Talk:Dual-thrust rocket motor

The dual thrust can also be created by using appropriate propellant geometries, e.g. a tubular grain with a few internal slots cut into its rear part which do not quite reach the outside of the grain (resembling a finocyl, but not quite a finocyl) and different angles between those slots results in a boost-cruise configuration which can be adapted by changing some of the geometry (angles, lenghts, ratios etc.)

The tubular part is progressively burning while the slotted part is strongly degressive. By adjusting their ratio and using different numbers of slots and angles between them it is possible to get a short spike to maximum burning surface area and a long, perfectly flat boost phase (e.g. 50% of max value of surface area) for the remainder of the burn, and another short rise to 60% or so during the last 10% or so of the burn. Will try to find drawings.