Estes Industries
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Estes Industries (AKA Estes-Cox Corporation) is a company based in Penrose, Colorado, USA that designs and builds model rocket and model aircraft engines and kits. They were the best known model rocket company during the "golden age of rocketry" in the 1970s and early 1980s, competing primarily with Centuri Engineering and a host of smaller firms like Canaroc and Flight Systems, Inc. In the 1990s the hobby had almost disappeared, and Estes bought Centuri, folding their product lines together. Throughout the 1990s Estes owned North Coast Rocketry which served as their Mid-High Power Model Rocketry division, which was discontinued in 2000. Today, in addition to producing model rocket engines, Estes offers model rocket kits for various skill levels of modelers, as well as remote control airplanes.
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[edit] History
Estes Industries was founded by Vernon Estes in 1958, after he created "Mabel". "Mabel" was a machine designed to inexpensively manufacture model rocket engines for Model Missiles Incorporated. On August 30, 2002, Barry Tunick, the Chief Executive Officer since 1991, acquired Estes-Cox Corporation from the private equity fund, TCW Capital, for the sum of $15 million.
[edit] Estes rockets
Estes produced a wide variety of rocket model kits, normally using cardboard tubing for the fuselage and balsa wood for fins and nose cones. Early models tended to be relatively simple in design terms, differing in terms of size, number of stages and recovery method. One particularly well-known design from this era was the Camroc, a small camera that replaced the nose cone of larger models that was designed to take a single image on a small disk of film when the motor had burned out and the rocket was facing downward. The Cineroc used a small movie camera that could be launched from larger rockets, taking a series of frames as the rocket ascended.
Later model kits from the late 1970s and early 1980s tended to be more for show than performance, including a series of scale or sport-scale designs and "exotics". Centuri was also well known for these sorts of designs, and the two companies often copied design elements from the other's latest models. The downturn in the hobby in the later 1980s led to consolidation of the two companies. During the 1990s the model line was dramatically reduced, and the ones that were left were typically very simple "three fins and a nose cone" designs that were partially or entirely completed.
[edit] Estes rocket engine color coding
Estes engines are color-coded for recommended use. GREEN engines are for use in single stage models; PURPLE engines for the top stages of multistage rockets and very light single stage rockets; RED engines for all booster and intermediate states of multi-stage models. BLUE are “plugged” and are used for rocket powered racers, tumble recovery rockets, and radio controlled gliders, they contain no delay or ejection charge.
[edit] Estes number coding[1]
| Type | Total Impulse (Newton seconds) |
|---|---|
| ¼A | 0.31-0.62 |
| ½A | 0.63-1.25 |
| A | 1.26-2.50 |
| B | 2.51-5.00 |
| C | 5.01-10.00 |
| D | 10.01-20.00 |
| E | 20.01-30.00 |
Each rocket engine has a code printed upon the outer jacket. This code is defined by the National Association of Rocketry (NAR). An example of one such code is A8-3.
The capital letter (e.g., A) indicates total impulse produced by the engine. Each succeeding letter represents a power range with maximum total impulse twice the impulse as the previous letter. (Example: A single C engine can produce anywhere from 5.01 to 10 newton-seconds of impulse, a G engine 80.1 to 160 newton-seconds.) Anything over a G engine is considered high power model rocketry.
The first number (e.g., 8) specifies that engine's average thrust in newtons or the average push exerted by the engine. Thus a B6-0 and a C6-0 will both produce the same average thrust of 6 newtons, but the C6-0, having twice the total impulse, will fire for twice as long. The rocket engines produce maximum thrust shortly after ignition and thrust declines to a steady-state which is maintained for up to 2.5 seconds prior to burnout.[2]
The final number (e.g., 3) indicates the delay between the thrust and the ejection charge, in seconds. Engines with a delay of zero are typically used as booster engines in multi-stage rockets and there is no ejection charge. In this case, the burning propellent ruptures through the top and hot bits of propellent enter the nozzle of the upper stage engine, thus igniting that engine and forcing the booster assembly away, usually to tumble safely to earth.
[edit] Estes engine construction
The engines are constructed within a sturdy cardboard tube. Inside are placed a ceramic nozzle, solid propellant, delay charge, ejection charge, and a clay retainer cap.
The solid propellant is ignited by a coated wire inserted through the nozzle and in contact with the propellant. An electric current heats the wire and ignites the solid propellant. An engine can also be ignited by the hot bits of propellant from a booster engine.
[edit] Notes
- ^ "Estes Model Rocket Engines, Catalog Chart". http://www.estesrockets.com/assets/downloads/2007estescatalog.pdf?p=20.
- ^ "Estes Model Rocket Engines, Time/Thrust Curves". http://www.estesrockets.com/assets/downloads/2007estescatalog.pdf?p=21.
[edit] External links
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