Sent from my iPhone
On Sep 5, 2017, at 8:57 PM, James Dougherty <jafrado@xxxxxxxxx> wrote:
You can also modify a CTI for HEI if you use the right epoxy like CO4525
On Tue, Sep 5, 2017 at 8:55 PM, James Dougherty <jafrado@xxxxxxxxx> wrote:
Putting blue-tape over the cavity will give a small amount of smoke, but no
ejection charge.
The easiest way to fly one of those with electronics is to dump out the
charge; and use your altimeter chargers.
You will still get blow-by.
If you don't want blow-by, use epoxy.
Yes, it is pricy though.
On Tue, Sep 5, 2017 at 8:50 PM, Dave M <dmarc-noreply@xxxxxxxxxxxxx> wrote:
Eric,
So to clarify you are removing BP and putting blue tape over the cavity?
Sent from my iPhone
On Sep 5, 2017, at 8:36 PM, Eric Melville <eric@xxxxxxxxxxxxx> wrote:
I put blue tape over the touch hole. It might sound ridiculous but I have
not seen a single burn through, on at least a dozen flights now.
- iPhone mail
On Sep 5, 2017, at 7:40 PM, Dave M (Redacted sender "muldavea" for DMARC)
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
So what should I do otherwise with the BP cavity? Is there a better way
than filling with epoxy?
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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.
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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
