Brief:
T' Trion is a retro-futuristic scratch build designed around t' FlisKits Tres motor mount. T' construction will be very difficult for builders without a high or expert experience level.

Construction:
Here is a list o' parts, shiver me timbers, with part numbers referrin' t' parts from Balsa Machinin' Service, Fliskits, shiver me timbers, etc.:

• 2 Nose cones, BMS CENV2NC
• 2 Boat tails, me hearties, me bucko, arrr, BMS CENV2BT
• Tube, me hearties, BMS BT60 T60-34 8.5 inches
• Tube, me bucko, BMS BT20 T20-34 29.5 inches
• 3 Engine hooks, shiver me timbers, ya bilge rat, me bucko, BMS EH275
• 3 Engine blocks, BMS EB18-P
• Launch lug, arrr, BMS LL316-200
• Balsa, BMS BSH18336 1/8 x 3 x 24
• Screw eye, Fliskits SE-S
• 18in Parachute (not nylon t' conserve space), any vendor
• Keelhaul®©™, shiver me timbers, me bucko, Fliskits SLK-08-288 3 feet
• Tres 18mm Motor Mount, ya bilge rat, Fliskits
• Nose weight (fishin' bullet weight sinkers), arrr, 1 3/8 oz

T' only legitimate way I know t' obtain t' Tres motor mount is t' buy a Tres and cannibalize t' motor mount.

Before beginning, note one confusin' aspect o' t' instructions below: t' parts called "nose cones" create t' nose and tail o' t' rocket. T' parts called "tail cones" (with holes all t' way through) create t' transitions.

Begin by assemblin' t' motor mount. Glue in t' engine blocks. Begad! Tape and glue t' engine hooks, me bucko, notin' t' followin' two "gotchas": First, t' three hooks should lie on t' outside edges o' t' motor tubes (e.g., arrr, shiver me timbers, t' surfaces most distant from t' central axis). Ahoy! Second, leave a very generous length o' unattached hook so that motors are very easy t' insert. Avast, me proud beauty! This helps because insertin' motors will be tricky with adult fingers so you don't want t' be fightin' stiff motor hooks. Aye aye! Finally, make a small hole in t' upper centerin' rin' and tie t' Keelhaul®©™ thread through it. Ahoy! Begad! Secure it with a drop o' CA.

Cut 7 inches o' BT-60 tube. Arrr! Ahoy! Use t' Tres tube cuttin' template upside down t' trace out t' aft half o' three ellipses. T' bottom edge o' t' ellipses should be about 1/8 inch above t' aft end o' t' tube. Now use t' template right side up and complete t' forward half o' t' ellipses. Ya scallywag! Now slit t' tube at t' aft end o' each ellipse. Ya scallywag! You'll repair those slits later after t' motor mount is positioned.

Next test fit t' motor mount. Avast, me proud beauty! Avast, me hearties, me proud beauty! Actually, don't bother because t' ellipses will be too narrow. Widen them with a Dremel or knife, arrr, say about 1/16 on each side. Avast! Test fit t' motor mount. Blimey! Remove and widen by 1/16 each side again. Aye aye! Avast! Repeat until t' motor mount fits snugly without stretchin' t' aft end o' t' ellipses. Ideally, t' motor tubes should stick out a bit from t' face o' t' tube t' reduce heat damage so if you err, err in this direction. Ahoy! Make sure t' slitted portions fit well then glue t' motor mount in place.

Cut six fins usin' t' enclosed template or t' RockSim file. Well, blow me down! Make plumb guide lines for each fin assembly originatin' at t' center o' each motor tube. Glue t' fins t' t' rocket as shown in t' photos. Ahoy! Arrr! This can be quite tricky. Aye aye! If you are adventurous, you can add a gentle curve t' t' root edge o' each fin t' allow it t' curve around t' tube slightly. Blimey! This would aid fin mountin' by reducin' fin bending/twisting. Bevel t' outside edges so that they will fit smoothly together with a flat surface t' glue. Ya scallywag! Well, blow me down! Here is me suggestion about how t' glue t' fins in place: Position two fins as desired. Aye aye! Mark where their aft edges fit on t' body tube. Set t' fins aside and draw two more guidelines connectin' t' aft marks t' t' forward centerin' line. Well, blow me down! Repeat with t' other fins before gluin' anything. Aye aye! Next, hold two fins in position against t' aft tube end with your left hand keepin' everythin' in place and keepin' t' outer edges touchin' and centered. Blimey! Avast, me proud beauty! With your right hand, grasp t' leadin' points o' t' fins and pinch them together t' meet at t' forward guide mark. With your third hand, ya bilge rat, apply some dots o' CA at t' tips and at t' outer edges. Hope t' whole assembly holds while t' CA dries. After gently detachin' your skin from t' CA, you can glue t' whole assembly completely with yellow or white glue for strength. Begad! Avast! If you don't have three hands or a spouse, me hearties, try usin' a very tight rubber band t' hold t' forward end. When you are done with t' fins, fill and fillet everythin' for a seamless look. T' motor tubes will be somewhat recessed in t' fin assemblies.

Next, prepare t' attach one nose cone (the one that will be t' tail). Ya scallywag! Sand down t' shoulder sufficiently so it will fit. Ya scallywag! Blimey! T' motor tubes will also prevent cone insertion, so grind away conic sections on t' nose shoulder until everythin' fits. Begad! Ideally, me bucko, arrr, sand subtle round depressions in t' wide portion o' t' nose cone so that t' cone surface gently avoids t' blast o' t' motors. Keep these subtle t' avoid ruinin' t' sleek look.

Next, cut two equal sections o' BT-20 tube, ya bilge rat, each about 15 inches. Ya scallywag! Slit one tube lengthwise, me hearties, me hearties, and remove enough material lengthwise along t' slit so that this tube can slide completely within t' other. Well, blow me down! Ya scallywag! (I think it works out t' be almost 1/4 inch, ya bilge rat, but go slowly until you get it just right.) Next is a tricky part: you want t' glue t' one tube completely within t' other. Arrr! Do this over newspaper. Blimey! T' key point is t' beware o' binding. Arrr! I think t' best method is t' dredge t' inside o' t' outer tube and t' outside o' t' inner tube with excessive amounts o' white glue (not yellow glue!) Position t' outer tube vertically against a hard, covered surface. Begad! In a single extremely swift and very firm thrust, push t' inner tube inside. Blimey! Do nay hesitate at any point or you are doomed. Aye aye! If you get it in all t' way, wipe away all t' extra glue and let it dry. Ya scallywag! If you failed, matey, try again with new tubes. Well, blow me down! T' exact length o' finished double-wall tubin' is nay terribly important so if you get it close, just trim away any odd ends.

Glue t' double-walled tube into each o' t' tail cones (the balsa cones with holes all t' way through them) with t' wide cone ends toward t' outside. Aye aye! Blimey! T' tube can be flush with t' wide ends o' t' cones or a bit less. Begad! However, you need a considerable length inserted t' make it strong enough. Well, blow me down! Usin' coarse sandpaper and a lot o' patience, sand away t' excess balsa at t' narrow ends o' t' tail cones t' obtain nice smooth transitions. Arrr! Avast, ya bilge rat, me proud beauty! As you get close, me bucko, fill t' joint with wood filler t' help get a seamless look.

T' rocket separates at t' aft end o' t' aft transition. Aye aye! Ya scallywag! Sand down t' shoulder o' that tail cone t' 5/8 in. Well, me bucko, blow me down! Attach t' screw eye t' this shoulder. Well, blow me down! Tie a loop midway in t' Keelhaul®©™® then tie t' end t' t' screw eye. Begad! Blimey! Arrr! Blimey! Ideally, add a length o' elastic before you do this t' help prevent zipper damage. Assemble t' parachute and tie it t' t' shock cord loop.

Sand down t' shoulder o' t' upper transition t' 1/2 in. Ahoy! Aye aye! Glue t' remainin' 1 1/2 inches o' BT-60 tube onto this shoulder.

Sand down t' shoulder o' t' remainin' nose cone t' 1/2 in. Avast, me proud beauty! Drill out a bit o' a hole and glue in t' nose weight. Avast! Dry fit t' whole rocket. Ya scallywag! Avast! With no motors, t' balancin' point o' t' fully assembled rocket should be roughly at t' forward edge o' t' aft transition. Avast, me proud beauty! Adjust t' nose weight t' achieve this then glue in t' forward nose cone.

Finishing:
Sand and fill everything; prime and paint it. Avast! You're ready t' fly!

Flight and Recovery:
All three o' me flights were on a trio o' C6-5 motors. Aye aye! Dealin' with t' motors can be tricky. For instance, shiver me timbers, needle-nose pliers are required t' extract t' motors after flight. Begad! I would never advocate messin' with commercial motors. Avast! However, let me just mention that if someone were crazy enough t' peel away some outer paper layers from each motor in complete disregard o' all regulations and common sense, he would find t' motors t' be much easier t' insert and extract.

Preppin' t' recovery system is straightforward. I used a homemade mylar chute because t' storage space is very tight. Arrr! Cellulose insulation waddin' protected t' chute.

Havin' documented t' build on TRF and winnin' a Design o' t' Month contest, arrr, t' rocket (in its sleek gold finish) was first inspected by members o' me local club before launch.

T' first flight was perfect except that we were surprised t' see that t' rocket had a strong spin. Upon recovery, me hearties, I found that thar was some blisterin' o' t' paint next t' t' motors, but it wasn't too bad. Begad! Avast, me proud beauty! T' second flight was a repeat o' t' first, but t' chute melted a bit on ejection and t' harder landin' broke off t' tip o' one fin assembly. Blimey! I took this opportunity t' completely remove all t' fins and start from scratch, ya bilge rat, hopefully t' prevent t' spin. Avast! Ya scallywag! After a couple months in t' shop, t' Trion went for a third flight. Avast, me proud beauty! Avast! Boost was very nice again with a weak spin. Ya scallywag! Begad! Recovery be perfect.

At this point, me hearties, t' Trion still looks great. Ya scallywag! Blimey! I can't decide whether t' retire it while it's still undamaged, or perhaps t' keep flyin' until destruction. Well, t' decision isn't too tough--rockets are meant t' fly!