ENGINE BASICS I

The model rocket engine (or "motor") provides the thrust needed to lift your model rocket from the pad into the sky. We often are asked the question, "does that engine work just like the one's on the Space Shuttle?". The answer (as is so often the case) is "yes" and "no". Whether you are attempting to launch a 4 1/2 million pound NASA Space Shuttle off the pad at Cape Canaveral, Florida, or are launching your first 2 1/2 ounce model rocket off the pad at your neighborhood park, the engine serves the same purpose: to provide the thrust necessary to lift the vehicle off the pad and into the sky. The difference can be found in how each of these engines function to provide this necessary thrust.

Liquid Fuel Engines

NASA's Space Shuttle uses a "liquid fuel" engine. A liquid fuel engine works by holding the fuel and the source of oxygen (called the "oxidizer") needed for combustion in separate chambers. Thrust is created by mixing these two components in a burning chamber and directing the subsequent combustion through a specially designed nozzle to produce the thrust needed to lift the vehicle into the sky. Although today's liquid fueled engines are precisely manufactured, technological marvels, the essential design is very close in function to Robert H. Goddard's first rocket launched in 1926.

Solid Fuel Engines

In a "solid fuel" engine, the fuel and oxidizer are mixed into a solid propellant. When exposed to a source of heat for ignition, the solid fuel burns and produces hot exhaust gasses. These gasses are directed through a nozzle to produce the thrust needed for liftoff. Because of their simplicity, and reliability, solid fuel rocket engines are the "engine of choice" anytime a high thrust-to-weight ratio is needed. For example, the U.S. Military uses solid fuel engines to launch Tomahawk Cruise Missiles from submarines in the Atlantic, while the National Oceanic & Atmospheric Administration uses similar technology to launch sounding rockets for atmospheric and weather research in Alaska. The same qualities of simplicity and reliability make solid fuel engines - although on a much smaller scale - the perfect choice for Mrs. Brown (a fourth grade teacher in Anywhere, USA) to launch her students' first model rockets.

So back to MY model rocket engine...

Now that you understand how a solid fuel engine works, let's take more detailed look at the solid fuel engines used in model rocketry. The first model rockets (we're talking 1950's here folks) used homemade solid fuel engines that - as often as not - failed to ignite or worse, ignited unreliably. As interest in model rocketry grew the need for a better, safer propulsion system became apparent and - within a decade - commercially manufactured model rocket engines became available. These engines were reliable, safe and inexpensive and - unlike those home-built varieties - featured an battery-powered system to control ignition. The safety and reliability of solid fuel model rocket engines is proven by this record: since those early years, nearly 500 Million model rockets have been successfully and safely flown.