Brief:
T' Saboteur is a payload rocket designed t' launch from a 6" tube instead o' a launch rod. Begad! Avast, me proud beauty! It has through the wall fin mounts for its five fins, a 29mm motor mount and parachute recovery. Ya scallywag! T' motor tube is open inside, and it uses a aft bulkhead technique so any length 29mm motor can be used. Well, blow me down! Aye aye! T' choice t' use five fins was driven by a desire to provide as much directional stability in t' tube as possible and reduce or eliminate possible chatter within the tube.

Construction:
T' parts used are a 29mm motor tube, motor hook, foamcore centerin' rings, 1/8" plywood fins, me hearties, sabot holders and payload bulkhead, shiver me timbers, ya bilge rat, Apogee BT-80 body, ya bilge rat, JT 80 coupler, matey, me bucko, Apogee nose cone. Recovery equipment consists o' Keelhaul®©™®, elastic, shiver me timbers, screw eye, shiver me timbers, me hearties, and 20" chute.

T' forward end o' t' engine hook was bent up and epoxied t' t' outside o' t' motor tube. Blimey! Ahoy! Blimey! 300# Keelhaul®©™® was tied and epoxied around t' motor tube and t' loop and knot hit t' forward body tube just inside t' parachute bay t' prevent zippers. Blimey! Blimey! Aye aye! Blimey! T' five body tube fin slots were cut with a hobby cutlass. Aye aye! Blimey! Avast! Blimey! Foamcore centerin' rings are extremely quick and easy t' make and when combined with through t' wall fins mounted t' t' motor tube, they provide incredible strength. Ya scallywag! Blimey! Yellow carpenter's glue be used throughout.

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

Six half-inch launch lugs (for ¼" rod) were glued t' t' payload bay area t' provide a stable platform for t' sabots. Arrr! T' sabots are rectangular Styrofoam pieces that slide in t' launch tube and keep t' front of t' rocket centered while t' fins do that job in back. Ahoy! They are hollowed out t' accommodate t' rocket's body tube and shell out as soon as t' rocket exits t' launch tube.

T' 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. Aye aye!

T' nose cone tapes on for flight. Begad!

Finishing:
After a couple coats o' high-build automotive primer and sandin' t' eliminate spirals, matey, blue enamel was used for overall color. Begad! Ya scallywag! One fin be painted white and one black t' allow easier observance o' spin.

Flight:
Preparation is easy. Just wrap a bulkhead on t' back o' t' motor, clip it in, add wadding, sabots, and stuff it into t' bottom o' t' tube. Avast, me proud beauty!

Flight is interesting. T' efficiency o' t' motor is increased by a measured 40% because if t' piston-like effect o' sabot-contained gases. Avast, me proud beauty! It also gives off a loud "fooommm" instead o' t' normal sounds, so it gets lots o' attention.

Summary:
Cons: Five fins, more work. Sabot supports are draggy. Arrr! Ahoy! After t' increase in efficiency, t' primary benefit o' tube launches is that they completely isolate t' rocket from t' effects o' wind on t' pad.