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General Competition Tips
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Purpose -
The tips, designs, articles and other information here has been compiled to
help rocketeers get up to speed on contest flying. It is recommended that you check out the Competition Rocketry
page on the NAR website. Try other links there as well, such as the Competition Events
page and the Plans
page. The NAR's competition rule
book is officially called the "U.S. Model Rocket Sporting Code".
But since it has usually had a pink cover, it's more commonly referred to as
the Pink Book. The Pink Book has a lot of rules in it, and some
people feel overwhelmed by them. A lot of the rules cover things as to how to
run contests, or calculating contest points, which you realyl
do not need to wade through in order to compete. So, each of the individual
event tips pages posted here have their own short description and the basics
for each event. However, if you want to really understand the finer points of
the rules or are considering a design that may skirt the boundaries of the
rules, by all means you should consult the Pink Book.
For off-line access, a PDF
version of the Pink Book is available. Getting Started
- Everyone has to start somewhere. It may be useful to identify a few events
that you yourself find interesting to you, and concentrate more effort into
preparing for those events over the other events. Just Fly it
- Try some of the other events too, devoting less effort than some other ones
you are keying on, but try none the less, and fly them. A lot is learned by just
trying, and a lot is learned by competing for real, so the more experience
you get now can pay off later. Adaptability 101
- If you just can't make up contest models for many of the events, you can
draft some of your sport models that can be adapted or pressed into use. A
lot of 18mm models can be flown in B Streamer Duration. Others can be pressed
into use for eggloft with the addition of an egg
capsule. Of course, performance potential may be compromised. In some
duration events, reduced performance potential could be considered a
"good thing" - if a contestant loses their first model and needs to
make sure they get their second model back. Although with this year's NARAM
event selection, having specific "return flight" models is not as
critical. At least not involving adapting sport models, since only the glider
events and possibly helicopter event might make use of some low-performing
"return" models. Reliability 101
- In the long run, reliable models of lesser performance usually beat
unreliable high performance ones. The fanciest high-concept model that is
theoretically capable of outperforming everyone else's models means little if
it can not perform reliably. For the new flier, it is better to go with
something of a proven reliable design or competitive kit than try something
more advanced or complex. Even advanced competitors fall victim to trying to
squeeze performance too far, but when/if such models do fail, they understand
that it is a gamble they chose to take. Reliability 102
- Recovery Systems often fail. Kit type shock cords in general do not work
well for most parachute/streamer recovery contest models. Do not glue shock
cord anchors inside of body tubes (at least not the common kit types that are
attached inside of the tube wall). These anchors are likely to make the
recovery system jam inside the body tube and after a few flights the shock
cords tend to break at the anchor and are impractical to fix. The most useful
parachute/streamer shock cord system for most lightweight contest rockets is
to use 100 pound Kevlar cord. For models with any significant weight, elastic
shock cords are useful to absorb shock. Single egglofter
type models can use 1/8" elastic, as can some not-too-heavy plastic
models. Beyond that, 3/16" to 1/4" elastic can be employed to
absorb shock in larger/heavier models such as plastic and scale models. For
heavier rockets the parachutes should be strong enough. Over-the-top shroud
line reinforcement is one method to strengthen a plastic parachute (See the Eggloft, Scale, or Plastic model articles on how to do
this). In Scale, some modelers use fabric type chutes, but only if they have
adequate room to store and safely eject the chute, since they take up more
room for any given body tube storage space when compared to plastic chutes. Reliability 103
- Wherever possible, test/practice fly your models. This might not be a solid
requirement for kits or some designs built from a plan. However the more out
of the ordinary something is to you, the more you should consider flying it
at your home field to see how it performs. If you have designed your model
yourself, absolutely test fly it. This can be a
double edged sword, you want to fly it to see how it performs, but you do not
want to lose your rocket if it performs well. You might want scale back on
the engine power, but don't under power it to the point of crashing before
ejection. Some full power testing might be needed though. A B Rocket Glider
flown on an A does not prove the wing is strong enough for a B. However, if you
have confidence the model (wing in that case) is built strong enough, then
that might do. A really nice way to test, where possible, is to fly shortly
after dawn, when the winds tend to be light. That only does you any good if
you can fly at a site on short notice though. Other testing doesn't necessarily risk losing the
model, but shows that you have learned how to prep the model and fly well.
Packing a chute for Egg Duration or Parachute Duration is an important thing
to learn. The objective is to pack it in such a manner that you go with a big
chute that deploys quickly after ejection. Or to test by prepping and flying
models that use a unique method of recovery, such helicopter and rocket
glider models, and the burn-thread/rubber band activation systems which many
of those designs use. Testing for events like Sport Scale and Plastic
Model Conversion can be important as well. If you are making your own scale
model, rather than building from a kit, a boilerplate model can be very useful.
Same for Plastic Model. If you achieve first place after static judging, but
the flight is disqualified, the static score doesn't count for anything.
Boilerplate testing should include using the same shock cord and parachute
system as you intend for the real model to use. If you test using one kind of
chute and then use a different chute type for the actual contest model, then
your testing did not prove out the recovery system. If there is any doubt as
to stability, be sure that if your boilerplate flew successfully, that the
"real" model has it's CG no further
rearward than the boilerplate's CG location. Why are some plans so old, or so few? - Various reasons. Some plans are fairly well
proven. The Rotaroc design for helicopter has not
changed much since 1978. Same for Streamer models and some Gliders. Some
events are not flown very often, while for other events the rules have
changed significantly over time (B Payload, such as Jim Cook's 1980 plan for
the old 1/2" long lead payload). Many of the higher performance engines
that used to be available in the past are no longer produced or contest
certified (like Apogee 10.5mm micro motors and 13mm B7's). Plans for those
models are now moot. Also, simply, the pool of electronic versions of good
plans has not hit critical mass yet. The NAR website's competition pages are the first
one to really begin compiling plans, thanks to the efforts of Wolfram Von Kiparski. Some of the older plans that were only in
print, he scanned and redrew. This NARAM tips page is a further expansion of
those efforts. NAR magazine Back-issues - The NAR's magazine (Sport Rocketry now, previously named
American Spacemodeling and the Model Rocketeer) has published articles and plans for contest
models, and scale data. NARTS sells back-issues, and in cases of originals
being out of stock, photocopies. Check out this magazine index,
compiled by Lila Schmaker, to see what scale data has
been published in the magazine through 1999. Some plans have been published in Sport Rocketry
Magazine, and magazines before it, but some of those plans have not made it
to electronic form on the web yet. Back-issues are available
NARTS. There is a magazine
index, compiled by Lila Schmaker, you can use to see what contest articles, plans, and
scale data have been published in the magazine through 1999. It's not a beauty contest (except for the craftsmanship events) - For
Duration and Altitude events, great finishing and painting can make for great
looking models, but the model's appearance won't get you any bonus seconds or
bonus meters. A lot of finishing and paint can be detrimental to many
duration type models, because of the extra weight making the models descend
faster than if they were lighter. A lot of people fly duration models that
are unpainted, or use some magic marker for coloring. For Altitude models it
is a closer call, since low drag means smooth surfaces. So some try to hit a
balance between a really good smooth finish without really weighing down the
model too much. But build them well - Build the models to fly straight and true. Work towards
attaching all of the fins so they are straight and parallel to the body. This
should translate to a straight boost, with minimal wobbling that would hurt
the altitude. Even Duration models get better times when they fly higher than
they would if they wobbled. To eject, or not to eject? - That is the question. Very few contest rockets use
engine hooks. So the engines are often friction fitted in, using tape on the
engine to build up the diameter. Sometimes the friction fit is not enough
though, and the combination of the recovery system, wadding, and in some
events tracking powder, is too much for the ejection charge to push out
forward, so the engine ejects out the back instead. So, at the least, be sure
to get a good friction fit of the engine in the tube. Some designs move the fins up a bit on the body
tube, so the body tube sticks down about 1/4-1/2" or so below the
trailing edges of the fins. This allows for a second line of defense to be
used to try to keep the engine from ejecting out. A collar wrap of tape is
applied so that half the tape width is around the end of the body tube, and
the other half is around the engine. You will see several plans that have
this design feature. If you are using a plan or kit that does not have this
feature, and want to move the fins up, make sure it is a very stable design
or you may need to make the fins a little bit bigger. Also, try to not cram things tightly inside the body
to begin with. Test-prep the model without engine, and using lung power, blow
into the engine mount simulate and ejection charge (of course, do not do this
with tracking powder or you will have a mess everywhere, including on yourself!). If you can't get the nose and recovery system
to eject out, or if it was very hard to do so, that will increase the chances
that the engine will eject. So, refine the prepping methods and keep testing
till you find a method that ejects easily enough. And remember to prep that
same way when you fly for real. Lariat Loop Shock Cord attachment - Ed LaCroix (creator and
former owner of Apogee Components) has popularized a method that allows a
Kevlar shock cord to be directly attached to the engine. Tie a slip knot in
the end of the Kevlar shock cord and tighten it around the nozzle end of the
engine. Wrap one layer of 1/2" mylar tape
(available from ASP) around the Kevlar. This keeps the kevlar
in place and also acts as a thrust ring. The tape in front of the engine will
go INSIDE the body tube so that the bulge in the tape from the Kevlar becomes
the thrust ring. Insert the Kevlar and engine into the body tube until about
1/4" of the engine still sticks out. Then wrap the body tube and engine
with another layer of mylar tape. If the engine
should manage to eject, it remains with the model so a DQ is avoided (as long
as some means of safe recovery deploys). The above method has some extra benefits. Since the
Kevlar is not attached to the body tube, it can be easily replaced. It also
does not block the inside of the tube, as some other internal shock cord
mounts used. It has a couple of drawbacks, though. The Kevlar cord is not
easily burned, bit it CAN be burned apart if exposed to too much of an
ejection charge. 100 pound Kevlar holds up well to 18mm Ejection charges and
smaller. But a D12 or E9 ejection charge will definitely burn 100 pound
Kevlar. So for larger engines, use stronger Kevlar, at least for the first
few inches in front of the ejection charge. Or add some form of protection
such as heat-shrink tubing in the portion of the Kevlar that is exposed to the
ejection charge heat. Another drawback is that Kevlar cord does not absorb
shock. For some events this is not too much of an issue, such as Parachute
& Streamer Duration, as the models are fairly light. But for others such
as Egglofters, Plastic Models, and Scale Models, it
is an issue. Those models usually need to have their shock cords stretch to
absorb shock at chute deployment. So, the appropriate size and length of
elastic is suggested for most of the shock cord (Kevlar and elastic can be
used together such as Lariat Loop to run the cord inside the body then
transitioning to elastic outside of the top of the tube). Flights per event & scoring - In most events, you are allowed two flights,
weather permitting. In Altitude events, your score is based on the best
single flight. If a qualified flight is not tracked (or the tracking data
does not close), you can get a re-flight. In Duration events, usually, your score is a TOTAL
of the flights made (the exception being Eggloft
Duration, where the best single flight with the egg returned intact is your
score). In Multi-Round Duration events, three flights are
allowed, each with a maximum time cap. If there is a tie for first at the end
of three rounds of flying, then those who are tied enter an additional flyoff round. In Craftsmanship events (like Scale & Plastic
Model Conversion), two flights are allowed. The best qualified flight score
of the two is used. So if your model flies well, and you do not think it
would score better, there is no need to risk flying it again. Various other events only allow one flight, like
Spot Landing. And Drag Race is one flight per heat, but involves multiple
heats (if you keep winning), as with automotive drag racing. NARAM-46 is
not holding Spot Landing or Drag Race, these are
mentioned just for general (and future) reference. Models per event
- Usually, you are allowed to use two models in each event. Events that only allow one model are Craftsmanship
events (like Scale & Plastic Model Conversion), events that only allow
one flight (like Spot Landing), or Drag Race (one model for multiple heats).
In case of a "catastrophic failure", which normally means an engine
malfunction, a replacement model is allowed. Launch Equipment -
At NARAMs, a centralized electrical launch control
is used. Each NARAM pad has a 1/8" rod, and a few 3/16" and
1/4" rods are available for some pads. If you want to use your own Launch Pad (i.e. rod,
tower, piston, C-rail, etc), you may. You'll set it up in the assigned launch
lane, hook up the electrical leads from the NARAM launch control system and
fly. That's why we fly 'em - Regardless of performance potential, reliability,
and everything else, it all comes down to flying and seeing what happens.
Some days you'll do well, other days not so well. And the same goes for your
fellow competitors. So, keep at it and learn as you go. As you have
time, observe what the other fliers are doing, model-wise and flying-wise. Fellow competitors - Fellow competitors are a good source for learning about
designs, flying, and so forth. Most are happy to give such advice, and most
of them learned the same way from other competitors. And flying against them
is also a good way to learn. |
More Information - See the RMR Competition and Records FAQ (Frequently Asked Questions).
______________________________________________________________________________________________
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More sources for competition info |
Author |
Notes |
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"Contest
Etiquette" (from the WOOSH website) |
written by Kevin Wickart |
Practical and personal on-the-field advice for
competitors. |
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"R.S.V.P.
Principle" (from the WOOSH website) |
written by Kevin Wickart |
Great advice for contest flying, stressing
Reliability, Stability, Predictability, and Visibility. |
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"General
Strategy Notes" (from the WOOSH website) |
written by Pavel Pinkas |
Competition preparation and flying notes |
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ASP Rocketry's
Tips Page |
written by Andy Jackson |
Tracing Paper Streamers, Selecting Parachutes for Egglofting, Adhesives, Hardening of Unmixed EPOXO 88
Resin #1 |
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Last
Updated 4/19/04