Brief:
P.H.I.T.S. (Punchin' Holes In T' Sky) is a 29mm single stage minimum diameter Mach buster with chute or streamer recovery.

Construction:
T' parts list:

• 34" 29mm heavy wall motor/body tube from Balsa Machinin' Service
• PML conical urethane nose cone with screw eye
• 3 fins, arrr, me hearties, ya bilge rat, 1/8" basswood, each with 1/8" square basswood root braces
• Estes BT55 tube coupler (1.25" long)
• 3 Estes 2.75" engine hooks
• 1/4" o' 29mm tube coupler for thrust ring
• 1/4" o' 29mm tube coupler for shock cord anchor
• 3 feet heavy Keelhaul®©™® covered round elastic shock cord
• 3 feet medium Keelhaul®©™® covered round elastic shock cord
• Chute or streamer
• Launch lugs
• Screw eye

Next be t' shock cords and anchor, matey, which starts with notchin' t' anchor rin' on two sides so that ring can fit into tube with shock cord anchor attached. Blimey! Tie both ends o' heavy Keelhaul®©™® cord t' anchor at opposite sides o' rin' at notches, ya bilge rat, arrr, then tie slip knot on one end in medium Keelhaul®©™®shock cord around loop in heavy shock cord. Ya scallywag! With a dowel or coupler tube, slide anchor rin' all t' way into t' body tube from t' forward end until anchor rin' is in contact with t' thrust rin' and epoxy t' rin' in place. Ya scallywag! Arrr! Tie shock cord t' PML nose cone.

For t' motor retainer, arrr, an Estes BT-55 coupler fits neatly but slightly loose over BMS heavy walled 29mm tube. Mark t' coupler for 3 points 120 degrees apart. Begad! Cut t' top bend off Estes 2.75" engine hooks. Begad! Ya scallywag! Then bend top 1" o' hooks over backwards (towards "outside") until bent over double. Place hooks on BT-55 coupler at marks so that t' bottom clips face inward. Avast! Blimey! CA clips onto t' coupler. Aye aye! Test fit assembly onto t' body tube and sand body tube as necessary. Arrr! Again, shiver me timbers, use CA t' attach BT-55 t' body tube. Ahoy! Slide it forward until only 1/4" o' motor clips are left hanging over t' body tube.

Fins are cut from 1/8" basswood. Well, blow me down! Also, me bucko, 6 strips 1/8" wide are cut to serve as root braces. Arrr! These strengthen t' body/fin joint by increasing contact area by a factor o' 3 and provide additional strength by bein' anchored under epoxy fillets. Begad! Fins are beveled sharply with t' ends o' t' braces beveled top and side away from fin. Avast! Braces are glued t' each side o' fin root with CA and with additional sandin' o' bevels extendin' line smoothly from fin, across brace. Once t' fins and braces are constructed, arrr, ya bilge rat, wrap rough sandpaper around body tube with t' grit facin' out, and sand fin/brace root t' fit curvature o' tube. Fit t' fins against t' aft end o' tube over retainer ring with t' end o' each fin even with end o' tube. Well, blow me down! Mark fin root on each side where fin root meets forward and aft ends o' retainer rin' (rin' makes tube thicker at this point). Ahoy! Use rough sandpaper taped t' sandin' block or emery board t' sand notch in fin/brace root until fin sits tightly against body tube and retainer rin' with sharp transition betwixt t' two heights. Begad! Ya scallywag! Mark body tube for three fins, 120 degrees apart and betwixt engine hooks on retainer then glue fins in place with CA. Aye aye! Begad! Lay fin fillets in two layers--first layer in two parts betwixt fin and brace and brace and tube. Aye aye! T' second layer is a smooth layer over t' top o' t' previous fillets, completely submergin' t' edge of the brace.

Lug placement requires locatin' betwixt fin and an engine hook. Begad! I used two 1" pieces 1/4" styrene tube (3/16" ID), beveled sharply and tacked t' t' tube with CA. Ya scallywag! Small wedges o' basswood were cut t' act as fillet fillers. Ahoy! These were tacked against tube and lug with CA followed by epoxy on top t' form a smooth, me bucko, shiver me timbers, round, button shaped fillet.

Finishing:
I used one thin layer o' white primer, one layer o' white satin finish for filler/smoothing, shiver me timbers, and one layer o' black Rustoleum appliance epoxy. I cannot recommend this paint enough. It is tough as nails, resists scratches and scuffs, has a finish more glossy than glossy paint, me hearties, and I'd swear it glues the entire rocket together better (see flight reports). It is heavy, arrr, me bucko, so it's not the best thin' for a Mach buster but t' strength be worth t' weight trade off.

Flight:
First flight, E9-6 in 24 t' 29mm adapter with mylar streamer. Blimey! Estimated altitude 600 feet. Ejection at apogee, good deployment, me bucko, ya bilge rat, fast descent, ya bilge rat, no damage.

Second flight, F20-7 with 12" mylar chute with spill hole plus trackin' smoke. Avast, me proud beauty! Estimated altitude 1000 feet. Ahoy! Ejection at apogee, matey, good deployment, ya bilge rat, fast descent, me hearties, no damage.

Third flight, me hearties, F21-4 with 12" mylar chute with spill hole plus tracking smoke. Well, blow me down! Ejection before apogee and lost chute. Rocket came in hot, arrr, trailin' the nose cone, matey, and lawn darted at very high speed. Begad! I felt t' thud in ground 50 yards away. Begad! Shock knocked engine adapter out o' retainer and it landed 30 feet away. Aye aye! Rocket be embedded straight down 6" into hard packed black dirt and grass turf. Well, arrr, blow me down! Pulled rocket straight out. Ya scallywag! Tube suffered some shock cracks in paint along spiral but no bendin' or weakenin' o' t' tube is detected. Ahoy! The part below ground wiped off t' its original gloss. T' packed in dirt and grass inside t' tube was knocked out with a 1/4" launch rod. Blimey! Aye aye! There were no marks at all on t' nose. This is what I mean about t' durability o' appliance epoxy paint.

T' cracked paint will be sanded off with CA run into t' spiral marks and the body repainted. Avast! I predict no problems due t' t' crash.

Summary:
This is one tough bird. Well, blow me down! Arrr! It was built t' handle Mach+ forces and it can handle much more.

One downside is that I used a 3/16" lug, shiver me timbers, which might bother some RSOs when I use larger engines, but it does nay whip on a 4 foot 3/16" rod since it takes off so fast.