- It was very tempting to run this doc through a LLM to make sure we don't have too many offset phrasings and typos. But I want to keep this devlog as authentic as I can, which means there will be no use of AI - so do bear with me and my - at times - quirky sentences.
The rocket equation (and its “tyranny”)
In my previous post I talked about dV, the currency of space travel.
But that's only half the fight. Before reaching space we face the really difficult part (assuming we depart from Earth) of exiting the atmosphere and fighting the gravity.
To get to space, we need fuel, but fuel has a mass - so when we carry fuel we need to carry fuel to carry the fuel. But having added more fuel to carry the fuel, we need to add even more fuel to carry the fuel that carries the fuel… I guess you can see where this is going.
This is known as “The tyranny of the rocket equation” and is quite brutal.
So essentially weight becomes the most important factor. A fuel tank can only help us if it contains fuel to power an engine. Once the fuel has been depleted we end up carrying dead weight - this we need to get rid of.
Therefore we have booster and stage separation. An engine is only good if it provides thrust, if it doesn't its useless and must be discarded.
- Liftoff. Main engine & boosters running
- Booster separation
- Passed karman line - orbiter remains, all other stages has separated
- Same example on the moon, where different rules apply (less gravity, no atmosphere). And also because it looks cool
Isp - Specific impulse
So to determine how good an engine is, the rocket equation relies on a variable called Isp -Specific Impulse. Think of Isp as the “miles per liter” of a rocket engine. It tells us how efficiently an engine turns fuel into thrust.
This is something you will meet in the game, when trying to get off the ground.
If you were to leave the moon instead of Earth, you would not face the same problems since we have very little gravity and no atmosphere to fight us.
But leaving the moon in a rocket means we got to the moon in a rocket that contained a rocket capable of landing and leaving again.
That could only come from one place -> Earth.
And that is why the Saturn V rocket (those used for the moon landings) was until recently the most powerful rocket ever built. (NASA Artemis and SpaceX starship now both deliver a significantly larger amount of thrust)
And here we are. Physics and nerding…
In the next post i’ll introduce you to some actual game related stuff.
(also all images are ingame screens from the early game, so what you see - you _will_ get - only probably even better )