DIY Ignitor test

[cwbullet]

Guys and gals,

I want to share some testing I did. I did some ignitor testing today. I had the last week off and nothing to do but wait for a flight confirmation, so I decided to make and test some ignitors.

Each ignitor blank was made relatively the same with 30 gauge Kynar wire with soldered 40 gauge nichrome. The nichrome was wrapped 5 times. All were checked for continuity prior to dipping. I made 80 blanks and then dipped them pyrogen. I used an equal portion in dipping in Quickburst (20), Magnelite(20), Fire Star(20), and Skylighter(20).

I then proceeded to use a 12 volt ignition source and ignite away. My kid got a kick out of it.

Here are the results:

Quickburst
18/20 or 2 failures. One failed to light due to operator error so it could have been 19/20.

Magnelite
20/20 with no failures.

Fire Star
18/20 or 2 failures.

Skylighter
17/20 or 3 failures.

It is not scientific, but I think it shows it is easy and all are reliable mixtures. Each ignitor blank is different. I like magnilite. I have used it for 3 months and have had only on failure in probably 20 launches at the range and none in static testing.

I hope you like it and find it useful. I have already noticed that I may need to try one were they were all aged about the same time. The oldest was the magnalite - 2 months approx.

[Mr Peabody]

I would suspect that failures were more a function of the ignitor leads used than the pyrogen they were dipped in.

[cwbullet]

How could I measure the heat produced by an ignitor?

[FROB]

How could I measure the heat produced by an ignitor?

It would be a bit tricky, but i'd probably try to construct a crude calorimeter;
maybe using a couple of feet of brass or copper tube crimped & sealed at one end with solder, inserted through a rubber stopper into a long test tube or similar shaped vessel that can be filled with water "around" the metal tube. add a precise thermometer, fill with a measured amount of water, and the igniter at the bottom of the metal tube. I'd probably want to keep the outer vessel not too much larger than the inner "tube" to minimize the total amount of water while keeping at least a foot or so of the inner tube under water - as to allow as nearly complete transfer of heat to the surrounding water as possible, while limiting the volume so as to allow a greater and more easily measured temperature rise, which might be only a couple of degrees or less.

You can also estimate it mathematically if you know the ingredients and proportions and weight the igniter before and after dip & dry, you can figure out the most likely reaction products and look up the heat of reaction of each, assuming nearly complete combustion.

It seems likely that the "real" value would be somewhere between the calorimeter-measured one and the theoretical one.

[delta22]

I did a bunch of testing of Rocketflite ematches / igniters with very good results over the course of last year.

Details at: http://www.bpasa.com/Rocketflite.htm

[cwbullet]

Would something like this work?

http://www.tpi-store.com/product.php?product=110353

[delta22]

Would something like this work?

http://www.tpi-store.com/product.php?product=110353

No. The product description states that it is for measuring surface temperature, and the minimum area is 1/2" diameter.

Igniters are for igniting engines. Best way to test them it to try firing many different engines with them repeatedly. That is what I did in the link in my post.

It is also a fun way to run a test, because field testing = flying rockets

There are many characteristics to consider, not just calories. Such as: duration of heat, peak temperature, nature of hot particles ejected, gas generation, and more.

[FROB]

Would something like this work?

http://www.tpi-store.com/product.php?product=110353

That will give you the average temperature of the spot its pointing at, so the igniter and area immediately around it, not the heat produced. unfortunately, the only thing that will give you a measure of the total energy or heat released (think Joules or Kcal.), if that is what you really want to measure, is a calorimeter or something equivalent. I assume that is what you want because it would seem to be a better measure of an igniter's ability to heat up a nearby motor fuel grain to ignition.

http://www.dartmouth.edu/~chemlab/techniques/calorimeter.html
http://en.wikipedia.org/wiki/Calorimeter
http://www.science.uwaterloo.ca/~cchieh/cact/c120/calorimetry.html