Tip jet

Tip jet refers to the jet nozzles at the tip of some helicopter rotor blades, to spin the rotor, much like a Catherine wheel firework.

Some tip jets use compressed air, provided by a separate engine, to create jet thrust. Others use an afterburner type system to burn fuel in the compressed air at the tip (tip-burners) to enhance the thrust. Some are ramjets or even a complete turbojet engine. Some are rocket tip jets that run off stored propellant such as hydrogen peroxide.