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Estes Rocket Engines

Model Rocket Store, Estes Model Rocket Engines
The origins of Estes model rocket engines and what model rocket engine codes mean.

Estes rocket engines are widely regarded as the best model rocket engines on the market. Estes have been manufacturing model rocket motors for over 50 years and it was Vern Estes that invented the very first machine that mass produced model rocket engines. 

Here’s a brief history of Estes model rocket engines and some guidance on how to choose the best model rocket engines for your rocket.

The History of Estes Model Rocket Engines

Vernon Estes, or Vern as he is known, was working for the family fireworks business when the first ever model rocket manufacturer in the US, Model Missiles Incorporated, was looking for an external supplier to meet the ever growing demand for model rocket motors and came to the Estes family fireworks company.

The young Vern decided to see if he could build a machine that would automate the manufacture of rocket engines and he came up with the idea for Mable, the very first machine for mass producing engines for model rockets. The machine, which was powered by compressed air and hydraulics, could produce an engine in just 5.5 seconds.

Here’s a fascinating Estes rocket video that includes early footage of Vern Estes making model rocket engines with his machine Mable:

From those early beginnings, the legend of Estes Model Rockets grew. The company that Estes first began supplying rocket engines to closed down, so Estes stepped in to fill the gap in the market by producing their own range of model rockets to go with their rocket motors. Today, the company that Vernon Estes founded is one of the best known model rocket manufacturers in the world.

How Modern Estes Rocket Engines Are Constructed 

The modern Estes engines are manufactured with a robust cardboard tube. Inside the tube there is a solid propellant, a ceramic nozzle, a delay charge, an ejection charge, and a clay retainer cap. The propellant is ignited by means of a coated wire that is inserted through the nozzle. When an electric current heats up the wire, the solid propellant is ignited. Engines are also sometimes ignited by the hot exhaust from a booster motor.

You can find a nice graphical explanation of how Estes rocket engines are constructed and how they work here.

How Estes Model Rocket Engines Are Classified

There is a huge range of Estes engines available and they are classified by a colour coding system and a numerical coding system. The colour coding represents the recommended use and the numerical coding are the rocket engine codes that are defined by the National Association of Rocketry (NAR).

Estes Colour coding

Estes rocket engines are colour coded according to their recommend use.


Green engines are recommended for use in single-stage rockets


Purple engines are designed to be used in the top stages of multistage rockets and in single stage rockets that are very light


Red engines are recommended for use as booster engines and the intermediated stages of multistage rockets.


Blue engines are the Estes plugged rocket engines that are generally used in aerobrake recovery rockets and rocket-powered racers. This type of rocket engine does not have a delay charge or an ejection charge.

Rocket Engine Number Coding

The numerical coding that you will see on model rocket engines in defined by the National Association of Rocketry (NAR). A typical code will look like: A8-3.

The letter in the code signifies that impulse produced by the engine, which is measured in newton-seconds. Each increment in the letters represents double the impulse. So, and “A” rocket engine produces 1.26-2.50 Newton-seconds and a “B” produces 2.51-5.00 Newton-seconds, and so on. Any engine that has a letter above “G” is considered to be a high powered rocket engine.

The first number in a rocket engine notation indicates the average thrust in newtons that the engine exerts.  A B6-0, then, will produce the same average thrust as a C6-0, but the C-60 will fire for twice the length of time as the B6-0.

The last number in the sequence indicates the time delay, in seconds, between the thrust and the firing of the ejection charge. Rocket engines with a zero delay are usually used as booster engines in multi-stage model rockets. They have no ejection charge; the propellant ignites the upper stage of the rocket instead.    

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