the gases pass the turbine, the reduction of heat
The tailpipe ends in a jet nozzle, located
losses improves engine performance by retaining
just forward of the end of the fuselage. Most
the maximum permissible temperatures, resulting
installations employ a single direct exhaust to get
in maximum velocity in the jet. A typical insula-
the advantages of low weight, simplicity, and
tion blanket and the temperatures at the various
minimum duct losses.
locations in the exhaust section are shown in
The construction of the tailpipe is semiflexible.
Again, the need for this feature is dependent on
figure 1-42. This blanket contains fiber glass as
the low-conductance material and aluminum foil
its length. On an extremely long tailpipe, a bellows
as the radiation shield. The blanket is covered to
arrangement allows movement both in installation
prevent its becoming soaked with oil. The heat
and maintenance and in thermal expansion. This
cuts stress and warping, which would otherwise
shroud type of configuration consists of a stainless
be present.
steel envelope enclosing the exhaust system
(fig. 1-43).
tailpipe could conceivably injure the airframe
parts surrounding these units. For this reason
some means of insulation had to be devised. There
are several suitable methods for protection of the
fuselage structure; two of the most common are
insulation blankets and shrouds.
An insulation blanket type of configuration,
shown in figures 1-41 and 1-42, consists of several
layers of aluminum foil, each separated by a layer
of bronze screening or some other suitable
material. Although these blankets protect the
fuselage from heat radiation, they primarily
reduce heat losses from the exhaust system. Since
Figure 1-43.-Exhaust system shroud.
engine temperature limits are of little concern after
Figure 1-42.-Insulation blanket, with the temperatures that would be obtained at the various locations shown.
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