This two-stager always gets attention when I bring it out at our South Florida joint NAR/TRA monthly launch. Everyone loves Reddy-Kilowatt fins!

CAT-Scratch Rocketry
Chain Lightning is one of my series of "CAT-Scratch" rockets, where CAT stands for Collect Any Trash. CAT-Scratch rockets avoid the use of any commercial rocketry items (barring the engine). (You, on the other hand, are free to build your own Chain Lightning with standard tubes and cones.)

Two Stages: Double The Fun
The booster stage accepts a 24mm engine, a D12-0. When this engine completes its thrust phase, the ejection charge occurs without delay. This charge ignites the D12-7 or D12-5 in the upper stage. Two 3/16" vent holes near the top of the booster prevent gases from separating the stages before upper ignition. The booster tumbles to recovery.

General Construction
The 24" body of the upper stage and the 4" body of the booster were cut from the same 2"-diameter Christmas wrapping paper tube. (I believe Estes BT-70 tubing would be close enough as well.) The upper stage motor mount is a long "stuffer tube" to minimize the pressurization space for recovery ejection. I rolled a bit of cardboard to make a coupler that I glued into the top of the booster stage. I used yellow carpenter's glue throughout this project.

Motor Mounts
As a diehard CAT-scratcher, I rolled my own 24mm engine tubes. I used manila folder cardboard, placed a D12 in the center, and rolled to about two thicknesses, securing the final edge with plain old masking tape. (The initial edge was held with a piece of tape and some yellow glue). Tacky? I've found that after cutting and applying sturdy cardboard centering rings, such an engine mount is plenty strong. I bent my own engine hooks as well, from 1/32" steel "piano wire" from the hobby store. Feel free to use commercial tubing, rings and hooks.

Styrofoam Nose Cone
Craft stores like Michael's and places like Wal-Mart offer styrofoam cones. Buy one with a diameter a bit larger than that of the body tube. Then carefully roll the lower end of the cone against a table, crushing it into a cylindrical shoulder of about 1.5" length. Fit-test it periodically as you roll; if you've gone too far (as I did), wrap the shoulder with masking tape until it fits snugly into the upper stage end.

How Do You Put An Eye-Hook Into Styrofoam?
The eyehook for the shock cord and parachute is a small piece of clothes-hanger wire bent into an "8"-shape by needle-nose pliers. The upper loop is pressed into the bottom of the cone. Then a 1.75" straight piece of wire is pressed laterally into the side of the cone shoulder so that it intersects that upper loop. The result: the hook stays embedded in the cone very securely.

Recovery System
Attached to the top of the stuffer tube is a 10" steel fishing leader. To this I tied a 36" piece of 3/8"-wide flat elastic from the cloth-store as a shock cord. The other end goes to the eye-hook on the nose cone. I then cut a hexagonal piece of bright yellow ripstop nylon, attached six notebook-paper hole-reinforcement circles to the corners, perforated the corners and tied on some kite string shroud lines. In typical fashion, I passed the three shroud loops through the nose cone eye-hook. (The booster tumbles to recovery.)

Launch Loops
Instead of standard launch lugs, I cut the larger end of a large paper-clip and bend it at a 45-degree angle. This produces a "launch loop" which accepts a 1/4" launch rod. I epoxied two such launch loops to the upper stage, one near the bottom and one about 11.5" from the end. Remember that the booster fins will be aligned in between the upper stage fins; align your launch loops so the rod will not hit any fins!

Those Cool Fins
The fins are cut from 3/32" basswood from the craft store. All it took was a razor-knife and some patience. These were surface-mounted to the two stages, three to a stage, with yellow carpenter's glue.

Finishing Touches
I sprayed the rocket fire-engine red and the nose cone yellow, then dust-sprayed the tips of those glorious fins yellow. The "Chain Lightning" logo was created with Sierra's PrintArtist software, printed by an HP color inkjet printer onto an 8x11 sheet of Avery sticky-backed label paper, cut out and affixed to the rocket.

How It Flies
You may have noticed that this rocket appears overstable. Bingo! Most multi-stagers are. The dramatic thunderbolt fins result in sizable weathercocking. And what about damage to those pointy things? Remarkably, the fins have remained in great shape; basswood is tough.

Final Notes
Make sure the coupler between the booster and upper stage is not too tight. If you hold the rocket upside-down by the booster, the upper stage should almost be trying to come out. When you assemble the two stages for flight, align the fins out of kilter, not in line with each other.

Here's The Parts List Again

• Yellow carpenter's glue
• 2.0" diameter wrapping paper tube by 4" long (booster)
• 2.0" diameter wrapping paper tube by 24" long (second stage)
• 2" - 3" diameter styrofoam cone from Michaels or Wal-Mart
• 3" wide by 3/32" thick basswood from Michaels or hobby store
• Manila folder cardboard rolled into two 24mm motor mounts
• Additional cardboard for coupler, centering rings, engine blocks
• 1/32" piano wire for engine hooks
• Two paper-clips cut into 1/4" "launch loops"
• Clothes-hanger wire for nose cone eye-hook
• 10" steel fishing leader for shock cord relief
• Ripstop nylon for parachute
• Kite string for shroud lines
• Six notebook paper hole reinforcement stickers for parachute
• Lightweight spackle to fill the nose cone
• Primer and paint