Jeff's Rocketry Postal Contest Entry

April 2011 -- FAI S6A A Streamer Duration

Jeff with his S6A SD model.

April 2011 -- FAI S6A A Streamer Duration

This month's event was FAI S6A, or streamer-recovered "rockoons" as Ed LaCroix might put it. :) I had high hopes for the event, building on the work I did to make a paper model for S3A in January. Things didn't quite work out as planned, as you'll see.

I decided to go the paper model route again since it worked pretty good last time. But this time I got a ream of Wausau AstroBrights paper (with a 40% off coupon at Michael's) to use for the model bodies. This paper weighs out at about 15% heavier than the plain white paper I was using before (even though they are both nominal 24 pound papers), but it comes pre-colored in bright eye-catching colors, so you don't need to add color to your model.

I had used George Gassaway's templates last time around (see here.) These are fine, but they are created for 10mm motors, so, given a bit more time this time around, I created my own. I used Inkscape, an open-source, multi-platform, vector-based drawing program to create my drawings. I've included both the .SVG vector graphics files and .PDF Acrobat documents below. (The .SVG file is good if you have Inkscape installed and/or if you want to edit the files, like add change the NAR number. I haven't tested the printing of the PDF file, so use caution, and be sure you are printing 1:1 and not "shrink to fit".) The included patterns are two 8.5" x 11" documents to be printed on the body and shroud material and two 4" x 6" documents that I printed on photo paper to use as fin and centering ring templates (for making the jig George describes.)

FAI 40mm Patterns
Body tube SVG file PDF file
Tail shroud (13mm motor) SVG file PDF file
Fins SVG file PDF file
13 - 40mm centering rings SVG file PDF file

Something that I didn't like about my S3A model was the nose cone, a paper cone with a sharp tip and an awkward transition to the body tube. I'm no professional aerodynamicist, but it looked really rough on any passing air molecules. So I put in an order to Apogee Components for some of their 40mm vacuform nose cones (#20061.) I got super fast service from Apogee (about a four business day turn-around on a mail-in order) and the cones are indeed superlight (1.1 grams.) Some seem to have a bit of a rough surface in spots, but it had to be better than that paper cone!

I happened to have some choice 1 mil mylar streamer material obtained about 20 years ago from Ken Mizoi (what can I say, my teammate Chuck Weiss usually flies the streamer events.) I followed the tips in the excellent May 2007 Sport Rocketry article on FAI spacemodeling. I built up two paper models like before, each about 9.5 grams empty. I made two 5" x 50" mylar streamers with an ironed-in "scorpion" pleat pattern, each about 5.5 grams. Prepped and ready to fly, my model was 26.2 grams.

So, I had all of these ducks in a row by mid-month. Then things kinda fell apart. Our family had a wedding scheduled on the 22nd, so much of the third week of the month was spent preparing for or participating in that event. Which wasn't that much of a loss, since that same week it was raining almost every day. (And everyone knows that the archenemies of the paper FAI model are puddles and rainy weather. :) But then the final week of the month was more of the same! It finally cleared on Friday, April 29th. But the price for ending the rain was a passing front that would also bring breezy conditions for the last two days of the month.

My plan was to try to fly early in the day, before the wind kicked in for good. I got set up at the local park around 11:00am (which, for me and my circumstances, is relatively early. :) Unfortunately, the breeze was already starting to kick up at 8-10 mph from the North. I made a flight anyway, since the weather was unlikely to get any better this month. I flew the model with an Estes A3-4T from a piston and it had a good boost and clean deploy. But the wind just kept carrying it over an area of brush dividing the playing fields. Unfortunately, the wind wasn't quite strong enough, and dropped the model in the brush shortly before it would have cleared it and landed in the next field. :( The flight time was 55.78 seconds.

The model landed about 15-20 feet up in thick brush. I wasn't wearing the right clothes (shorts) or have the right tools to recover it, so at this point I decided to cut my losses. After all, the weather was deteriorating and losing a second model and not making a third round flight wouldn't put me in a much better competitive position than just standing on my single flight (and I'd still have my second model and streamer to fly another day.) I came back two days later and tried to retrieve the model, taping together a couple of dead tree branches to reach it, but it was too entangled in the brush to dislodge it. (Also, at this point, the humidity overnight had destroyed the body, but I had hoped to salvage the Apogee cone [they ain't exactly cheap] and the low-mileage streamer.)

So, it was a mixed bag. I was disappointed with my flight results, but that was more a matter of circumstances than the actual performance. I had thought S6A, with it's lower duration performance, would be a good chance to fly and recover these paper models, but it didn't work out that way with the weather I had to work with (and after two tries I still have yet to recover one after flight.) On the other hand, everything held together and the model had a decent time for the conditions, so there is some room for optimism, if you overlook the initial disappointment.

Future postal contests include:

May 2011NAR 1/4A Parachute Duration
June 2011NAR C Rocket/Glider Duration
July 2011FAI S9A (multiround A Helicopter Duration)

See Rocketry_Postal_Contests Yahoo Group for more details.

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Photo Gallery

(click on an image to view a larger version)

Jeff's paper S6A model.

It is still a whale among guppies, but it is sleeker and brighter than the January S3A model.

And how do you like those skies overhead?...

The model ready to fly.

I wasn't sure how I would launch this, so it does have two small 1/8" launch lugs. I ended up using a floating head piston, a Quest Q2G2 igniter, and running the leads externally to slip-fit paper clip connectors.

An in-flight shot, with the streamer lashing out at those threatening skies. :)

Another descent shot.

Going... going...

Gone.

As you can see, it couldn't have picked a better place to play "hard to get" -- so close and yet so far.

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