Make: Projects
Model Rocket Igniters
Igniters for model rocket motors are fragile, and replacements are expensive. Making your own is easy and cheap; the results are very reliable and suitable for most uses.
Modern commercial igniters can send a rocket soaring with just a touch of current. When inserted properly they’re very reliable. Unfortunately, they are fragile, and folks new to the hobby sometimes ruin them by inserting them improperly. Packs of spares are expensive, and not all outlets carry them. There’s a cheap alternative: hand-wound Nichrome igniters.
Nichrome is a high-resistance alloy. Run a current through it and it glows red hot. Until the mid ’60s rocket motors came with a length of the wire, which rocketeers cut and shaped into an igniter. If placed correctly they are very reliable. I enhanced the austere original design with a few tricks picked up from old newsletters and personal experience.
Nichrome igniters can only be used with black powder motors, and have one other drawback: they need a lot of current to work. This isn’t a problem if you’re using a 12V launch system powered by a car battery. But they’ll quickly suck the juice out of the alkaline AA cells or 9-volt batteries used in commercial launch panels. Plan accordingly by bringing extra batteries, or test your Maker chops by making a sturdy 12V launch system!
Steps
Step #1:
Next
- Assemble your tools and parts.
- 1/4" masking tape can be hard to find. The freebie mailing labels sent out in charity fundraising letters are a good substitute.
- Nichrome wire is most commonly used as the hot "blade" of electric foam cutters. Costs and lengths vary widely. A big roll of nichrome wire makes a good club purchase; it will take your club many years to go through yards of the stuff! Some nichrome alloys include iron; I've heard this makes the wire prone to rust, but I haven't run into that problem myself.
- Sample Suppliers:http://jacobs-online.biz/nichrome_wire.h... http://shop.pitsco.com/store/detail.aspx...
