- 4.1 Definition
- Model Rocket motors shall meet the requirements of the NAR Standards and Testing
Committee and NFPA 1122.
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- 4.2 Reloadable Motors
- 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.
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- 4.3 Limits
- A single solid propellant model rocket motor shall contain no more than 62.5 grams
of propellant, and shall produce no more than 160.0 Newton-seconds of total impulse.
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- 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.
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- 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).
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- 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:
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| 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.)
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- 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.
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- 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.
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- 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.
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- 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.
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