TCC NAR Competition Primer: USMRSC Rule 30, Parachute Duration (PD)
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:
* Comply with the NAR Model Rocket Safety Code: http://www.nar.org/NARmrsc.html 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: http://www.nar.org/SandT/NARenglist.shtml 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: http://ojames3.tripod.com/tccnarcontesttips/USMRSCLight.html
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?
*This event can be flown as Multi-Round.
What is the Goal?
The goal of Parachute Duration (PD) is to attain the longest flight time with a single stage model rocket using one or more parachutes for recovery. USMRSC 30.1
Are There Any Special Considerations?
* PD is divided into classes based on the total impulse of the motor(s) you must use. USMRSC 30.2
* Your entry must be single stage, but can be clustered. USMRSC 30.1
* If your entry is clustered, enough motors must ignite to meet the impulse limits for the event class you are flying. USMRSC 4.6, 4.8, 30.2
* This event can be flown as Multi-Round.
Do I Have to Return My Entry?
* You must return your entry after at least one qualified flight in order to place in 1st-4th. USMRSC 15.10, 13.1
* If you cannot return your entry after at least one qualified flight, you’ll only get Flight Points. USMRSC 13.1, 13.4, 13.5
* The Contest Director can require that you return your entry. USMRSC 9.10
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 final score is the sum of your entry’s flight durations (in seconds) on up to two official flights. USMRSC 10.1, 10.3
What Will Disqualify My Entry?
* Your entry will be disqualified if it separates into two or more parts or ejects the motor(s). USMRSC 15.2
* Your entry may be disqualified if, in the opinion of the contest officials, it does not comply with the competition rules or is unsafe in operation. USMRSC 11.1, 11.2
How About Some Suggestions for New Competitors?
Almost any rocket that can fly on the motor used for a particular PD event can be competitive. Rockets with a smaller diameter and lower weight will go higher and usually get a longer duration.
A rocket with a diameter of 0.5 inches to 0.75 inches will usually be best for 1/8A to A. The 0.5 inch 1/4A, 1/2A and A motors will be your best choice. However, and Estes Alpha using an A8-3 motor would also be good as your first entry. For B and C PD, 1 inch diameter rockets will be competitive and easier to prepare.
Your recovery system must deploy if you are to get the best possible duration. Use a rocket with the smallest diameter in which you can pack a parachute that will reliably deploy. Use the largest parachute that you can pack into your rocket and still have reliable deployment. Lightly dust the parachute on both sides with talcum powder before you fold and pack it.http://ojames3.tripod.com/tccnarcontesttips/BobKaplowNAR18LCompParachute.pdf
* Use a piston launcher, tower launcher or pop-lug to reduce drag by eliminating the launch lug.
Piston Launcher: Apogee Components
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
* 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 such as wRASP32 (http://tccnar.tripod.com/sims/082_wRASP32_221.zip) to help you select the best motor.
* 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 (wRASP32 http://tccnar.tripod.com/sims/082_wRASP32_221.zip) to help you select the best delay time.
Many vendors have Parachute Duration models and competition supplies:
What Else & What Next?
Good info on building and packing competition parachutes:
Online Competition Rocket Plans:
NAR Competition Guide http://www.nar.org/contest-flying/competition-guide/
Competition Model Rockets (Howard Kuhn) Plans http://www.oldrocketplans.com/cmr.htm
TCC NAR Competition Bibliography
Yahoo group for discussing model rocket competition:
Free sink rate simulation: http://www.onlinetesting.net/cgi-bin/descent3.3.cgi
You can get some useful info from the International Model Rocketry Competition site:
Aerospace Specialty Products Streamer and Parachute Tips:
George Gassaway’s Competition Tips (note: Some links on George’s page are inactive):
US Spacemodeling (International Competition Tips):
US Spacemodeling Home Page (International Competition):
rmr Frequently Asked Questions – Part 9: Competition and Records: