[AR] Re: Falcon 9 flight today
- From: Ben Brockert <wikkit@xxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Sun, 6 Oct 2013 23:14:18 -0600
I wasn't so much a source as the instigator. As far as I know from the
blogs and news sites that I watch, I was the first one in English to
point out the cloud and definitely show from orbital parameters that
the UFO was the Falcon 9's cloud.
I know Alan Boyle in real life, I guess he saw my post about it and
thought it was worth a story.
With some further work on other images I found that the propellant
cloud was 108 miles wide.
http://wikkit.tumblr.com/post/63351208465/how-big-was-the-cloud-of-propellant-from-the
Ben
On Sun, Oct 6, 2013 at 9:56 PM, Nathan Mogk <nm8911@xxxxxxxxx> wrote:
> I like how Ben Brockert was included as a source on this article. You must
> do a good job of getting your blog out there, Ben.
>
>
> On Sun, Oct 6, 2013 at 4:16 PM, Henry Vanderbilt
> <hvanderbilt@xxxxxxxxxxxxxx> wrote:
>>
>> On 10/6/2013 2:54 PM, Henry Spencer wrote:
>>>
>>> On Sun, 6 Oct 2013, Henry Vanderbilt wrote:
>>>>
>>>> ...the 2nd-stage restart attempt resulting in a hard start bad enough to
>>>> disable the engine and scatter some debris, but not bad enough to
>>>> rupture the stage tanks or feed lines.
>>>
>>>
>>> Hmm, yes, a very interesting possibility. A hard start can be violent
>>> enough to do damage, e.g. by the acceleration transient, without actually
>>> *bursting* anything. (Gemini 6's Agena target was lost due to a hard
>>> start that damaged control electronics.)
>>>
>>>> Speculative, of course, but it is worth noting that while they've
>>>> acknowledged a restart problem, they've said nothing about its nature
>>>> yet. It was FWIW apparently bad enough to immediately rule out a retry,
>>>> given that remaining propellants were vented right afterward.
>>>
>>>
>>> If (dim) memory serves, there is at least one expendable item (igniter
>>> hypergol cartridge?) needed for a start on the Merlin, and the engine has
>>> fittings for only two of them, so two starts is all it's good for without
>>> human attention. So the immediate propellant venting might not be
>>> significant -- indeed, might have been pre-programmed -- because they
>>> weren't going to be able to try again anyhow.
>>>
>>> Although, hmm. They said the stage "underwent a controlled venting of
>>> propellants". In the spirit of hermeneutical analysis (read Arocket and
>>> improve your vocabulary!) :-), note that they don't say it was on
>>> command,
>>> or as planned, just that it was controlled. Maybe that *wasn't* meant
>>> to happen immediately. If the tanks vented before anything could be done
>>> about it, that would certainly explain why they quickly gave up on trying
>>> again.
>>
>>
>> And yes, getting into the spirit of lawyerly parsing, I did deliberately
>> phrase "It was FWIW apparently bad enough to immediately rule out a retry,
>> given that remaining propellants were vented right afterward" to cover both
>> commanded-venting and uncommanded-venting (at a "controlled" rate)
>> possibilities.
>>
>> Looking at the video of the venting at
>> http://www.nbcnews.com/science/ufo-over-indian-ocean-spacex-falcon-9-rocket-sparks-sightings-4B11297922,
>> by the way, I notice that the two-lobed effect I'd also seen in stills of
>> the vent cloud is present pretty much through the first couple minutes of
>> the video. It still may be (as I'd first thought from the stills) an
>> optical effect of some sort, but it also looks consistent with bidirectional
>> venting (via a T fitting or otherwise) intended to produce no net thrust.
>> IE, more likely via the intended vents rather than via hypothetical damaged
>> engine plumbing, if it's not just an effect of sunlight on the vent cloud or
>> a lens effect.
>>
>> I hadn't known about the specific limit on Merlin starter cartridges
>> though. A quick search didn't turn anything up. Any idea where to find out
>> more about that?
>>
>> Henry
>>
>>
>
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