Brief:
The Saboteur is a payload rocket designed to launch from a 6" tube instead of a launch rod. It has through the wall fin mounts for its five fins, a 29mm motor mount and parachute recovery. The motor tube is open inside, and it uses a rear bulkhead technique so any length 29mm motor can be used. The choice to use five fins was driven by a desire to provide as much directional stability in the tube as possible and reduce or eliminate possible chatter within the tube.

Construction:
The parts used are a 29mm motor tube, motor hook, foamcore centering rings, 1/8" plywood fins, sabot holders and payload bulkhead, Apogee BT-80 body, JT 80 coupler, Apogee nose cone. Recovery equipment consists of Kevlar®, elastic, screw eye, and 20" chute.

The forward end of the engine hook was bent up and epoxied to the outside of the motor tube. 300# Kevlar® was tied and epoxied around the motor tube and the loop and knot hit the forward body tube just inside the parachute bay to prevent zippers. The five body tube fin slots were cut with a hobby knife. Foamcore centering rings are extremely quick and easy to make and when combined with through the wall fins mounted to the motor tube, they provide incredible strength. Yellow carpenter's glue was used throughout.

Since it launches from a tube, there are no launch lugs per se.

Six half-inch launch lugs (for ¼" rod) were glued to the payload bay area to provide a stable platform for the sabots. The sabots are rectangular Styrofoam pieces that slide in the launch tube and keep the front of the rocket centered while the fins do that job in back. They are hollowed out to accommodate the rocket's body tube and shell out as soon as the rocket exits the launch tube.

The payload bay is a 1/8" plywood bulkhead and a substantial screw eye epoxied into a JT-80 coupler with a BT-80 glued on.

The nose cone tapes on for flight.

Finishing:
After a couple coats of high-build automotive primer and sanding to eliminate spirals, blue enamel was used for overall color. One fin was painted white and one black to allow easier observance of spin.

Flight:
Preparation is easy. Just wrap a bulkhead on the back of the motor, clip it in, add wadding, sabots, and stuff it into the bottom of the tube.

Flight is interesting. The efficiency of the motor is increased by a measured 40% because if the piston-like effect of sabot-contained gases. It also gives off a loud "fooommm" instead of the normal sounds, so it gets lots of attention.

Summary:
Cons: Five fins, more work. Sabot supports are draggy. After the increase in efficiency, the primary benefit of tube launches is that they completely isolate the rocket from the effects of wind on the pad.