tall, this ship is expected to carry twice as much cargo to orbit. This is also the vehicle that is expected to take us to colonize Mars in the future. The current Raptor engine, while powerful, is not yet powerful enough to support such a ship, at least according to Elon's plan. Therefore, an upgrade or a new engine had to be developed for this version. There is another hidden clue that Elon gave in a tweet on his X account. Thrust will exceed 300 tons with Raptor 3.X, enabling 10,000 tons of thrust at liftoff, getting close to the limit of known physics. Hmm, what is that Raptor 3.X might be? I can't say for sure, but it seems like this version will pack some serious power. 10,000 tons at takeoff would dwarf any rocket ever built. The legendary rocket that took us to the moon, the Saturn V, said to be the most powerful of its time, had a liftoff thrust of just over 3,400 tons. Even NASA's current biggest rocket space launch system can only produce around 3,900 tons. To meet this giant liftoff thrust, each of these new Raptor engines is said to be able to produce 300 tons and can go up to 330 tons in the long run, which is about half the thrust of the F-1 engine used on Saturn V. Impressive. But how will these new engines achieve such power? Well, there are many ways to improve the performance of a rocket engine. The first solution is you increase the nozzle size while the flow rate, chamber pressure, and throat area remain constant. This leads to an increase in specific impulse. A quick explanation about specific impulses. Specific impulse, usually abbreviated ISP, is a measure of how efficiently a reaction mass engine like a rocket using propellant generates thrust. Specific impulse, measured in seconds, can be thought of as how many seconds one kilogram of fuel can produce one kilogram of thrust. Basically, the more ISPs your engine has, the more efficient it is in using propellant. Elon also mentioned that this version will increase specific impulses by five seconds. While this may seem like a small gain, it will have a significant impact on overall performance. Now back to the solution. Even though expanding the size of the engine's nozzle could make it use fuel more efficiently, not to mention the change can slightly boost the thrust as well, this modification results in a significant increase in both the nozzle area and overall weight. SpaceX always wants to avoid adding weight as much as possible, and increasing the area may also prevent them from fitting all 33 engines into the super heavy booster. Of course, they could also do something like the Russian N1 rocket with an engine area that expands to 17 meters in diameter. Another way to increase the performance of the Raptor is to maintain the nozzle size and chamber pressure while adjusting the throat size. Reducing the throat size can increase the exhaust velocity, improve specific impulse, and increase the thrust to weight ratio. However, this leads to a decrease in flow rate and consequently thrust. SpaceX kind of does this in their Raptor 2 version. A minor difference is that they do the completely opposite. Instead of reducing the throat size, they open it up a little. Increasing the throat size would allow more propellant to flow into the system, therefore resulting in a higher flow rate and greater thrust. While this change does slightly decrease the specific impulse, the gain in thrust far outweighs the loss, so you can say it is a necessary sacrifice. Now, if you don't want to reduce the engine's performance while keeping its size, there is still a way to increase the engine's thrust while still meeting these two conditions. You simply need to adjust the chamber pressure. With higher chamber pressure, the specific impulse will only see a slight increase, but this allows more fuel to be burned at a faster rate, producing a greater force. This results in a higher thrust to weight ratio, which is crucial for improving the vehicle's performance. This sounds like an efficient method, and it is. Throughout its history, SpaceX has always wanted to raise the pressure as high as possible. Even Elon joked, saying you have too much thrust like saying you too good looking or something. The only problem with this method is that you can only increase chamber pressure so much before reaches its physical limit. One way to raise the output pressure and plow rate in the combustion chamber is to spin the turbo pumps faster. This can be achieved by changing the mixture ratios of the methane and the oxygen, so they generate more combustion products. On the other hand, this would also create a higher temperature that might exceed the melting point of the turbine fan or the chamber wall material. SpaceX encountered this issue multiple times throughout the development of the Raptor engine, resulting in the explosion of dozens of engines and the melting of even more combustion chambers. To address this, SpaceX employs a range of innovative solutions, including the installation of advanced cooling systems for the combustion chambers. The Raptor 3, for instance, features a highly integrated cooling system that spans multiple components, ensuring optimal performance and efficiency. There has been an idea of using a cooling system on the turbine fan itself, similar to those used in jet engines. Elon replied that SpaceX has had a lot of discussions about it. However, the problem with using a cooling system is that you have to use it very carefully as it could lower the temperature in the combustion chamber, ultimately reducing engine performance. Another way to address this is to make the chamber of the material with a higher temperature resistance. SpaceX has done this as well. The SpaceX Raptor engine is made from a variety of strong materials that can withstand harsh environments and have high heat resistance. One of them is an alloy called SX500. It is a proprietary nickel alloy developed by SpaceX for the Raptor rocket engine. This alloy is a variant of Inconel, a nickel-chromium-based super-alloy commonly used in extreme environments. SX500 is capable of withstanding pressures up to 12,000 pounds per square inch, 830 bar, far surpassing the capabilities of conventional alloys. If SpaceX decides to select or develop a new material, the key factor they will need to consider is cost. Still, it's not worth it to turn a $1 million engine into a $10 million engine for a little extra thrust, especially since SpaceX is working hard to reduce the cost of engine manufacturing so it can lower the overall cost of Starship flights. In order to reduce manufacturing costs, SpaceX also wants to reduce the Raptor's 3D-printed parts as much as possible. When developing the Raptor engine, 3D printing was essential for creating complex costly parts. The full-flow staged combustion cycle, with its intricate fuel and oxidizer components, benefited from this technology. However, as SpaceX moves toward mass production for the Starship program, it plans to shift to more traditional manufacturing methods for certain parts to speed up production and lower costs. This transition aims to make the engine production more efficient and scalable for Starship's high-frequency launches. All that being said, it's hard for those like us who aren't SpaceX engineers to speculate how they'll build Raptor 4. It's rocket science, after all. But SpaceX doesn't need to build a new engine for Starship Foei 3. They can just use Raptor 3. Wait, didn't you just say it wasn't powerful enough? Yes, but that's only if it's in current numbers. SpaceX is using 33 Raptor engines for the Super Heavy booster. However, according to an environmental impact report submitted by SpaceX for launching 44 Starship flights at LC-39 published by the FAA, SpaceX proposed Starship launches configured with up to 35 Raptor engines. I think 35 Raptor 3 engines might do the trick here because, come on, let's not forget how crazy Raptor 3 really is. Although not yet officially operational, the test results for the Raptor 3 indicate that it will become the most efficient rocket engine ever developed. The most noticeable thing about the Raptor 3, especially when placed next to the Raptor 2 and 1, is that it is much more compact. As I mentioned earlier, the Raptor 3 now incorporates an integrated cooling system, reducing the need for traditional heat shields and cutting down on weight. Additionally, several bolts and flange components have been removed, further lightening the engine by approximately 7% compared to the previous version. The biggest improvement, however, lies in the sea-level Raptor 3's thrust, which reaches up to 280 tons of force, 21% more than the Raptor 2, and up to 51% more than the Raptor 1. Compare that to Blue Origin's BE-4 engine, a much larger and heavier engine that only achieves about 250 tons of thrust. This makes Raptor 3 the highest thrust-to-weight ratio engine ever built. 33 Raptor 3 engines would provide 90.75 million newtons of thrust for a 33-engine super-heavy booster. So 35 Raptor 3 engines would provide 96.3 million newtons of thrust for a 35-engine super-heavy booster. That is 61.8 million newtons of thrust, more than the Saturn 5. Now, that number is hard for us to wrap our heads around. Many people believe that the Raptor 3 engine represents the pinnacle of combustion technology, and that surpassing it is impossible. But SpaceX has a long history of defying the impossible. When no one believed reusable rockets could be made, they did it. When the idea of a massive spaceship-like starship seemed unfeasible, they built it. I think they will absolutely create Raptor 4, only they can. SpaceX's journey to Mars is a promise, and Raptor 4 is just one crucial milestone on that path. And that just about wraps it up for today's episode. Thank you, and we look forward to seeing you next time.