The ad in Aviation Week indicated a need for experienced engineers at NASA’s newly-minted Manned Spacecraft Center in Houston. At this time I was employed by the FAA as an engineering test pilot and engineer in Oklahoma City. With my advanced aerospace engineering degree and experience as a jet-qualified large multi-engine aircraft pilot, I had hoped to be engaged in the new US Supersonic Transport program. However that program was beset upon with both technical and political improbabilities.
I had also applied for a research pilot job opening at the NASA Lewis Research Center in Cleveland Ohio. The opening occurred because a pilot by the name of Neil Armstrong had left Lewis the fly X-15‘s at NASA’s Flight Research Center in the California desert.
I was highly encouraged when I received the resulting score for my application, but erroneously discounted my wife’s negative prayers toward a life in Cleveland. Her prayers were answered when another young NASA pilot, Fred Haise was chosen for the opening.
With a notification of my second-place standing, the Lewis Personnel Department notified me that they had forwarded my application to MSC. NASA was recruiting engineers with at least five years of aerospace experience to take on the challenge to land a man on the Moon by the end of the decade. MSC invited me to visit for an interview.
Going home to Houston was just fine with my bride! During the Easter holidays our family headed for Houston and a visit with Babs’ family…. and an interview for me at MSC’s Flight Crew Operations. During the interview I had the impression that supporting Flight Crew Operations was fairly broad-based in its mission. I felt I could be useful in the development of crew flight procedures and spacecraft trajectory development. I committed to a NASA onboard date of May 26, 1963.
Pilots Needed For Simulations
During the first few weeks at MSC I was approached with the opportunity to participate as a stand-in pilot-astronaut for the engineering simulations used in design development for Gemini and Apollo spacecraft systems. I would be used as a pilot in both aircraft and flight simulator studies. The astronauts were overloaded with training and public appearances, and they could not reliably be scheduled to perform in extended simulation studies. A few too-tall Astronaut wannabes would “Fill the bill” nicely.
In the early 1960s engineering simulations possessed limited capability to technically evaluate systems definition/development within the space program. Real-time simulations of the period were strictly limited to analog computers. Digital machine’s had not as yet attained sufficient speed to solve dynamic problems. The real time simulations at that time were usually used for aircraft stability and control configurations. The test runs were of very short time duration, one or two minutes at the most. Performance results usually were measured by test run end conditions and pilot effort (handling quality) ratings.
July 1963. The Big Question
The first major simulation program that I was assigned was a Lunar Module (LM) landing simulation at Grumman Bethpage. The task initial condition was flying horizontally at an altitude of 1000 feet and a distance of 1000 feet from a circular landing target which was 50 feet in diameter. We two NASA pilots had been advised that the Grumman pilots were having difficulty landing in the circle.
We each performed 100 runs and met the end-case criteria in less than 60 to 70 seconds runtime. Departing a very pleased set of Grumman engineers, our minds begged a different question.
“ What had happened upstream in the study of the Lunar descent trajectory that caused us to begin with the initial conditions of this manned simulation?”
…… And the Answer!
During 1963 and ‘64 the major thrust of the Lunar Landing Program was to flesh out the design concepts that were candidates for incorporation in the LM system hardware and software. The major concept driver was the amount of LM descent propellant necessary to provide reliable landing capability in light of the Lunar navigation and environmental uncertainties.
The LM structural baseline was being driven by it’s propellant tankage which was in turn directly affected by the Apollo Program baseline descent and landing procedure. The resultant increase (or decrease) in the LM gross weight drove the earth launch Apollo-Saturn “stack” gross weight The Apollo Program baseline did not take advantage of the pilot’s eyes and flying experience in the decision-making process during the approach-to-landing trajectory.
The answer to the question was “The pilot can perform the landing if he can do it successfully with equal or less propellant than the baselines Automatic System”
1964 We Have a Descent Profile!
With the help of our friends in the Guidance and Control Division, we set to work to solidify a descent profile that would satisfy both the Program Office and Flight Operations. I put my “flight dynamics hat” on to define a more flexible trajectory which could include pilot assessment of errors, their remediation and the associated propellant flexibility.
I had developed a descent profile procedure which could provide adequate LM crew visibility, decision and execution capability along with adequate abort recognition and application (R&A) time if the landing was deemed unsafe. The procedure allowed for 60 additional seconds of flexibility for the LM Pilot to make any unexpected changes in touchdown position.
After several conversations with the interested parties a baseline descent profile and procedure was approved.
1965. To Work in the Guidance and Control Division
My transfer to the Guidance and Control Division focused my attention toward the completion of the Pilot Control Requirements for the LM Primary Navigation, Guidance and Control System (PNGCS). My job description as a guidance and control system analyst also included an additional task as the Division’s simulation pilot. That task required me to recommend and demonstrate pilot skills, techniques and procedures to operate the LM PNGCS.
PILOTAGE is an important technique to be employed during lunar approach and landing. It can be defined as navigation by determining vehicle position relative to known landmarks, surface characteristics, or apparent relative motion. Pilots use this technique to operate aircraft during flights as a complement to other modes of navigation which may be degraded, inoperable or unnecessary.
During the two minutes of LM approach time in which the pilot is allowed to observe the relatively inhospitable lunar surface for an acceptable landing site, Pilotage is absolutely necessary.
LM Lunar Descent Profile
The LM lunar descent profile begins from a 60 nautical mile circular orbit with a 180 degree retrograde injection to a pericynthion altitude of 50,000 feet. Then, the powered descent is initiated to a targeted landing point about 240 miles downrange. The LM pitch angle is approximately 95° with reference to the local vertical. Essentially the LM windows are facing upward, and the crew are flat on their back with their feet pointing down range. At an altitude of approximately 40,000 feet the LM Landing Radar (LR) may begin updating the PNGCS.
At 8 1/2 minutes of powered descent, the range to the landing site approaches 26,000 feet; at an altitude of 7,600 feet the LM pitches up to an attitude of 45°. This attitude allows the pilot to see the targeted landing site in the lower 15° of his triangular window. The LM Descent Engine has been throttled back, and the LM decelerates and descends at a lower rate, allowing the pilot to assess the area for an acceptable landing point.
Within two minutes the landing point has been chosen and the final descent to touchdown is accomplished. 1 minute of Descent Engine propellant remains for contingencies.
With this profile as a requirement, the LM hardware and software development begin to take shape. The next three years were used to analyze and test the LM PNGCS to ensure it worked satisfactorily. And also analyze and test potential failure modes and methods of safely recovering to complete the mission or abort if necessary.
Disaster and Recommitment
1966 had been a less than productive year. The Apollo flight software was behind schedule in its development. The development and fabrication of the Command and Service Module (CSM) was beset with discrepancies.1967 began with “business as usual” but was quickly galvanized by the January 27th Apollo Command Module disaster. During a full-up flight simulation at the Cape a flash fire occurred within the spacecraft which killed the flight crew; Gus Grissom, Ed White and Roger Chafee. Good friends had been lost but their sacrifice would live forever.
Immediately, George Low was brought in as Apollo Program Manager. A Tiger team headed by Frank Borman was initiated to identify and resolve any deficiencies that would hinder a lunar landing by the end of the decade. Technical personnel were brought in to manage spacecraft systems that needed rework and reschedule.
I was assigned as Technical Manager of the Grumman Full Mission Engineering Simulator (FMES).
The Manned Missions Begin
Apollo 7. October 11, 1968
Wally Schirra, Walt Cunningham, Donn Eisele
11 Day CSM-Only Earth Orbital Mission demonstrated extended flight duration, Service Propulsion System (SPS) reignition capability, Rendezvous Radar transponder performance.
Apollo 8. December 21, 1968
Frank Borman, Jim Lovell, Bill Anders
6 Day CSM-Only Lunar Orbital Mission demonstrated the full CSM Earth Reentry heat shield capability, confirmed CSM/Earth communications
Apollo 9. March 3, 1969
Jim McDivitt, Rusty Schweickart, Dave Scott
10 Day CSM/LM Earth Orbital Mission demonstrated LM-active rendezvous and docking, confirmed LM Habitability
Apollo 10. May 18. 1969
Tom Stafford, John Young, Gene Cernan
8 Day CSM/LM Lunar Orbital Mission demonstrated full Lunar Mission with exception of LM Powered Descent-to-Landing
During the last half of 1968 and mid 1969 I was sharing time between Grumman Bethpage and Houston. The FMES was the simulation facility used for integrating and verifying the LM PNGCS flight hardware and software. Included also was the Stabilization and Control System hardware as well as electrical drivers for the Reaction Control System and the Descent and Ascent Propulsion controls. Wrapped around these systems was a massive digital simulation that essentially deceived the flight system into thinking it was flying. The facility was set up to support each mission one month prior to launch. The FMES tested the full up LM flight system per the specific mission flight procedures, starting with Apollo 9 and continuing with each mission thereafter.
In Houston we were focused on the Powered Descent phase only. We were testing for failure modes, abort modes, safety of flight issues and integration with the Abort Guidance System.
As we approached the launch date for Apollo 11 the focus within the Grumman FMES testing was on stressing the flight system in anyway imaginable.
The mortality of the crew was an issue that we were aware of constantly. In May 1968 we had a reminder when Neil Armstrong lost control of the Lunar Landing Research Vehicle (LLRV) and was forced to eject and parachute when only a few hundred feet above the ground.
The LM PNGCS Flight Computer with its 36 kiloword hardwired memory was purposely tortured with continuous INTERRUPT signals during powered descent simulation runs in order to identify the effects on cockpit displays and controls as well as engine commands. At night with sleep came dreams of new ways to confuse the flight system. Daylight brought execution of our previous night dreams. The flight system continued to operate robustly.
July 16, 1969. Apollo 11 Launch
Early morning coffee was served at the Center in the engineering staff support room where we watched the progress of Prelaunch Operations on our TV monitors. Launch ignition occurred about 7:30 AM. The Saturn launch vehicle did its’ job completing Translunar Injection.
Our work was not yet finished; that afternoon Grumman management informed our Division Subsystem Hardware Managers that a possibility existed that the LM Landing Radar antenna might freeze in the 25 degree approach position and not be able to rotate to the vertical landing position during the powered descent-to-landing. That failure could probably corrupt the update to the PNGCS state vector. We brought together a team and commandeered the division LM simulator to examine the problem. After several powered descent runs we determined that the antenna lockup in the approach configuration caused minimal error in the state vector and the resulting display accuracies to the pilots. All that was required was a two word pad load uplinked to the PNGCS Computer making it aware of the anomaly. The pad load was constructed and checked with several simulation flights. This time, it was early morning of the 17th. Time to freshen up and take our little surprise to Building 30 Mission Operations at their 7AM status briefing.
Operations was not really pleased with the surprise Grumman had provided us. They also were hesitant to accept the pad load which we had developed overnight. Dr. Kraft, however instructed them to check the validity of the pad load, and we hastily departed. Later that day we received a call from Dr Kraft verifying the usefulness of the payload and thanking us for our effort. Now it was time for the big quiz, and we were ready.
July 20th. The Eagle has Landed
A bit before noon, eight of us from the Guidance and Control Division were seated at a table prepared to monitor the LM descent to landing. My video display essentially contained the same LM cockpit information that I had seen for so many years and hundreds of simulator landings. We watched the data as the LM coasted to its pericynthion altitude of 50,000 feet and the ignition of the Descent Engine.
Five minutes into the descent at about 30,000 feet as landing radar initiated updates into the PNGCS, several 1201 and 1202 alarms subsequently occurred. These alarms indicated a flight computer executive overload. Essentially the computer could not do the jobs the executive assigned. Fortunately, these types of interruptions were the ones with which we mercilessly tortured the computer. Jack Garman at Mission Control was also aware of the potential anomalies and resultant tests. The call was a “GO”!
As the LM progressed to Highgate and the P64 pitch-over was executed so that Neil could see the terrain, he executed a Landing Point Designation to extend the flight trajectory. Shortly after he executed the P66 Low Gate landing mode and initiated rate-of-descent control. He had chosen his touchdown point……and not a moment too soon. Low fuel light! 60 seconds remaining! He was running out of gas! I looked for the landing probe contact light on my display. Knowing that the probes were about 4 feet long and his descent rate was about 2 ft./sec, I immediately recognized when they had touched down. Moments later, Neil made the classic statement from Tranquility Base.
After the post-landing safety checks were made we relaxed a bit. An hour later we were released from duty, and I headed home. We had a new Bell and Howell video tape recorder cocked-ready-to-record the powered descent phase from the TV network. Babs had promised to turn it on so we could see it together. We watched the recording and relaxed a bit, drinking coffee and talking about what had transpired during the day.
Then it was time for Neil to get out and take a walk on the moon. We sat quietly and just watched. What had been accomplished was just beginning to sink in. I slept well that night.
July 21st. Heading Home
I was out at the Center at 11AM to watch the noon LM lift off from the moon. The LM Descent Stage was the launch pad for the Ascent Stage hurling the crew and the rock samples home to the CSM. The thrust to weight ratio of the LM Ascent Stage and it’s engine gave an earth-like gravitational feeling to the astronauts in the cockpit, as well as fighter-like handling qualities. Three hours later the LM was station-keeping, ready to dock with the CSM.
Shortly afterward my Branch Chief, Dave Gilbert, and I sat down privately to review our accomplishments during the mission. The discussion quickly transitioned from a review to the new challenges necessary to accomplish flight readiness for Apollo 12 and its’ precision landing point requirements……in only 4 months hence.