Mike:
If lateral acceleration is normal to the vehicle axis then it seems to me
that the curve in Drew’s data is exactly what I would expect for a buildup
of coning induced lateral acceleration leading to vehicle breakup.
It is certainly possible that there is another underlying cause of the
coning but I’d suggest that building the rocket so that it does not fail
structurally will show whether the coning is caused by the structural
failure or has some other underlying cause.
Bill
On Tue, Nov 16, 2021 at 9:41 AM Mike Caplinger <mc@xxxxxxxx> wrote:
On 11/16/21 8:30 AM, William Claybaugh wrote:
Looking at your posted image and your description, I would first guess
that the rocket had a structural failure just above the motor which
failure proceeded first as an offset of the top of the rocket wrt to
bottom
I've had a number of structural failures ("shreds" in HPR parlance) in
this exact area on extreme flights. Obviously it's a weak point, but
it's never been clear to me if it was the root cause of the shred or an
effect of instability. I also usually see a slow ramp-up in lateral
acceleration (the Raven has a two-axis accelerometer with the lateral
normal to the velocity vector) right before the shred which is not
consistent with a lot of coning, but I've never had three-axis
orientation data on these flights.
I looked at an aeroelastic resonance as a possible cause but it didn't
seem like a viable hypothesis.