Cesaroni Igniter Replacement

Cesaroni Igniter Replacement

Post by Phil Stei » Thu, 03 Mar 2005 12:13:08





Quote:


>> On Tue, 01 Mar 2005 14:23:27 -0600, Dwayne Surdu-Miller


>> >> Cat -

>> >> Here's the scoop:
>> ><snip>
>> >---------------------------------------

>> >You've posted a valuable gem, Mike.

>> >Thank you,

>> >Dwayne Surdu-Miller
>> >SAROS #1

>> Yep.  That's what I was talking about when I mentioned motor makers
>> that try to provide a service.

>Hmmmmmmmmmmmm.

Hmmmmmmmmmmmm  what, moron?  Do you have anything relevent to say?
 
 
 

Cesaroni Igniter Replacement

Post by Mark Daughtry, S » Thu, 03 Mar 2005 21:13:56



Quote:




>>> On Tue, 01 Mar 2005 14:23:27 -0600, Dwayne Surdu-Miller


>>> >> Cat -

>>> >> Here's the scoop:
>>> ><snip>
>>> >---------------------------------------

>>> >You've posted a valuable gem, Mike.

>>> >Thank you,

>>> >Dwayne Surdu-Miller
>>> >SAROS #1

>>> Yep.  That's what I was talking about when I mentioned motor makers
>>> that try to provide a service.

>>Hmmmmmmmmmmmm.

> Hmmmmmmmmmmmm  what, moron?  Do you have anything relevent to say?

I think what he meant to say is "That should be put in the FAQ!".

(And it should be too)

--
Best regards,
Mark Daughtry, SR

 
 
 

Cesaroni Igniter Replacement

Post by Mike Dennet » Fri, 04 Mar 2005 00:29:30


We have a completely reworked website in the works. There is info about this
in the FAQ section. It will be up sometime pretty soon.

Cheers,

Mike D.


Quote:

> I agree with Alex, Mike.  This was a great post!  I hope you put it up
> on the Pro38 site.

> Doug

> --
> Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

 
 
 

Cesaroni Igniter Replacement

Post by Mike Dennet » Fri, 04 Mar 2005 00:34:56


Quote:
> bla bla bla... The plastic sleeve
> accomplishes this - I did witness paaper tests to prove the idea, plus
some
> hurried field testing when someone had problems with a Pro54 J. So do
> yourselves a favor and don't skip this step - it is described on the
little
> paper instruction sheet accompanying the igniter. If this is done as
> described, the match will ignite the propellant reliably even when
separated
> by a short standoff distance. But don't intentionally cause there to be a
> standoff distance - get that igniter right up to the top.

Should really read:

If this is done as described, the match will ignite the PELLET reliably even
when separated
 by a short standoff distance.

Though I could defend this typo by pointing out that the igniter pellet is a
propellant... but it doesn't help the clarity of the explanation much.

Mike D.

 
 
 

Cesaroni Igniter Replacement

Post by rober » Sun, 06 Mar 2005 23:40:51


Mike,
Nice post.
We had a similar issue with the igniter falling down in a M motor.

So, with all motors it is very important that the igniter be secured so it
can't fall especially in larger cores.

Robert


Quote:
> Cat -

> Here's the scoop:

> You could use an aftermarket igniter with the Pro38's, as long as you are
> diligent about making sure it is all the way up the core and in contact
with
> or in very close proximity to the igniter pellet. But don't use something
> with 5 grams of thermonuclear goo on it, you won't change a thing about
how
> quickly the motor ignites. Just use something that will ignite the igniter
> pellet, and that doesn't take much - your description of a nichrome-BP
> igniter sounds suitable.

> The reason we tell people not to use aftermarket igniters is as follows:

> (1) It is unnecessary - properly installed, the supplied e-match will
light
> the igniter pellet every time.

> (2) The main reason:   Pyrogen dipped igniters will ignite the propellant
> directly, the e-matches will not. Using an igniter with pyrogen overdip
can
> (and has) caused the occasional mid-port ignition and subsequent disaster.
> One would think that with that easily ignited pellet at the top of the
core,
> that even if you accidentally touched off the propellant lower down the
core
> the darn thing would still go and the motor would function nominally. This
> is true most of the time, however, there have been notable exceptions.
> Stagnated cold gas in the core above the ignition event is far more
stubborn
> at allowing fire transfer than you might think - it is a far better
> insulator than you'd suspect.

> One fellow sent us the remains of a 6G casing and reload parts, with an
odd
> description of the event. What we recieved was the upper 2/3 of the
casing,
> a hardened puddle of aluminum slag,  and the remains of the upper part of
> the reload inert bits. Hmmm we thought... how did this happen. As he
> decribed it, the button was pushed, there was a pop from the ignitor, then
> nothing more than a road flare flame from the rear of the motor, that
lasted
> something like 1-1-/2 minutes.  Eventually molten aluminum was seen to be
> dripping from the rear of the motor..

> We asked the usual questions, did you get the igniter all the way up the
> core, did you use the supplied igniter, etc etc. Yes to all.

> Baffled, I scratched my head overnight on the issue, wondering if the
nozzle
> had ejected at ignition, or if there was a blind drilled grain lower down,
> or had we shipped a whole batch of propellant missing most of the oxidizer
> (not likely), or what. But the problem was, as he described it the nozzle
> did not blow out, and he had said he used the stock igniter which I knew,
or
> "knew" let's say from experience, would not ignitie the propellant
directly.
> I came to the conclusion that it must have suffered a mid to lower port
> ignition somehow, sothought I that maybe the matches will on occasion
ignite
> the propellant directly. It is not unheard of that the match might snag
> between grains and cause a misfire, it has happened a few times.

> So, armed with some e-matches, a couple of 6G cases and J330 reloads I
went
> out to the test stand to play. I tried getting a midport igniton with the
> stock e-match. Nothing, and in fact I have never successfully ignited
Pro38
> standard propellant directly with an e-match.

> Next step - I rigged a pyrogen igniter using an Oxral match and about two
> inches of double over igniter cord, and put this about 2" into the core.

> Bingo!

> A 2 minute road flare, and after about a minute the nozzle just sort of
fell
> out, and the bottom couple of inches of the casing melted away into a
puddle
> of aluminum. The motor never even came close to reaching operating
pressure,
> I doubt it would even have moved under its own power lying sideways on the
> asphalt. The reamins were hard to tell apart from those sent to us by our
> customer.

> So, a quick email to the customer to report our findings. AHA! He
confessed,
> after thinking about it, that he had indeed used an aftermarket igniter,
and
> the conclusion was that it must have snagged in the core and felt like it
> was all the way up.

> We all laughed about this, because on the very positive side we had
learned
> something important from the event.

> Now, all that said, in the installation instructions for the Oxral
igniters
> (now supplied with all Pro38 2G and larger reloads) I describe cutting off
a
> short piece of the red plastic tube used to shunt the bare leads, and
> sliding this over the match head. This single feature increases igntion
> reliabilty hugely - without the sleeve the output from the ematch goes in
> all directions except straight back of course. Problem is, we want that
> output to all go forwards towards the igniter pellet. The plastic sleeve
> accomplishes this - I did witness paaper tests to prove the idea, plus
some
> hurried field testing when someone had problems with a Pro54 J. So do
> yourselves a favor and don't skip this step - it is described on the
little
> paper instruction sheet accompanying the igniter. If this is done as
> described, the match will ignite the propellant reliably even when
separated
> by a short standoff distance. But don't intentionally cause there to be a
> standoff distance - get that igniter right up to the top.

> FYI, we used to supply Daveyfire M28F's with all motors. Now, we only
supply
> them with the Pro38 1G G reloads, as they have nozzle throats too small
for
> the Oxral. Everything else gets Oxrals. These are the only two types of
> igniters we provide.

> Mike Dennett
> Cesaroni Technology Incorporated



> > Hello All,

> > Sorry for the dumb question, but at the last launch I left behind a box
> with
> > 4 igniters that came with the Cesaroni pro38 reloads. I was told not to
> use
> > a "HOT" igniter to replace the lost ones, what would you recommend as a
> > replacement e-match? I do not have an ATFE LTC so I'm stuck with few
> > options, I however use nichrome/bp igniters for just about everything
else
> > they work with aerotech would they be ok? How about hotshot? Besides the
> > starter grain, why would a pro-38 be any different then any other APCP
> > reload?

> > -cat

 
 
 

Cesaroni Igniter Replacement

Post by Niall Oswal » Wed, 09 Mar 2005 09:07:45



Quote:

>> We had a similar issue with the igniter falling down in a M motor.

>> So, with all motors it is very important that the igniter be
>> secured so it can't fall especially in larger cores.

> I know a lot of people who use very thin dowels to support the
> igniter for the big motors.

So does that dowel remain in the motor up to the point of ignition? How thin
is thin?

Just wonderin'

--
Niall Oswald
================================
http://www.bits.bris.ac.uk/niall
UKRA 1345
EARS 1151
MARS

 
 
 

Cesaroni Igniter Replacement

Post by Rick Dickinso » Wed, 09 Mar 2005 09:48:10


On Tue, 8 Mar 2005 00:07:45 GMT, in rec.models.rockets "Niall Oswald"

Quote:



>> I know a lot of people who use very thin dowels to support the
>> igniter for the big motors.

>So does that dowel remain in the motor up to the point of ignition? How thin
>is thin?

>Just wonderin'

Typically, people trying to ignite a large motor (especially
single-throat L or M motors) will use a 1/8" dowel with several
igniters taped to it, each igniter having been augmented with some
sort of pyrogen.  To avoid over-pressurizing the motor, the entire
assembly should be able to *easily* slide up through the nozzle
without blocking a significant portion of the nozzle throat.

This way, the igniters are held right at the head end of the motor,
yet the entire assembly can be easily ejected as the motor comes up to
pressure.  If the whole thing can't slide easily out of the motor, you
risk nozzle blockage and a CATO due to overpressurizing the motor.

 - Rick "5..4..3..2..1..ignition!"***inson

--
"I've always been taught that if you code an arbitrary limit, try to
make it a power of two, or at least avoid powers of ten, so people
think there's a good technical reason for it."
            -- Good advice from Peter Corlett

 
 
 

Cesaroni Igniter Replacement

Post by Jerry Irvin » Wed, 09 Mar 2005 13:53:50




Quote:



> >> We had a similar issue with the igniter falling down in a M motor.

> >> So, with all motors it is very important that the igniter be
> >> secured so it can't fall especially in larger cores.

> > I know a lot of people who use very thin dowels to support the
> > igniter for the big motors.

> So does that dowel remain in the motor up to the point of ignition? How thin
> is thin?

1/16" works great (since 1972 :).

It is ejected during the ignition ramp-up, typically within the first
14ms.

The reason to use a thin dowel is so the Kni is not very substantially
modified thus preventing overpressure on any reasonable motor design.

Quote:

> Just wonderin'

Just techin'

Jerry

--
Jerry Irvine, Box 1242, Claremont, California 91711 USA

Please bring common sense back to rocketry administration. (too late)
Produce then publish.  http://www.usrockets.com
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