At the same time the first Apollo launch abort test flight with the Little Joe II was taking place (see The First Apollo-Little Joe II Launch), the Apollo program was already pushing forward towards its first orbital test flight. The first mission to launch Apollo hardware into orbit, designated A-101, took place as part of the sixth test flight of the Saturn I development program called SA-6.
The Saturn I was developed for NASA at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama by a team headed by famed German-American rocket pioneer, Wernher von Braun. SA-6 was the second flight of the improved Block II model of the Saturn I with a first stage sporting eight uprated Rocketdyne H-1 engines generating a total of 1.5 million pounds-force of thrust (6,700 kilonewtons) and a live S-IV second stage. The S-IV stage employed six hydrogen-fueled Pratt & Whitney RL-10 engines to generate 90,000 pounds-force (400 kilonewtons) of thrust. This would be only the fourth flight using the RL-10 engine including the Atlas-Centaur launches which used a pair of RL-10 engines in each of two test fights launched in 1962 (a failure) and 1963 (a success). The two-stage Block II Saturn I was America’s first heavy lift launch vehicle and, with its first orbital launch on January 29, 1964 for the SA-5 mission, was the most powerful launch vehicle in the world at that time (see “The Largest Launch Vehicles Through History“).
Wernher von Braun in the blockhouse at Launch Complex 37 during the SA-6 countdown. (NASA)
Like the other early flight tests of Apollo hardware, the A-101 mission used a boilerplate model of the Apollo Command and Service Modules (CSM). Boilerplate models mimic the mass, shape and dynamic properties of flight models but otherwise only carry systems and instruments needed for the tests being conducted. Their low costs and adaptability make them ideal for early testing of a new spacecraft design. For this first test flight, the objectives included a demonstration of the compatibility of the Apollo spacecraft and Saturn launch vehicle, verification of the aerodynamic properties of the Apollo spacecraft and a demonstration of the jettisoning of the Apollo launch escape system (LES). An inexpensive and readily constructed boilerplate model was perfectly suited for this early test mission.
Apollo boilerplate BP-13 being hoisted into place on April 2, 1964 on top of SA-6. (NASA)
The payload for the SA-6 Saturn I flight was Apollo BP-13 (Boilerplate number 13). BP-13 was a 6.6 meter tall aluminum structure with a maximum diameter of 3.9 meters and mass of 7,622 kilograms. The exterior of the Command Module (CM) was covered with cork insulation to prevent overheating during ascent. In order to simulate the dynamic properties of an actual CSM combination, 1,500 kilograms of strategically placed ballast was carried in addition to instruments designed to make 116 measurements of strain, pressure and accelerations transmitted by three telemetry systems. On top of BP-13 was a 7.7 meter tall LES that would be jettisoned during ascent. Once in orbit, BP-13 and the S-IV stage of SA-6 would remain attached to each other. This satellite would have a total length of 24.4 meters and a mass of 16,900 kilograms. Data would only be collected for a few hours in orbit before the batteries were depleted and no recovery would be attempted.
Ground-level view of SA-6 at Launch Pad 37B with Apollo BP-13 as its payload. (NASA)
The S-I first stage of SA-6 arrived by barge at Cape Kennedy on February 18, 1964 and was erected on Launch Pad 37B two days later. The only major anomaly during the preshipment testing of this S-I was an engine fire during static testing in Huntsville on May 15, 1963 that resulted in damage to the stage’s engine number 8. The damaged H-1 engine, serial number H-2009, was replaced with a spare, H-2007, five days later. The stage completed its second static firing of 142 seconds on June 6 without incident. The S-IV second stage arrived by plane at Cape Kennedy on February 21, 1964. On March 19 the S-IV stage was mated to the S-I stage followed by the Instrument Unit (which controlled the Saturn I) on March 23. The Apollo BP-13 topped by the LES finished the stack on April 2.
Liftoff of the SA-6 on the Apollo A-101 mission took place at 12:07 PM EST on May 28, 1964. All eight H-1 engines of the S-I first stage operated as planned until 117 seconds into the flight. At that point, outboard engine number 8 (the same one that was replaced after the static test incident a year earlier) unexpectedly shut down 24 seconds earlier than planned. The Saturn I was designed to continue operating under an “engine out” situation like this and that capability had been tested earlier during the SA-4 test flight launched on March 28, 1963. The guidance system immediately adapted to the engine loss altering the ascent profile slightly and burning the remaining seven engines 2.7 seconds longer than planned to compensate. The S-IV stage then began its burn followed ten seconds later by the successful jettisoning of the LES. Not long afterwards, eight onboard cameras that had filmed key parts of the flight were jettisoned from the now spent S-I stage and were subsequently recovered.
Launch of the Apollo A-101 mission on SA-6 on May 28, 1964 as viewed from the launch tower. (NASA)
The hydrogen-fueled S-IV stage successfully placed Apollo BP-13 into a 182-by-227-kilometer orbit inclined 31.8° to the equator. While venting of residual propellants from the S-IV stage once in orbit had increased the roll rate to a slightly higher than planned 28° per second, orbit insertion was almost perfect and the spacecraft continued to transmit telemetry until the the fourth orbit when the batteries reached the end of their life. The now inert satellite continued its flight for a total of 54 orbits when it finally reentered Earth’s atmosphere east of Canton Island in the Pacific on June 1.
Despite the unexpected loss of engine number 8 on the S-I during ascent, all of the mission’s test objectives were successfully met. An inquiry into the engine failure by engineers from MSFC and Rocketdyne pinned the problem with engine H-2007 to a failure in the turbopump machinery resulting from the teeth in a gear being stripped. A change in the machinery that included an increased width of the affected gear’s teeth was already in the works for this particular turbopump model so the problem would not affect subsequent missions. Indeed, no problems with the H-1 engines would be encountered for the following decade of Saturn I and IB flights. And with this successful flight, the Apollo program made one more important step towards reaching the Moon.
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Related Video
Here is a short NASA film from 1964 describing the Apollo A-101 mission. It includes spectacular footage of the separation and ignition of the S-IV stage.
Related Reading
“The Coolest Rocket Ever”, Drew Ex Machina, March 30, 2014 [Post]
“The First Apollo-Little Joe II Launch”, Drew Ex Machina, May 13, 2014 [Post]
General References
Roger E. Bilstein, Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles, University Press of Florida, 2003
Alan Lawrie, Saturn I/IB – The Complete Manufacturing and Test Records, Apogee Books, 2008
Mary Louise Morse and Jean Kernahan Bays, The Apollo Spacecraft – A Chronology Volume II, SP-4009, NASA, 1973