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View Full Version : Structural Crack Found on Shuttle Tank



Fraser
2010-Nov-10, 10:20 PM
The chances of space shuttle Discovery launching on the STS-133 mission in 2010 could be in jeopardy. Cracked foam on the shuttle’s external tank was removed early Wednesday morning and underneath engineers found a structural crack on the tank itself. The serpentine crack is about 22 cm (9 inches) long and is located on a [...]

More... (http://www.universetoday.com/78088/structural-crack-found-on-shuttle-tank/)

Jerry
2010-Nov-12, 04:21 AM
Nine inch structural crack?

There will be no launch...

swampyankee
2010-Nov-12, 11:42 AM
Since the shuttle external tank is a single-use structure, this obviously is not a high-cycle fatigue issue. Since the link says it has occurred during construction, I'd have some serious concerns about the production quality. I used to work in aerospace; we would get worried if cracks showed up after a few hundred flights (I worked with helicopters and gas turbines, not missiles or rockets). Cracks showing up before the vehicle had its first flight would have had quite a few people running around trying to figure out what is so basically wrong that a vehicle can't even be delivered!

danscope
2010-Nov-13, 12:16 AM
They can simply weld it. They know people who weld real good. Really .

Jerry
2010-Nov-15, 02:56 AM
It won't be that simple. When did the crack occur, and why was it not detected sooner? Are there other cracks that are hidden? Is it even possible to inspect all places in the tank where a stress fracture may exist after ancillary hardware is in place? What is the procedure for a field welding? How can a field weld effect painted surfaces, insulation, tank lining, sensors, lines, wiring, harnesses, and other hardware? Will field welding introduce new stresses? What about the field range ordnance? The last thing you want to do is set your torch down to wipe off some swet and ignite a linear shape charge.

danscope
2010-Nov-15, 05:02 AM
Like any crack, you drill a hole just after it and relieve the stress . then, you apply the proper weld . Done.
It's been done before. We know how to weld.

swampyankee
2010-Nov-19, 03:20 AM
Like any crack, you drill a hole just after it and relieve the stress . then, you apply the proper weld . Done.
It's been done before. We know how to weld.

My experience is that welding is not that common in current (well, current when I worked in aerospace ;)) aircraft structures. Aluminum aircraft are still largely riveted together, although I believe that Boeing has used a mix of spot welding and adhesive bonding in some of its aircraft. Welds? Just can't trust them.

There are aircraft with largely welded structures, but those structures are something like 4130 steel tubing, and made by people in organizations like this one (http://eaa.org/).

danscope
2010-Nov-19, 05:06 AM
Uh....... this is thick aluminum, not your .012 aluminum skin . Different animal,Sir .
It has been done before.