- 4.1 Definition
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Model Rocket motors shall meet the requirements of the NAR Standards and Testing Committee and NFPA 1122.
- 4.2 Reloadable Motors
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Only reload kits that are presented in factory, new, unopened packages may be used. As part of the check-in procedure, the
contestant must present the reloadable motor and reload kit for inspection to determine proper type and tampering. The type
of reload kit, the motor case designation, and the letters "RMS" must be recorded on the flight card. The reload kit and
motor case will then be returned to the contestant for normal prepping and check-in. In the case of multiple reloads in a
single kit, the contestant will remove the required components from the kit for prepping and the remaining items in the kit
will be impounded at check-in for further use and returned at the end of the competition.
- 4.3 Limits
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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
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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
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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
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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 |
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(Note: All motor classes listed above continue to be recognized for certification
purposes independent of current commercial availability considerations.)
- 4.7 Published Values
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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
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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
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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
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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.
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