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TCC Competition Primer: USMRSC Rule 50, Scale Competition (SC)

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This primer presents, in one place, all the information you need to succeed in NAR model competition in this event.

TCC has provided a link to the official rules whenever we discuss a rule.

All Entries

Your entry must:

* Comply with the NAR Model Rocket Safety Code: USMRSC 2.2

* Be a model rocket as described by the United States Model Rocket Sporting Code. USMRSC 3.1-3.9

* Use NAR Contest Approved motors: USMRSC 4.1, 4.4

* NOT eject its motor casing(s) without a recovery system. USMRSC 9.2

* Have your NAR number or your name on the outside, large and clear enough that the contest officials can easily read it. Teams must use the Team number or name. USMRSC 9.4

* Have been constructed by yourself or by one or more members of your Team. You may not enter Ready-To-Fly rockets (no construction required) in NAR sanctioned competition. USMRSC 9.9


Know the rules

Your having a grasp of the bigger picture can increase your enjoyment of NAR competition. You can read the Pink Book Lite to see only the rules for competitors, not for Contest Directors or other contest officials. Read the full USMRSC (Pink Book) to see all the rules.

* Pink Book Lite:

* Full USMRSC:


General Competition Tips:

TCC NAR Competition 101

TCC NAR Competition Strategy and Tactics

Contest Etiquette by Kevin Paul Wickart, NAR 59720, cr 1998, the author

Beginning Competition -- The RSVP Principle by Kevin Paul Wickart, NAR 59720, cr 1998, the author

Guide to NAR Contest Rocketry Information for Beginners by Jeff Vincent, NAR 27910, Northeast Regional Contest Chair

Which are the Main USMRSC Rules for This Event?

·        The main rules are 9, 16 and 50.

What is the Goal?

* You want to produce a flying scale model of an existing or historical (not fictional) guided missile, rocket vehicle, or space vehicle (prototype). USMRSC 50.1

* You want to build your entry as accurately as you can because the judges will measure the main dimensions to within 0.5 millimeter. USMRSC 50.12.2

* You want to construct your model carefully, to the best of your ability, because the judges will award points based on the quality of your work and how closely your entry matches the data you provide about the appearance of the real guided missile, rocket vehicle, or space vehicle. USMRSC 50.1, 50.12.1, 50.12.5

* You want your entry to match the flight performance of the prototype (see Mission Points below). USMRSC 50.1, 50.13.1

Does it Qualify for SC?

* The model you choose to replicate must meet three main criteria:

1.   Is an accurate scale model of an existing or historical guided missile, rocket vehicle, or space vehicle. USMRSC 50.1

2.   Is not a scale model of an amateur rocket or missile, unless the prototype is of obvious historical significance. USMRSC 50.2

3.   Must not be built from a plastic model kit that was not intended to fly, such as a PMC entry. USMRSC 50.4

Are There Any Special Considerations?

* You can use parts from commercial plastic kits on Scale models. However, you must point this out to the judges in you supporting documentation. USMRSC 50.4

* For maximum points, no one can catch the model as it descends. You may choose to catch the model or have someone else catch it as it descends (human intervention). If anybody catches the model as it descends instead of letting it hit the ground, the judges will award maximum damage points as a penalty. USMRSC 16.7

* If the ‘human intervention’ (see above) is accidental (in the opinion of the Range Safety Officer), you can choose to accept maximum damage points or do the flight over (unofficial flight). USMRSC 16.7

* You must supply data to substantiate your model’s adherence to scale in dimensions, color, and paint pattern. USMRSC 50.7, 50.12.1

* If the prototype is staged, you can fly it single staged. That is, your model will have all the stages, but only the first stage will have a motor. USMRSC 50.8

* If you enter an upper stage by itself, you must provide documentation that the upper stage did, in fact, fly by itself. For instance the WAC Corporal is a popular single stage kit. However, the actual prototype never flew without the Tiny Tim booster and is thus not suitable for Scale Competition. USMRSC 50.8

* For maximum points, you should build a model of one particular serial numbered prototype (round). If your prototype was massed produced (such as a military missile/rocket), it does not have to be a serial numbered round. However, you may lose points in this case. USMRSC 50.6

Do I Have to Return My Entry?

* You must return your entry to the judges so they can award damage points. USMRSC 16.8, 50.13.1

* The Contest Director can require that you return your entry. USMRSC 9.10

How Many Flights Can I Make?

* You can make two flights, but the judges will use only the best flight for scoring. USMRSC 10.1

How is the Competition Scored?

There are two sections for scoring - STATIC USMRSC 50.12 and FLIGHT 50.13

* In STATIC scoring, the judges award points for the scale data you provide. Minimum allowable data is listed in USMRSC 50.12.1. The judges are looking for accuracy of major dimensions, accuracy of color and markings, accuracy of details, and craftsmanship, taking into consideration the difficulty of building the model and adapting it for flight. USMRSC 50.12

* In FLIGHT scoring, the judges award points for conducting a ‘mission’, for achieving a safe and stable flight, and deduct points for damage (damage points) the model receives on landing. If you cannot return your model to the judges after its flight, the judge will award maximum damage points which will be subtracted from your final score. USMRSC 50.13

* Judges can award extra points for a particularly good data packet. Such a packet, for example, is easy to read and understand i.e. it presents data in the order of the Scale Judging Guide (CB-8-80). It also presents dimensions beyond the minimum allowable, multiple substantiating sources for dimensions and/or color, affidavits from sources connected with the prototype, paint samples, detailed photos, etc. USMRSC 50.12.1

* Don’t go overboard. The judges will deduct points for “data not pertinent to the prototype model” or that complicates judging. USMRSC 50.12.1

* Only present data for things you have actual included in your entry.  Your entry will be judged by the data presented in your scale packet. NOT by what your opinion, not by the opinion or knowledge of the judge. USMRSC 50.12.1

* The judges will get “up close and personal” with your entry, using calipers to measure “small scale dimensions”. USMRSC 50.12.2

What Will Disqualify My Entry?

* “Any entry not accompanied by the minimum allowable data as listed…shall be disqualified.” (USMRSC 50.12.1) Minimum data is:

·         Scale factor

·         Overall length

·         Significant body diameter(s)

·         Nose cone length

·         Fin length and width (if applicable to the prototype)

·         Length of transition pieces (if applicable)

·         Color pattern (documented either in writing or by photographs)

·         One clear photograph, halftone, or photo-reproduction

·         For at least all required dimensions listed above, both the actual (prototype) dimensions and the scaled (model) dimensions presented in a table or on a drawing

* Contest or Safety Officials will disqualify your entry if it fails to make a safe and stable flight. USMRSC 50.10

How About Some Suggestions for New Competitors?

* Build a commercial kit that was based on an existing or historical guided missile, rocket vehicle, or space vehicle.

* Aerospace Specialist Products has Saturn Press (Peter Alway’s) kits:

* Apogee Components has some very nice Saturn kits and others:

* Use plans from Sport Rocketry (, NARTS ( or other acknowledged sources.

What Else & What Next?

George Gassaway’s Scale Competition tips:

Good info on building and packing competition parachutes:

TCC NAR Competition Bibliography

Yahoo group for discussing model rocket competition:

Yahoo group for discussing Scale Competition:

Use computer simulations to determine altitude and sink rate for various rocket/motor/parachute combinations.
* Free altitude simulations: 
wRASP 32 -

* Free sink rate simulation:


US Spacemodeling (International Competition Tips):

US Spacemodeling Home Page (International Competition):

George Gassaway’s NARAM Tips:


rmr Frequently Asked Questions – Part 9: Competition and Records:


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