Thinking it's operator error. Just not sure why on those two launch attempts.
Too coincidental.
Sent from my iPhone
On Sep 5, 2017, at 7:48 PM, Andrew Wimmer <xenonrocket@xxxxxxxxx> wrote:
http://pro38.com/pdfs/Pro54_instructions.pdf
"If using an electronic recovery system, pry the white plastic disc from the
end of the delay/ejection module and transfer the powder to your remote
ejection charge holder and follow the recovery system instructions. Reinstall
the module into the reload assembly. We recommend that you leave the delay
unadjusted for these applications to minimize delay residue ahead of the
motor forward closure."
Though to be fair, from your description it doesn't sound like the ignition
issue was related to the ejection charge modification.
-Andrew
On Tue, Sep 5, 2017 at 7:40 PM, Dave M <dmarc-noreply@xxxxxxxxxxxxx> wrote:
So what should I do otherwise with the BP cavity? Is there a better way than
filling with epoxy?
Sent from my iPhone
On Sep 5, 2017, at 6:47 PM, Dave M (Redacted sender "muldavea" for DMARC)
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
I just emptied the cavity of the BP.
Sent from my iPhone
On Sep 5, 2017, at 6:12 PM, Dave Barr <dhbarr@xxxxxxxxx> wrote:
To clarify: did you keep the delay grain or was that epoxified as well?
On Tuesday, September 5, 2017, Dave M <dmarc-noreply@xxxxxxxxxxxxx> wrote:
54mm. I believe they were a J295 and a K570.
Good point Kurt. Maybe I was just unlucky with those two launches. At
first I thought I was cutting off the oxygen supply somehow at the base
of the motor (I helped a guy who was down to his last igniter when I
noticed he had heavily taped up the bottom of the motor) but I just had
the red cap on and even cut an X cut into it after igniters failed. It
was only later that I realized it was the motors I filled with epoxy so
I got suspicious. Now I'm paranoid to do that again. On some small
Aerotch motors I've just used Vaseline instead of BP with some tape over
it, but figured epoxy is a better alternative?
Sent from my iPhone
On Sep 5, 2017, at 4:54 PM, Kurtgug@xxxxxxxxx <kurtgug@xxxxxxxxx> wrote:
Once you burn the first igniter without lighting the motor, it is always
harder to light it with the second, and even harder with the third. The
core gets coated with soot which acts as an insulator. If you had the
pyrodex pellet in there, it is hard to imagine that not lighting. Maybe
it did light but fail to light the fuel. That would really coat the
inside with soot.
Sent from my iPad
On Sep 5, 2017, at 4:44 PM, Dave M (Redacted sender "muldavea" for
DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
No I was very careful next not to disturb anything. And the epoxy dries
so quickly that I didn't think it would have any chance to soak thru
anywhere.
Sent from my iPhone
On Sep 5, 2017, at 4:36 PM, Gregory Lyzenga <lyzenga@xxxxxxxxx> wrote:
On Sep 5, 2017, at 4:22 PM, Dave M (Redacted sender "muldavea" for
DMARC) <dmarc-noreply@xxxxxxxxxxxxx> wrote:
A while back, I had two Cesaroni motors that were not plugged but I
didnt want the motor to blow the BP charge. So I removed the BP and
filled up with epoxy. Problem was, in each case, it took maybe three
attempts to launch. Kept burning out igniters. Any thoughts?
In the process of removing the ejection charge, did you disturb or
damage the igniter pellet at the top of the grain? Since Cesaroni
igniters are basically just e-matches without a bunch of pyrogen, there
is a pyrodex pellet at the top of the motor to get the ignition going.
If the epoxy ran onto that, it might explain your problem. But on
second thought that seems unlikely, since there would be a delay grain
between it and the ejection charge well. Hmmm… I’m not sure...
- Greg
----------------------------------------------------------
Gregory A. Lyzenga <lyzenga@xxxxxxx>
Dept. of Physics, Harvey Mudd College (909) 621-8378
Claremont, CA 91711-5990 mobile (626) 808-5314
