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TCC NAR Competition Primer: USMRSC Rule 31, Streamer Duration Competition (SD)

 

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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.

 

All Entries

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

* Full USMRSC:  http://www.nar.org/pinkbook/

 

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, 15 and 31:

http://www.nar.org/pinkbook/9_Entries.html

http://www.nar.org/pinkbook/15_Timing_Data.html

http://www.nar.org/pinkbook/31_SD.html

* This event can be flown as Multi-Round.

 

What is the Goal?

The goal of Streamer Duration Competition (SD) is to attain the longest flight time with a single stage model rocket using one streamer for recovery. USMRSC 31.1

 

Are There Any Special Considerations?

* The model may not separate into two or more parts or eject the motor(s). USMRSC 15.2

* Recovery wadding does not count as a part of the model. USMRSC 1.1

* A streamer is defined for this event as a piece of cloth, plastic film, or paper, whose shape is approximately rectangular. The streamer must have a length- to-width ratio of five to one (5:1) or greater and have a minimum area of 100 square centimeters. USMRSC 31.2

* The streamer and model must be connected by only a single line or cord, attached at the narrow end of the streamer. The cord may not be connected to either the streamer or the model at more than one point (e.g., no yokes are permitted). The streamer may not be cut, slit, or otherwise altered in such a manner as to affect its nature as a simple connected plane. USMRSC 31.2

* Several pieces of material may be assembled into a single streamer to overcome length restrictions imposed by the length of commercially available material. All pieces of the streamer shall consist of identical material (e.g., the same type of crepe, plastic, or so on). Lengths of streamer material assembled in this manner must be joined in a manner so as to keep the aerodynamic effects of the joint as small as possible. All such joints shall be parallel to the narrow axis of the streamer. USMRSC 31.3

* SD is divided into classes based on the total impulse of the motor(s) you must use. USMRSC 31.4

* Your entry must be single stage, but can be clustered. USMRSC 31.1

* If your entry is clustered, the sum of the total impulse of the motors you use cannot be more than the total impulse limit for the event class you are flying. USMRSC 4.6, 4.8, 31.4

* 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, 31.4

* 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

* The duration starts at the first motion on the launch pad and ends when the entry lands or the timer loses sight it. USMRSC 15.6

 

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 SD event can be competitive. Many Estes and Quest rocket kits available at local hobby stores are good candidates for SD. 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 SD. The 0.5 inch 1/4A, 1/2A and A motors will be your best choice. However, an Estes Alpha using an A8-3 motor would also be good as your first entry in A SD. For B, C, D, and E SD, 1 inch diameter rockets will be competitive and easier to prepare. For F and G SD, use minimum diameter models that are as light as possible will be best.

 

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 streamer that will reliably deploy. Use the longest streamer that you can pack into your rocket and still have reliable deployment.

 

Tim Van Milligan, of Apogee Components, recommends a streamer length to width ratio of 5:1 (Apogee Components Newsletter #128, page 4 http://www.apogeerockets.com/education/downloads/newsletter128.pdf.

 

Chris Kidwell, Contest Manager author, recommends a streamer length to width ratio of 10:1 or greater (Streamer Duration Optimization, R&D for NARAM 43, http://www.narhams.org/library/rnd/StreamerDuration.pdf).

 

Many vendors have Streamer Duration models and competition supplies:

http://ojames3.tripod.com/tccnarcontesttips/competitionrocketvendors.html

 

If you are not using a kit from ASP or QCR, you’ll probably get longer flights if you build your own streamer. Mylar birthday banners, which are readily available at hobby stores, can be cut into competition streamers. Use sturdy tape other than cellophane (Scotch) or masking tape to attach your shock cord or line to the streamer. Tie some knots in the end of the shock cord/line that you tape to the streamer. Attach the shock cord/line to one end of the streamer so that it sticks out of the tape at a corner rather than at the center of the end of the streamer. A simple folding method is to repeatedly fold the streamer in half lengthwise until it fits in the rocket. You may need to make the streamer shorter to fit.

 

Use a pop-lug, tower or piston launcher for greater altitude. (see below)

 

What Else & What Next?

Streamer Folding Technique by Steve Humphrey NAR 17888, NARHAMS 139

Here's a trick I learned from Ross Hironaka for folding mylar streamers: Roll the material onto a suitable "mandrel"--I use a BT-5 tube. If the material comes wide enough for a few streamers, roll it up before slicing it. Slide the rolled-up material off the mandrel, then clamp it between two boards. I use a couple of poplar 2x2's. I don't use clamps, rather I screw the pieces together with a few deck screws; but clamps work OK. Then toss the whole thing in the oven set to the lowest setting (180 or so). Come back in a couple of hours, or the next day if you forget about it (I did once!) Remove the clamps and presto--folded streamer. If you clamped up the wide stuff, now slice it into individual streamers.

 

Streamer Attaching, Rolling and Packing by Chuck Weiss NAR 35775, ASTRE 471

The key to having success with even paper streamers is to take the stress off of the streamer during ejection. There are several little tricks to this that all add up in the end. You can reinforce the streamer a bit with some Mylar or scotch tape on the edges but you don't need to go very far up the streamer. Here are the primary tricks that make a difference for me:

 

1. Use 3 to 4 model lengths of shock cord between the nose cone and the model. I just use 15 to 30 lb. braided ice fishing line (not monofilament). Attach a second shock cord 2 to 3 feet long to the streamer and tie it to the main shock cord a few inches behind the nose. You can tie and remove this for several flights. Learn some fishing cinch knots.

 

2. Attach the shock cord to the streamer with strapping tape so the fiber of the tape runs perpendicular to the shock cord. Let about ½ inch of cord extend beyond the tape. Fold it back over the tape and tape it down again. This method makes a very strong attachment that doesn't bulge out much from the streamer.

 

3. Roll the streamer so that it is not tight in the body tube. This is a major factor. Sprinkle a little talc based powder on the streamer before you roll it. This stops things from sticking. Make sure you don't use too much and shake off all of the excess. Close up the pleats of the pleated section and then fold the streamer in half along the line of the pleats before you roll it. This cuts the starting diameter in half right off the bat. The streamer should be rolled to a diameter that allows it to slide freely out of the body tube. If it doesn't, you need to try again. This can take some practice.

 

4. Hold the streamer so it can't unwind and then wrap the shock cord about 3 times around the middle of the streamer. This step is critical. If you don't do it the streamer just unwinds and presses tightly against the body tube. You have to practice this a little and allow for the thickness of the shock cord inside the body tube. If you use too few wraps it won't keep the streamer coiled. Use too many and the streamer won't unfurl.

 

5. Sprinkle talc base powder on the rolled streamer and inside the body tube before you insert it in the model. Use a brush something like a test tube brush to distribute the talc on the inside of the tube.

 

6. Your model should be long enough so that with wadding in place and the streamer inserted, there is about 1/4 to 1/2 inch space above the streamer for the shock cord. Take into account the portion of the nose cone that sticks in the model. After the streamer is inserted, coil the cords neatly on top of the streamer. Neatness makes a difference. I usually coil the cord around my finger and then stick the coiled cord in the tube. If you use hollow nose cones, you can let the coil extend up into the nose a little. On a side note, don't use too much wadding. Practice this. Too much/ too tight causes a high pressure ejection. Too little and you can burn or fuse the streamer so it won't unfurl. This one gets me once in a while. Polymer based or the mica film streamer material is more subject to this. Make sure that the nose doesn't fit to tightly also.

 

I have used these techniques with very good success for paper, Mylar and mica-film streamers. They work well for up to 4x40 inch streamers in BT-5 and 6x60 inch streamers in BT-20 body tubes. These size streamers are generally quite competitive. These are the basics but you have to work with them a little. You should not hear a loud pop when the streamer ejects, If you do, the streamer is being stressed and you need to work at it a little more. When you get the technique down you should have a 80-90% success rate. If you have 100% success, you aren't pushing the envelope enough :). But if you are winning, I guess that doesn't matter does it?

 

Online Competition Rocket Plans:

NAR Competition Plans http://nar.org/competition/plans/duration.html

Competition Model Rockets (Howard Kuhn) Plans http://www.oldrocketplans.com/cmr.htm

 

Pop-lug: Competition Model Rockets, Howard Kuhn  http://www.oldrocketplans.com/pubs/CMR/pop_lug.pdf

 

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

 

Complex Tower:

http://www.narhams.org/old/library/zog-43/19-06/launcher.html

 

Piston Launchers Explained – Apogee Components:

http://www.apogeerockets.com/Education/downloads/newsletter47.pdf

 

Floating Head Piston Launcher – The Odd Couple Team T-085, Jeff Vincent NAR 27910 and Chuck Weiss NAR 35775:

http://mysite.verizon.net/wjvincent/RandD/fhp1/fhp1.html

 

TCC NAR Competition Bibliography

http://ojames3.tripod.com/tccnarcontesttips/TCCNARCompArticleBib.html

 

Yahoo group for discussing model rocket competition:

http://groups.yahoo.com/group/contestRoc/messages

 

Use computer simulations to determine altitude, motor performance and coast/delay time. Free altitude simulation: 

http://www.mrhq.org/digdug/wRASP32/wRASP32.shtml

 

You can get some useful info from the International Model Rocketry Competition site:

http://www.spacemodeling.org/new/home.html

 

Aerospace Specialty Products Streamer and Parachute Tips:

http://www.asp-rocketry.com/model-rocket-tips.cfm

 

George Gassaway’s Competition Tips (note: Some links on George’s page are inactive):

http://tccnar.tripod.com/tcctnp/

 

US Spacemodeling (International Competition Tips):

http://www.spacemodeling.org/new/how_to/construction.html

 

US Spacemodeling Home Page (International Competition):

http://www.spacemodeling.org/new/home.html

 

Detecting Thermals:

http://www.apogeerockets.com/education/detecting_thermals.asp

 

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

http://www.ninfinger.org/rockets/rmrfaq.9.html

 

 

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