Ed,
What I meant was a significant failure within the pneumatic system that might
have (a) poured out gas within the internal volume and (b) prematurely
moved/retracted one of more of the locking pins exposing a port to escape out.
Without seeing the mechanism or retention system, that may well not be a
possibility.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Edward Wranosky
Sent: Friday, 22 October 2021 4:26 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Test Launch
The retention of the payload through the pins to the motor was *VERY* robust.
You could rotate the rocket when it was engaged and even use it to hold the
rocket when leaning. By far one of the most robust connections of payload to
motor I have seen.
On Wed, Oct 20, 2021 at 4:54 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Duh, yes, that’s what I actually meant ie. a significant failure event. My bad.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Thursday, 21 October 2021 9:11 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Test Launch
Troy:
Unlikely, as I said, there are two o-rings between the pressure and ambient,
but I will be looking for that when I disassemble it,
The planned gas vent does produce significant force and is therefore forced
through a diffuser and contained w/i the payload compartment for a subsequent
slow leak down. So if something failed in a big way it could account for the
sudden turn, particularly if it was able to vent overboard.
Bill
On Wed, Oct 20, 2021 at 3:56 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Is it possible there was enough gas in the pneumatics (if leaky) to create a
significant (enough) lateral thrust from … perhaps… one of these pin orifices?
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Thursday, 21 October 2021 8:40 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Test Launch
Troy:
We can surmise that the payload came off around this time as it was recovered
about 300 feet from the launch tower and on the ‘new’ azimuth.
The attach system isn’t given to a partial failure since the four pins are held
in place by pressure. When the payload came off, all four pins had to be pulled
inward; thus a pressure failure is indicated.
Because loss of pressure was high on the list of failure modes, all leak paths
had two orings. It was also extensively tested, it was not, however, tested for
a 20 degree turn in 1/4 second at 450-ish ft/sec and 11-ish g’s acceleration.
I’ll be carefully pulling the pneumatic system apart over the next few days to
see if there is any evidence for a breech.
Bill
On Wed, Oct 20, 2021 at 3:26 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Bill,
Looking at one of Ed’s frame grabs, it looks like the airframe is not entirely
straight at that moment (of the turn). That could be an optical illusion of the
different colour sections though as the bend seems to occur where the shades
transition?
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Thursday, 21 October 2021 8:04 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Test Launch
Looking at two videos I see the turn starting around 100-120 feet (based on the
known 24 foot length of the launch tower). I counted 14 frames to complete the
turn. Given the trajectory, this implies the video was shot at 60 frames/second
and the turn took place in 0.25 seconds. (At Mach 0.38....)
The vehicle is flying straight and true up to the start of the turn, which
makes a stuck belly band questionable: why didn't it turn as soon as it left
the launcher if a belly band was adding drag to one side? Conversely, why did
it stop turning if not because a stuck belly band coming off?
Similarly, if the sudden turn was due to an internal failure leading to an
off-axis mass asymmetry, why did it straighten out and fly true on the new
heading?
And then there is the telemetry LOS occurring at about the same altitude as the
turn and the subsequent finding that the antenna had snapped off at the base.
For now, I am tentatively assuming that was an effect of the sudden very sharp
turn but I'm open to other suggestions.
All thoughts are welcome....
Bill
On Tue, Oct 19, 2021 at 6:13 AM William Claybaugh <wclaybaugh2@xxxxxxxxx
<mailto:wclaybaugh2@xxxxxxxxx> > wrote:
Troy:
Antenna was mounted vertically and internally.
Bill
On Mon, Oct 18, 2021 at 8:03 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Yeah, you’re most likely correct Ken. We mount all our antennas internally, so
it that didn’t occur to me, but Bill might be constrained to mount his
externally with a metal airframe or surrounding structure.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of roxanna Mason
Sent: Tuesday, 19 October 2021 12:31 PM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Test Launch
Sounds like damage from the launcher,
Ken
On Mon, Oct 18, 2021 at 6:15 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
Bill,
Any ideas why the antenna snapped off? Was it in the same area at the chute and
shock cords? Any photos to share?
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx ;<mailto:arocket-bounce@xxxxxxxxxxxxx> ] On
Behalf Of William Claybaugh
Sent: Tuesday, 19 October 2021 11:32 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Test Launch
Launched a 6” rocket at the MTA this weekend.
The rocket part worked fine: clean ignition, full 8 second burn. Bellybands
worked and separated as planned.
The payload had multiple failures: telemetry stopped at 119 feet and 425 ft/
sec when the antenna snapped off at the base. About the same time the payload
separated from the rocket. (The two may well be related.) Payload was
recovered and I will download the data for review when I get home.
The bellybands were pretty chewed up by the ride up the rail. The fins clearly
tore into the bottom band on ignition (bands were 0.020” 2024-T3). A redesign
with stronger bands appears a good idea.
Bill