How SpaceX Reinvented The Rocket Engine!

If there's one thing that sets SpaceX apart from its competition in the aerospace industry, it's the courage to come up with crazy ideas that no one else would consider possible. If there's a second thing that makes SpaceX a very special company, it's its ability to take those crazy ideas and make them a reality, and the starship's Raptor

engine

is a perfect example of this innovation in action. The Raptor is more than just another

rocket

engine

.

rocket

is the rocket engine

reinvented

let's start at the beginning with the first production rocket engine From SpaceX, the Merlin we saw a few different iterations of the Merlin design as SpaceX moved forward with its initial test of the Falcon 1 rocket.

The Merlin 1C was The engine that powered the first successful launch of the Falcon 1 and was used in the first five flights of the Falcon 9 SpaceX is currently using the Merlin 1D engine across its line of Falcon 9 and Falcon heavy boosters. The Merlin engine design was a product of SpaceX's chaotic early days as a private California technology startup. Entering the field of orbital rocket launches was scandalous in the early 2000s, unprecedented, no one thought they would be successful and therefore no one invested money in the project. Elon Musk was self-funding everything with his Paypal Fortune, which was a lot. of money, but SpaceX was burning cash as fast as they burned rocket fuel, so Elon's mission for the Merlin was to build a rocket engine as simple and cheap as possible.

So what does that look like? Let's briefly talk about how the rocket engine works. So we're all on the same page, the basic concept here is actually not that difficult to understand. Inside the main body of a rocket there are two propellant tanks, one is for oxygen and the other is for fuel. The oxygen side is the same for all types. rocket because fire needs oxygen to burn, this is like blowing air into the campfire to intensify the flames and convert the oxygen into rocket propellant. First you have to liquefy it, you convert the oxygen from a gaseous state to a liquid state by cooling it to a cryogenic temperature. the boiling point of oxygen is 83°C or - 297 F, so at any temperature below that temperature it will stabilize as a liquid, it's pretty cold, then on the fuel side Merlin uses a chemical called rp1 which is basically purified kerosene, is cheap and accessible. and is liquid at room temperature when the rocket engine starts, two pumps will move both the oxygen and the fuel at very high pressure to the combustion chamber where the two liquids combine and ignite and that combustion will release an enormous amount of energy as the rocket engine starts.

The propellants burn and expand to create pressure. All this energy will leave the combustion chamber through the throat. This is like blowing out a candle. By pushing the air from your lungs out through a small opening in your lips, you create high pressure inside your mouth and force the gas out through a small opening, then all that high pressure combustion exhaust and High temperature exits through the nozzle where it expands from the size of the throat to the size of the nozzle opening. This expansion actually accelerates the escape at an even faster rate. that when it came out of the throat, the greater the expansion ratio from the throat to the end of the nozzle, the greater the acceleration of the exhaust, this process converts pressure into thrust, the faster we can expel the exhaust gas out the back of the nozzle, the faster the rocket will advance each action has an equal and opposite reaction in the Merlin engine design those twin pumps for fuel and oxygen are driven by something called a gas generator, it's like a miniature rocket engine with its own combustion chamber and nozzle, except instead of pointing directly to the bottom, this mini engine fires directly into a turbine, now the pressure from the combustion reaction spins a turbine that is connected to a main shaft that feeds ERS from both the main fuel and oxygen pumps after the gas has done its job.

As the turbine spits, the excess is expelled out the side of the engine through an exhaust pipe. This is what we call an open cycle gas generator and this design dates back to 1944 and the first long range ballistic missile ever created, the German V2. rocket, so when Elon asked for the easiest and cheapest rocket engine possible, this is exactly what he got. Now imagine being able to see this incredible view of outer space through your window every day. I can't offer you a spaceship, but I do have the following one. It is best to exhibit while we continue to explore the wonders of the universe.

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Like oxygen, methane needs to liquefy at a cryogenic temperature to convert it into a suitable rocket fuel, which adds an extra layer of complexity to the system, but it's worth it, let me explain that kerosene is a long chain. Carbon is a hydrocarbon, which means it is very difficult to burn completely and turn it into a gas. You'll end up with a lot of solid matter left behind as a byproduct of combustion, even within an environment like a rocket combustion chamber. Solid carbon is what we would normally call soot, just black dust, and just like the inside of a chimney, soot tends to stick to the inside of a rocket engine and cause a buildup known as cing now from a typical rocket engine. . it goes straight to the bottom of the ocean after being used once, that usually doesn't matter, but on a reusable engine like the Merlin, everything has to be cleaned between launches and that's just not going to cut it with the rapid reuse program.

What Elon has in mind for Starship, he wants these things to launch multiple times a day. Methane is mostly hydrogen with a single carbon atom for every four hydrogen atoms, so it's pretty easy to completely burn that carbon and leave nothing as a byproduct, for example. If you have natural gas in your house, which is almost entirely methane and you can burn it all day in your oven or stove without having to worry about carbon residue, then that is fuel now, how does the internal gas system compare? a Raptor engine with the old Merlin? The Raptor's design is called a full-flow staged combustion cycle and is an exceptionally complex design of pumps, turbines and plumbing.

Let's go back to our engine diagram on the Raptor cycle, the fluids move from the tanks to the main pumps and then directly to a pair. In gas generators, both fuel and oxygen hit their own individual turbines, so unlike all previous engines which used a single turbine on the oxygen side or, in rare cases, on the fuel side , the Raptor is the only engine with dual gas turbines now instead of everything. Rotating on a main axis, we have independent turbines and pumps for each tank, when the cryogenic liquid reaches these turbines, the first thing you will find is a preburner which is a miniature rocket engine and the preburner burns the liquid enough to transform it . into gas, but since neither oxygen nor methane can burn on their own, there needs to be a cross connection between the two preburners that allows some oxygen to join the methane stream and some methane to join the stream. . oxygen flow once combustion is achieved the exhaust gases are released into the turbine casing where it spins the blade, the turbine blade spins the pump and that sends our now gaseous propellants into the combustion chamber at extreme pressure, but wait a second if the turbine spins the pump. and the pump sends the liquid to the turbine, so how does the process start in the first place?

SpaceX uses equipment on the launch stand to externally spin the turbines. This is why the Starship launch stand is considered a zero stage for the main rocket it is critical to the successful ignition of the booster two things to keep in mind here number one, this system does not have an exhaust pipe for the gas to escape afterwards of the turbine, this is why we call the Raptor a closed cycle compared to the Merlin's open cycle, so In a Raptor, all the pressure from both gas generators is kept within the system, making this extremely high pressure operation.

This is also another area where methane shines as a clean burning fuel source because we are not venting the exhaust from the pre-b burner if you tried this with kerosene fuel the soot would build up very quickly inside the system and ruin the whole number two , there is no direct path from the fuel or oxygen pump to the combustion chamber, which means all the methane and all the oxygen. they have to go through a pre-b burner before they get to the chamber, that's why we call full flow staged combustion of the Raptor cycle, so now we have both our oxygen and our methane coming out of their turbines as very hot gases and very high pressure, and that gas The reaction of the gas when they hit the combustion chamber will produce the most efficient combustion possible.

Significantly more energy will be generated from gas on gas than from liquid on liquid. Elon Musk claims that this reaction has an efficiency greater than 99%, the maximum that physics will allow Elon says that only God himself could do a better job combining molecules than the Raptor's combustion chamber now if all that sounds very complicated it is because It's rocket science after all Elon has referred to starting the Raptor's engine as a delicate dance. Between the fuel system and the oxygen system, everything is interconnected and everything affects everything else, so if something goes wrong or Even if the methane and oxygen cycle become even slightly out of sync with each other, then the entire engine will explode or at least some parts. will melt so we know how the Raptor does what it does, let's talk about what all that means for the performance and power of this engine.

The Raptor is a relatively small engine that produces a relatively massive amount of thrust. The current version 2 of the Raptor is creating 230 metric tons of thrust at sea level this is not the most powerful rocket engine that title goes to the F1 engine that lifted the Saturn 5 rocket it had more than twice the thrust of a Raptor but it also it was an absolutely huge engine that could be parked. In comparison, the inside of a Jeep, the Raptor, is super compact at 3m high and 1.5M wide at the nozzle, allowing SpaceX to pack 33 of them into the 9M diameter raptor booster, which is much smaller than a close equivalent such as the rs25 engines that powered the space shuttle and was also adapted to the SLS Moon rocket, but the rs25 only produces about 1990 metric tons of thrust, so the Raptor has an unmatched power-to-weight ratio.

The Raptor weighs only 1600 kg, while the RS25 weighs almost 3200 kg and the Raptor achieves this by running the combustion chamber at a significantly higher pressure than any other rocket engine in the world. The Raptor 2's chamber pressure is currently 300 bar, which converts to approximately 4,351 lb per square; In comparison, the chamber pressure of the old Merlin engine has dropped by around 100 bar. Remember that the engine of theRocket uses the throat and nozzle to convert pressure into thrust, so more pressure means more thrust. Elon Musk says that future work on the Raptor design will mainly be to make the engine more simplified and therefore cheaper and faster.

To produce this he returns to one of Elon's favorite sayings, the best part is no part, which is the core of his first principles philosophy. The steps Elon takes when he designs something is to first question the constraints and requirements and make them less silly. don't follow any rules that don't make sense, then delete any part of the design process that isn't necessary if you're not obligated to return at least 10% of the stuff you deleted and then deleted. t eliminate enough step three optimize step four speed up step five automate and we can already see that in action with the transition from raptor 1 to Raptor 2 there are significantly fewer visible parts in the new engine Elon says he wants to eliminate all the complicated elements engine pieces, that means integrating more small pipes and wiring into larger conduits and replacing bolted flanges and solid welds.

Elon says that by integrating more engine components, they can actually remove the covers that are essentially protective. Obviously, heat shields removing anything from a rocket's design will make it lighter and cheaper, which is absolutely critical for flight. sustainable spaces. This process will also continue to make Raptor cheaper and more production friendly, which is the main goal. You might be wondering why they need so many engines if the rocket is going to be completely reusable, well we have to think long term, that's where Elon's head is at. His ultimate goal with Starship is to make these rockets as common as airliners are today.

At least 1,000 ships or more, these ships would be in constant operation for transit between Earth and Mars, Earth and the Moon or even using the ship as a point-to-point transport on Earth itself, the ultimate goal of the Starship is become one of the most important vehicles ever created in the history of humanity. It is on par with the first sailboats that crossed the ocean and connected the world. The Starship can connect the solar system.