AviationWeek (link)"SpaceX envisions an initial test of the upgraded Falcon 9 first stage’s “fly back” capabilities later this year as part of the third International Space Station Dragon mission launched under the company’s NASA Commercial Resupply Services (CRS) agreement, CEO and chief designer Elon Musk told a March 28 teleconference.The Hawthorne, Calif.-based launch services provider will attempt a propulsively controlled landing in the Atlantic Ocean following the launch of a mission from Cape Canaveral Air Force Station, Fla., tentatively set for late September. ..."
... AviationWeek got its dates wrong. It was mid next year for fly back. Also they said that SpaceX is waiting till the next CRS flight to test the water landing, they got that wrong too.
Any ramifications of Falcon v1.1 on the instantaneous launch window?
They also claimed they "elected to skip a test" that would have found the problem with the valve... That sounds like AviationWeek is trying to spin things differently than what was said. There was no test skipping done.
Musk: It was a tiny design revision change from the supplier. The supplier made some mistakes and we didn’t catch those mistakes. Ran system through low pressurization tests, but didn’t run them through the high presssurization functionality tests. Didn’t get stuck in the low pressurization functionality tests. Make sure we don’t repeat that in the future. Need a magnifying glass to see the difference.
IE trying to avoid an end-of-life issue like the M1C fail on SpX-1.]
Quote from: mlindner on 04/01/2013 11:02 pmThey also claimed they "elected to skip a test" that would have found the problem with the valve... That sounds like AviationWeek is trying to spin things differently than what was said. There was no test skipping done.Musk has said that more thorough testing would have found the problem (link):-QuoteMusk: It was a tiny design revision change from the supplier. The supplier made some mistakes and we didn’t catch those mistakes. Ran system through low pressurization tests, but didn’t run them through the high presssurization functionality tests. Didn’t get stuck in the low pressurization functionality tests. Make sure we don’t repeat that in the future. Need a magnifying glass to see the difference.(My highlight)[Edit: Musk seems to be implying (but hard to be certain) that they didn't put the valve through a full suite of tests (inc high pressure) because the supplier didn't tell them of the design change.If that reading is correct, it perhaps implies that the low-pressure tests are part of standard Dragon testing. Perhaps they avoid high-pressure tests to avoid putting too much lifetime on the components, IE trying to avoid an end-of-life issue like the M1C fail on SpX-1.]cheers, Martin
SpaceX was not made aware of the design change by its supplier, and while company’s engineers conducted a pre-mission low-pressure functionality test of the hardware, they elected to skip a high-pressure test that might have revealed the problem, he said.
[Edit: Musk seems to be implying (but hard to be certain) that they didn't put the valve through a full suite of tests (inc high pressure) because the supplier didn't tell them of the design change.cheers, Martin
Check valves are not always so reliable. I've heard anecdotes of rocket folks who kind of hate them since they can be glitchy compared to other valves (though other valves are often not suitable). I looked for a source for this anecdote but could not locate it.
Quote from: Robotbeat on 04/02/2013 11:21 pmCheck valves are not always so reliable. I've heard anecdotes of rocket folks who kind of hate them since they can be glitchy compared to other valves (though other valves are often not suitable). I looked for a source for this anecdote but could not locate it.The original question was why the system test was done at low pressure instead of at high pressure, and my point was that if a check valve opens at low pressure, there's no reason to think it won't open at high pressure, especially when (a) it was *designed* for that high pressure, and (b) it has already (presumably) been acceptance tested at the vendor. So if you're SpaceX doing a pressure test on the assembled system, it's perfectly logical for you to do the test at low pressure.As for check valve failures, the usual failure modes are stuck open or stuck closed, and again, the check valves in question opened during the low pressure system test, but apparently the vendor's design change meant that the next pressure cycle caused the valve to stick closed. So what's strange in this case is not a *random* failure but a subtle design change that didn't prevent the valve from working normally in qual or acceptance tests, but prevented the valve from opening after a system-level test at low pressure in which the valve *did* open normally.
IIRC, one of the MERs Delta II vehicles had a check valve issue prior to launch and the launch team cycled the valves several times to get them working properly, then they launched. Doesn't seem to be an uncommon occurance.
Quote from: beancounter on 04/03/2013 02:19 amIIRC, one of the MERs Delta II vehicles had a check valve issue prior to launch and the launch team cycled the valves several times to get them working properly, then they launched. Doesn't seem to be an uncommon occurance.It was the LOX fill and drain valve. No where close to the same thing
anik's updated schedule has SpX-3 launching on November 11. (Added on March 26, date changed on March 30)If anik posts it, I believe it. His posted date for SpX-2 was accurate and stood for five months before launch. We should use "Nov-11" to update the thread title.edit: correct silly typos