Editing Model rocket (section)

==Motor nomenclature==
[[Image:Model Rocket Motors.jpg|thumb|right|Rocket motors. From left, 13mm A10-0T, 18mm C6-7, 24mm D12-5, 24mm E9-4, 29mm G40-10.]]

Model rocket motors produced by companies like [[Estes Industries]], Centuri Engineering and [[Quest Aerospace]] are stamped with a code (such as A10-3T or B6-4) that indicates several things about the motor.

The Quest Micro Maxx engines are the smallest at a diameter of 6mm. The company Apogee Components made 10.5mm micro motors, however, those were discontinued in 2001. Estes manufactures size "T" (Tiny) motors that are 13&nbsp;mm in diameter by 45&nbsp;mm long from 1/4A through A class, while standard A, B and C motors are 18&nbsp;mm in diameter by 70&nbsp;mm long. C, D, and E class black-powder motors are also available; they are 24&nbsp;mm in diameter and either 70 (C and D motors) or 95&nbsp;mm long (E motors). Estes also produces a line of 29mm diameter by 114mm length E and F class black powder motors. Larger composite propellant motors, such as F and G single-use motors, are also 29mm in diameter. High-power motors (usually reloadable) are available in 29mm, 38mm, 54mm, 75mm, and 98mm diameters.

===First letter===

The letter at the beginning of the code indicates the motor's total [[impulse (physics)|impulse]] range (commonly measured in [[newton (unit)|newton]]-seconds). Each letter in successive alphabetical order has up to twice the impulse of the letter preceding it. This does not mean that a given "C" motor has twice the total impulse of a given "B" motor, only that C motors are in the 5.01-10.0 N-s range while "B" motors are in the 2.51-5.0 N-s range. The designations "¼A" and "½A" are also used. For a more complete discussion of the letter codes, see [[Model rocket motor classification]].

For instance, a B6-4 motor from Estes-Cox Corporation has a total impulse rating of 5.0 N-s. A C6-3 motor from Quest Aerospace has a total impulse of 8.5 N-s.<ref>National Association of Rocketry web site: {{cite web |url=http://nar.org/SandT/NARenglist.shtml |title=National Association of Rocketry &#124; NAR Certified Motors |access-date=2006-07-29 |url-status=dead |archive-url=https://web.archive.org/web/20060813110342/http://nar.org/SandT/NARenglist.shtml |archive-date=2006-08-13 }}</ref>

===First number===

The number that comes after the letter indicates the motor's average thrust, measured in [[newton (unit)|newton]]s. A higher thrust will result in higher liftoff acceleration, and can be used to launch a heavier model. Within the same letter class, a higher average thrust also implies a shorter burn time (e.g., a B6 motor will not burn as long as - but will have more initial thrust than - a B4). Motors within the same letter class that have different first numbers are usually for rockets with different weights. For example, a heavier rocket would require an engine with more initial thrust to get it off of the launch pad, whereas a lighter rocket would need less initial thrust and would sustain a longer burn, reaching higher altitudes.

===Last number===

The last number is the delay in seconds between the end of the thrust phase and ignition of the ejection charge. Black Powder Motors that end in a zero have no delay or ejection charge. Such motors are typically used as first-stage motors in [[multistage rocket]]s as the lack of delay element and cap permit burning material to burst forward and ignite an upper-stage motor.

A "P" indicates that the motor is "plugged". In this case, there is no ejection charge, but a cap is in place. A plugged motor is used in rockets that do not need to deploy a standard recovery system such as small rockets that tumble or R/C glider rockets. Plugged motors are also used in larger rockets, where electronic altimeters or timers are used to trigger the deployment of the recovery system.

Composite motors usually have a letter or combination of letters after the delay length, indicating which of the manufacturer's different propellant formulations (resulting in colored flames or smoke) is used in that particular motor.

===Reloadable motors===

[[Image:WikiReloadableMotorCases.jpg|thumb|right|Aerotech Reloadable motor cases. From left: 24/40, 29/40-120, 29/60, 29/100, 29/180, 29/240]]

Reloadable rocket motors are specified in the same manner as single-use model rocket motors as described above. However, they have an additional designation that specifies both the diameter and maximum total impulse of the motor casing in the form of diameter/impulse. After that, there is a series of letters indicating the propellant type. However, not all companies that produce reloadable motors use the same designations for their motors.

An Aerotech reload designed for a 29-millimeter-diameter case with a maximum total impulse of 60 newton-seconds carries the designation 29/60 in addition to its impulse specification.

However, Cesaroni Technology Incorporated (CTI) motors use a different designation. They first have "Pro" followed by a number representing the diameter of the motor in millimeters, for example, a Pro38 motor is a 38mm diameter motor.<ref name="Cesaroni Technology Inc. (CTI) Pro38 rocket motors">{{cite web |url=http://pro38.com/ |title=Pro-X - A better way to fly |access-date=5 July 2012}}</ref> After this, there is a new string of characters such that the [[impulse (physics)|impulse]] in [[newton-second]]s is first, followed by the motor classification, the average [[thrust]] in [[newton (unit)|newton]]s, followed by a dash, and the delay time in seconds. For example, a Pro29 110G250-14 is a G-motor with 110 Ns of impulse, 250 N of thrust, and a 14-second delay.<ref>{{cite web |url=http://pro38.com/products/pro29/motor.php |title=Pro29® high power rocket motor reload kits |access-date=5 July 2012}}</ref>