A combustion system for a gas turbine engine includes a housing defining a pressure vessel. A master injector is mounted to the housing for injecting fuel along a central axis defined through the pressure vessel. A plurality of slave injectors is included. Each slave injector is disposed radially outward of and substantially parallel to the master injector for injecting fuel and air in an injection plume radially outward of fuel injected through the master injector. The master injector and slave injectors are configured and adapted so the injection plume of the master injector intersects with the injection plumes of the slave injectors. The slave injectors can be staged for reduced power operation.