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SECTION 2.
SYSTEM DESCRIPTION
2.1
GENERAL
a. The X353-5B lift fan is designed for installation in the wings of
an airplane (Figure 2.1) and combines desirable VTOL features of high thrust,
low sfc, low exhaust velocities, low noise levels and low weight.
It is a
convertible system which augments the thrust of a turbojet engine for
vertical takeoff and landing.
b.
The J85 turbojet engine and the lift fan are pneumatically coupled
by the diverter valve and additional ducting as may be required for a
specific installation.
For vertical flight, the diverter valve deflects
exhaust gases from the turbojet into a tip turbine which drives the lift
fan.
During transition from hover to horizontal flight, louvers located
on the lower surface of the fan vector the fan exhaust rearward to provide
horizontal thrust for forward acceleration.
Once the aircraft has reached
a speed sufficient for wing supported flight, the diverter valve is moved
to the straight-through position, the exit louvers and the wing surface over
the fan inlet are closed and the J85 turbojet operates in a conventional
manner.
2.2
BASIC FAN DESCRIPTION
a.
The X353-5B is a light-weight, high-performance, compact V/STOL
lift fan propulsion system.
The major components (Figure 2.2) include a
diverter valve, a single-stage axial flow fan, a power turbine attached
to the fan blade tips, a front frame with an inlet guide vane assembly, a
rear frame containing the fan and turbine exit stator, a scroll which con-
tains the partial admission turbine nozzle, and exit louvers supported irom
the rear frame.
The leading system particulars are listed in Table 2.1.
1-2.1
R-2
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