I have just received from preliminary information from the UH team - it appears
that first stage burn completed successfully, and a deshrouding maneuver (used
by Sandia for suborbital flights) at staging failed to properly align the
second stage - and tumbling began.
More information may change this analysis … but this is current.
K
On Nov 4, 2015, at 9:56 AM, Lars Osborne <lars.osborne@xxxxxxxxx> wrote:
Probably FOD. Did anyone else see all the particles in the exhaust?
Thanks,
Lars Osborne
On Wed, Nov 4, 2015 at 9:38 AM, KEN BIBA <kenbiba@xxxxxx
<mailto:kenbiba@xxxxxx>> wrote:
I seem to remember, from my quick research on this flight, that the intended
roll rate for the first stage boost was 2.5 Hz with a suggestion of a slowing
to 1 Hz at the end of first stage burn. But those were annotations of a
briefing slide of uncertain age.
Also … this flight was actually pulled forward from 2016 - with a statement
that the increased risk was worth it. I wonder if the risk item is the
cause.
K
On Nov 4, 2015, at 9:22 AM, Paul Mueller <paul.mueller.iii@xxxxxxxxx
<mailto:paul.mueller.iii@xxxxxxxxx>> wrote:
More speculation without data (which is fun!):
We understand gravity turns pretty well--it would be a colossal error if
they set the elevation angle of the launch rail to the wrong setting.
I would think a fin loss would mean the failure would happen much more
quickly, rather than what looked like slowly increasing divergent coning
motion (aka roll-pitch coupling).
I think it was roll-pitch coupling, but not because the roll rate was too
slow. If the roll rate is slow (and there's a decent amount of aerodynamic
damping), or if the roll rate is very high, there won't be significant
roll-pitch coupling. It's the in-between rate that's resonant with the pitch
natural frequency (think Bode plots from back in school) that ruins your
day. Many unguided sounding rockets like the Super Loki spin up immediately
(using a corkscrew rail) to get past the resonant roll rate right from the
start. It looks to me that the roll rate started out at less than 1 Hz (60
rpm) (from the onboard video) and then increased to over 2 Hz (120 rpm) and
then the coning motion started. It lasted for a few seconds before loss of
video. So the roll rate increased until it reached the pitch-roll resonant
frequency and it was all over. At least that's my guess!
The animation looked pretty bogus to me--was the center of mass really that
far forward (that close to the nose cone)?
On Wed, Nov 4, 2015 at 9:47 AM, Aplin Alexander T <ATAPLIN@xxxxxxxxxxxxxxxx
<mailto:ATAPLIN@xxxxxxxxxxxxxxxx>> wrote:
Classification: UK OFFICIAL
Handling Instruction: DISCLAIMER - this is a personal e-mail and only
represents the views of the sender
FWIW the Black Arrow had a solid third stage.
On my mind as I had the pleasure of a close encounter with the spare Black
Arrow on display at the London Science Museum earlier this week).
http://www.sciencemuseum.org.uk/objects/space_technology/1972-325.aspx?keywords=black+arrow
<http://www.sciencemuseum.org.uk/objects/space_technology/1972-325.aspx?keywords=black+arrow>
BTW I also saw a Russian TK Lunar lander on (temporary) display at the
‘Cosmonauts’ exhibition there – the contrast in size to the (relatively)
huge US LM mock-up on display elsewhere was striking.
http://www.sciencemuseum.org.uk/visitmuseum/Plan_your_visit/exhibitions/cosmonauts.aspx
<http://www.sciencemuseum.org.uk/visitmuseum/Plan_your_visit/exhibitions/cosmonauts.aspx>
Alex Aplin
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