We've considered 'wind shear' and observations have shown it will occur maybe
one time in a launch that often is during volleys of four or five rockets and
on days when 50 or more rockets might be launched and often with a rocket with
a high acceleration rate. On windy days we'll often see weather cocking
especially with large or low-velocity rockets off the pad and in the direction
of the wind. We are in a desert and so we've sometimes wondered if it were
going through a dust devil not visible without any dust in it. Since you cannot
'see' it, that explanation is just a possible hypothesis.
On that day, I think Bill's flight is the only one that was observed to have
this sudden direction change.
Years ago on our MiniSShot II flight we observed a nominal Mach+ flight and
then a sudden wiggle course change at ~15,000' and then back to nominal flight.
At the time we couldn't explain it until we picked up the signal from the nose
cone transmitting back at FAR. The nose cone and recovery bay had snapped off
and landed just outside the fence.
Rick
From: William Claybaugh <wclaybaugh2@xxxxxxxxx>
Date: Thu, 21 Oct 2021 08:12:21 -0600
Subject: [AR] Re: Test Launch
Rick, Troy:
There is a well known wind shear about 100-120 feet up at the MTA.
Apparently due to winds from the dry lake separating from the terrain as
they reach the top of the rise where the MTA is located.
However, that shear only occurs on windy days and pitches rockets on the
down range direction.
This pitch was in the opposite direction on a windless day.
After sleeping on it I’m increasingly thinking that Troy may be right:
venting of the pneumatic system could cause that sort of pitch change.
I’ll pressurize that system today and see if it leaks.
Bill
On Wed, Oct 20, 2021 at 8:37 PM Rick Maschek <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
I have no idea 'why' but every year at 'HPR' events, I'll see a few solid
propellant rockets leave the rail straight and fast and about 50 to 100
feet above the launch rail take a quick change in direction and then again
proceed in a straight line nominal flight. I'll try to find some videos of
this phenomenon.
Rick