NOTE: The exhaust or jet nozzle
airframe. The nozzle attaches to
gives to the exhaust gases the all-
the rear of the tailpipe if there is a
important final boost in velocity.
need. It is attached to the rear
The jet nozzle, and the tailpipe, is
flange of the exhaust duct if a
not a part of the basic power
tailpipe is not necessary. There a re
plant, but is supplied as a part of
basically two types of jet nozzles--
fixed-area and variable-area.
There are two types of jet nozzle design. They
are the converging design, used on most freed-area
nozzles for subsonic velocities, and the converging-
diverging design, for supersonic gas velocities.
The fixed-area type is the simpler of the two jet
nozzles, since there are no moving parts. It is
attached to either a tailpipe or exhaust cone, and any
adjustment in nozzle area is mechanical.
Adjustments in a fixed-area nozzle are
sometimes necessary because the size of the exit
orifice will directly affect the operating temperature
of the engine. There are several ways to adjust a
fixed-area nozzle. One method is to trim or cut away
strips from the conical section of the exhaust nozzle.
Provided, of course, the temperature was too high. If
the inlet temperature is too low, a nozzle of less area
is used to replace the inadequate one.
Another method of reducing the nozzle area is to
use inserts. The inserts fit inside a joggled retainer
held in place by two screws.
Figure 1-44.-Segment-type nozzle assembly.
Figure 1-45.-Variable exhaust nozzle assembly.