system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: Why do we need rockets that go straight up to get into space instead of using a ship that could just gradually increase altitude like an airplane?

I understand that structurally, it can't just be an airplane. I've just never understood why a rocket is needed.
gpt
Rockets do not go straight up all the way into space. They go straight until the air resistance is greatly reduced then angle over. This helps to reduce fuel consumption.

Fuel consumption is basically the answer. To "escape" Earth's gravity you have to go *very fast* and doing that down where there is high air resistance simply wastes fuel.