when the AIR COND MASTER switch is at
i n l e t duct to maintain a computer duct
temperature of 4.4 2.8C (40 5F). The
NORM. Under these conditions, the circuit from
temperature controlled air flows through the
the 28-volt dc essential bus to the solenoid of the
ballistics computer set. Sonic venturis in the
engine bleed air shutoff valve is complete. Bleed
ballistics computer outlet duct and the transmitter
air now flows to the air cycle refrigeration unit.
modulator inlet duct limit the flow of cooling air.
The discharge from the cooling turbine supplies
the cooled bleed air used by the equipment cooling
A computer cooling shutoff valve upstream
of the computer temperature control valve
system.
provides a safety override for the computer
When the aircraft is airborne and the ram air
temperature control valve. If the computer duct
temperature is below 46.1C (115F), voltage
from the 120-volt ac primary bus runs through
t e m p e r a t u r e exceeds 65.6C (150F), the
computer thermal switch opens. This de-energizes
the overpressurization relay, and the unoperated
the computer overheat indicator relay and
ram air thermal switch to the equipment cooling
completes the circuit to the COMPUTER OVER-
valve, the forward compartment ram air valve,
HEAT caution light. Voltage from the 28-volt
and the aft compartment ram air valve. The
essential dc bus runs to the computer overheat
equipment cooling valve runs to the fully closed
indicator relay. This energizes the computer
position, and the forward compartment and aft
cooling control relay, thereby closing the
compartment ram air valves run to the open
computer cooling shutoff valve. If the computer
position. Ram air flows to the right forward and
duct temperature drops below 65.6C, the
aft equipment compartments and the cooled,
bleed airflow is shutoff.
contacts of the computer thermal switch close,
When the ram air temperature exceeds 46. 1C,
energizing the computer overheat indicator
relay. This action interrupts the circuit to the
the ram air temperature thermal switch operates.
Voltage from the 120-volt ac primary bus goes
COMPUTER OVERHEAT caution light. The
computer cooling control relay remains energized
through the overpressurization relay, and the
operated ram air thermal switch to the equipment
through the computer emergency cooling switch
cooling valve, the forward compartment ram air
and its own contacts. Placing the CMPTR
EMER COOL switch momentarily to RESET
valve, and the aft compartment ram air valve. The
de-energizes the computer cooling control relay,
equipment cooling valve runs to the open position,
completing the circuit to open the computer
and the forward compartment and aft compart-
ment ram air valves run to closed position.
cooling shutoff valve. If the COMPUTER
Undried, cooled bleed air flows to the forward
OVERHEAT caution light should cycle on and
off indicating a constant overheat condition, place
and aft equipment compartments. The ram air to
t h e CMPTR EMER COOL switch to ON,
these compartments is shutoff.
permanently closing the computer cooling shutoff
When an overpressurization condition occurs,
valve. This allows uncontrolled, cooled bleed air
the pressure switch operates. This closes the
to duct to the ballistics computer.
overpressurization relay. Voltage from the
Air exhausted from the ballistics computer set
120-volt ac primary bus runs through the
overpressurization relay to the equipment cooling
and from the cockpit circulates through the less
valve, the forward compartment ram air valve,
critical electronic equipment compartments. This
air supplies direct cooling requirements for
and the aft compartment ram air valve. The
communication, navigation, and identification
equipment cooling valve goes to the open position
(CNI) equipment in the aft equipment compart-
and the forward and aft compartment ram air
ment.
valves run to the closed position. Under these
conditions, the overpressure dumps into the
CABIN AND VENT SUIT
forward and aft equipment compartments.
TEMPERATURE CONTROL SYSTEM
The computer pressure regulator maintains a
pressure of 2 to 3 PSI in the equipment cooling
The cabin and vent suit temperature controller
line. The pressure-regulated, partially-dried cooled
is a transistorized electronic device. It operates on
bleed air from the regulator automatically mixes
120 volts, 400 hertz. Maximum power con-
with controlled quantities of hot bleed air. The
sumption is 28 watts.
servo-controlled computer temperature control
Electrically, the controller consists of two
valve controls the mixture process. This valve
channels--the cabin temperature channel and the
modulates in response to temperature signals from
ventilated suit channel. Both channels operate in
the computer temperature sensor in the computer
