System 112A - The Black Vault

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second runs; the other has completed five 160-second
runs. Severe tube leakage occurred du.l'ing the testing
of the second thrust chamber. This was due to an
injector discrepancy. In accordance with these results,
recommendations have been made to cut all
new thrust chambers with throat plugs.
A test program is being conducted to det\-l ­
mine the effect of between-run servicing procedures
on thrust chamber durability and the adequacy of performing
such operations on the test stand or motor
mount. The major items involved are the nushing
of the regenerative coolant tubes and the application
and baking of the ceramic thrust chamber linell. The
first chamber in this program had a life of eleven 160­
second runs at 500 psig chamber pressure. The
chamber was removed from the test stand, waterflushed,
dried, recoated with ceramlc,and baked in an
oven prior to each run. For succeeding chambers
this procedure will be varied and methylene cloride
will be used as a flushing ageilt.
As a result of the success of the Linde Flame
Plating process on the 4000-lb drilled-aluminum
thrust chamber, the pos81b1l1ty of plating the COnvergent
and throat sections of the tubular thrust chamber
is being investigated. It is believed that, if 0.003 in.
of tungsten carbide could be applied in the throat area
of the tube bundle, the thrust chamber durabUitywould
be increased.
b. Drilled-Aluminum Thrust Chambers
Drawings were released to fabricate three
drilled thrust chambers of 5052 aluminum alloy. These
will be used to evaluate chamber erosion of aluminum
when copper and silicon are not present in the alloy,
and when coatings such as Hardkote, tungstenca.rbide,
and microme are appUed to chamber walls of this
alloy.
Activity on the drilled aluminum thrust
chamber during this quarter was again largely confined
to injector evaluation. This phase of the program is
covered in section 2, d, of this report.
Two thrust chambers with tungsten-carbidecoated
chamber sections were fire-tested to compare
the durab1l1ty of the coating utilizing chrome r.1ckel as
a bi;tder with that employing a cobalt binder. The
thrust chamber with the chrome nickel binder exceeded
engine qualification .. equirements by a considerable
mugln. Testing on the chamber withthe cobalt binder
was concluded after six 160-second runs when the regenerative
coolant pasBages were exposed. However,
this testing was not considered conclusive because the
cobalt binder coating was accidentally scored during
machining and failure occurred at this point. At
least one additional chamber With each coating Will be
fire-tested to confirm these results.
c. Refractory Coatings
A drilled aluminum chamber coated with
Norton Company flame-sprayed zirCOnia (Rokide "Z")
was evaluated by firing a coated chamber on a test
stand. The coating was .moderately durable, but
spilled neu the nozzle end of the chamber. A second
chamber Is being coated; the coating thickness will be
held to a maximum of 0.010 In. to reduce the spall1ng
tendency.
d. Fuel Injectors
During this quarter, 29 injectorsfor the 75L*
thrust chamber assemblies were tested and accepted.
To date, 264 units of this configuration have passed
preliminary acceptance tests. Nine lI,d.dit:t.onal1nj~ctOI'l'
of the same configuration were ACcepted for
future assembly of test engines.
Other steel injector testsincluded the evaluation
of the effects of redueing the fuel-dome-injeetor
fuel valve seal area to accommodate the self-contained
injector fuel valve. No performance or heat
rejection differences were noted as a result of this
change.
Testing of injectors for use on drilledaluminum
thrust chambers continued during thilf.
quarter with durabllity tests on both "doublf!t" and
standard stainless steel injectors. This program has
been separated into two phases and may be classified
as follows: .
(1) To develop a coating for the aluminum
chamber which wlll allow extended operation
with standard production injector
using inhibited acid.
(2) To develop an injector which will be
compatible with the present Aiumillte
Hardkote thrust chamber, also using
inhibited acid.
Testing on the phase I program was continued
With the evaluation of an additional tungstencarbide-coated
chamber. T'nis chamber was the first
tested using a chrome-nickel binder for the tungsten
ca.rbide coating. The injector used was a standard 72­
pair caunterbored injector. 'The chamber was tested
over a total duration of 3320 seconds at which time a
gouge appeared in the chamber Wlfll and invalidated
further testing. Operation af thilll unit included 17
full-duration tests conducted at rated thrustconditions
and ambient propellant temperatures. One hot test
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