September 24, 2003

Special Effects Rocket Motors

An ongoing debate among rocket hobbyists is the use of ‘effects’ motors. By adding carefully selected impurities to the chemical composition of a motor, you can create a variety of results. Common among these are smoky motors, sparky motors, and even exhaust flames of different colors. Such impurities can also produce sound variations like a crackling during the motor burn. In order to keep their product lines distinct, propellant formulations are closely held by commercial motor manufacturers (all of this applies to Ammonium Perchlorate motors and not the common model rocket motors available from Estes or Quest).

A high-efficiency propellant formula produces almost no smoke and very little visible flame. Most of the power of the motor goes to producing thrust and not the visible byproducts. That’s the bottom-line purpose of the rocket motor.

But what fun is that? A small but vocal group of rocketeers are devoted to pure power and maximum thrust for a given engine size. Anything less than the ideal have been dubbed ‘knob’ motors.

I am a knob. I love the knob motors. So what if I lose some power or efficiency, when my rocket takes off trailing a thick plume of smoke, or leaps into the sky atop a long tongue of neon green fire? That's what's fun for me, and I think the majority of rocketeers agree with me. Here's a description of some of the knob motors that I love to fly.

Aerotech makes motors in a variety of sizes and propellants, including Blue Thunder which has the most power, a thin blue flame, and almost no smoke, White Lightning with it’s orange flame and thick white smoke, Redline with an intense red flame and moderate smoke, and BlackJack which roars and produces thick black smoke. They also manufacture EconoJets, which are smoky, loud and crackly motors, but you pay for the effects at the cost of motor power. Their selection is probably the best all-around available.

Ellis Mountain makes the Thor’s Hammer line, which are super-aggressive motors with lots of thrust right from the get-go.

Animal Motor Works started a couple of years ago, and is slowly expanding their line. Their offerings include Green Gorilla, White Wolf, Blue Baboon, and Super Tiger. I’m looking forward to Skidmark Squirrel, which is a sparky motor. Imagine a fireworks sparkler about two feet long, two inches around, and going straight up at a couple hundred miles per hour. Definitely not for the dry season!

There are others, but these pretty much show the range available. Of course, the motor and rocket airframe have to be matched up carefully. A rocket that can handle the relatively gentle thrust of BlackJack propellant may shred into confetti under the kick of Thor’s Hammer. Likewise, you might need the big spike of thrust at the start of a Blue Thunder burn to get a heavy rocket off the pad and flying stably.

In my range box right now, I have an H-165 Redline, an H-128 White Lightning, a G-75 BlackJack, plus a handful of EconoJets and some smaller mid-power propellant reloads. I’ve also got a pair of reloads left for my nitrous-hybrid motor. With a rocket launch this Sunday, and BattlePark in Culpeper, Virginia the first weekend of November, I’m looking forward to being a knob.

Posted by Ted at September 24, 2003 12:32 PM
Category: Rocketry

Well, I once lit a Black Cat™ under a beer can, and did it ever fly high! ;)

Posted by: Tiger at September 24, 2003 05:55 PM
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