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Enhanced Reliability Features of the RL10E 1.pdf

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48th IAF Congress

Figure e 3: RLIOE-I


Engine modifications
which would provide the
greatest reliability
and performance improvements with
the lowest risk and cost were selected based upon
detailed trade studies using analytical models, previous
program experience. and industry data on valves and
valve actuators. Reliability
improvement, with a 40%
trade weighting factor, was the most important factor in
the indrvtdual trades. The baseline configuration was
established at the conclusion of the trade studies in
September 199-I.
like the RLIOA-4-I.
is rated at
Ibf full thrust operation with a corresponding
6 IO psia chamber pressure. A change from the
nominally trimmed 5.5 oxidizer-to-fuel
mixture ratio for
to a 5.35 MR for the RLIOE-I
being developed to match vehicle propellant utilization
histoty. This modified trim condition provides slightly
higher thrust compared to the RLIOA-4-I
at a given
MR. The RL IOE-I engine has demonstrated throttle
capabili? down to 47% thrust. The minimum thrust
level is lrmited by the turbine bypass effective flow area
afforded by the mated gearbox housing and thrust
control valve combination. The RLIOE-I
includes the
same basic turbomachinery,
injector, thrust chamber
and nozzle extension as the RLIOA-4-I.
The number d
valves and solenoids has been reduced from twelve on
to six valves on the RLIOE-I
3). Engine weight without the nozzle extension is 384
Ibs, a 64 Ibs increase with respect to the RLIOA-4-1.

Flow Schematic.

Nevertheless, the delivered payload capability is not
projected to decrease, due to reduced propellant
consumption for engine chilldown and elimination d
the vehicle
pneumatic plumbing, and prechill system.
All of the valves are electromechanically actuated
(EMA) and controlled by a Digital Electronic Rocket
Engine Controller
valve control
eliminates the three pneumatic solenoids. Modified
engine operation enables elimination of one of the two
hydrogen cooldown valves. All six EMA actuators are
identical in design and are electrically redundant with
brushless. direct current motors. Each EMA
includes a position feedback system. The EMAs can
move the valves at a maximum slew rate of 360” per
second (whereas the valves open and close within 900).
is engine mounted
radiation hardened processors, redundant cables to the
EMAs and built-in fault detection and accommodation
logic to further enhance reliability features.
Every propellant control valve was newly designed
for the RLI OE- I. The oxygen and fuel inlet valves (OIV
and FIV) have similar
ball valve designs. The
cooldown valve (CDV) and oxidizer control valve
(OCV) are identical and have a partial ball, or visor,
valve design. The design of the fuel shutoff valve (FSV)
is similar to that of the OCV and CDV. The thrust
control valve (TCV) has a rotary sleeve valve which is