Model Rocket Igniters
Model Rocketry Overview
The Soviet Union launched Sputnik – which translated from Russian means "satellite one" – in 1957, kicking off what became known as the "Space Race" and stimulating the greatest and fastest growth in science and technology the world had seen to that point. Their first manmade satellite circled the earth every 96 minutes for about three months before it fell out of low earth orbit and burned up in the atmosphere. During its first 22 days it transmitted radio signals at 20 and 40 MHz until its batteries were depleted. These signals were monitored by governments and ham radio operators around the world.
Just like Sputnik, the rest is history. The Apollo program and those that followed after it spawned countless technological advances ranging from Teflon that was adapted for cookware to geostationary satellites that power our GPS navigation systems today.
The space race also spawned the development of model rocketry. Estes, founded in 1958, is the premier model rocketry manufacturer in the world. They began as a manufacturer of model rocket engines and grew into a supplier of complete rocket systems and accessories to feed the ever-growing market of rocketry enthusiasts.
Hobbyist rocket engines are rated in Newton-seconds. A Newton is the amount of force needed to accelerate one kilogram of mass at a rate of one meter per second squared. (One Newton of force is equal to about 4.45 pounds. You can see that even a small rocket engine lifting just a few ounces of model rocket makes for a great flight!) A Newton-second is a measure of impulse or strength of the rocket engine. Hobbyist rocket engines are separated into groupings based upon their impulse. Class A engines have a rating of 1.26 to 2.50 Newton-seconds. Class E engines are much more powerful with ratings between 20 and 40 Newton-seconds. Engines in Class A through E all use black powder as the propellant. Larger engines use a composite fuel.
IgnitersBlack powder engines in Class A through E can all be ignited using a Nichrome 60 wire. (Composite fueled engines require a different type of igniter). Nichrome igniter wire heats up to 2100°F (1150°C) which is far more than enough heat to ignite black powder. Igniters for these black powder fueled engines are available from many model rocketry companies, but they're expensive. Just four to six igniters can cost from $4 to $6 – about a dollar each. Nichrome 60 and Kanthal resistive wire can be purchased in bulk rolls for as little as about a penny or two per igniter. If you're into model rocketry, it pays to consider making your own igniters. |
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Instructions
The key to a successful launch lies in forming your igniter wire properly and assuring that it's inserted fully into the engine, making solid physical contact with the black powder. Here's how you can make your own igniters.
1. Cut about five inches of igniter wire from the spool. Wrap it around a paper clip as shown in Figure 1.
Tape the wire so the "legs" cannot short out.
2. Bend each end of the wire to give your micro clips a solid electrical connection.
3. Twist the igniter wire twice around the paper clip, leaving a space between the wraps. If the wire wraps touch, your igniter will short out and your launch is likely to fail. See Figure 2.
4. Remove the paper clip and dip the twisted end of the igniter wire in paint or nail polish. This prevents possible shorting of the twists as you push the igniter wire firmly into the engine.
5. Now, push the igniter as far as possible into the engine. Bend the legs so they're at a 90-degree angle to the axis of the engine.
6. Connect your micro clips.
7. Using Nichrome or Kanthal wire, you'll need to heat the wire to its maximum temperature. Using AA or 9-volt batteries do not provide enough current flow to heat the wire adequately. Therefore, you'll want to use a 12-volt battery such as a car, lawn mower or motorcycle battery.
Again, the key to making igniters that deliver a successful launch time after time require that:
• The wraps around the paperclip do not touch.
• The wraps are insulated by a dip in paint or nail polish.
• The igniter wire is pushed solidly into good physical contact with the black powder of the engine.
• The power source used to heat the igniter is a 12-volt source.
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Figure 1: Make Your Own Black Powder Rocket Engine Igniter Igniter |
 Figure 2: Avoid letting the twisted wires contact one another. If they touch, the igniter may short out, and your launch will fail. |
What Gauge Wire Should I Use? Nichrome or Kanthal?
Depending upon the "throat" dimensions of your rocket, you can use igniter wire ranging from 32 AWG in Nichrome 60 to 28 AWG in Kanthal A-1. Kanthal A-1 has an operating temperature of 2550°F (1300°C), giving you a hotter igniter wire than nichrome. However, either will work nicely in Class A through E black powder engines.
Nichrome is the oldest resistive wire. It was patented in the early 1900's and is the most cost-effective resistive wire available. For serious model rocketry enthusiasts, view our product selectione for additional technical specs and detail on each of our resistive wire products.