WINNING STREAMER DURATION

ROCC is flying D Streamer Duration in the contest next month, and I've been
asked to provide some tips for winning the event.

As a rule of thumb, for any duration event, you want to build the lightest,
minimum diameter bird you can, and then put the largest possible recovery
device in the rocket. Most often, these goals will conflict, so it will be
up to you to make design choices that will gain you optimal performance.

For D Streamer duration, you actually have a choice of 2 minimum diameter
rockets you could build, depending upon which motor you choose to fly with:
18mm with a D21, or 24mm with a D12. Reloadable motors are allowed, but I
don't use them since the there's a high risk you'll lose the model.

Construction: Most competitors use 3 fins on their model, and launch from a
tower, piston, or a combination piston augmented tower. Avoid using models
with launch lugs, as the launch lug will give you a significant drag
penalty. I usually try to size the model to the event and recovery device.
The formula I use is: (length of motor)+(2*diameter of model)+(size of
recovery device)+(length of nose cone shoulder)+(a fudge factor). For this
event, I got just less than 14", so with the fudge factor; I made the tube
15" in length. I use Kevlar� for the shock cord, and attach it to the
outside of the model. If you attach the Kevlar� so that the model hangs
horizontally with a spent engine, you'll improve your times greatly. I also
extend the Kevlar� out the back of the model and tuck it into the back end,
as an additional layer of redundancy. Finish the model using your favorite
technique, but again, keep it light.

The Streamer: The pink book has a definition of what is allowed in a
streamer, so I'll just copy it here for you:
31.2 Streamer Specifications
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. 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.
The type of material you may use is crepe paper, mylar, cloth, etc. The 2
online vendors I checked with use tracing paper for their streamer duration
models. I've had good success using model airplane coverings. I'm
currently experimenting with a covering called Ultracoat by Hanger9. In the
past, I've also used micafilm by Coverite, but I can't seem to find it
locally. Streamers are typically made with a length to width ratio of 10:1.
This seems to be the optimum ratio for maximum performance. Streamer
construction techniques will be covered in a separate posting, but as for
the size of the streamer, for a BT20 model, you should be able to fit a
6"x60" easily inside the model, and for a BT50 model, you should be able to
fit a 8"x80" streamer. Follow the guidelines in the streamer construction
post, and you should be able to pull this off easily.

Strategy: Scoring for streamer duration is sum of 2 flights, and one of the
flights needs to be returned. Normally what I'll try to do is to get a
qualified flight using a smaller streamer, and then go for broke on the
second flight. Of course, this depends greatly on the conditions at the
flying field during the contest.

I hope that this will help you build winning streamer duration birds.

Bob Bernachez