Moon Lander: How We Developed the Apollo Lunar Module (Smithsonian History of Aviation and Spaceflight)

by Kelly, Thomas J.

  6

  Mockups

  I enjoyed building model airplanes as a teenager, even though I was not skilled at it. I particularly liked working on the finishing touch: covering the balsa-wood framework with a paper skin and using dope or paint to shrink it tightly over the structure. I often worked with a classmate who excelled at making models, and he helped me build some fairly good looking ones. Most of my models were detailed replicas of real airplanes, which I chose for their graceful appearance. They were flyable, rubber-band-powered models, and I made sure they could all fly adequately, although my main interest was in building rather than flying them. Most elaborate of all my models was a Waco low-wing monoplane. It had an enclosed two-place cockpit with sliding cellophane glass cover, a radial engine, and streamlined wheel pants covering the fixed landing gear. Painted dark blue and white, it was probably my best-looking model airplane.

  Now to my great delight I realized that I would be building models again—this time full-sized mockups of the LM. We needed the mockups in order to fit check the LM’s complex shapes and assemblies and to determine whether astronauts and ground crews would be able to perform all required functions during the mission and during prelaunch preparations and maintenance. At contract negotiations in Houston we had agreed upon a long list of full and partial LM mockups. In the ensuing months we shortened the list to concentrate on three mockups during the first year of the LM program: M-1, a wooden mockup of the ascent stage and crew compartment; TM-1, a wooden model of the complete LM; and M-5, a detailed metal model of the entire LM.

  M-1

  As our ideas took shape for the standup crew position and cylindrical flat-faced crew compartment with canted triangular windows, we checked out their feasibility in a simple wood-and-foam-board mockup of the forward interior portion of the cockpit. We converted this mockup into drawings and sketches from which the more complete M-1 could be made, adding the tanks, rocket engine bell, electronic equipment bay, antennas, and other external features of the LM ascent stage. Throughout spring and early summer 1963 the engineering design groups added to this mockup design definition. A formal review of M-1 was scheduled with NASA for mid-September.

  A wave of anticipation swept over me when I saw the NASA review team list: in addition to Gilruth, Faget, Maynard, Rector, and others with whom I was acquainted or had regular dealings, it included the Mercury astronauts and Walter Williams, director of Manned Spaceflight Operations. The Mercury Seven—Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, and Deke Slayton—were world-famous spaceflight pioneers. They would be right here working with us in Bethpage, just like professional colleagues! I looked forward to meeting them and profiting from their precious experience in space.

  The M-1 was displayed in Grumman’s mockup room in Plant 5, where the navy’s mockup reviews were also held. Plant 5 was a large, roughly square, high-bay area with a polished black-asphalt tile floor and white cinder-block walls. Large steel trusses, visible under the ceiling, supported the roof, and rows of fluorescent light fixtures were suspended from them. A traveling overhead crane was available to move large mockups throughout the room. The ceiling was three stories high. At the second- and third-story level on one wall were exposed balconies and catwalks leading into interior laboratories and the Preliminary Design center, protected by waist-high chainlink guardrails. This area was known as the “hanging gardens.” From the balconies one could look down on the whole panorama of a mockup review in progress. Spotlights were mounted on the roof trusses and the balconies when needed for extra illumination of the mockups.

  The M-1 did not need any special lighting, but we mounted the ascent-stage mockup on a low platform and added steps to the platform for easy access. Several rows of collapsible metal chairs with armrests were arranged facing a metal conference table and lectern in front of the mockup. A small speaker and microphone on the lectern provided voice amplification in the cavernous hall.

  On 16 September 1963 the mockup room was full of NASA and Grumman officials and participants, sending a busy hum of conversation up to the exposed rafters. George Titterton and Joe Gavin welcomed our visitors to Grumman’s first formal review by NASA on the Apollo program, and Bob Gilruth responded that they were glad to be here and pleased to have Grumman on the Apollo team. Several more conference tables and chairs had been set up to accommodate the large NASA delegation. The Mercury astronauts and Walter Williams sat front and center next to Gilruth, Maynard, and Rector. The astronauts were kept busy signing autographs for awed Grummanites until the meeting was called to order.

  For the next two days the astronauts and engineers explored every aspect of M-1. Our Crew Systems Section leaders, John Rigsby and Gene Harms, and Human Factors Section head, Howard Sherman, together with their NASA counterparts, George Franklin and others from the Houston Crew Systems Group, guided the astronauts through various drills inside the LM cabin. They tried getting in and out through the front hatch wearing a simulated backpack (no good, too tight), checked out the hand controllers and visibility out the windows from the pilot and copilot stations, evaluated the displays, controls, and equipment stowage within the cabin, and tried and discussed alternative schemes for providing restraint while piloting LM and while resting and sleeping. The astronauts liked the standup crew stations and the wide field of view provided by the windows. They asked whether the forward landing gear footpad would be visible out the window—it would. We drew a chalk circle on the floor with the footpad’s proper size and position so they could see it from inside M-1.

  For restraint at the pilots’ stations Rigsby and Harms demonstrated a spring-tensioned cable-and-pulley arrangement, anchored to the cabin floor and clipped onto either side of a belt each astronaut wore. They provided slipper-shaped foot restraints into which the astronauts’ boots would fit while they stood in the pilot station. With minor adjustments and improvements this met with crew approval. There was less agreement on the rest and sleep provisions. M-1 showed the crew leaning against the rear bulkhead behind the cylindrical table-high cover over the ascent rocket engine, restrained for sleep by an open-mesh hammock. This met with grudging tentative approval, accompanied by a plea for us to do better if possible.

  As the review progressed my colleagues and I sensed a difference in attitude toward Grumman among some of our celebrity visitors. Some of them, notably Bob Gilruth, John Glenn, and Wally Schirra, were very welcoming and supportive to us as the newest members of the manned spaceflight team. They seemed eager to share with us experiences they considered possibly useful in designing the LM, and they did it straightforwardly, treating us as professional colleagues and peers. Others, particularly Walter Williams and Alan Shepard, made it clear that they thought the Grumman people were space “greenhorns” who had much to learn and were not in the same league as themselves. This attitude was conveyed indirectly, as I overheard snatches of their conversations with one another and watched whispering, elbow digging, and sniggering when Grumman people were presenting their views. Some of them were condescending; others were even rude. Maynard and Rector noticed some of the byplay and counseled us to ignore it. They told stories about some of the Mercury astronauts to assure us that it was nothing personal against us or Grumman—they were like that with everyone.

  On 18 September the Mockup Review Board met, with Maynard as chairman, Rector, Chris Kraft, and Deke Slayton for NASA, and Carbee and me for Grumman. There were only a few dozen chits and they were readily disposed of—most called for minor changes or further study of known problem areas. One thing the astronauts insisted upon was identical displays at both crew positions, including the eight-ball flight attitude indicator. M-1 showed some displays shared between pilot and copilot, but this was clearly unacceptable to the veteran astronauts and we acquiesced to their wishes.

  The board approved M-1 with the agreed-upon changes. I was relieved that our basic crew compartment design approach was acceptable to the astronauts and that we could
proceed with it. We had jumped over our first major Apollo program hurdle, clearing the bar with many inches to spare.

  At home Joan was nearing the end of her fifth pregnancy, and that night she was very restless and uncomfortable. In the morning she asked me not to go right into work because she felt something was about to happen. By mid-morning we were at Huntington Hospital, and not long afterward she delivered a beautiful nine-pound baby girl, whom we named Jennifer. The baby was delivered by the doctor under the old rules, which meant I was not allowed to participate in any way. I learned the good news from a nurse as I waited anxiously in the hospital lobby. They took the baby away from Joan right after birth (why did we let them get away with such things back then?), but she soon demanded to see her, and the nurse relented and brought in our newest treasure. I saw the little darling through the glass window in the nursery.

  Having just completed the M-1 review, I took a couple of days off from work and proudly drove Joan and Jennifer home in brilliant sunshine to the greetings and (germ-laden) kisses of our four boys. We had so much to be thankful for. I had it all: a talented, beautiful, loving wife; five marvelous growing children; and a fulfilling, exciting career. What more could one ask for?

  TM-1

  Our next mockup was a full-sized wooden model of the complete LM, descent and ascent stages, containing as much engineering detail as we could get into it before the review in March 1964. Its focus was on the crew compartment—especially the support and restraint, displays and controls, equipment stowage, and lighting—and on egress to the lunar surface. We were able to include realistic mockups of some equipment, such as the ascent and descent, engines, environmental control system components, and radar and communications antennas. Working models of the hand controllers with which the astronauts would fly the LM were provided at both pilot stations, allowing the crew to experience the tactile feel of the controls as they stood in flight position hooked into the support and restraint devices.

  All the LM design configuration decisions that had been made since M-1 were rushed into TM-1, often by using sketches or engineers’ “arm-waving” in the mockup shop, so that by the time the mockup review convened on 24 March they saw an up-to-date LM as it was then defined. Only Deke Slayton of the Mercury astronauts attended this review because the others were busy with their crew assignments in Project Gemini, which was at a peak of flight activity. Several astronauts from the second group, selected in April 1962, participated, with Ed White and Charles “Pete” Conrad designated to give LM special attention.

  Grumman had learned from the M-1 review that the astronauts had to be treated as a special breed. We needed to communicate with them through another pilot; no Earth-bound engineer or manager, no matter how capable, would command their full respect. Jack Stephenson, our LM consulting pilot, was asked to act as liaison to the astronauts, to make that his priority while continuing the engineering consultation and simulator flying and development that had been his primary activities. Stephenson was an experienced navy pilot and honors graduate of the Air Force Experimental Test Pilots School. With more than forty-four hundred hours of flying time in twenty-seven types of military aircraft, he was in the same experience bracket as the astronauts. At Grumman he was the project pilot on the A2F-1 Intruder, conducting engineering development flights of its complex weapons systems and man-machine interfaces. Stephenson had helped us during the LM preproposal studies and proposal, and since the contract award had been with LM full time.

  To enable Stephenson to manage his expanded role we authorized an assistant for him. He selected Scott MacLeod, a former navy fighter pilot who had flown many Grumman airplanes, including the swept-wing F9F-5 jet. At Grumman MacLeod was a production pilot in the Flight Test Department flying aircraft as they came off the assembly line. Stephenson and MacLeod worked directly with the astronauts on TM-1, forging personal bonds through joint problem solving.

  Prior to the TM-1 review we had given considerable thought to the problem of egress to the lunar surface. To help evaluate possible techniques, Rigsby and Sherman designed an apparatus called the “Peter Pan rig,” a cable-and-pulley device suspended from the mockup room’s overhead traveling crane that counterbalanced five-sixths of a spacesuited subject’s weight. This crudely simulated the gravitational force on the lunar surface, which is one-sixth that of Earth. By supporting the subject from a chest harness, belt, and thigh straps attached to the Peter Pan rig and moving the overhead crane to follow the subject’s movements, we could evaluate the feasibility and relative difficulty of performing various maneuvers on the Moon’s surface.

  We evaluated a number of means of getting onto the lunar surface and back into the LM. We thought it could be done by using a knotted rope to climb up and down from the LM and a block and tackle to lower and raise scientific equipment and sample containers. This required a platform on top of the landing-gear support strut in front of the forward hatch upon which the astronaut could stand before descending the rope. This platform was nicknamed the “front porch.” Stephenson and Harms tried this maneuver in spacesuits a few days before the review. They found it slow and strenuous but feasible. Objective evaluation was difficult because it took time and practice to adapt to the Peter Pan rig and attain proficiency in moving about with it. We definitely needed NASA’s opinion.

  During the formal mockup review eighty NASA engineers and astronauts inspected TM-1 and wrote more than one hundred chits, fifty-two of which were presented to the review board. Improvements were made in the feel and positioning of flight controls, equipment stowage within the cabin, the positioning of circuit breakers switches, and other crew compartment internal details. After a full day of evaluation by Ed White, Grumman’s proposed use of rope, block, and tackle for lunar surface egress was declared unacceptable. White found it too difficult and unnecessarily hazardous for what should be a routine activity. We agreed to devise alternate schemes and to conduct evaluation sessions on the Peter Pan rig with Ed White and others, aiming at a decision review on TM-1 in May 1964. The cabin lighting was also considered in need of further improvement, especially the electroluminescent panels. A lighting review was scheduled to take place in May (at the same time as the egress evaluation) with the astronauts.

  The issue of whether LM needed docking capability at the front hatch in addition to the overhead hatch was examined by the TM-1 review team. Forward docking was a hangover from Grumman’s LM proposal but was no longer considered necessary for redundancy. The remaining argument in its favor was LM pilot visibility during the close docking approach maneuver. LM would be the active vehicle during rendezvous maneuvers and approach to the CSM. The LM pilot would fly this segment from his normal flight position, standing in his flight station and looking at the CSM out the front window. If LM could dock with its front hatch upon return from the Moon, the LM pilot would not change his flight position when he handed off active maneuvering command to the CM pilot, who would capture and dock the LM.

  I thought it desirable to eliminate the docking requirement from the forward hatch for several reasons. It would save weight by eliminating the forward docking tunnel and docking impact loads on the front face structure, and it would give us more design flexibility with the forward hatch if we needed it to be larger or other than circular. We could probably simplify the hatch-locking mechanism as well. Both Grumman and NASA engineers had suggested that a small rectangular window be placed in the cabin ceiling, directly over the LM pilot’s head, to provide visibility of the CM during the close docking approach maneuver.

  During the TM-1 review, White, Conrad, and others evaluated this possibility They tried bending their heads backward to look out the overhead window while wearing spacesuits and restrained at the normal flight station. They noted the difficulty of using the LM controls in this position and of switching eye contact back and forth between the instrument panel and the overhead window. They concluded that the position was somewhat awkward but not unworkable, and it would probably be easier
at zero gravity. The astronauts recommended and the board approved a month of study and simulation at Houston before making a final decision, but the overhead docking scheme appeared promising.

  TM-1 had most of the electronic equipment mounted externally on the ascent stage behind the pressurized crew compartment. The electronic “black boxes” were mounted on vertical racks facing each other, with a ladder up the side aiding access. During the review a simpler concept of mounting the boxes lengthwise on vertical rails in a single array facing aft was discussed with NASA and accepted for further study.

  Several other TM-1 design issues were reviewed with NASA, including the stowage of scientific equipment in the descent-stage bays, the placement of antennas and of handholds to aid crew mobility on both stages, and ground clearance of the descent engine bell. The review stimulated ideas from NASA and Grumman on means of resolving these and other issues. We also used TM-1 during discussions with LM Manufacturing on possible design and manufacturing approaches to building the front face of the crew compartment. It was a flat, pressurized, sheet-metal structure with complex geometry and angles and major penetrations for the forward hatch and windows. I favored welded construction in order to save weight and provide a leak-tight compartment, but the geometry appeared to preclude that solution.