Engine Cooling System
For the forty years following the
of the Wright brothers, airplanes used
internal combustion engines
Today, most general aviation or private airplanes are still
powered by propellers and internal combustion engines, much like your
We will discuss the fundamentals of the
internal combustion engine using the
Wright brothers' 1903 engine, shown in the figure, as an example.
The brothers' design is very simple by today's standards, so it is a good
engine for students to study and learn the
fundamentals of engines
On this page we present a
computer drawing of the cooling system of the Wright
brothers' 1903 aircraft engine.
In any internal combustion engine,
fuel and oxygen are combined in a
to produce the power to turn the
crankshaft of the engine.
The job of the cooling system is to prevent damage to
the engine parts which could result from high temperatures.
The cooling system of the Wright brothers is composed of
three main components; a radiator mounted on the airframe, the hoses
which connect the radiator to the crankcase, and a water jacket around the
cylinders of the motor.
The radiator and hoses are colored blue on the computer drawing at the
top of this page.
The radiator is mounted high on the wing strut next to the pilot
because the brothers used gravity to feed the coolant (water)
into the engine.
Water flows through a large rubber feed hose from the radiator
to the bottom of the engine.
The water is circulated around the engine and
picks up heat
from the cylinders.
The water then returns to the radiator through the two
return hoses located on the top of the engine.
In flight, air flows through the vanes of
the radiator and the heat is
to the air and carried away from the aircraft.
On this figure we show the details of the coolant system associated with
the engine itself.
On the right side of the figure we have removed
the fuel and electrical systems from the engine and peeled back the
covering of the
to show the water jacket surrounding the cylinders. Notice that
the brothers' design only cooled the engine cylinders and not the
combustion chambers located on the outside of the crankcase. Because of
this design, the combustion chambers would glow, red hot, during flight.
Unlike modern automobiles,
the Wright brothers did not use a water pump to circulate the cooling
water on the 1903 engine.
They relied on a fluid dynamic effect called diffusion to
move the fluid. Diffusion is the result of the random motion of the molecules
and tends to even out all differences in a fluid. If one part of a fluid
is hot and the other cold, eventually it all comes to the same temperature
through diffusion. Unfortunately, this a much weaker effect than
convection which is movement of a fluid because of ordered motion,
Modern water pumps use convection to move fluids.
The brothers 1903 cooling system
did not move much water and was very inefficient. Luckily, it did not have to
work for more than a few minutes. On later engines, the
brothers used water pumps.
- Beginner's Guide Home Page