Next launch September 27th at Horning #2!
We are trying something new!
The first JMRC NAR sanctioned contest launch!
Please note that this is a bring your own equipment (launch pads and controllers) event and will be run "mis-fire alley" style. The JMRC trailer will not be available. And bring something for lunch as well as the JMRC cafe will not be serving.
Rockets on "D"raft
D Altitude (altimeter)
D Boost Glider
D Streamer Duration
Provisional Event - Classic Model
Contest Director - Buzz Nau
Entry Fee - $5 (to help cover port-a-john). No other launch fees will be charged for this event.
If you have any questions please send a note to Buzz at firstname.lastname@example.org.
Here is some more information on contest launches courtesy Buzz Nau.
There are several documents you should be familiar with before your first contest meet. They are,
NAR United States Mode Rocket Sporting Code aka Pink Book
NAR/CAR/TRA Combined Certified Motor List
NAR Certified Altimeter List
That's really all you need. The rule book, the list of motors you can use and altimeters (if the event calls for it). That's it.......... If only it were that simple. Below is a list of guides ad articles to help you on the road to contest flying.
To start I recommend reading Jeff Vincent's "Flying Your First Contest" for a great basic intro.
Also, George Gassaway's "General Competition Tips" is an excellent read. George has been flying competition for a very long time and has great ideas to steal, er... borrow!
The pink book is the book competition fliers love to hate. A lot of it reads like lawyer mumbo jumbo and leaves you crying that there has to be a better way to describe this stuff. Fortunately several folks have taken on the task and have written pretty easy to digest Pink Book primers. Jeniffer Ash-Poole wrote a really nice "Guide to Competition for the Casual Competitor" ,
O. Lee James also wrote the "The Pink Book Lite" which is another quick and dirty guide to navigating the various events,
I recommend reading these especially if you find explanations in the official Pink Book lacking or confusing. You're also welcome to fire any question you have to me or the JMRC mail list. There's plenty of other experienced competition fliers besides myself on the list.
Competition is a lot of fun. I enjoyed it for 10 years and performed well in regional meets and NARAMS. There can be a dark side to contest flying though. Kevin Wickart's "Contest Etiquette" article does a great job of explaining the various types you might run into at a meet. I can definitely say in all my time flying contests that running into a poor sportsman is the rare exception and not the rule.
Unfortunately it only takes one to ruin a good time. A good contest director is quick to identify when this is happening and stop it before it spoils the good mood being had by all. Kevin's article can be found here,
If you are looking for supplies this is a good list for find vendors,
Here is a page with contest plans you can use, borrow, up/down scale, or serve as inspiration for your own designs.
Streamer and Altitude:
Streamer and Altitude events share many of the same attributes and strategies. In both cases you want to build minimum diameter, small thin fins, smooth finish, ogive nose cone, and low impulse motor. The main difference between the two is the size of the recovery streamer. In streamer duration you want to pack the largest streamer possible and in altitude you want the smallest possible. It is possible to use the same model for both events though a SD model may be longer to accommodate the streamer.
There is a lot of good advice on the NAR’s Competition site for Altitude events.
Here is the link to the Streamer Duration page with advice on streamer material, folding and attachment.
Do not use launch lugs
Make smooth fin fillets or no fillets
Keep away from sharp angle transitions to avoid flow separation
Maintain a clean nose cone body tube joint
Avoid conical nose cones
Use blunted 2-to-1 to 3-to-1 ogives (This prevents flow separation during slight nose oscillations) Prevent fin tip vortex drag by using elliptical fins or sanding a sharp taper in the tip chord
Launching: Use a tower/piston combination, don't exaggerate launch angles to compensate for wind.
Construction: Balsa is lighter than waferglass. Waferglass is thinner, easier to finish, and more durable.
Kraft paper is lighter than phenolic. Phenolic is more durable, easier to finish, and will not crimp, but it will crack. Repairs easy with CA.
Use velum airframes for the lightest models. Harder to build than phenolic and waferglass but cuts weight by more than half.
Stay with the minimum diameter. Exception is 13mm events. One "throw away" model can be built with an 18mm chute compartment or a velum airframe that tapers from 18mm down to 13mm for an extra large chute.
NOTE - Vellum construction is a “hard core” technique and I would highly advise against it until you have flown the event and qualified consistently.
Streamer Duration Tips:
Streamer Material: Mylar and mica film are the best choices. Both are thin, light and hold accordion folds well.
Folding: Make 0.5"-1.0" accordion folds starting at the attachment point for 2 thirds of the total length.
Attachment: Mount shock line externally. Use Kevlar and avoid elastic polyester or rubber shock lines. With an expended motor installed, find the CG and tape the shock line to the airframe at that point. Attach shock line to one corner of the streamer, not the center.
Generally you want to fly minimum diameter and generally you don’t have an advantage to staging (altitude is one event that allows staging). In the case of D Altitude there are composite 18mm D motors that can be used, the D8 being a very popular one. If you are approaching this event casually and still want to be competitive it’s worth a look at staging a pair of C6’s.
Spot Landing is divided into three classes, parachute, streamer, and open (either or). Everyone hosts open spot landing though. As defined in the Pink Book,
"The purpose of this competition is to land the entry so that the tip of its nose cone is closest to a predetermined spot on the ground."
Seems simple enough. How is it scored?
"Spot Landing Competition shall be scored as follows: the distance between the tip of the nose cone (or motor nozzle if the model has no nose cone) of the model and the target spot shall be measured by the officials. If the tip of the nose cone lands more than 50 meters from the spot, the model shall not place, but shall receive flight points; otherwise, the model shall be given a score equal to its distance in meters. The contestant achieving the smallest score shall be the winner."
From a competition tips & strategies talk that Al de la Iglesia and I did at the 94 MASCON,
"Open Spot Landing -
Kind of a crap shoot really. The spot is always random, the weather and wind is always different, your launch angle is unlikely consistent. The best advice is to use a short, large diameter model with a streamer and low impulse motor."
From the NAR Competition page,
"The location of the target spot is set by the contest director prior to the start of the event. The spot might be placed close to the launch site, or it might be set farther away. Both options provide challenges.
The standard strategy is to fly a very simple model. The launch rod or tower is usually tilted (within 30 degrees of vertical) to send the rocket towards the target. The model typically has a small recovery device (streamer or parachute) to minimize drift due to wind. An alternate approach is to use featherweight recovery to further simplify the flight. "Flying Saucer" models are popular."
Random Duration is is one of three classes from the Precision Duration event. The other two classes are Predicted and Set. As the names imply Predicted means you predict the duration time (greater that 30 sec min), Set means the Contest Director sets the duration at the time of the meet announcement (range of 30 to 120 seconds). Random means the Contest Director randomly selects a time (range30 to 120) at the day of the meet.
As you might think, random duration is the hardest of three. From the 94 MASCON seminar,
"Random Duration -
The closest thing to Wheel of Fortune in the Pink Book. You can try and actually plan for this event or just bring along a predicted duration rocket you are consistent with and make changes in impulse and streamer size to try and hit the mark."
Of course this is assuming you "have" a predicted duration rocket that you have tested extensively. Right, only BTC's (big time competitors) have one of those. However, it isn't hard to take a small rocket like a Centuri/Semroc Javelin or an Estes Wizard and time it with a B6-4 and a 20" crepe paper streamer. IIRC you'll get close to 45 seconds. Try it with a C6-3. Again with a smaller streamer. You get the point. After a handful of sport flights you should have a pretty good idea what time you get with different motor / streamer combinations. You will get more consistent times using an unfolded streamer than a parachute.
From the NAR competition page,
"Random Duration. This is a very challenging event since the target duration is not known until immediately before the event. One strategy is to have single model that can be widely adjusted including mass, recovery device size, and motor impulse/size. A second strategy is to have a family of models that are targeted to specific durations or ranges of duration. For either strategy, many test flights may be needed to tune the model(s)."
Boost gliders come in all shapes, sizes and types. There's front engine (pop-pod), rear engine, scissor wing, parasite, flop-wing, etc, etc, etc... Estes published several Tech Reports on gliders whose information still holds up well today and explains well many of the different types of boost glider.
George Gassaway has an article specifically on D Boost Glider and mentions some kits that can be used. Unfortunately, it looks like QCR is no longer around and Edmond kits are getting hard to find.
Regardless, it's still a good article to read in D BG specifically.
There are plenty of pod-pod, front engine boost glider designs that can be upscaled for D and there is also Trip Barber's D-Light plans for a D powered BG.
If you are inclined to design your own pop-pod front engine BG a great place to start is reading Dr. G. M. Gregorek's "Design Rules For Boost and Rocket Gliders". I reference this when designing my own. The guidelines are simple to follow and will result is a solid performing glider.
Trip Barber's "Competition Boost Gliders" is another excellent guide.
Geoff Landis has a more detailed more detailed article on gliders and aerodynamics located here.
The best designed and best built glider is useless if it isn't trimmed well. There are several good articles on trimming your glider. David Newill has a very good two page article to get started.
Kevin McKiou also has a good article on trimming.