Why do space rockets often have many stages?

Those of you who often follow space missions will certainly often see space rockets with many stages and they will separate each stage during flights. But why is that? Why don't they just make a single stage rocket just for it? If you are curious about this issue, we will find out together soon.

Launching cargo into orbit is horribly fuel-intensive, and rockets don't have enough fuel to carry unhelpful mass.

To launch a satellite into space and orbit the earth without falling back, the booster must help it reach a speed of 7.9km/s. That's an incredible speed and to do that, the rocket also consumes monstrous fuel.

For you to imagine, we will take the two-stage Falcon 9 rocket of the aerospace company SpaceX as an example. It was developed by SpaceX in conjunction with the SpaceX Dragon spacecraft and has repeatedly transported cargo to the International Space Station (ISS). At the same time, this is one of the most effective space rockets that man has ever built. Each rocket when fully loaded will weigh 540,000 kg, of which more than 510,000 kg is fuel (including hydrogen and liquid oxygen), which is about 94.5% of the total mass of the rocket. All the remaining things such as engines, fuel tanks, rocket shells. only account for about 5.5%. And a huge rocket like that and more than half a million kilograms of fuel can only put a load of 22,800kg into low earth orbit.

Saturn V rocket diagram, you can see how 'empty' it is when it contains no fuel

The heavier the rocket, the more fuel it will burn, and it certainly shouldn't carry any extra mass to waste more fuel. Therefore, any unnecessary mass should be trimmed so that the rocket always has minimum mass and maximum fuel.

Multistage rockets are the most efficient way to deliver cargo to orbit

To get rid of the excess mass, rocket engineers have devised a multistage rocket to carry more cargo into orbit with a smaller amount of fuel. And this type of design is still being widely used today.

Dividing the rocket into multiple stages allows the rocket to remove unnecessary mass to fly faster and further. For a single-stage rocket, its non-fuel mass (engine, shell, fuel tank, etc.) will not change during flight. Multistage rockets are different. When a rocket stage runs out of fuel, it will separate that stage and throw it away, then it will start the engine of the next stage and continue flying without having to carry the stage that has run out of fuel. Each stage of the rocket is individually designed to be most effective.

As for how the stages are designed differently, we can take NASA's Saturn V rocket as an example. This is the largest space rocket in history, with a full load of more than 3,000 tons. It was used by NASA in the Apollo and Skylab programs and has the largest payload capacity of 140 tons in history. This rocket model has 3 stages, and each stage has a different amount of fuel and propulsion system.

Stages of Saturn V boosters

1st floor:

1. Mission: Help the rocket take off and accelerate to a speed of 6,000mph (9,650km/h)
2. Engine: 5 rocket engines F-1
3. Thrust: 3,400 tons
4. Fuel: 1,204,000 liters of liquid oxygen and 770,000 liters of kerosene
5. Operating time: 150 s

2nd Floor:

1. Mission: Help the rocket reach a speed of 25,000mph (40,230km/h) – Speed ​​enough to escape the gravity of the earth. For missions in Earth orbit like in the Skylab program, just this floor is enough
2. Engine: 5 J-2 . rocket engines
3. Thrust: 500 tons
4. Fuel: 984,000 liters of liquid hydrogen and 303,000 liters of liquid oxygen
5. Operating time: 360 s

Floor 3:

1. Mission: Help spacecraft carry out space missions, such as sending spacecraft to the moon
2. Engine: 1 J-2 . rocket engine
3. Thrust: 100 tons
4. Fuel: 252,750 liters of liquid hydrogen and 73,280 liters of liquid oxygen
5. Operating time: 165 + 335s (2 burns)

Of course there are also many modern single-stage rockets that can actually carry cargo into orbit, but the problem is that the amount of cargo it can carry is much less than a multistage rocket. The reason is because in addition to the package, it also has to carry unnecessary weight.

Above is an article explaining why space rockets often have many stages and separate each stage when flying. Hope to have brought you interesting information. Thank you for your attention and hope that you will always accompany GVN 360.

*More information:

The space shuttle, although not a rocket, works in a similar way. When launched, the ship "hugs" 2 boosters and 1 external fuel tank, when it has reached the appropriate height, it will leave 2 rockets and then again, it separates the outer fuel tank to cargo to space. It will then return to earth and land.