Quote from: DanClemmensen on 10/01/2022 03:37 pm... IMO SLS/Orion is riskier. It must either fly in November or not fly for at least a year, based on rollout-rollback and SRB constraints. ...You don't know that, unless you know more than what has been publicly revealed.*Perhaps* a two year stack-time will be declared the maximum for those SRBs, but all we currently have from NASA is that they are tracking life-limited items and are revisiting and, where possible, reevaluating those limits as necessary. At some point a true limit will be reached, but we've no idea just how finely they can "sharpen their pencils".
... IMO SLS/Orion is riskier. It must either fly in November or not fly for at least a year, based on rollout-rollback and SRB constraints. ...
Quote from: Mr. Scott on 10/01/2022 04:04 am... Again hypothetically, what if Orion was on top of a Super Heavy Booster? 😱. That would likely be a pretty awful sight. Be very careful what you wish for!There is a guy on Twitter called 'The Cursed Rockets Guy'. He does what it says on the tin. [Orion and ICPS on Superheavy]
... Again hypothetically, what if Orion was on top of a Super Heavy Booster? 😱. That would likely be a pretty awful sight.
...You mention "the true limit". How do they determine that?
Is there anyway to send a camera inside of the solid boosters to check the condition of the solid material? This would tell if they need to restack and repair or replace the solid material.
Quote from: Jim on 10/01/2022 02:04 pmSpaceX would be very negative about it.Have you ever met someone named Pollyanna at SpaceX?QuoteNo Orion, no need for SLS.Yes as of now. But there are other blocks for SLS.
SpaceX would be very negative about it.
No Orion, no need for SLS.
Quote from: DanClemmensen on 10/01/2022 08:10 pm...You mention "the true limit". How do they determine that?Reporters have been trying to nail down such specifics with their questions during the various Artemis 1 related media briefings with no success to date. (I suppose that it is simply an article of faith with me that a *some point* a nonextendable limit would be reached. Though with as little information as NASA seems willing to share, I wouldn't be surprise if it was out of left field and not one of the main life-limited items the public is aware of.)
(snip)Then we can focus our efforts and our treasure on things that actually contribute to a human spaceflight program that makes sense, a decent ROI and actually contribute to becoming a space fairing civilization; something that SLS not only cannot do, but actually prevents because of its truly unforgivable waste of time, effort and treasure. WRT Artemis, it's designed to give the Orion/SLS something to do. It will never allow us to do anything actually useful on the moon. We should be going there once a month, with regularly scheduled flights to service a robust lunar exploration and exploitation program, not once every year or so just so we can say we did the moon. We should be building an entire economy there to create a 2-planet economic system, not peeking out thru tiny windows at the lunar landscape once in a great while. SLS/Orion cannot - ever - support such a thing. It's a guarantee that we will NEVER do anything like that.(snip)
Quote from: spacenut on 10/01/2022 07:55 pmIs there anyway to send a camera inside of the solid boosters to check the condition of the solid material? This would tell if they need to restack and repair or replace the solid material.No. Segment delamination since initial stacking that is sufficient to damage the propellant cohesion is not visible to the naked eye.
Imagine any and every science fiction future where humans live on the moon. SLS/Orion is *actively preventing this*...
SLS [is] about as useful as a 3-legged horse in a race horse stable.
Quote from: kdhilliard on 10/01/2022 08:26 pmQuote from: DanClemmensen on 10/01/2022 08:10 pm...You mention "the true limit". How do they determine that?Reporters have been trying to nail down such specifics with their questions during the various Artemis 1 related media briefings with no success to date. (I suppose that it is simply an article of faith with me that a *some point* a nonextendable limit would be reached. Though with as little information as NASA seems willing to share, I wouldn't be surprise if it was out of left field and not one of the main life-limited items the public is aware of.)This says to me that there is no "true limit" in the engineering sense.
There is only a gradual acceptance of increasing risk: a slippery slope (or pick you metaphor of choice).
We can only hope that this gamble pays off and we get a successful Artemis I mission.
Quote from: DanClemmensen on 10/02/2022 02:27 pmQuote from: kdhilliard on 10/01/2022 08:26 pmQuote from: DanClemmensen on 10/01/2022 08:10 pm...You mention "the true limit". How do they determine that?Reporters have been trying to nail down such specifics with their questions during the various Artemis 1 related media briefings with no success to date. (I suppose that it is simply an article of faith with me that a *some point* a nonextendable limit would be reached. Though with as little information as NASA seems willing to share, I wouldn't be surprise if it was out of left field and not one of the main life-limited items the public is aware of.)This says to me that there is no "true limit" in the engineering sense.No, I think that is completely wrong. I'm not a fan of the SLS, but I know there have been a couple of limits that have been made public.The SRB limits are probably the best known and understood given how long the Shuttle program was using similar SRB's, and unfortunately the only way to know if you have exceeded the limits on the SRB is to watch it launch and fail. And no one wants to that to happen, so being cautious should be OK.IIRC there are structural concerns with the entire SLS stack, with some (or all) of that being caused by the shaking that occurs when the SLS is moved to the pad or back to the VAB.QuoteThere is only a gradual acceptance of increasing risk: a slippery slope (or pick you metaphor of choice).There should be a concern at NASA regarding "Go Fever", where they feel they HAVE to launch. And certainly a lot of unwanted attention would happen if they have to de-stack and replace components of the SLS stack. I think they are aware of all of that though.QuoteWe can only hope that this gamble pays off and we get a successful Artemis I mission.Lots of drama so far, that is for sure...
Quote from: clongton on 10/02/2022 12:21 amQuote from: spacenut on 10/01/2022 07:55 pmIs there anyway to send a camera inside of the solid boosters to check the condition of the solid material? This would tell if they need to restack and repair or replace the solid material.No. Segment delamination since initial stacking that is sufficient to damage the propellant cohesion is not visible to the naked eye.I thought the SRB age limit related to the segment joints, specifically the adhesion of the PSA and the flexibility of the J-legs. I would have thought that the bulk propellant would last a longer time, based on the lifetime of other solid rocket motors like those in SLBMs. Based solely on the diagrams, I speculate that your main point is still valid and that it is unlikely that anything is visible to show deterioration.
What I was trying to say is that kdhilliard was looking for a specific quantitative "true limit": an actual specific number that can be stated and evaluated, but we can see that there is no such number. The engineers provided their numbers: 12 months for the SRB stack limit, 20 days for the FTS batteries, some specific number of roll-outs, and probably others we don't know. The program managers then asked the engineers to change those numbers, so they clearly were not "true limits".
In other words, what we are seeing overall are planned changes in what is allowed for an SLS launch that is having trouble getting off the pad.
Quote from: DanClemmensen on 10/02/2022 02:38 pmQuote from: clongton on 10/02/2022 12:21 amQuote from: spacenut on 10/01/2022 07:55 pmIs there anyway to send a camera inside of the solid boosters to check the condition of the solid material? This would tell if they need to restack and repair or replace the solid material.No. Segment delamination since initial stacking that is sufficient to damage the propellant cohesion is not visible to the naked eye.I thought the SRB age limit related to the segment joints, specifically the adhesion of the PSA and the flexibility of the J-legs. I would have thought that the bulk propellant would last a longer time, based on the lifetime of other solid rocket motors like those in SLBMs. Based solely on the diagrams, I speculate that your main point is still valid and that it is unlikely that anything is visible to show deterioration.Will point out that the solid rocket motors in strategic ballistic missiles are monolithic. AFAIK no strategic ballistic missile use segmented solid rocket motors.
Too much focus on analysis and process above building and getting things done. Also, the tech we had then with rocketry was close to the optimal already (for expendables). And they had more money and wages were lower.