Eli5 how do SLS and Space shuttle SRBs burn for the same time when SLS SRB has an extra segment?

Question

Wouldn’t SLS SRBs burn longer? Or is because the solid fuel burns from the inside out ie. not bottom to top?

In: 0

Answer 1

https://youtu.be/Eis3A2Ll9_E and other YouTube videos. Some search terms might include something as simple as ‘solid rocket’ or ‘solid rocket booster’.

Yes, they burn from the inside out. By selecting different shapes of the cavity, the burn profile can be controlled.

https://www.grc.nasa.gov/www/k-12/airplane/srockth.html

https://www.nakka-rocketry.net/th_grain.html has pictures of several cross sections compared to their thrust profiles.

https://en.wikipedia.org/wiki/Solid-propellant_rocket should link to the article specifically for the Space Shuttle and SLS ones but gives an overview.