Air turborocket

In addition, it provides thrust throughout a much wider speed range than a ramjet, yet is much cheaper and easier to control than a gas turbine engine.

The air turborocket fills a niche (in terms of cost, reliability, ruggedness, and duration of thrust) between the solid-fuel rocket motor and gas turbine engine for missile applications.

Cooling the engine is not a problem because the burner and its hot exhaust gases are located behind the turbine blades.

During low-speed flight, controllable flaps close the bypass duct and force air directly into the compressor section of the turbojet.

During high-speed flight, the flaps block the flow into the turbojet, and the engine operates like a ramjet using the aft combustion chamber to produce thrust.

Since a ramjet must already be traveling at high speeds before it will start working, a ramjet-powered aircraft is incapable of taking off from a runway under its own power; that is the advantage of the turbojet, which is a member of the gas turbine family of engines.

A turbojet does not rely purely on the motion of the engine to compress the incoming air flow; instead, the turbojet contains some additional rotating machinery that compresses incoming air and allows the engine to function during takeoff and at slow speeds.

[3] In applications which stay relatively in the atmosphere and require longer durations of lower thrust over a specific speed range the air turborocket can have a weight advantage over the standard solid fuel rocket motor.

In terms of volumetric requirements, the rocket motor has the advantage due to the lack of inlet ducts and other air management devices.