Model Rocket Motor Standards

« Introduction

4.1 Definition

Model Rocket motors shall meet the requirements of the NAR Standards and Testing Committee and NFPA 1122.

4.2 Reloadable Motors

Contest approved reloadable motors may be checked in by presenting the unassembled components in entirety, along with the manufacturer’s instructions that accompanied them to the check-in official. Components may be from a new or previously opened package. Check in official will inspect or initial a sample propellant grain in same manner as a black powder casing and return components to contestant for assembly.

4.3 Limits

A single solid propellant model rocket motor shall contain no more than 125 grams of propellant, and shall produce no more than 160.0 Newton-seconds of total impulse.

4.4 Certification

All motors used in a model rocket in NAR sanctioned competition, or for the purpose of establishing a United States Model Rocket Performance Record, shall be of a type currently holding NAR Contest Approval. No model rocket motor shall be flown at any NAR Sanctioned activity unless that motor holds current NAR Certification.

4.5 Alterations

A model rocket motor shall not be altered in any manner that changes its dimensions and/or its performance characteristics. No material shall be affixed to the motor in a permanent fashion (e.g., via glues or epoxies).

4.6 Classification

An NAR-certified model rocket motor is assigned a type classification based on its mean sea total impulse at a temperature of 20 degrees Celsius as determined in static tests conducted by the NAR Standards and Testing Committee. NAR-certified model rocket motor classifications are as follows:

Motor Class Total Impulse (Newton-seconds)
1/8A 0.00 – 0.3125
1/4A 0.3126 – 0.625
1/2A 0.626 – 1.25
A 1.26 – 2.50
B 2.56 – 5.00
C 5.01 – 10.00
D 10.01 – 20.00
E 20.01 – 40.00
F 40.01 – 80.00
G 80.01 – 160.00

(Note: All motor classes listed above continue to be recognized for certification purposes independent of current commercial availability considerations.)

4.7 Published Values

The total impulse values measured and published by the NAR Standards and Testing Committee shall be the values used in all NAR sanctioned competition and for United States Model Rocket Performance Record attempts.

4.8 Total Impulse

When multiple motors are used in a single model rocket (e.g., clustering and staging), the total impulses of the individual motors shall be summed to compute the total impulse of the configuration and to determine the impulse class of an event for which the model qualifies. Only those motors actually intended to ignite and produce useful thrust are to be included in this total.

4.9 Contest Approval

NAR Contest Approval shall be granted only to model rocket motors that are currently and readily available commercially, and that also meet the requirements of Rule 4.1 through Rule 4.8.

4.10 Contest Use

All Contest Approved motors shall be permitted in any NAR sanctioned competition for which the total impulse of the motor is appropriate for the event and in compliance with state and local laws.