Speculation*, probably stimulated the high gee ascent loads, but the 1 gee
cantilevered loads riding to the launch pad, a compressive load on the
spoke opposite the tensile ascent loads?
If the Dragon trunk collapsed, the nice round IDA1
http://www.nasa.gov/sites/default/files/thumbnails/image/17179167311_01f3959c44_o_1.jpg
would fit nicely over the LOX bulkhead truncated cone.
https://www.flickr.com/photos/spacexphotos/17076243136/
Or, not. But, as the LOX pressure dome is crushed by the IDA and Dragon
under high gees, the pressure would go up in the LOX tank. Even if the
pressure relief valve open, or the Lox tank was holed, IDA/Dragon would
keep the pressure inside the LOX tank high. Like the plunger on a syringe,
LOX would be spewing out of the tank at high pressure, not low pressure as
one would expect from a ruptured tank.
Maybe this is counterintuitive comment
https://twitter.com/elonmusk/status/615185076813459456
*pure speculation with no new data
On Wed, Jul 1, 2015 at 10:13 PM, Steve Traugott <stevegt@xxxxxxx> wrote:
Okay, I'm going to go way out on a speculative limb and make some sort of
noises about the mounting bolts attaching the IDA to those spokes being
compromised in some way during transport, after they were last NDT'd and
installed. Or maybe they were never NDT'd by anything other than dye
penetrant and they should have been x-rayed, or somesuch. Or maybe someone
did the math wrong in the first place. Happens. We may never know.
Anyone know the water depth where the debris came down?
Steve
On Wed, Jul 1, 2015 at 5:53 AM, Craig Fink <webegood@xxxxxxxxx> wrote:
From a prelaunch video, it sounded like the Boeing supplied IDA is hung
below dragon to distribute loads equally around the trunk. Also, in a
prelaunch video, a reporter asks about the difficulties/problems that
spacex encountered while mounting the IDA inside the trunk. The Spacex
launch guy looked confused while recalling all the reports he had read
leading up to the launch. He couldn't recall any problems.
https://www.youtube.com/watch?v=lX7s-sA7bEk
So, the IDA would be cantilevered to the trunk spokes while horizontal,
then hung by the spokes during launch and late first stage high gee region.
If the trunk became compromised, it might crush like a tin can, Dragon, IDA
would land and be supported on the pressure dome decreasing ullage volume
and increasing pressure before puncturing the dome.
On Tue, Jun 30, 2015 at 11:38 PM, Henry Vanderbilt <
hvanderbilt@xxxxxxxxxxxxxx> wrote:
Even without being in a closed-loop control circuit, or faulty, sensors
can react to inputs other than what you'd expect - pressure sensors, for
instance, can also act to varying extents as microphones picking up shocks
in structures they're attached to.
More subtly, in looking at data traces, it can be hard sometimes to
determine definitively what's cause and what's effect. EG, a tank
structural failure under load may well have some interesting pressure
spikes closely associated with it, and absent other data resolving the
ambiguity, which came first?
On 6/30/2015 8:58 PM, Troy Prideaux wrote:
In a purely general context: a “counterintuitive” explosion can also
mean a faulty sensor input, especially if the
flow/pressure/vent/relief/control mechanisms were governed by such
readings. Of course, active (only) controls are probably an extremely
rareoccurrencefor critical systems and a bad sensor reading can be
generally correlated with other sensor readings (in complex systems with
lots of sensors) to identify possible issues with its readings.
Troy
The "counterintuitive" comment may mean that we're all up in the night
here and anyone from SpaceX reading this is not getting any useful
information. Of course, something that seems "counterintuitive" to those
not familiar with cryogenics may be more intuitive to those who have
experience with weird things like geysering or film boiling...or someone
who really understands BLEVEs (not me).
--
Craig Fink
WeBeGood@xxxxxxxxx
