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
Events:
D Altitude (altimeter)
D Boost Glider
D Streamer Duration
Spot Landing
Random 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 ussmidway@gmail.com.
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.
General Tips
Drag Reduction
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.
Altitude Tips:
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:
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."
Strategy
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 Glide
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.
