Elon Musk officially announced New PROBLEM Inside Raptor 3, and here's Solution

Nobody saw this coming. Elon Musk just dropped a bombshell that’s sent shockwaves through the aerospace industry. Despite the Raptor 3 engine’s unprecedented power, it comes with a critical flaw—one that could quite literally make it explode if not handled with extreme care.

In this article, we’ll take a deep dive into:

What exactly the flaw is in Raptor 3
Why the startup sequence is so dangerously complex
How SpaceX plans to fix it using Block 3 upgrades and redesigned fuel systems
What this means for the future of Starship and Mars missions

What Is the Raptor 3 Engine and Why Is It Revolutionary?

Back in August 2024, SpaceX revealed the Raptor 3—a game-changing rocket engine designed for Starship, the fully reusable launch system meant to carry humans to Mars. When the engine was unveiled, it blew the rocket community away.

Sleek Design, Extreme Power

The first thing engineers and enthusiasts noticed? The clean, minimal design. Gone were the traditional external cooling pipes and cluttered hardware. Everything was neatly packed inside.

And yet, it boasted 280 tons of thrust at sea level and over 308 tons in vacuum—a whopping 22% increase over the Raptor 2. It was so futuristic-looking that people initially thought it was just an unfinished prototype.

Even top aerospace execs, like Tony Bruno from ULA, voiced skepticism. But just days later, SpaceX’s COO Gwynne Shotwell shut down the critics by sharing a video of the engine test-firing successfully.

The message was clear: this was no prototype. This was the real deal.

But There’s a Catch: The Engine Could Blow Up During Startup

Just when we thought Raptor 3 was ready to take Starship to orbit, Elon Musk revealed a serious challenge. In a post on X (formerly Twitter), he said:

“Very complex startup sequence, insane timing precision is needed to avoid blowing up the engine.”

That single sentence sent engineers and fans alike into a frenzy. Many had assumed the Raptor 3’s clean design came with simplified operation.

Turns out, it’s the opposite.

Why Is Raptor 3’s Startup So Risky?

To understand the issue, you need to understand how the Raptor engine works—and how it’s completely different from any engine that came before it.

A Full-Flow Staged Combustion Cycle

Raptor 3 runs on a full-flow staged combustion system powered by liquid methane and liquid oxygen (LOX). It’s the first engine of its kind ever flown.

Instead of wasting fuel or oxidizer like other engines, Raptor burns everything, resulting in unmatched efficiency—a crucial trait for deep space missions like going to Mars.

But that efficiency comes at a cost: extreme complexity.

Multiple Pumps, Dual Pre-Burners, and Zero Margin for Error

Unlike traditional engines that use a single turbopump, Raptor has two:

One for liquid methane
One for liquid oxygen

Each is powered by its own pre-burner—one fuel-rich, one oxygen-rich. This setup creates hot gases that spin turbines, which drive the pumps. Then everything ignites in the main combustion chamber.

Every step of this process must be perfectly timed, especially during startup.

Breaking Down the Raptor 3 Startup Sequence

Let’s walk through what makes the startup process so dangerous and difficult:

1. Engine Chill Phase

Before ignition, super-cold LOX and methane are allowed to flow through internal cooling channels. This pre-chills the engine to prevent gas formation and instability.

If this step is skipped or mistimed, you get vapor bubbles in the fuel lines, which can lead to pump cavitation and damage.

2. Turbopump Spin-Up

Each pump must be spun up using high-pressure helium stored in Composite Overwrapped Pressure Vessels (COPVs). These are the same tanks seen in Booster 13’s recovered hardware.

Both pumps must spin at the right speed and in sync. Even a slight imbalance can cause:

Resonance vibrations
Pump failure
Full engine explosion

3. Pre-Burner Ignition

Once pumps are running, a small portion of fuel and oxidizer is burned in each pre-burner to power the turbines.

This stage is the most delicate. Fuel ratios and flow rates must be precise—any deviation can cause a “hard start,” which damages or destroys the engine.

4. Main Combustion Chamber Ignition

Now, all remaining fuel and oxidizer is injected into the main chamber. This transition must happen within 10 milliseconds. That’s less than the blink of an eye.

Get it wrong, and the result is:

Combustion instability
Loss of thrust
Engine shutdown—or worse, detonation

How SpaceX Is Fixing the Problem

Now for the good news: SpaceX has a plan, and they’ve already started implementing it.

Enter Superheavy Block 3 with Central Fuel Transfer Tube

On July 9th, SpaceX revealed a major innovation: a long fuel transfer tube running straight down the center of the Superheavy Block 3 booster.

Here’s how it helps:

Acts as a secondary fuel tank
Regulates pressure and maintains a stable fuel flow to all 33 Raptor engines
Prevents sloshing and cavitation during flight maneuvers like belly flips and hot staging

This means even during high-G maneuvers, the engines will have a steady, uninterrupted fuel supply, reducing startup risks and improving reliability during both liftoff and landing burns.

The Slosh Problem: Why It’s a Big Deal

Imagine trying to drink from a bottle of water that’s being shaken violently. That’s what the fuel inside Superheavy does during complex flight moves.

Key Stats:

Superheavy carries up to 775 metric tons of fuel
LOX density: 1,100 kg/m³
Methane density: 430 kg/m³
Each Raptor 3 needs 400 liters/second during landing burns

If the pressure drops from 300 bar to under 200, you risk flameouts or engine failure. The central fuel tube minimizes this risk.

Raptor 3 Also Features Actively Cooled Shells

Every Raptor 3 engine is now wrapped in an actively cooled metal shell, with fuel flowing through tiny internal channels. This prevents overheating during:

Liftoff
Re-entry
Landing

It’s like liquid armor, and it’s only possible thanks to metal 3D printing, which SpaceX uses to build highly complex parts as a single unit.

Less Hardware, Fewer Parts, More Efficiency

SpaceX has also dramatically reduced the number of parts in Raptor 3:

Fewer flanges
Combined assemblies
Integrated thermal controls

This makes the engine cheaper to build, though slightly harder to repair. But overall, it makes manufacturing faster and more scalable—essential for Mars missions.

What’s Next? The Raptor 4 Engine Is Likely in the Works

While Raptor 3 is revolutionary, it’s still not perfect. Behind the scenes, Raptor 4 is likely already in development.

Here’s what Raptor 4 might bring:

Simplified startup logic
Higher thrust (over 330 tons)
Modular parts for quick replacement
Deeper Starship integration
Improved cooling and heat resistance

And perhaps most importantly, fewer chances of blowing up on startup.

Why This Matters: The Journey to Mars Depends on It

SpaceX’s mission is simple: make life multiplanetary. And the Raptor engine family is the backbone of that plan.

Every improvement brings us one step closer to:

Launching 100+ tons to orbit at once
Refueling Starships in space
Landing on Mars and returning home

But for that dream to come true, engines like Raptor 3—and eventually Raptor 4—must be bulletproof.

Final Thoughts: A Problem Worth Solving

Yes, Raptor 3 has a startup flaw, but SpaceX has acknowledged it, explained it, and is already engineering around it. Few companies would be this transparent.

From actively cooled shells to central fuel tubes, SpaceX is attacking the problem from every angle. And with Elon Musk’s vision driving it forward, the rocket world is in for some serious innovation.

FAQs

1. What is the Raptor 3 engine?

Raptor 3 is SpaceX’s latest iteration of its full-flow staged combustion rocket engine, designed to power Starship and Superheavy for missions to orbit, the Moon, and eventually Mars. It uses liquid methane and liquid oxygen (methalox) for fuel and features major design improvements over Raptor 2.

2. How powerful is Raptor 3?

Raptor 3 produces 280 tons of thrust at sea level and over 308 tons in vacuum, making it 22% more powerful than Raptor 2 and one of the most powerful rocket engines ever built.

3. What is the main flaw in the Raptor 3 engine?

The main flaw lies in its extremely complex startup sequence. If the timing is off by even a few milliseconds, the engine could explode due to unstable combustion or fuel flow issues.

4. What did Elon Musk say about Raptor 3’s startup?

Elon Musk publicly stated on X (formerly Twitter):

“Very complex startup sequence, insane timing precision is needed to avoid blowing up the engine.”
This highlights the critical timing sensitivity during engine ignition.

5. Why is the Raptor 3 startup so difficult?

Because it uses a full-flow staged combustion cycle, which involves dual pre-burners, dual turbopumps, and a tightly choreographed ignition process. Any slight delay or imbalance can result in combustion instability or engine failure.

6. What is a full-flow staged combustion cycle?

It’s an advanced engine cycle where 100% of fuel and oxidizer passes through pre-burners and is used to power the turbopumps before entering the combustion chamber. It offers high efficiency, but also high complexity.

7. How is SpaceX solving the Raptor 3 flaw?

SpaceX is addressing the startup issue with innovations like:

A central fuel transfer tube in Superheavy Block 3
More stable fuel delivery systems
Improved pressure regulation
These help ensure steady flow and synchronized engine ignition, especially during maneuvers.

8. What is the fuel transfer tube in Superheavy Block 3?

It’s a long vertical pipe running through the center of the booster that helps evenly distribute super-cooled methane and LOX to all 33 engines. It prevents fuel slosh and pressure drops during flight.

9. What are COPVs and how do they help?

COPVs (Composite Overwrapped Pressure Vessels) are used to store helium under high pressure. Helium is released during startup to pressurize the fuel tanks and spin up the turbopumps for ignition.

10. What is a hard start in rocket engines?

A hard start is a violent, uncontrolled ignition event that occurs when too much propellant enters the chamber before ignition. It can damage or destroy the engine and is one of the risks during Raptor 3 startup.

11. Why is engine chill important before startup?

Engine chill allows cryogenic fuels to cool the engine hardware before ignition. If skipped, hot metal surfaces could cause flash vaporization, creating vapor bubbles that disrupt fuel flow and risk engine failure.

12. How does Raptor 3 manage re-entry heat?

Each Raptor 3 is enclosed in an actively cooled shell. Cryogenic fuel flows through tiny channels in the metal to absorb and dissipate heat during high-temperature phases like re-entry and landing burns.

13. Is Raptor 3 the most advanced rocket engine in the world?

Yes. Raptor 3 currently leads in thrust-to-weight ratio, efficiency, throttle range, and reusability, thanks to cutting-edge design, 3D-printed components, and its full-flow combustion system.

14. What improvements might Raptor 4 bring?

Raptor 4, though unannounced, is expected to improve:

Startup simplicity
Engine modularity
Thrust output (possibly >330 tons)
Maintenance and reliability
It will likely power future deep-space missions beyond Mars.

15. How many Raptor engines does Starship use?

The Superheavy booster uses 33 Raptor engines, while the Starship upper stage uses 6 Raptor engines—three optimized for sea level and three for vacuum.

16. When will Raptor 3 be used in a real mission?

While Raptor 3 has already been test-fired, its full deployment in an orbital Starship launch is expected soon, possibly by late 2025 or early 2026, depending on flight readiness.

Elon Musk officially announced New PROBLEM Inside Raptor 3, and here’s Solution