John:
I am not irritated and did not mean to so seem, if I did do.
Like you, I have seen many hundreds of rocket launches and I am confident
of my ability to recognize coning when I see it. I am pretty certain that
if you take a close look at the public flight video you too will recognize
that the vehicle begins a gentle coning starting about 2/3 of the way
through the burn.
If the Kate was reporting at 100 hertz than it should have shown the
differential acceleration as well as the associated rates. If it did not
do then the data does not conform with the video.
Bill
On Fri, Nov 19, 2021 at 7:19 PM John DeMar <jsdemar@xxxxxxxxx> wrote:
Bill,
I have no interest in the company, but I was invited as a long-time
mentor from their HPR/EX days. I can only pass along what I observed and
speculate along with you. For the fun of it.
With the dampening during motor burn, I wouldn't expect much coning on
this rocket. The fins were match-machined and overly beefy, and well
aligned from what I could tell. The 6Hz spin-up is well beyond the
resonance, so another reason not to expect significant coning.
The telemetry was done by Multitronics based on their Kate telemetry
system. The commercial version does 100 sps, but this had some custom
updates which I'm not sure about.
-John DeMar
Las Cruces, NM
On Fri, Nov 19, 2021 at 6:57 PM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
John:
This is not really something I’m inclined to debate.
I can see what I take to be coning in the exhaust during the last third
of the burn. I count three, maybe four such turns. That would imply around
one hertz; if the telemetry was at ten hertz, it strikes me as possible
that the sample rate might be too low to have captured it.
Bill
On Fri, Nov 19, 2021 at 6:46 PM John DeMar <jsdemar@xxxxxxxxx> wrote:
Bill,
The complete set of telemetry data for all DOF's looked reasonable
and indicative of the flight profile. The spiral in the plume isn't obvious
as it is burning but shows as the exhaust disperses. I'm just guessing, but
maybe it's from the fin vortexes and not from coning.
Here are my photos from the launch at FAR. My video is at the end of
the album:
https://photos.app.goo.gl/xekJPoNda3oAkGy1A
-John DeMar
Las Cruces, NM
From: William Claybaugh <wclaybaugh2@xxxxxxxxx>
Date: Fri, 19 Nov 2021 18:20:21 -0700
Subject: [AR] Re: Fwd: Evolution Space | Too Busy Chasing Stars Mission
| S Mot
John:
The corkscrew in the smoke trail says it was coning. If the telemetry
shows absolutely no sinusoidal pitch and yaw then an explanation for the
failure of the accelerometers to detect it would be my next question.
Bill
On Fri, Nov 19, 2021 at 6:15 PM John DeMar <jsdemar@xxxxxxxxx> wrote:
The fins were canted to induce ~6Hz spin at burnout. The telemetrydata
didn't show significant pitch/raw movement, at least at the forwardend
where the electronics were positioned. The overall construction of the
rocket was quite stout, but the marman clamp apparently failed. So, no
recovery.
-John DeMar
Las Cruces, NM
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