I was worried about that on the ME-8 so I clipped off the side electrode to
change it into a pseudo-surface gap plug. I don't know if it affects the spark
energy but was reliable enough for my igniter. I run the spark for 1 second max
or until I see igniter pressure. The igniter fuel and GOX valves stay open for
2 seconds. If the main chamber pressure isn't up by then I shut it all down.
-Bob
On Apr 28, 2016, at 12:56, Doug Jones <djones@xxxxxxxx> wrote:
The main issue with Rimfire plugs is that the side electrode is low mass and
low thermal conductivity. It takes careful (proprietary) design of the
igniter to prevent burning it off altogether. But after we figured that out
we can do thousands of runs with no erosion. Also, keeping the igniter run
duration as short as possible helps a lot.
I don't have documentation in front of me, but I'm pretty sure we use the VR2
model.
Doug Jones, Chief Test Engineer
XCOR Aerospace
1325 Sabovich
Mojave CA 93501
(661) 824-4714 x117
cell 661 313-0584
On 4/27/2016 6:12 PM, Robert Watzlavick wrote:
I discovered today that the NGK ME-8 spark plug is no longer made. I've been
using the 1/4-28 plugs in my Augmented Spark Igniters so I'm looking for a
replacement in the same size. In addition to the cheap import knockoffs,
the Rimfire VR2 looks to be a near exact match:
http://sparkplugs.morrisonandmarvin.com/14-32.php ;
Has anybody used the Rimfire plugs in a rocket application? The only thing
I'd be concerned with is the prolonged heat and temperature causing a
leak around the insulator. I suppose I could do a little igniter test
program to qualify them myself. On this page, they claim XCOR, NASA and
other aerospace companies use them:
http://sparkplugs.morrisonandmarvin.com/main2.php ;
-Bob
