A model jet engine design can vary from one manufacturer to another, but they all work on the same principle. The most common type nowadays is the centrifugal flow turbine, as opposed to the lengthier axial flow turbine.
A centrifugal turbine mostly differs in the stage of compression - air entering the turbine is thrown outwards as it passes over the spinning impeller. The air hits against the inside of the can and so is compressed greatly, before passing into the combustion chamber. This intense compression increases the temperature of the air, as well as the pressure.
The fuel, which is nearly always kerosene ('Jet A1'), is introduced into the combustion chamber as a very fine spray, and so mixes easily with the now very compressed air. This fuel/air mixture is then ignited by a small glow plug, much the same as the one found on a 2 or 4 cycle model airplane engine.
As the fuel/air mixture ignites and explodes within the chamber, it is forced rearwards towards the turbines. The turbines accelerate the velocity of the passing gases, and increase the pressure of them too. The gases (exhaust) finally get squeezed through the narrowing jet pipe at the very rear of the engine, exiting at great speed and pressure, thus generating the high levels of thrust.
The turbines are connected to the front impeller by way of a main shaft, so that they power the impeller as they spin.
The drawing below shows the basic principle of a centrifugal flow model jet engine.
Most model jet engines use an electric motor to initially power-up the turbine. Only when the compressor has reached the necessary revolutions per minute (RPM), can the fuel be introduced into the chamber and the engine can then operate normally. Click here to see a graphic video
The Ultimate Model Turbine use !!
Pilot: Yves Rossy was born on August 27th 1957 in Neuchatel in Switzerland, as a professional military pilot flying Mirage III for 8 years, Yves then left and now fly's Boeing 747 for a living.
He used a qty of Turbines on his flying wing (picture here) to obtain several World records
Sportsturbine is part of the Sportsmoto Ltd Company