Igniter Issues

[topbrahmen]

I think I know the answer to my problem, but I wanted to get another opinion. So I was using the slim gem igniters from Quickburst, and I had 2 out of 3 igniters fail on me in both the same way. It looks like the coil heated up and ejected some of the pyrogen, and did not ignite the rest of the pyrogen. My initial thought looking through my launching system is that I'm using 24 v instead of 12 and that's overheating the wire so fast that it doesn't have time to heat up the entire pyrogen.

Any thoughts?

 

[Donnager]

I think I know the answer to my problem, but I wanted to get another opinion. So I was using the slim gem igniters from Quickburst, and I had 2 out of 3 igniters fail on me in both the same way. It looks like the coil heated up and ejected some of the pyrogen, and did not ignite the rest of the pyrogen. My initial thought looking through my launching system is that I'm using 24 v instead of 12 and that's overheating the wire so fast that it doesn't have time to heat up the entire pyrogen.

Any thoughts?

First thought... I think you're on the right track. I'd drop the voltage first to see if that is causing the issue.

I've had trouble when an e-match lights very quickly and literally blows the dope off the match, sometimes without full ignition, usually with a hot battery/ignition system.

Never tried 24v before.

 

[cwbullet]

I concur. I make this type of igniter. I have never used 24v but if I were making them for this type of system, I would use thicker Nichome.

 

[Donnager]

thicker Nichome

Would be where I headed first, if I had to use a hot 24V launcher, but I'd have to do some testing.

 

[Art Upton]

Curious , why are you using 24 volts?

 

[topbrahmen]

Curious , why are you using 24 volts?

So, two things, the system I'm using for solid motor testing is actually built off of a testing system made for testing different igniter systems for any rocket engine type. And we were trying to future-proof it by keeping the voltage at it original higher level for beefier igniters. But we've been testing small motors to build confidence In the system as a whole and I think didn't even consider the igniter not being able to take it, so I'm going to spend some time redoing the system to have the igniter voltage options and hopefully that fixes this issue on the smaller igniters

 

[jsdemar]

Options...
1) Put a power resistor in series with the igniter. Test with 2 to 8 ohms to find best igniter performance.
2) Make a current limiter from a LM317 voltage regulator. Try 2 to 4 amp limit.
3) Use a relay with a 24VDC coil to connect a 12V battery source on the igniter side. 10A rating.

 

[jqavins]

I had the same thought as No. 1, but then decided I was overcomplicating things. Just put a voltage selector on the battery box. What is the battery arrangement? Have you got units in series to get up to 24V? Is cell balancing critical? You might be able to just switch the output half way down the stack and call it a day.