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130 CHAPTER FIVE

Engine Power Non-super-charged
Supercharged

Altitude
Fig. 5.8. Engine power as a function of altitude for a
non-turbo-charged and a turbocharged engine.

density in the cylinders and the power drops off with further increase in
altitude. Figure 5.8 shows the engine power as a function of altitude for
a non-turbo-charged engine and a turbocharged engine.
Turbochargers are usually not used to increase power above the
On Nov. 12, 1906, Brazilian
maximum rated power at sea level. Engine temperatures and
Alberto Santos-Dumont made the
loads would be too great, resulting in damage to the engine.
first sustained powered flight in
The thing to keep in mind with piston-engine-powered
Europe. He was hailed as the
airplanes is that the engine’s power is a function of altitude
first to fly, since the Wright
but not of the speed of the airplane. As shown in Figure 5.3,
brothers’ success was still
thrust of the propeller decreases with speed but the propulsive
unknown.
power is pretty much constant until high speeds are reached.

The Turbine Engine

So, how is a turbine engine, which is the heart of all jet engines, dif-
ferent from a piston engine? For one thing, it is a little harder to sepa-
rate the “engine” from the device that produces thrust. So, we start this
discussion by introducing the basic elements of the turbine engine in
what is called the engine core. An important result you will learn is that
a turbine works such that the available power increases with speed
and the thrust is independent of speed. For a piston engine/propeller
propulsion system the available power is constant with speed and the