Parts List

• 1 - slotted (3 fin) 2.64 LOC body tube, 30"
• 1 - non-slotted 2.64 LOC body tube, 30"
• 1 - tube coupler for 2.64 tubes
• 1 - 29mm motor mount tube (a long length that can double as a baffle)
• 3 - plywood centering rings
• 1 - LOC nose cone - (Graduator type)
• 1 - 36" nylon parachute
• 3 - 1/8" plywood 'witch' fins. You can download a tif file with the pattern here
• 2 - T-nuts and screws for positive motor retention

 Construction

 Fins
 
 

Download the fin pattern, print it out at full size, trace onto some 1/8" plywood and cut out the fins. A table saw helps get some big pieces off - although you could probably do the whole job with a jig saw. If you're careful about laying them out, you can get all three fins from one of the full size pieces of model plywood. Just so you can verify the scale of the pattern - the tab portion of the fin should measure 4 19/32" (almost 4 5/8").

Cut the 30" non-slotted body tube into two 15" lengths. We only need one of the 15" lengths - so you'll have an extra piece for another rocket. If I had known about it a year ago, I would have used the 'hose clamp' technique. Unless you've already got a jig set up for cutting body tubes, I'd recommend that method. There was a write up about it in the March/April 98 Sport Rocketry - or you can find the thread about it on RMR by doing a search with Deja News. Glue the coupler into the slotted tube at this point - but hold off on gluing the top piece of body tube (15" piece) to the slotted piece.

The motor mount (MMT) tube will double as a baffle. I used a length of 29mm motor mount tubing about 34" long. This was long enough to get into the second piece of body tube - my thought being that it would add some strength, act somewhat as a 'stuffer tube', and keep the chute from sliding too far back during liftoff.

 Find and mark the MMT where the middle centering will go. This will be at the forward side of the fin tabs, which should be the forward part of the fin slots in the body tube. Glue the middle centering ring into place.

Before adding any more rings, mark the MMT at 90 degree increments, and draw straight lines from the middle centering ring to the forward most end of the MMT. Along each of the 4 lines - mark 5 or 6 spots evenly spaced for drilling holes (1/4"). Drill the holes along each line. Once the holes are drilled out and cleaned up a bit - add a small amount of CA around each of the holes for added protection against burning.

 You'll also need to drill 4 holes in the upper centering ring. The tube and this centering ring will act as the baffle (no wadding required). While you're at it - figure out a way to plug the forward end of the MMT. I found a dowel that fit well - and glued about a 1/2" piece in the end of the MMT.

 The bottom centering can be worked on some also. Drill the holes and install the T-nuts for positive motor retention. There is a detailed description (with pictures and everything) of the technique at the Info Central site, click on the motor retention link.

 With only the middle centering ring glued to the MMT, glue it into the slotted body tube. The centering ring should be just above the fin slots, the aft end should be flush with the aft of the body tube. You can insert the lower centering for stability - but don't glue it yet.

 Once that sets up a bit - glue the forward centering ring (with the 4 holes) to the top of the MMT (sticking out past the coupler). Make sure you align the holes in the ring, in between the holes in the MMT. The holes should not line up. Once that's done, you can glue the upper portion of body tube onto the lower assembly. Test fit everything and sand where necessary before gluing.
 
 

Epoxy the fins into place. I used 30 minute epoxy for this - and I would recommend fillets on the outside, inside body tube and along the fin/MMT joint. Add a 1/4" launch lug along one of the fins, and put a smaller piece along the 'hands' on the same fin.

I used a LOC style mount on mine - which has worked fine. You can do the same or use one of the other common methods. Wire to the top centering ring would certainly be a good choice. I used about 3/8" or 1/2" elastic for the shock cord itself - about 3 times the body length of the rocket. A 36" inch nylon chute will provide a reasonable descent rate - without any fin damage.

This is the fun part. I used the image at the top of this page as a guide for painting the fins. I made each fin with different color hair - florescent yellow, green and red. The rocket body ended up with spider web look. I painted the whole rocket black, then added some spiders we cut out of contact paper, then some race stripe tape (in different sizes) for the 'web'. After taping, a couple coats of a nice orange paint did the job. The image to the left gives a little better view of how it ended up. I still need to get a better close up picture.

• Weight (without motor): about 2 lbs.
• Length: 56 1/2"
• Center of Pressure (CP): Came out to 17" from aft end of BT using the cutout method. You will probably need to add some nose weight to get the center of gravity (CG) one caliber (2.5") forward of the CP.

As I mentioned at the top, this rocket flies great on a G64-4. I've also had good luck with the G80-4 (single use). This October I plan on trying an H128 and/or H180. A G75 (black jack) would also be nice if it's not too windy - the black smoke would look cool.

 If any of you do make one of these - I would be very interested in hearing about it. Feel free to email me with any comments and/or questions.