My WIP has two spacefaring cultures. One has mastered it and can blast off into space in a moment, with the crew feeling no effects. The other one isn't that much more advanced than 21st century Earth, and I'm wondering how to depict a takeoff from inside the ship. I know that real-life astronauts experience immense g-forces, but is there a minimum speed that needs to be reached, and therefore a maximum amount of time that an orbit-breaking blast can take?