Apollo 6
Published on Apr 4, 2008 at 12:00 pm.
5 Comments.
Filed under NASA, history.
Forty years ago today, Apollo 6 was launched. Apollo 6 was the last of the unmanned Apollo missions and only the second time that a massive Saturn V rocket was launched. This was to be the final test launch of the Saturn V before qualifying it for manned missions. Ironically, it was the only Saturn V launched to have serious problems. The launch did prove the integrity of the Saturn V vehicle, however. Two of the second stage engines shut down early. The remaining three engines fired longer than normal, but failed to achieve the speed expected. The third stage’s engine also fired longer than would have been burning. However, when the third stage engine was to have burned again to lift the command module to a much higher orbit needed to simulate an extreme reentry condition, the J-2 engine failed to reignite. Problems were traced to a broken fuel line to the igniter, but there was nothing that could be done. So, the command module engine was fired as long as possible (far longer than would ever be done in a standard manned mission); however, this, too, failed to achieve the necessary orbit. 
So, the extreme reentry test was not possible. NASA, however, proceeded with all remaining Apollo missions as manned missions. Given the incorrect orbit, the capsule did not land where anticipated, but it was still found and recovered by Naval forces. The capsule is now on display in Atlanta, Georgia, at the Fernbank Science Center.
Apollo 6 was the first mission to use High Bay 3 in the Vehicle Assembly Building (VAB). It was also the first to use Mobile Launcher 2. Each Saturn V was assembled in the VAB onto a mobile launch platform. Then a Crawler Transporter picked up the entire assembly (Saturn V, launch platform, and gantry) and carried it to the actual launch pad. The Launch Control Center at the Kennedy Space Center has three Firing Rooms that can be used to control the launch vehicle (and a fourth fully functional firing room used to checkout hardware and software). Apollo 6 was the first to use Firing Room 2. 
Incidentally, Firing Rooms 1 and 4 have been extensively modified in anticipation for the different needs of the upcoming Constellation Program.
Since Apollo 6 was essentially a test flight, cameras were fitted in places that would not normally carry such devices on a Moon mission. One of those places was on the second stage looking back towards the first stage and the second stage engines. The famous images of the Saturn V first stage separation and the jettisoning of the interstage ring while the second stage engines are firing were taken on Apollo 6. These images are often shown during stories of the manned Apollo missions, but the cameras were in place for the Apollo 4 and Apollo 6 test flights of the Saturn V. Some of the prettiest launch images from Apollo were taken from the gantry of the Saturn V launch, and one of of those is at the top of this posting.
Despite the glitches with the engines in the second and third stages, the launch was pretty much a success, with all but a few goals being met. These failures were the only serious ones ever to strike the marvelous Saturn V rocket. Note: I am not counting the oxygen tank explosion of Apollo 13, since the Command Module, while part of the Apollo moon rocket, can be considered as a payload to the Saturn V booster. One could argue that point, though, in which case Apollo 13 would be the most serious failure associated with a Saturn V.
All future Apollo missions were manned. When the Apollo Program was terminated early for lack of funding, there were three Saturn V rockets already built to go to the Moon. One was used to launch Skylab, America’s first space station, into orbit. The other two, along with test stages not designed to fly, are now on display at various places around the country. The Saturn V at the Johnson Space Center, in Houston, is composed entirely of stages built as actual flight hardware, but never flown, though the stages displayed were not originally designated as belonging to the same assembled Saturn V.
-Astroprof
Images courtesy of NASA
BPCooper on April 4, 2008 at 8:12 pm: 1
Today also marks the 25th anniversary of STS-6, the first flight of the orbiter Challenger; April 4, 1983.
Astroprof on April 5, 2008 at 3:40 pm: 2
Yes, I should have mentioned that, too. I wrote about that a couple years ago:
http://astroprofspage.com/archives/103
CCPhysicist on April 5, 2008 at 6:49 pm: 3
Thanks for that info about the Saturn booster at Johnson SFC. Is there some place that details the build info (the NASA equivalent of VIN and build codes for cars) on each of the stages and vehicles on display at the various museum sites around the country? Which canceled mission or mission prototype each was built for?
If you can dig that out some time, it would make a good blog.
JOHN D FRANKLIN on April 28, 2008 at 1:30 pm: 4
I WAS READING “CHARIOTS FOR APOLLO” AND THE BOOK STATES THAT THE LM ARTICLE (MOCK-UP) ON APOLLO- SIX FELL OUT AS PANELS BELOW THE CSM BROKE FREE, AS POGO WAS GOING ON. THIS IS THE ONLY PLACE I HAVE READ THIS. SO I ASSUME MR PELLEGRINO $ STOFF ARE INCORRECT, AS ONLY THE PANELS CAME LOOSE, AND NOT THE LM ARTICLE. ANYONE ELSE READ / OR NOTICE THIS PART OF THE BOOK??
JOHN D FRANKLIN on April 28, 2008 at 1:39 pm: 5
I have not seen, but have heard that there is a Saturn V, in Huntsvills. (sitting vertical) Has anyone seen it. I assume it is a mock-up, but is it worth seeing??
JDF