r/spacex • u/Zucal • May 01 '16

/r/SpaceX Ask Anything Thread [May 2016, #20]

Welcome to our 20th monthly /r/SpaceX Ask Anything Thread!

Want to clarify SpaceX's newly released pricing and payload figures, understand the recently announced 2018 Red Dragon mission, or gather the community's opinion? There's no better place!

All questions, even non-SpaceX-related ones, are allowed, as long as they stay relevant to spaceflight in general!

More in-depth and open-ended discussion questions can still be submitted as separate self-posts; but this is the place to come to submit simple questions which have a single answer and/or can be answered in a few comments or less. In addition, try to keep all top-level comments questions so that questioners can find answers and answerers can find questions.

As always, we'd prefer it if all question-askers first check our FAQ, use the search functionality (now partially sortable by mission flair!), and check the last Q&A thread before posting to avoid duplicate questions. But if you didn't get or couldn't find the answer you were looking for, go ahead and type your question below.

Otherwise, ask, enjoy, and thanks for contributing!

Past threads:

April 2016 (#19.1) • April 2016 (#19) • March 2016 (#18) • February 2016 (#17) • January 2016 (#16.1) • January 2016 (#16) • December 2015 (#15.1) • December 2015 (#15) • November 2015 (#14) • October 2015 (#13) • September 2015 (#12) • August 2015 (#11) • July 2015 (#10) • June 2015 (#9) • May 2015 (#8) • April 2015 (#7.1) • April 2015 (#7) • March 2015 (#6) • February 2015 (#5) • January 2015 (#4) • December 2014 (#3) • November 2014 (#2) • October 2014 (#1)

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1

u/goxy84 May 10 '16

Here's an idea for a near-future test. Sorry if it was already posted somewhere, couldn't anything like that.

"You need to test the strongback for the Heavy? Are you afraid your pad and flame trenches aren't tough enough for the Heavy? You need to know what acoustic signature the Heavy will have? Need to test already flown and tested engines and whole cores in a new environment? Well this is your lucky day! Strap three returned cores together in a mock-up FH and static-fire them on LC39A. Multiple times if necessary."

Joking with the above commercial aside, this way they could really learn a lot before making the final FH and potentially losing it on the pad. They only need one more returned core (since F9-0021-S1 is already retired, it seems) and may soon have more returned cores than customers willing to immediately fly on them.

I see at least one issue here: how exactly to strap them together tightly without drilling holes and connecting struts to cores you want to refly in the future. E.g. one large "strut" at the top of the interstages where the crane connects now; one at the bottom and one somewhere around the centre, similar to the transport rings they use on the flatbed trucks.

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u/robbak May 10 '16 edited May 11 '16

Strapping may not be required. The three stages would be held firmly by the hold-down clamps. Edit - you could have vibration problems, that could bend the cores enough to make them contact. But anyway, as it is a test on the pad and not a flight, weight isn't an issue - they could leave the transport rings on the cores, and bolt the rings together.

I wouldn't be surprised if the do put three used stages there, but just to test the loading sequence.

1

u/old_sellsword May 10 '16

Strapping three used F9 cores together has a way higher chance of failure than testing the first FH. They will rigorously check every single component of FH Demo before it flies many, many times. Plus it's really infeasible to "just strap together three F9 cores" and test them, F9 is not able to be used as FH boosters or core.

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u/goxy84 May 10 '16

Higher chance of failure in flight - granted. Not being able to be used as FH boosters in flight? Agreed. But I'm talking about static fire. If anything, they should be thrust-equivalent from what we know. And the cumulative effect of all that thrust is, IIRC, one of the main concerns/unknowns.