SLS Block 2 BOLE Booster Test Anomaly [Discussion Only]

[Skye]

Things were looking nominal, until thy weren’t. I haven’t done any super detailed analysis of the “observation”, but at first glance it seems that the nozzle blew apart / disintegrated due to high exhaust temp / speed / force etc.

3 times in under a decade, NG’s nozzles have failed - on 3 different motors & 3 different rockets: CASTOR for OmegA, GEM 63XL on Vulcan, & finally BOLE for SLS Block 2. Clearly it was a SpaceX sniper!

Seriously though, what happens now? In all likelihood, they’ll just continue testing & try to resolve the issue, but given that SLS block 2 may not ever fly, is it worth continuing BOLE?

[catdlr]

Sky, 

A thread for this event has already been started here: https://forum.nasaspaceflight.com/index.php?topic=63143.msg2696971#msg2696971

NSF Phillip Sloss was on site and interviewed the Northrop official (pre-test).  Phillip's post is in the Artemis Status thread, and I suggest you jump to this timestamp:  03:20 Nozzle anomaly at the end of the first test of next-gen SLS solid rocket motor, and note the official hesitancy of the prospect of this material making it through the test.  The rated power of the rocket was to be 3.8 million pounds, but it produced 4.0 million. Thus, the new combustion material and design contributed to a more powerful motor (a good thing); however, the new protective material wasn't sufficient to withstand this increased power/heat/pressure. That's the initial takeaway, but we have to wait for official confirmation.

https://forum.nasaspaceflight.com/index.php?topic=62717.msg2697796#msg2697796

The essence of this issue is that Northrop may have underestimated the temperature of the new combustion material for this updated version of the rocket, resulting in the ablative material protecting the skirt area from burning through. Subsequently, the observed cascading energetic events commenced. This indicates that once the ablative material failed and the flames entered the nozzle control areas, the destruction progressed, ultimately leading to the destruction of everything (in phases) except the skirt. It is essential to note that the nozzle failure was not the initial cause, but rather a consequence, as indicated by the exceptional video that Jack Beyer (NSF) provided of the test.  In it, you can see the fire started at the top of the skirt (where the flames initially puncture that area) and progressed downward on both sides, then proceeded through and began to destroy the nozzle and other equipment and a wild series of energetic events leadng to a complete loss of everything below the skirt.

Watch the entire video, but focus on the slow motion at 3:50 (turn up the sound to hear the various energetic events).



Furthermore, it is advisable not to hastily conclude that other NG’s nozzle failures are the same, as each instance possesses its own distinct design, challenges, and final solutions. NG possesses the relevant data, and given that their instrumentation was thorough, I am confident that they will, as they have consistently done in the past, arrive at a resolution and conduct subsequent re-testing. These solids are not intended for any immediate launch; rather, they are planned for use much later in the Atrimus schedule, years from now.

If you're an L2 member, you might want to see Jack's walk-through video of the history of all the various rockets on display at NG's Rocket Garden:  https://forum.nasaspaceflight.com/index.php?topic=63147.msg2697461#msg2697461

Here is a fun short video from Jack at the NG rocket garden:  https://youtube.com/shorts/us-w6xKl2sk

Tony

[Skye]

Thanks for the explanation, makes sense. Should be a fairly easy fix, then.

Watch the entire video, but focus on the slow motion at 3:50 (turn up the sound to hear the various energetic events).



Furthermore, it is advisable not to hastily conclude that other NG’s nozzle failures are the same, as each instance possesses its own distinct design, challenges, and final solutions. NG possesses the relevant data, and given that their instrumentation was thorough, I am confident that they will, as they have consistently done in the past, arrive at a resolution and conduct subsequent re-testing. These solids are not intended for any immediate launch; rather, they are planned for use much later in the Atrimus schedule, years from now.

If you're an L2 member, you might want to see Jack's walk-through video of the history of all the various rockets on display at NG's Rocket Garden:  https://forum.nasaspaceflight.com/index.php?topic=63147.msg2697461#msg2697461

Here is a fun short video from Jack at the NG rocket garden:  https://youtube.com/shorts/us-w6xKl2sk

Tony

Once I get home, I’ll be able to check the videos, thanks for them

Sadly, I am not an L2 Member, (I absolutely would be if I had the money), and cannot access the second thread you sent

And as for my talking about the other failures, I don’t think they had the same cause, just saying 3 nozzles all falling off / disintegrating in just over 5 years is interesting

[catdlr]

Thanks for the explanation, makes sense. Should be a fairly easy fix, then.

Furthermore, it is advisable not to hastily conclude that other NG’s nozzle failures are the same, as each instance possesses its own distinct design, challenges, and final solutions. NG possesses the relevant data, and given that their instrumentation was thorough, I am confident that they will, as they have consistently done in the past, arrive at a resolution and conduct subsequent re-testing. These solids are not intended for any immediate launch; rather, they are planned for use much later in the Atrimus schedule, years from now.


Tony

And as for my talking about the other failures, I don’t think they had the same cause, just saying 3 nozzles all falling off / disintegrating in just over 5 years is interesting

They're all for various reasons.

Analogy:  Suppose the frequent flat tires you're experiencing over four years, and having to re-purchase the same ones from the same manufacturer.  You suspect something is oddly familiar, but the flat tires are caused by encountering potholes, nails, neglecting proper air maintenance, and other factors. The outcome remains the same: a flat tire from the same tire model and manufacturer, but the causes of the flats are numerous, and the issue is not attributed to the manufacturer, a fact you called 'Interesting'.

[sdsds]

For various reasons, the frequent flat tires on your vehicle do not necessarily indicate a defective and continuous batch from the manufacturer. Instead, causes may include encountering potholes, nails, neglecting proper air maintenance, among others. The outcome remains the same, but the causes are numerous, and it is not attributed to the manufacturer.

Yes and still the blow-out in one and continuous slow leaks in three others leads me to think something was wrong with those discontinued and highly discounted tires I put on my car last year. Simply because they were branded with the name of a company I trust doesn't give me any confidence in the quality of their manufacture.

Same holds for rocket motor nozzles.

[catdlr]

For various reasons, the frequent flat tires on your vehicle do not necessarily indicate a defective and continuous batch from the manufacturer. Instead, causes may include encountering potholes, nails, neglecting proper air maintenance, among others. The outcome remains the same, but the causes are numerous, and it is not attributed to the manufacturer.

Yes and still the blow-out in one and continuous slow leaks in three others leads me to think something was wrong with those discontinued and highly discounted tires I put on my car last year. Simply because they were branded with the name of a company I trust doesn't give me any confidence in the quality of their manufacture.

Same holds for rocket motor nozzles.

I rewrote my statement since you posted, to clarify.  However, I understand your point as well, especially coming from a company that holds a monopoly on the product.

[eeergo]

[/size]
Things were looking nominal, until thy weren’t. I haven’t done any super detailed analysis of the “observation”, but at first glance it seems that the nozzle blew apart / disintegrated due to high exhaust temp / speed / force etc.
3 times in under a decade, NG’s nozzles have failed - on 3 different motors & 3 different rockets: CASTOR for OmegA, GEM 63XL on Vulcan, & finally BOLE for SLS Block 2. Clearly it was a SpaceX sniper!
Seriously though, what happens now? In all likelihood, they’ll just continue testing & try to resolve the issue, but given that SLS block 2 may not ever fly, is it worth continuing BOLE?

[/size]
From that video and the official one below, a certain timeline emerges:


- The anomaly happens near the end of the burn at precisely T+100 s (reminiscent to OmegA's CASTOR-600 2019 nozzle failure, FWIW), just after some vigorous testing of the TVC -one of the test's main objectives, again reminiscent of CASTOR-600's 2019 test objectives- going from full right to null, and seconds after a call for "Open enable accumulator valves - Accumulators enabled".


- Again FWIW, CASTOR-600's nozzle failure was attributed to improper accounting of normal, unchanging atmospheric pressure conditions vs ambient environmental pressure drop during an actual launch: https://www.thespacereview.com/article/3986/1 . Smaller SRBs with less nozzle surface area were stiff enough to withstand this effect, but a larger bell could not. Nozzle throat erosion was normal though, so the cause seems to be different in this case, where the nozzle was intact until well into the anomaly.


- First frames show a burnthrough appearing at the outer edge of the nozzle skirt. The burnthrough is most apparent on the top of the booster's skirt, a few milliseconds after the first indication of something anomalous happening. But looking closely at the official video (2:02), one can see there is an initial couple of frames showing a shockwave propagating from the BOTTOM of the skirt circumferentially towards the top, where it finally breaks through and allows a large plume out.


- The plume then repropagates/starts coming out circumferentially again back towards where it started, while the nozzle starts disintegrating against the burnthrough plume. This is visible also in NSF's video.


- There's then a progressive deterioration of the SRB aft protections around the nozzle, going down from the top towards the bottom, and letting out a progressively hotter plume, until the nozzle is blown apart (1:49 in NSF's video). This seems to place the blame further upthroat than the visible nozzle protruding from the skirt, if the pre-flight picture of what's inside the skirt is any indication.


- Finally, the outside of the skirt starts giving way, first letting out exhaust through progressively melting rivets, until the panels are blown out at 1:43 in NSF's video. This seems to be from recirculation effects, since there don't appear to be any plumes blowing into that space once it opens up, and the bottom ring stays on.


PS: Sorry for the large number of (hopefully illustrative) attachments!

[Apollo22]

SpaceBOLEs !  Unbelievable to think that, with all the pork money flowing into SLS-Orion, they still screw the pooch like that. 

[laszlo]

SpaceBOLEs !  Unbelievable to think that, with all the pork money flowing into SLS-Orion, they still screw the pooch like that.

As the real estate world knows, it's all about "location, location, location". If this had happened in Boca Chica, it'd be good experimental data, hardware-rich iterative testing, not a setback and anyone who said otherwise would be a concern troll who didn't understand that space is hard. But in Promontory...

At least these guys had to actually ignite the fuel to damage the booster 

[AS-503]

SpaceBOLEs !  Unbelievable to think that, with all the pork money flowing into SLS-Orion, they still screw the pooch like that.

As the real estate world knows, it's all about "location, location, location". If this had happened in Boca Chica, it'd be good experimental data, hardware-rich iterative testing, not a setback and anyone who said otherwise would be a concern troll who didn't understand that space is hard. But in Promontory...

At least these guys had to actually ignite the fuel to damage the booster 

Speaking of a certain place in Texas with as you stated "hardware-rich iterative testing", look at how many kabooms and iterations have happen in one calendar year at said Texas place.
It is the textbook definition of the thing you derided.

In contrast look at how many kabooms of the BOLE have happened or will happen at the Utah test place.
The design philosophies could not be more different.

For example, when do you think the Texas place will "iterate" their next test as compared/contrasted to when do you think the Utah place will have another BOLE test "iterated"?

[laszlo]

Speaking of a certain place in Texas with as you stated "hardware-rich iterative testing", look at how many kabooms and iterations have happen in one calendar year at said Texas place.
It is the textbook definition of the thing you derided.
...

I was deriding the double standard of the spectators, not the methodologies of the testers.

[SpaceLizard]

Speaking of a certain place in Texas with as you stated "hardware-rich iterative testing", look at how many kabooms and iterations have happen in one calendar year at said Texas place.
It is the textbook definition of the thing you derided.
...

I was deriding the double standard of the spectators, not the methodologies of the testers.

Not really a double standard since the observers are observing two different standards of testing where similar results can have wildly different consequences in terms of delays and tax dollars spent. How quickly will NG be able to test another article and at what taxpayer cost? Meanwhile the "certain site in Texas" already has more articles to test and is rapidly finding a way to test them, all at approximately zero taxpayer cost...

[sdsds]

[...] two different standards of testing where similar results can have wildly different consequences in terms of delays and tax dollars spent. How quickly will NG be able to test another article and at what taxpayer cost?

There's no evidence this outcome will in any way increase cost or slip schedule beyond plan. That's pure speculation on the part of doomsayers.

[SpaceLizard]

[...] two different standards of testing where similar results can have wildly different consequences in terms of delays and tax dollars spent. How quickly will NG be able to test another article and at what taxpayer cost?

There's no evidence this outcome will in any way increase cost or slip schedule beyond plan. That's pure speculation on the part of doomsayers.

So rather than test it again to be sure it works they will just apply some simulated solutions and say it's fixed...  Safe, cost effective, and on schedule! 

[sdsds]

So rather than test it again to be sure it works they will just apply some simulated solutions and say it's fixed...  Safe, cost effective, and on schedule! 

You're aware this was the first in a long sequence of planned development and certification motors?

[SpaceLizard]

So rather than test it again to be sure it works they will just apply some simulated solutions and say it's fixed...  Safe, cost effective, and on schedule! 

You're aware this was the first in a long sequence of planned development and certification motors?

As a matter of fact I was not, I had assumed this was an inaugural-certification-firing-of-sorts. Color me surprised that 99% of testing isn't being done on paper. I shall now retreat in shame...

[sdsds]

[...] I had assumed this was an inaugural-certification-firing-of-sorts. Color me surprised [...]

I want to take a moment to publicly thank you for this exchange. I'm 99% confident you weren't the only one who thought everyone involved was counting on total success of this particular motor test. So hopefully our talking it through helps them understand it as well.

For full disclosure, I don't support the BOLE effort but that's not because I disrespect those working on it. That work has been super-important, and along with the effort to fly out the remaining steel SRB segments it has preserved a vital part of the nation's industrial/technology capabilities during a time when that infrastructure was at risk of being lost. Times have changed though and other important users of large solid motors are keeping the industrial base busy. I now support winding down SLS segmented solids in part to make that solid motor capability available for those other high priority users. In addition the underlying premise of the Shuttle design (with a ground-lit hydrolox core sustainer stage) now looks doubtful, with hydrocarbon cores performing so exceptionally well.

[Skye]

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