Most of us can only dream of having a private jet airplane, but radio-controlled jets have become a practical and increasingly affordable reality. This is because of advances in model jet engine technology in recent years.
Jet engines are very simple devices, in principle. Air from an intake is fed through a rotating compressor stage, where a series of fan blades increases the air pressure. This compressed air flows into the combustion chamber, where fuel is injected. The resulting combustion creates a flow of hot, expanding gases. These exhaust gases flow over a turbine with another set of fan blades. Since the turbine is connected to the compressor by an axle, part of the power of the exhaust gases is used to drive the compressor. The shaft may be used to drive a machine or to generate electricity.
While this type of engine is simple in principle, the performance is so high that structures and materials must be well engineered. Consider for example one of the model turbine engines produced by AMT, the Pegasus HP. The system weight is 5.9 lb, and it produces 35 lb of thrust with a maximum rpm of 120,000. The idle speed is 37,000 rpm, larger than the top speed of most conventional model airplane engines! The normal exhaust gas temperature is a very warm 1,110 degrees F.
These engines produce a sound just like the turbines on modern jet airplanes, and can power models to speeds well over 200 mph. The engines are often used in very realistic military and commercial jet rc models. While this type of model was virtually unheard of a couple decades ago, now there are many engines, models and even flying events dedicated to jets.
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Model Jet Engines.
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About the Author
Andre is a regular contributor to the RC Airplane Advisor:
www.rc-airplane-advisor.com.