# 12.4.2: Mass relations


##### Hypothesis 12.7 Variable mass

The aircraft is modeled as variable mass particle.

The variation of mass is given by the consumed fuel during the flight:

$\dot{m} + \phi = 0.$

12.4.2: Mass relations is shared under a CC BY-SA 3.0 license and was authored, remixed, and/or curated by Manuel Soler Arnedo via source content that was edited to conform to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.