ROCKETS - 1

Ignition (probably the zeroest basic thing you need to know before diving to rockets.)

Why not planes, instead of Rockets?

Space isn't just "high up"; it’s a different physical environment.

A standard airplane is a "fluid" machine. It stays up by moving air over its wings to create Lift. But as you climb, the air molecules get further and further apart. Eventually, the atmosphere becomes so thin that even at supersonic speeds, there isn't enough "stuff" to push against.

This boundary is the Kármán Line (100 km). Once you cross it, your wings are just dead weight. To survive here, you stop being a "flyer" and start being a "projectiles." You don't need lift; you need Momentum.

...so, how to move when there is nothing to push against?

In a vacuum, there is no ground for tires to grip and no air for propellers to churn. So, how does a rocket move? It uses Mass Expulsion.

Think of standing on a skateboard with a heavy backpack. If you hurl that backpack away from you as hard as possible, you will roll in the opposite direction.

A rocket engine does this at a molecular level. It heats up gas and shoots it out of a nozzle at 3,000 meters per second. The "push" doesn't come from the gas hitting the air outside; it comes from the recoil of throwing that mass away. If you want to go forward, you have to throw something backward.

Engineering a rocket is a battle against three specific constraints

To get a payload to the stars, we have to solve these three puzzles:

1. The Weight Trap: Chemical fuel isn't very efficient. To get a tiny satellite into space, the rocket has to be roughly 90% fuel by weight. You are basically launching a giant firework where the "useful part" is only 5%.
2. The Steering Problem: Without air, rudders don't work. We have to "Gimbal" the engine. Literally tilting the fire to change direction. It’s like trying to balance a broomstick on your finger while it's moving at Mach 10.
3. The Speed Goal: To stay in space, you have to hit 7.8 km/s (28,000 km/h). If you go slower, gravity wins and pulls you back. If you hit that speed, you "fall" around the Earth forever.

So, one should focus to align his design when designing a new rocket.

Thanks for being up to here, see you next time!