section_path: Physics/Delta-v (rocket equation)
section_name: Delta-v (rocket equation)
paragraph_text: Delta-v (rocket equation)
  
  The delta-v capacity of a rocket is the theoretical total change in velocity that a rocket can achieve without any external interference (without air drag or gravity or other forces).
  
  When v e {\displaystyle v_{e}} is constant, the delta-v that a rocket vehicle can provide can be calculated from the Tsiolkovsky rocket equation:
  
  where:
  
  When launched from the Earth practical delta-vs for a single rockets carrying payloads can be a few km/s. Some theoretical designs have rockets with delta-vs over 9 km/s.
  
  The required delta-v can also be calculated for a particular manoeuvre; for example the delta-v to launch from the surface of the Earth to low Earth orbit is about 9.7 km/s, which leaves the vehicle with a sideways speed of about 7.8 km/s at an altitude of around 200 km. In this manoeuvre about 1.9 km/s is lost in air drag, gravity drag and gaining altitude.
  
  The ratio m 0 m 1 {\displaystyle {\frac {m_{0}}{m_{1}}}} is sometimes called the mass ratio.