Module releases 

Mass released in flight: ballast dropped or a payload let go on a trigger, with the rest of the rocket flying on in six degrees of freedom and the part falling to the ground on its own.

A MassRelease lets one part carried inside the airframe, with everything inside it, leave at an instant. At that instant the rocket’s mass properties step to the rest’s (hpr_design::MassProperties::without_part), and its state carries straight across: the state is the nose tip’s, which the rest keeps, as a sustainer keeps it at a powered separation. The part leaves at the velocity its own center of mass had as part of the airframe, v_O + ω × c, so the mass and the momentum of the two together are those of the rocket just before. The part then falls as a point mass under its own drag area to the ground (the decision record on released mass, ADR-088).

Method: the documentation site’s Released mass page.

Structs

MassRelease

A part carried inside the airframe that leaves it on trigger, and then falls to the ground on its own under drag_area_m2.

ReleasedFlight

A released part’s own flight, from the instant it left the rocket to its landing.