Spitting out igniters?

[bill_s]

When the motor spits out the igniter, is this just the normal thing when the igniter lights but the motor does not? I was thinking maybe the First Fires are a (little) more reliable because they don't come out as easily. Maybe could super glue a bit of paper or even some wire to the side of a Copperhead for the same effect? On the other hand, I've seen what happens when the igniter is too tight.

I just snagged some of the last of the 8" crappers, twice as many for less $$. I had good luck with them until I said something good about them here ... Also I've been using the 4" ones for 24/40s, used up the ones that came with them, and they're a bit looser. Did learn to make sure the clip leads aren't pulling on the igniter at all, give it a chance at least.

 

[shreadvector]

If the nozzle is vented, the pyrogen buring cannot pressurize the motor and spit the igniter out by itself. The propellant has to ignite or start to ignite to generate pressure to spit out the igniter.

The only reason you would need to hold an igniter inside is if it somehow was slowly generating heat and had to slowly ignite the surface of the propellant. Igniters do not burn slowly.

 

[stickershock23]

Like Shread said.

Make sure the motor is VENTED. if it builds pressure to fast POP out comes the igniter before it ignites the motor.

If you are usingthe little red caps. use a knife (CAREFULLY) and trim it at an angle to there is a notch out of it. this still holds the igniter in but lets the pressure out until the motor fully ignites!

 

[bill_s]

I've tried the cap well vented, with the 24/40 once and it spit. I didn't cram it on as hard and far as possible, though, being concerned that could cause its own problem. 1 spit and 2 successes with copperheads/F24W & masking tape on the nozzle side only of those. At least 1 spit, 4 successes with a First Fire Jr., 1 spit and 5 successes with First fire 3"/E20W, 1 fail one success Sonic/G40W, 2 fails Sonic/E20, 1 success after aforementioned E20 fails with a Copperhead 6".

 

[jadebox]

On the other hand, I've seen what happens when the igniter is too tight.

I was going to make that point then I saw that you had.

I'd be careful adding anything to the igniter to try to keep it inside the motor because you risk clogging the nozzle and causing bigger problems.

If you follow the directions posted by Aerotech, the Copperheads work fine.

-- Roger

 

[bill_s]

I haven't been scraping them with a knife, but didn't include the one short in that tally (which was probably from trying to trim the pyrogen lump with my fingernail. These all definitely fired though. It says I was correct with the red cap. I guess the question, do the igniters ever fire without lighting the motor and NOT spit out?

 

[stealth6]

.. do the igniters ever fire without lighting the motor and NOT spit out?

yes, definately.

s6

 

[stealth6]

I think you also have to realize the difference between an ignitor being "spit out" and merely falling out. I would venture that some of those times that you are imagining the igniter beings "spit out" it in fact simply fell out - not due to pressurization, but to simply not being held in securely enough.

s6

 

[ckreef]

If you are using the little red caps. use a knife (CAREFULLY) and trim it at an angle to there is a notch out of it. this still holds the igniter in but lets the pressure out until the motor fully ignites!

I wondered about the slit in the red cap. Now I understand -- DUH

 

[NAR29996]

Like Shread said.

Make sure the motor is VENTED. if it builds pressure to fast POP out comes the igniter before it ignites the motor.

If you are usingthe little red caps. use a knife (CAREFULLY) and trim it at an angle to there is a notch out of it. this still holds the igniter in but lets the pressure out until the motor fully ignites!

Hell, cut off the whole end of the red cap with scissors.

 

[DizWolf]

I had some harder to light G78's. blew out a few copperheads, lit off on a First fire Jr. Looking at photos of the ignitions, they all blew out some decent flames, but the FF were obviously hotter. I think it's less pressure and being 'stuck' inside, and more bang.

 

[NSR]

Hi i am new to the forum but not to rocketry just thought i would add an example two pictures of my rocket Vitamin G on an aerotech G79W spitting out a firstfire igniter you can see in the first pic the sparks from the igniter hitting the pad.