TCC NAR Competition Primer: USMRSC Rule 25, Payload Competition (PAY)
This primer presents, in one place, all the information you need to succeed in NAR model rocket competition in this event.
TCC has provided a link to the official rules whenever we discuss a rule.
Your entry must:
* Be a model rocket as described by the United States Model Rocket Sporting Code. USMRSC 3.1-3.9
* 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: http://ojames3.tripod.com/tccnarcontesttips/USMRSCLight.html
* Full USMRSC: http://www.nar.org/pinkbook/
General Competition Tips:
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?
What is the Goal?
The goal of this competition is to achieve the highest flight while carrying one or more NAR standard payloads and recover the entry and payload(s). USMRSC 25.1
Are There Any Special Considerations?
* PAY is divided into classes based on the total impulse of the motor(s) you must use and the number of NAR standard payloads your entry must carry. USMRSC 25.7
* Your entry can be staged and/or clustered. If staged, your entry must carry the payload(s) in the uppermost stage. USMRSC 25.1
* After the flight, you must present the model, unopened, to the contest officials and only remove the payload(s) in the presence of the contest officials. USMRSC 25.6
* Nothing (tape, glue, etc) can be affixed to the payload and it cannot be alteedr or modified in any way. USMRSC 25.2
* Your entry must carry the payload(s) inside the rocket. The payload(s) cannont separate from the rocket and must be removable. USMRSC 25.3
* Rule 10.4 does not apply.
Do I Have to Return My Entry?
* You must return your entry to receive any points in Payload. USMRSC 25.6
* Rule 10.4 does not apply.
How Many Flights Can I Make?
* You can make up to two flights. USMRSC 10.1
* You can use more than one model. USMRSC 9.7
How is the Competition Scored?
* Your official score is the highest single altitude achieved by your entry on up to two official flights. USMRSC 25.1
What Will Disqualify My Entry?
Your entry will be disqualified if:
* You cannot return the entry with the payload. Separation is not allowed. USMRSC 25.5
* You remove the payloads from your recovered entry without a contest official present. USMRSC 25.3, 25.6
* If it is unsafe in operation USMRSC 11.1, 11.2
How About Some Suggestions for New Competitors?
* Keep it simple. Build a kit using the manufacturer’s directions and fly it using the recommended motor(s).
* Optionally, you can use a tower and/or piston launcher for better performance. The launch lug adds a lot of drag and reduces altitude. See “What Else & What Next” below.
* Single stage is more reliable than multi-stage. A single motor is easier to ignite than a cluster of motors.
* Three fins, a nosecone and a payload section. Any rocket will do as long as it can carry, fully enclosed, the NAR standard payload. Use a streamer for recovery. Your entry will drift less than with a parachute and be easier to return.
* Make sure the payload section and/or the NAR standard payload is securely attached to, and does not separate from, your entry.
* The NAR standard payload will not fit into an Estes BT-20 (0.75 inches outside diameter). The NAR standard payload is 70mm (2.756 inches) long, but it can be as short as 60mm (2.362 inches) or as long as 80mm (3.150 inches). It is 19.1mm (0.752 inches) in diameter, but can be as narrow was 18.6mm (0.732 inches) or as wide as 19.6mm (0.772 inches). USMRSC 25.2
* Your payload section should be about 81mm (about 3.2 inches) long INSIDE and 20mm (about 0.8 inches) in diameter INSIDE. This will enable you to fly any legal NAR standard payload.
* Kits you are likely to find at the hobby store can make qualified entries, but will not be as competitive as specialized models. Here are some examples:
Estes Nova Payloader (for A, B, and C PAY) http://www.estesrockets.com/products.php?number=1302 NOTE: You can modify the Nova Payloader to use D12 and E9 motors for D and E PAY
Quest Payloader One (for A, B and C PAY) http://www.questaerospace.com/itemdesc.asp?ic=1018&eq=&Tp
Quest Gamma Ray (for B and C PAY) http://www.questaerospace.com/itemdesc.asp?ic=2004&eq=&Tp
Quest Zenith II (for A, B, C, and D PAY) http://www.questaerospace.com/itemdesc.asp?ic=3005&eq=&Tp NOTE: You can modify the Zenith II to use D motors, in both stages, or a single E9 and enter it in E PAY.
NOTE: all of the above models can use 18mm APCP motors for C, D and E PAY.
* Kits you can find online:
QCR No-Part II (for A, B and C PAY) http://www.cybertravelog.com/qcr/rockets.html
ASP Versi-Loader (for A, B and C PAY) http://www.asp-rocketry.com/store/moreinfo.cfm?Product_ID=546&Category=176
ASP kit for building your own NAR standard payload http://www.asp-rocketry.com/store/moreinfo.cfm?Product_ID=547&Category=176
TCC Competition Vendor List for Kits and Parts
* Delay Selection:
Check with the contest officials to see if trackers will follow your entry to apogee of to ejection. If they are tracking to apogee, select a delay time such that ejection occurs after apogee. If they are tracking to ejection, select a delay time such that ejection occurs as close to apogee as possible; before or after apogee. Use a computer simulation (wRASP http://www.wrasp.com/ or wRASP32 http://tccnar.tripod.com/sims/082_wRASP32_221.zip) to help you select the best delay time.
* Motor Selection:
Select a motor that fits the event class. A impulse for A ALT, B motor for B ALT, etc. Generally, a lower average thrust (the number after the motor letter) will achieve a higher altitude and be easier to track. Use the minimum body tube diameter for the motor you want to use. Use a computer simulation (wRASP http://www.wrasp.com/ or wRASP32 http://tccnar.tripod.com/sims/082_wRASP32_221.zip) to help you select the best motor.
* Optically tracked: The trackers/officials MUST be able to see your entry to track its altitude. This is easier for the lower powered events. For higher powered events or if trackers are having difficulty spotting the rockets, you should consider using “tracking powder”. Tracking powder is colored powdered chalk or dry Tempra paint that you pack in your rocket so that it is ejected with the recovery system. You can buy chalk for a carpenter’s chalk line at almost any hardware store. Chose a color that contrasts with the cloud/sky conditions you expect to encounter. Red works well in most conditions. When you pack your recovery system, leave some space at the top for the powder. Tracking powder is messy. You can simply pour the powder in or wrap the powder in a small piece of recovery wadding to minimize the mess. Powder adds weight. Experiment before the contest to determine the minimum amount you can use and still get a noticeable cloud of powder at ejection. For example, for B ALT (about 1000 feet), using a ¾ inch body tube, use enough powder to fill the tube for ¾ inch (one caliber). This will be about 0.1 ounce of carpenter’s chalk.
* Electronic Altimeter: Follow the manufacturer’s instructions and USMRSC 14.10. Check with your HPR buddies or others who use electronic altimeters for suggestions.
* Use a piston launcher, tower launcher or pop-lug to reduce drag by eliminating the launch lug.
Piston Launcher: Qualified Competition Rockets: http://www.cybertravelog.com/qcr/pistons.html
Simple Tower: by Bob Supak, NAR 65523
- Take 3 1/4" aluminum rods, each about 24" long.
- Depending on what size model you want to launch, take an 18" piece of same body tube and put a few wraps of tape at each end.
- Place the 3 rods in a triangle around the body tube and secure with rubber bands, leaving 6" of the ends of the rods exposed.
- Now place the rods into a coffee can full of wet cement or plaster and let set. Voila - launch tower!
Pop-lug: Competition Model Rockets, Howard Kuhn http://www.oldrocketplans.com/pubs/CMR/pop_lug.pdf
What Else & What Next?
(If you find any, please contact me at firstname.lastname@example.org. Thanks)
Typically, APCP motors will go higher than black powder motors, but don’t work was well in piston launchers as black powder motors do.
What Type of Fins Shape is Best by Tim Van Milligan:
Design, Construction, and Flying Strategies for Achieving Maximum Altitudes by Tim Van Milligan
Take No Prisoners Tracking Powder
Simple Tower: by Bob Supak, NAR 65523
Take 3 1/4" aluminum rods, each about 24" long. Depending on what size model you want to launch, take an 18" piece of same body tube and put a few wraps of tape at each end. Place the 3 rods in a triangle around the body tube and secure with rubber bands, leaving 6" of the ends of the rods exposed. Now place the rods into a coffee can full of wet cement or plaster and let set. Voila - launch tower
Piston Launchers Explained – Apogee Components:
Floating Head Piston Launcher – The Odd Couple Team T-085, Jeff Vincent NAR 27910 and Chuck Weiss NAR 35775:
TCC NAR Competition Bibliography
Yahoo group for discussing model rocket competition:
Use computer simulations to determine altitude and sink rate for various rocket/motor/parachute combinations.
* Free altitude simulations:
wRASP - http://www.wrasp.com/
* Free sink rate simulation:
US Spacemodeling (International Competition Tips):
US Spacemodeling Home Page (International Competition):
Aerospace Specialty Products Streamer and Parachute Tips:
George Gassaway’s Competition Tips – Take No Prisoners!
rmr Frequently Asked Questions – Part 9: Competition and Records: