Recent Posts

Pages: [1] 2 3 ... 10 Next
1
Any chance they are building a berm on the road side to reduce prying eyes?

They almost seem like styrofoam. I just think there's no timescale to the GIF, so my brain is underestimating the momentum required to move them to position.
2
If you're assessing how large a space program an economy can support, GDP per capita doesn't really matter (otherwise Luxembourg would have already colonised Mars by now).

For a while, I've thought serious space countries support at most about .1% of their GDP on such programs,
so
USA (20.5t economy, 21.5b program/NASA)
France (2.8t, 2.6b)
Russia (1.6t, 3.3b).

[figures are from wikipedia GDP, and space budgets pages]

If anything, Russia is already 'punching above its weight', which does make it seem a bit hard to believe it can get much higher than what it already is.
It is representative of discretionary income not national priorities or propaganda...
3
Any chance they are building a berm on the road side to reduce prying eyes?
4
Patricia Sanders of ASAP: "Firing of eight SuperDracos resulted in an anomaly."

Is it possible to read this comment in a way which allows for the popular but questionable T-9 theory? It seems like if the anomaly occurred several seconds (or more) before T-0, she wouldn't have said that the firing of the SuperDracos resulted in the anomaly.

The shake table, however, does seem like a plausible reason for something dynamic to be happening around T-10, because that might be a reasonable time to start shaking the vehicle prior to commanding the abort.
5
Interesting conclusion to the article! See below:

Quote from: Chris B.
Depending on just how much work is taking place on the crew Dream Chaser, NASA could – in theory – providing funding to ramp up the work on the Dream Chaser crew vehicle and create a back-up option in case of further issues with the two primary Commercial Crew vehicles.

Despite the issues with Crew Dragon and Starliner, NASA is far more likely to continue to purchase more Soyuz flights to ensure it can launch American astronauts to the ISS and to provide an uninterrupted US presence on the orbital outpost.

I agree. Technically, CCtCap does have an on-ramp clause that could allow new entrants such as SNC (or Blue) into the crewed program but in practice, NASA is unlikely to get the extra funding for a third crew provider. SNC's best hope for crewed DC would likely be if NASA were to create a follow on program after CCtCap.
6
If the vehicle has no ability for margin to exist outside expected environments what is the point of a man rating program or any of these tests?
There isn't one and it shouldn't be flying people.

I don't want another 51L. Nobody else should either.

Human rated systems typically have a 50% structural margin, not 100%.

1.5 Safety margin. (And I'm over here assuming 2-3 or 4 margins...)

For non-flight systems the design criteria is the expected operating stress be no more than 25% of ultimate stress.  Flight systems use a lower safety margin otherwise they would be too heavy to get off the ground.
7

Starting to question the validity of liquid fueled pusher LAS but it's unfair to denegrate the entire idea of it based on this one incident. Still, there appear to be some tradeoffs.

Concur.  I was reflecting on that and wondering if the RCS feeds from the same system (lines, pressurization, and prop vessels).  Sorry if I missed previous posts that outline this one way or the other.  Also wondering if there was ever, or will be a design that utilizes solids for abort, which means far lower pressures in RCS system (if tied) and smaller prop vessels/pressurization/etc.

Yes, Draco and SuperDraco use the same fuel / oxidizer tanks, but not the same fuel / oxidizer feed lines.
I wonder how the 2 sub systems operate together. Dracos are used on orbit where SD are not used. SDs are used during abort where Dracos are not used (too weak).

So if SD require much higher tanks pressure P2 than Dracos (P1), probably there is a pressure regulator between helium and propellant tanks which has a pressure selection, or more probably 2 short parallel lines with a valve and regulator each, one for pressure P1, another for pressure P2. This has obvious advantage that risky higher pressure is supplied only in abort mode, where this risk is worth it.

So during flight and test prior to explosion all pipes downstream regulators were experiencing smaller P1, then during failed test P2 was supplied, and something cracked downstream in Draco piping (corroded nut?).

May be cargo version does not have this P1/P2 regulator assembly, but just regulator for P1, that is why there is no problem with next cargo flight...
8
Anyone still think SpaceX could have magically been assured of having purchased good struts even though evidently only destructive testing revealed the flaws in the manufacturer's process being ones which could impact SpaceX's application?

yes, because that is the purpose of lot testing is to reveal production problems.   SpaceX would have known that the flawed struts were being produced.

No, they likely wouldn't have. In the aftermath of CRS-7 SpaceX literally had to test hundreds of the strut ends to find just a few that failed below their rated strength.
Lot testing by definition is testing a small sample of said lot. Chances of finding the few random offending parts in a lot, via a random sample test, are very, very small.

To always find a few offending parts in a large lot you have to test the entire lot. Which is not the definition of lot testing, adds substantial cost to the product and fully and wholly negates the purpose of buying certified parts from a supplier.
You are approaching this one from the wrong angle Jim. You shouldn't be going after "SpaceX would have known that there were production flaws"...You should be going after the fact that SpaceX was using the wrong kind of material for their strut ends. Because that was the real problem.

I think I read here SpaceX provided for a safety factor of 8 for the temps involved, and if the manufacturer had so much as hit half their spec the application would never have seen a failure in the lifespan of the universe.  Non-ideal, or wrong?
9
Arghh ... if we only had a plumbing schematic for the D2 capsule!

In any case, since people keep claiming it from the poor video, we do not know if the anamoly happened seconds before the SD firing or right when the firing was to start due to the poor audio and sync issue. Another countdown can he heard where the failure happened at T- 0.
And I can't tell if they meant 2 times the normal vehicle vibration level for the test or 2 times the level expected during rocket break-up.
10
If you're assessing how large a space program an economy can support, GDP per capita doesn't really matter (otherwise Luxembourg would have already colonised Mars by now).

For a while, I've thought serious space countries support at most about .1% of their GDP on such programs,
so
USA (20.5t economy, 21.5b program/NASA)
France (2.8t, 2.6b)
Russia (1.6t, 3.3b).

[figures are from wikipedia GDP, and space budgets pages]

If anything, Russia is already 'punching above its weight', which does make it seem a bit hard to believe it can get much higher than what it already is.
Pages: [1] 2 3 ... 10 Next