Another really interesting article! Shuttle heaven here.
Chris, you really can write up an article!
Now as to content....
I'm still miffed about this:
“Primary contributor to trace shape variation observed on STS-119, STS-124, and STS-126 is a burn rate variation and location of added mixes in the segments,” notes the presentation."
ATK is using old propellant from previous segment castings and mixing it in with new castings. Yes, it is included near the end of the burn so its affects to the vehicle are minimized, but for a program so risk-adverse, you would think they would be against any such changes, because it does require the flight system to correct. But they cleared it.
I still don't get what miffs you about this?
I still don't get what miffs you about this?
Eliminate the risk: use new and uniform propellant throughout the entire SRB casting, just like they use to have. It's clear that it has an effect on the shuttle. It may be within the capabilities of the avionics to counter its effects, but that doesn't make it right.
When you make a big deal on TPS damage, ripcord damage on parachutes, FCVs, ...why should this be any different?
They did make a big deal, and the conclusion was that they were well within safety limits. They didn't just say "Sounds good, NEXT!" If you look on L2, there are extensive presentations on the topic, explaining why. And that's just the tip of the iceberg...
So the SRBs have been checked and double checked. Good. It made me raise an eyebrow though simply because the SRB manufacturer certainly doesn't need this kind of news while the spotlight is on Ares I and the gap - no matter how irrelevant that issue may be in a single booster configuration.