Apollo 6 near disaster
Discussion
Ineteresting writeup about how close Apollo 6 came to disaster. Apollo 6 was the second unmanned flight of the Saturn V
"Apollo 6, launched on April 4, 1968, nearly shook itself apart during launch. You may know about two J-2 engines going out on the second stage, but did you know that the SLA lost panels, the LES almost activated and the Service Module moved 3 inches on the SLA?
NASA's final report on the mission is rich with detail, but let's look at the one failure that never stops causing my mouth to drop: The failure of the Spacecraft LM Adapter, or SLA. Inside is a Lunar Module test article.
The SLA, designed by North American Aviation, was made of nearly 2 inches of aluminum honeycomb material. Now, the Saturn V's design was plagued by "pogo" oscillations that threatened to shake the vehicle apart. Pogo oscillations shook Apollo 6 early on, as the Launch Escape System was wildly vibrating at 1 min 28 sec into the flight.
At about 2 min 13 sec, several SLA panels began to bend, inward, and eventually buckle entirely, falling from the vehicle as the photos below show. If this event occurred earlier when the atmosphere was thicker, drag forces would have certainly caused the vehicle to break apart further. The report suggests that there were fears corrosion damage to the SLA aluminum (the things sat around in the Florida salty sea air).
What you may not know is that, at the same time, one of the three wires that control the Emergency Detection System (EDS) lost power. There are three such wires throughout the length of the Saturn. If two of them lost power, the Launch Escape System would've activated, pulling the Block I CSM-020 Command Module away and ending the mission.
("Apollo 13" film fans hear Lovell say "EDS to manual, inboard" during their launch, just prior to their first staging. Basically, he's turned off the EDS because they're near the end of the LES's usefulness and will jettison the LES just after staging.)
For the next mission (Apollo 7, the first manned mission) and later, some vent holes were made to check for corrosion and later for Apollo 8 to equalize any pressure differential. Also for 8, cork paneling covered the SLA to aid in temperature variations, and a type of ultrasonic inspection was done to all future adapters to check for voids in the aluminum.
The distance between the Service Module and the SLA apparently moved at least 3 inches in flight because of the SLA damage as well.
Read the report at your leisure. (This material may be too sensitive for younger space enthusiasts.)
https://ntrs.nasa.gov/search.jsp?R=19700025117
( in this last image the text at the top indicates the camera locations which gave the data used for the diagram )
"Apollo 6, launched on April 4, 1968, nearly shook itself apart during launch. You may know about two J-2 engines going out on the second stage, but did you know that the SLA lost panels, the LES almost activated and the Service Module moved 3 inches on the SLA?
NASA's final report on the mission is rich with detail, but let's look at the one failure that never stops causing my mouth to drop: The failure of the Spacecraft LM Adapter, or SLA. Inside is a Lunar Module test article.
The SLA, designed by North American Aviation, was made of nearly 2 inches of aluminum honeycomb material. Now, the Saturn V's design was plagued by "pogo" oscillations that threatened to shake the vehicle apart. Pogo oscillations shook Apollo 6 early on, as the Launch Escape System was wildly vibrating at 1 min 28 sec into the flight.
At about 2 min 13 sec, several SLA panels began to bend, inward, and eventually buckle entirely, falling from the vehicle as the photos below show. If this event occurred earlier when the atmosphere was thicker, drag forces would have certainly caused the vehicle to break apart further. The report suggests that there were fears corrosion damage to the SLA aluminum (the things sat around in the Florida salty sea air).
What you may not know is that, at the same time, one of the three wires that control the Emergency Detection System (EDS) lost power. There are three such wires throughout the length of the Saturn. If two of them lost power, the Launch Escape System would've activated, pulling the Block I CSM-020 Command Module away and ending the mission.
("Apollo 13" film fans hear Lovell say "EDS to manual, inboard" during their launch, just prior to their first staging. Basically, he's turned off the EDS because they're near the end of the LES's usefulness and will jettison the LES just after staging.)
For the next mission (Apollo 7, the first manned mission) and later, some vent holes were made to check for corrosion and later for Apollo 8 to equalize any pressure differential. Also for 8, cork paneling covered the SLA to aid in temperature variations, and a type of ultrasonic inspection was done to all future adapters to check for voids in the aluminum.
The distance between the Service Module and the SLA apparently moved at least 3 inches in flight because of the SLA damage as well.
Read the report at your leisure. (This material may be too sensitive for younger space enthusiasts.)
https://ntrs.nasa.gov/search.jsp?R=19700025117
( in this last image the text at the top indicates the camera locations which gave the data used for the diagram )
Eric Mc said:
I always knew that Apollo 6 had lots of problems but I hadn't realised that it was falling apart.
Amazingly, the next time they flew the Saturn V, there were three blokes on it - and they went to the moon.
Yeah whilst Apollo 11 got all the glory, 8 was far more brave and pioneering IMO.Amazingly, the next time they flew the Saturn V, there were three blokes on it - and they went to the moon.
London424 said:
Not really the best place for this but Apollo related.
Just finished watching a documentary on Netflix - Mission Control: The unsung heroes of Apollo.
Really enjoyed it and thought I'd let others know it was around. Not sure if its a repeat but listed as 2017 on there.
Me too, thought it was absolutely superb, and the CGI quite excellent.Just finished watching a documentary on Netflix - Mission Control: The unsung heroes of Apollo.
Really enjoyed it and thought I'd let others know it was around. Not sure if its a repeat but listed as 2017 on there.
The only problem for me, as has happened before, is that it once again felt like "The Gene Krantz Show".
Simpo Two said:
Eric Mc said:
I always knew that Apollo 6 had lots of problems but I hadn't realised that it was falling apart.
Amazingly, the next time they flew the Saturn V, there were three blokes on it - and they went to the moon.
So Apollos 7-10 were not Saturn Vs?Amazingly, the next time they flew the Saturn V, there were three blokes on it - and they went to the moon.
In the Apollo programme, there were 13 Saturn V launches.
Apollo 4, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and Skylab.
Saturn IBs were used 6 times -
Apollo 5, 7, Skylab x3 and the Apollo/Soyuz joint mission of 1975.
Apollo 1 should have been the first manned flight of the Apollo programme. It would have utilizes a Saturn IB with an early version of the Command/Service Module. This was the craft lost in the fire of January 1967 which caused the deaths of Grissom, White and Chaffee. The Saturn IB was undamaged and was later used to launch the unmanned Apollo 5 mission.
There were no Apollos 2 or 3
Before Apollo officially started flying in 1967, there were also ten Saturn I launches, all unmanned, between 1961 and 1965. Most of these were to test various aspects of Apollo hardware, such as boiler plate Command Modules and their heat shields.
Apollo 4, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and Skylab.
Saturn IBs were used 6 times -
Apollo 5, 7, Skylab x3 and the Apollo/Soyuz joint mission of 1975.
Apollo 1 should have been the first manned flight of the Apollo programme. It would have utilizes a Saturn IB with an early version of the Command/Service Module. This was the craft lost in the fire of January 1967 which caused the deaths of Grissom, White and Chaffee. The Saturn IB was undamaged and was later used to launch the unmanned Apollo 5 mission.
There were no Apollos 2 or 3
Before Apollo officially started flying in 1967, there were also ten Saturn I launches, all unmanned, between 1961 and 1965. Most of these were to test various aspects of Apollo hardware, such as boiler plate Command Modules and their heat shields.
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