This 1966 illustration depicts the J-2 engine of the S-IVB third stage firing to send the Apollo spacecraft to the Moon. (NASA)
16 July 1969: At 16:16:16 UTC, T+02:44:16.2, the Apollo 11 S-IVB third stage engine reignited for the Trans Lunar Injection maneuver.
One of the necessary features of the Rocketdyne J-2 engine was its ability to restart. The third stage was first used to place the Apollo 11 spacecraft into Earth orbit and was then shutdown. When the mission was ready to proceed toward the Moon, the J-2 was re-started. Using liquid hydrogen and liquid oxygen for propellant, Apollo 11′s S-IVB burned for 5 minutes, 41.01 seconds, with the spacecraft reaching a maximum 1.45 Gs just before engine cut off. The engine was shut down at T+02:50:03.03. Trans Lunar Injection was at 16:22:13 UTC.
Apollo 11 S-1C first stage separation at 2 minutes, 41 seconds, altitude 42 miles (67.6 kilometers), speed 6,164 mph (9,920 kph), has burned 4,700,000 pounds (2,131,884 kilograms) of propellant. (NASA)
16 July 1969: At 13:34:42.30 UTC, 2 minutes, 42.30 seconds after launch, the S-IC first stage of the Apollo 11/Saturn V has burned out and is jettisoned. Apollo 11 has reached an altitude of 42 miles (68 kilometers) and a speed of 6,164 miles per hour (9,920 kilometers per hour). The five Rocketdyne F-1 engines have burned 4,700,000 pounds (2,132,000 kilograms) of liquid oxygen and RP-1 propellant.
After separation, the S-IC first stage continued upward on a ballistic trajectory to approximately 68 miles (109.4 kilometers) altitude, reaching its apex at T+4:29.1, then fell back to Earth. It landed in the Atlantic Ocean approximately 350 miles (563.3 kilometers) downrange.
Apollo 11 gains altitude while the first stage Rocketdyne F-1 engines increase thrust. (NASA)
16 July 1969: Apollo 11/Saturn V AS-506 accelerates with all five Rocketdyne F-1 engines burning. As the rocket climbs through thinner atmosphere, the engines become more efficient and the total thrust for the S-IC first stage increases from 7,648,000 pounds of thrust to 9,180,000 pounds of thrust at about T+1:23.0.
In order to limit acceleration, a pre-planned signal to cut off the center engine is sent at T+2:15.2 (Center Engine Cut-Off, “CECO”). As the first stage burns fuel at a rate of 13 tons per second, the rapidly deceasing weight of the Saturn V and the increasing efficiency of the F-1 engines could cause the limits of vehicle acceleration to be exceeded.
Launch Vehicle acceleration vs. time
By T+2:30, the Saturn V has reached an altitude of 39 miles (62.8 kilometers) and is 55 miles (88.5 kilometers) downrange.
The photograph above was taken by a 70mm telescopic camera aboard a USAF/Boeing EC-135N A/RIA (Apollo Range Instrumentation Aircraft) serial number 60-374. The airplane is in the collection of the National Museum of the United States Air Force.
16 July 1969: At 1333 UTC (9:33 a.m. EDT) one minute, six seconds after liftoff, the Apollo 11/Saturn V reached Mach 1 at an altitude of 4 miles (6.4 kilometers). As it goes supersonic, condensation clouds, called “shock collars,” form around the S-II second stage.
29 June 1965: At 10:21:17.6 PDT, Captain Joe H. Engle, United States Air Force, flying the Number Three North American Aviation X-15A-3 research rocketplane, 56-6672, was air-dropped from the NB-52B Stratofortress mothership, Balls 8, over Delamar Dry Lake in Nevada. This was the 138th flight of the X-15 Program, and Joe Engle’s 12th. He fired the Reaction Motors XLR99-RM-1 engine for 81.0 seconds and accelerated to Mach 4.94 (3,432 miles per hour, 5,523 kilometers per hour). The X-15 climbed to an altitude of 280,600 feet (85,527 meters, 53.14 miles). He touched down at Edwards Air Force Base after 10 minutes, 34.2 seconds of flight. His parents were at Edwards to witness his flight.
Captain Engle qualified for Astronaut wings on this flight, the third and youngest Air Force pilot to do so.
Command Pilot Astronaut insignia, United States Air Force
From 1963 and 1965, Joe Engle made 14 flights in the three X-15s. After leaving the X-15 Program, he was assigned to the Apollo Program, the only NASA astronaut with prior spaceflight experience. He was the back-up Lunar Module pilot for Apollo 14 and he was the designated LM pilot for Apollo 17 but was replaced by Harrison Schmidt when Apollo 18 was cancelled. Next he went on to the Space Shuttle Program. He was a Mission Commander for the Enterprise flight tests and for Columbia‘s second orbital flight, during which he became the only pilot to manually fly a Mach 25 approach and landing. Finally, he commanded the Discovery STS 51-1 mission.
Joe Engle retired from the Air Force in 1986. He was then promoted to the rank of Major General and assigned to the Kansas Air National Guard. He has flown at least 185 aircraft types and accumulated 14,700 flight hours, with 224 hours in space.
Captain Joe H. Engle, U.S. Air Force, with the North American Aviation X-15A-2, 56-6671, at Edwards Air Force Base, California, 1965. (NASA)
