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<!DOCTYPE HTML>
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<title>Chariots For Apollo, ch6-5</title>
<meta http-equiv=Content-Type content="text/html; charset=UTF-8">
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<BODY BGCOLOR="#FFFFFF">
<p>
<h2>Engines, Large and Small</h2>
<p>
When Grumman began designing the lunar module in January 1963, its major
subcontractors began work on the vehicle's integral subsystems: Bell
Aerosystems, ascent engine; Rocketdyne Division of North American,
descent engine; The Marquardt Corporation, reaction control system; and
Hamilton Standard Division of United Aircraft Corporation, environmental
control. Identifying rocket engines as the most critical subsystem,
Grumman started their development first. The lander had 18 engines: 2
large rockets, one for descent to the moon and another for return to
lunar orbit, and 16 small attitude control engines clustered in quads
and pointing up, down, left, and right, around the ascent stage.<a href
= "#source22"><b>22</b></a><p>
During the spring of 1963, Grumman hired Bell to develop the ascent
engine, basing the selection on Bell's experience in Air Force Agena
development and hoping that the technology from that program might be
applicable to the lunar module. Grumman placed heavy emphasis upon high
reliability through simplicity of design, and, in fact, the ascent
engine did emerge as the least complicated of the three main engines in
the Apollo space vehicle (the descent and service module engines were
the other two).<a href = "#explanation1"><b>*</b></a> Embodying a
pressure-fed fuel system using hypergolic (self-igniting) propellants,
the ascent engine was fixed-thrust and nongimbaled, capable of lifting
the ascent stage off the moon or aborting a mission should a landing not
be feasible.<p>
There was one major concern about the ascent engine, and that was the
usual worry about the ablation material burning off too fast and causing
damage to the thrust chamber. Some ablative material eroded during
firing tests at Bell's plant near Niagara Falls and at the Arnold
Engineering Development Center in Tennessee. But this erosion was not
severe enough to warrant changes in the combustion chambers. In late
1964, Arnold was also the site of a fire-in-the-hole (FITH) static firing
test on a full-scale vehicle to supplement Grumman's previous
scale-model test. The FITH flight test had to wait for later trials at
White Sands.<p>
Not everything went well with ascent engine development, however. About
a year after the program began, the subsystem manager in Houston
discovered that Grumman and Bell were using testing criteria left over
from the Air Force Agena program. Since the Agena was unmanned, these
were less stringent than NASA demanded for manned spacecraft. More
rigorous standards were belatedly imposed by Houston, and a problem was
revealed. In "bomb stability" tests, where the engine had to
recover from combustion instability caused by an explosive charge within
the combustion chamber, the ascent engine "went unstable"
(failed to return to normal operation), and structural damage followed.
This problem would have to be resolved before the engine could be
trusted to bring a crew back from the lunar surface.<a href =
"#source23"><b>23</b></a><p>
The lunar module descent engine probably was the biggest challenge and
the most outstanding technical development of Apollo. A requirement for
a throttleable engine was new to manned spacecraft. Very little advanced
research had been done in variable-thrust rocket engines - NASA's
principal effort in this field, the hydrogen-fueled RL-10 used in the
S-IV stage of the Saturn, antedating work on the lunar module engine by
only a few months. Rocketdyne proposed a method known as helium
injection, introducing inert gas into the flow of propellants to
decrease thrust while maintaining the same flow rate. Although Bethpage
and Houston agreed that this seemed a plausible approach to
throttleability, it would be a major advance in the state of the art,
and the MSC Apollo office directed Grumman to carry out a parallel
development program and select the better design.<p>
On 14 March 1963, Grumman held a bidders' conference, attended by
representatives from Aerojet-General, Reaction Motors Division of
Thiokol, United Technology Center Division of United Aircraft, and Space
Technology Laboratories, Inc. (STL). In May, STL (which had lost out in
the original bidding for the engine) was selected to develop the
competitive motor. STL proposed a pressure-fed hypergolic system that
was gimbaled as well as throttleable. The engine's mechanical throttling
system used flow control valves and a variable-area injector, in much
the same manner as does a shower head, to regulate pressure, rate of
propellant flow, and the pattern of fuel mixture in the combustion
chamber.<p>
With two subsystem contractors working on such radically different
throttling techniques, NASA planners, as Rector later said,
"thought one or the other would stub his toe real quick . . . ,
that it would be obvious that we should go one [way] or the other - but
it wasn't happening. They were both . . . pretty good. . . ." STL
and Rocketdyne continued this head-to-head competition for the final - and
lucrative - engine development and qualification contract through the end
of 1964.<a href = "#source24"><b>24</b></a><p>
In November 1964, Joseph Shea, Apollo spacecraft manager in Houston,
told NASA Apollo Program Director Samuel Phillips in Washington that he
had established a committee<a href = "#explanation2"><b>**</b></a> of
propulsion experts from Grumman, the Marshall and Lewis centers, NASA
Headquarters, and the Air Force to review the contractors' efforts and
recommend a choice. Selection of one firm over the other rested with
Grumman and MSC, in the final analysis, and, Shea stated, "I do
feel that we should have the intelligence at our disposal to appreciate
all ramifications of [Grumman's] final recommendation."<p>
Panel members visited both companies the week of 7 December 1964, but
their findings were largely inconclusive. The progress of each firm was
nearly identical. Both contractors, although experiencing minor troubles
with injector designs, demonstrated satisfactory structural
compatibility between injector and thrust chamber. After a year and a
half, neither helium injection nor mechanical throttling had proved
superior over the other. On 5 January 1965, Grumman decided to stick
with Rocketdyne.<a href = "#source25"><b>25</b></a><p>
Manned Spacecraft Center Director Gilruth appointed a five-member
board<a href = "#explanation3"><b>***</b></a> to weigh Grumman's
recommendations, review the findings of the earlier committee, and study
a technical comparison prepared by Houston's Propulsion and Power
Division. On 18 January this review board, in a surprising move,
reversed Grumman's action and named STL instead of Rocketdyne. The board
said that the
<blockquote><p>recommendation of STL is based upon the assessment that STL
is in a more favorable position [and] is capable of supplying more
management and superior resources to this program without interference
of other similar programs. . . . there are potential benefits to be
gained for the Gemini and Apollo attitude engine programs at NAA by the
cancellation of the [Rocketdyne] descent engine development.<a href =
"#explanation4"><b>****</b></a></blockquote><p>
This decision, unusual because Houston rarely vetoed a recommendation
for a subcontractor made by a prime contractor, was sustained by
Phillips at Headquarters. Shea and Contracting Officer James L. Neal
then directed Grumman to proceed with STL.<a href =
"#source26"><b>26</b></a><p>
Grumman chose Marquardt to build the lunar module's third engine system,
the small 100-pound-thrust attitude control thrusters. In 1960, Warren
P. Boardman and Maurice Schenk of Marquardt had visited Robert Piland
and Caldwell C. Johnson at Langley to discuss their firm's propulsion
work. Piland and Johnson were intrigued with the idea for a bipropellant
thruster that promised to be far superior to the monopropellant engine
then used in Mercury. Testing of Marquardt's product - a dual-valve,
pulse-modulated engine with a radiation-cooled combustion chamber - at
the Lewis Research Center paved the way for its incorporation into
Apollo. Marquardt at first supplied engines for both the command and
service modules. In mid-1962, NASA decided to use the Marquardt engine
for the service module only, because the command module thrusters would
be buried within the heatshield, making radiation cooling impossible.
Rocketdyne would supply the command module thrusters, which were similar
to those it was already developing for Gemini.<p>
Marquardt would furnish attitude control engines and mounting structure
and perform some tests of the propellant system. Grumman would provide
tanks (purchased from Bell), propellant lines, and the pressurization
system. Apollo officials had expected that the service module thrusters,
with only slight modifications, could also be used in the lander, but
common use proved difficult. The end results, though beneficial, fell
far short of Houston's anticipations. Differing functional requirements,
as well as unique environmental and design constraints, precluded direct
incorporation of the service module thruster. Houston, however,
complained that Grumman failed to take advantage of all the common-use
technology available and attributed delays in procurement of many
thruster components to this failure.<a href =
"#source27"><b>27</b></a><p>
After thruster tests at Bethpage and at Marquardt's Magic Mountain
Facility in California during the first half of 1964, a technical
problem emerged: the engine spiked, or backfired, at ignition, and a
rapid rise in temperature and pressure caused the engine to explode. The
spiking appeared so significant that Grumman wanted to develop a backup
engine through another source, but Houston refused permission. Marquardt
eliminated spiking by installing a small, tubular
"precombustion" chamber inside the engine.<a href =
"#source28"><b>28</b></a>
<p>
<hr>
<p>
<a name = "explanation1"><b>*</b></a> The rocket engine of the ascent
stage developed about 15,500 newtons (3,500 pounds) of thrust, which
produced a velocity of 2,000 meters per second from lunar launch to
docking. The descent stage, a throttleable engine, reached a maximum of
43,900 newtons (9,870 pounds) and operated at a minimum of 4,700 newtons
(1,050 pounds) for delicate maneuvers. Considerably larger than the two
lunar module engines, the service module motor attained 91,200 newtons
(20,500 pounds) of thrust.<p>
<a name = "explanation2"><b>**</b></a> Committee members were Max Faget
(chairman), Rector, Joseph G. Thibodaux, and C. Harold Lambert (MSC);
Charles H. King and Adelbert O. Tischler (NASA Headquarters); Leland F.
Belew (Marshall); Irving A. Johnson (Lewis); P. Layton (Princeton
University); Major W. R. Moe (Edwards Rocket Research Laboratory, USAF);
and Joseph M. Gavin and M. Dandridge (Grumman).<p>
<a name = "explanation3"><b>***</b></a> Members of the Subcontractor
Review Board for the LEM Descent Engine were Faget (chairman), Dave W.
Lang (Procurement), André J. Meyer, Jr. (Gemini), Joseph G.
Thibodaux, Jr. (Propulsion and Power Division), and Rector.<p>
<a name = "explanation4"><b>****</b></a> Gemini manager Charles W.
Mathews was having trouble getting reliable engines for his spacecraft
from Rocketdyne. In its decision, the board was obviously supporting
both his program and Apollo.
<p>
<hr>
<p>
<a name = "source22"><b>22</b>.</a> Neal TWX to Small, 29 Jan. 1963; MSC
news release 63-14, 30 Jan. 1963; Grumman, "LM System
Description," from information package for <cite>Apollo 11</cite>,
July 1969; Bell Aerosystems, "Bell Aerosystems Company and Apollo
11," news release, July 1969; Aerojet-General, "Fact Sheet
about the Main Rocket Engine for the Apollo Command and Service
Modules," news release, July 1969; William R. Hammock, Jr., Eldon
C. Currie, and Arlie E. Fisher, "Descent Propulsion System,"
AER TN S-349 (MSC-05849), review copy, October 1972; Clarence E.
Humphries and Reuben E. Taylor, "Ascent Propulsion System,"
AER TN S-341 (MSC-04928), review copy, May 1972; Chester A. Vaughan et
al., "Lunar Module Reaction Control System," AER TN S-315
(MSC-04567), review copy, December 1971.<p>
<a name = "source23"><b>23</b>.</a> Dave W. Lang TWX to NASA Hq., Attn.:
Brackett, 5 Feb. 1963; Clyde B. Bothmer to George M. Low, "Bell
Aerospace Contract for LEM Engine," 11 Feb. 1964; LEM Program
Management Meeting, Grumman NASA, 22 April 1964; Rector TWX to Grumman,
Attn.: Mullaney, 21 Aug. 1964; minutes of LEM Ascent Propulsion
Subsystem Schedule and Technical Status Meeting at Grumman, 16–17 Sept.
1964; ASPO Weekly Management Reports, 23–30 July 1964 and 21–28 Jan.
1965; Rector TWXs to Grumman, Attn.: Mullaney, 2 Sept. 1964; Rector and
Gavin interviews; Alexander L. Madyda to LEM PO, "Response of GAEC
Propulsion to MSC Requests and Directions," 5 Nov. 1964.<p>
<a name = "source24"><b>24</b>.</a> House Committee on Science and
Astronautics, <cite>Astronautical and Aeronautical Events of 1962:
Report,</cite> 88th Cong., 1st sess., 12 June 1963, p. 145; Neal to
Grumman, Attn.: Snedeker, "Descent Engine Subcontract," 12
Aug. 1963; Rector interview; Charles W. Mathews to Asst. Dir., Research
and Dev., "Procurement Plan for Apollo Supporting Research -
Throttleable Engine Development," 16 Aug. 1962; Robert H. Voight to
Asst. Mgr., ASPO, "Parallel Development LM Descent Engine, Grumman
Aircraft Engineering Corporation, Audit Report MSC 11-67A," 8 March
1967; RASPO Grumman Activity Report, 10–16 March 1963, p. 1; Carl D.
Sword TWX to Grumman, Attn.: Snedeker, 27 May 1963; MSC news release
63-92, 29 May 1963; R. F. Mettler TWX to Charles W. Frick, 20 Nov. 1962;
Gavin interview; Jack N. Cherne, "Mechanical Design of the Lunar
Module Descent Engine," paper presented at the 18th International
Astronautical Congress, Belgrade, Yugoslavia, 24–30 Sept. 1967, p. 1;
Rector TWX to Grumman, Attn.: Mullaney, 5 May 1964; Roger D. Hicks to
Chief, Propulsion and Power Div. (PPD), "Report of trip to
Rocketdyne and STL, July 8 and 9, 1964," 10 July 1964; MSC Weekly
Activity Report for Assoc. Admin., OMSF, NASA, 28 June–4 July 1964, p.
3; Rector and Mullaney interviews.<p>
<a name = "source25"><b>25</b>.</a> Shea to Maj. Gen. Samuel C.
Phillips, 25 Nov. 1964; Shea TWX to STL, Attn.: J. Elverum, 30 Nov.
1964; Robert W. Polifka to Chief, PPD, "Trip to White Sands Missile
Range, . . . STL, . . . and Rocketdyne . . . in review of Rocketdyne and
STL LEM descent engine injector development, August 16–21, 1964,"
26 Aug. 1964; Voight to ASPO, 8 March 1967; Maxime A. Faget to Mgr.,
ASPO, "LEM Descent Engine Subcontractor Review," 23 Dec. 1964,
with encs.; Gavin to MSC, Attn.: Rector, "Selection of the LEM
Descent Engine Contractor," 5 Jan. 1965.<p>
<a name = "source26"><b>26</b>.</a> Gilruth to Asst. Dir., Eng. and
Dev., "LEM Descent Engine Subcontractor Review Board," 8 Jan.
1965 (identical memos sent to Chief, Procurement and Contracts Div.;
Senior Asst., Gemini Prog. Off.; Chief, PPD; and LEM PO, ASPO); Faget to
Dir., MSC, "LM Descent Engine Subcontractor Review Board
Report," 20 Jan. 1965, with enc., subject as above, 18 Jan. 1965;
Mathews to NASA Hq., Attn.: William C. Schneider, "Rocketdyne
Performance on the Gemini Program, . . ." 29 April 1964, with
encs.; Charles W. Yodzis to Chief, PPD, "Evaluation of Parallel LEM
Descent Engine Contracts," 11 Jan. 1965; Voight to ASPO, 8 March
1967.<p>
<a name = "source27"><b>27</b>.</a> MSC, Consolidated Activity Report,
24 Feb.–23 March 1963, p. 7; Piland note, 9 Dec. 1960; Charles J. Donlan
to LeRC, Attn.: Bruce T. Lundin, "Proposed program with Lewis
Research Center for evaluating developments in bipropellant reaction
control systems," 17 Nov. 1960, with enc.; Donlan to NASA Hq.,
Attn.: Low, "Support from Lewis Research Center for evaluating
developments in satellite attitude controls for application to Project
Apollo," 6 Dec. 1960; A. B. Kehlet et al., "Notes on Project
Apollo, January 1960–January 1962," 8 Jan. 1962, p. 12; D. Brainerd
Holmes to Assoc. Admin., NASA, "Change in Subcontractors for Apollo
Command Module Reaction Control Jets," 24 July 1962; Caldwell C.
Johnson TWX to North American, Attn.: E. E. Sack, "Command and
Service Module Reaction Control System Engines," 31 July 1962;
Decker TWX to Sack, 25 March 1963; Small to Decker, "Review of GAEC
Specification . . . for the Reaction Control System," 30 April
1963; Neal TWX to Grumman, Attn.: Snedeker, 15 July 1963; Maynard to
Grumman, Attn.: Mullaney, "Reaction Control Subsystem, . . . Bell
Aerosystems Company Proposal, . . . dated November 1963," 3 Dec.
1963; Faget to Systems Evaluation and Dev. (SEDD), Spacecraft Research,
and Life Systems Divs., "Investigation of similar or near similar
systems, subsystems and components on Mercury, Gemini and Apollo
(including Lunar Excursion Module) spacecraft," 17 Aug. 1962;
Rector to Decker and Neal, "Proposed Reply to GAEC TWX
LTX-150-7," 2 July 1963; Rector to Maynard and Alfred D. Mardel,
"Differences in Development, Environmental, Quality Assurance, and
Reliability Requirements between NAA/S&ID and GAEC for Potential
Common Usage Items," 17 Feb. 1964; Rector to Grumman, Attn.:
Mullaney, "LEM RCS Tank Specification No. LSP-310-405," 16
March 1964; B. Darrell Kendrick to LEM PO, "LEM RCS Propellant
Tanks," 23 April 1964; abstract of Proceedings, LEM RCS Meeting on
9 April 1964; Witalij Karakulko to Chief, PPD, "Review of the
problems associated with the common usage components of the LEM
RCS," 22 May 1964; Rector to Neal, "Implementation of the
common usage rule in LEM RCS components," 9 July 1964, with enc.;
Shea to NASA Hq., Attn.: George E. Mueller, "Grumman," 1 Aug.
1964; Rector to Chief, SED, "LEM RCS Propellant Quantity Gaging
System Design Approach," 30 Oct. 1964; Gaylor to Small, "Past
RASPO Activity Report Status on C. U. RCS Components," 20 Oct.
1964.<p>
<a name = "source28"><b>28</b>.</a> ASPO Weekly Management Report, 30
July–6 Aug. 1964; Decker TWX to Grumman, Attn.: Mullaney, 26 Aug. 1963;
LEM PO, "Problems," 14–20 May 1964; Richard B. Ferguson memo,
"SM and LEM Reaction Control Engine Development?" 8 June 1964; Gary
A. Coultas to Chief, Design Integration Br., "Trip report Service
Module/LEM RCS engines, the Marquardt Corporation," 25 June 1964;
Rector to Grumman, Attn.: Mullaney, "Thermal analysis of the SM/LEM
RCS Engine," 20 July 1964, with encs.; Rector to LEM Proc. Off.,
"GAEC Request for Development of Backup Source for a 'Common Usage'
RCS Engine," 21 July 1964; Henry O. Pohl to Chief, PPD,
"Meeting with The Marquardt Corporation (TMC) and North American
Aviation (NAA) to discuss the ignition pressure spike problem," 28
July 1964; Karakulko to Chief, PPD, "Trip report to The Marquardt
Corporation (TMC)," 2 Dec. 1964; Marquardt, Apollo Service Module
Reaction Control Engines, Monthly Progress Report, TMC Project 279,
A-1011-26, 30 Sept. 1964, pp. iii, 30.
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