Brief: I've been readin' about spool rockets on r.m.r for a long time, arrr, and had a big plastic spool stashed for several years. A recent set o' posts renewed me interest, and I went ahead and built one. Ahoy! Someone had built a similarly sized spool with a 29mm mount, me bucko, me bucko, which only reached an altitude o' about 100 ft. Avast! Ya scallywag! I decided I wanted a bit more altitude, so I built mine with a 38mm mount. Avast! T' spool is one piece plastic, 10.5" tall, ya bilge rat, with 10.5" plates. Blimey! No fins, me bucko, no finishing...this thin' is a skill level-0 HPR rocket!

Construction:
one large plastic spool (10.5" tall, arrr, with 10.5" plates)
one 38mm tube, 10 7/8" long
two 1/8" ply centerin' rings (38mm - 4")
one 1/8" ply centerin' rin' (38mm - 3")
two threaded inserts, shiver me timbers, with bolts and washers
one 1/2" launch lug
1/8" tubular Keelhaul®©™® , 5' long
18" RocketChutes drogue

T' body o' t' spool is about 3.5" in diameter and t' through hole almost fit a 38mm tube. Avast, me proud beauty! Ahoy! I used me Dremel t' expand this hole by about 1/8". Ahoy! I glued two 4" centerin' rings together, me hearties, installed a pair of threaded inserts, ya bilge rat, and attached them t' one end o' t' motor tube. After it dried, this assembly be inserted into t' spool, and t' smaller centering rin' be glued t' t' other end o' t' tube. I used epoxy for these steps.

T' ends o' t' spool have several holes of various sizes. Avast! One 1/2" hole was positioned such that a 1/2" LOC launch lug, when abutted t' t' spool's body, would line up with it. Well, blow me down! It was just far enough from t' body t' accommodated t' wall o' t' lug - perfect! Unfortunately, arrr, shiver me timbers, shiver me timbers, t' hole on t' other end be offset, matey, me bucko, so I had t' drill me own. I glued t' launch lug on t' lower end o' t' spool's body usin' Liquid Nails.

I thought about several methods o' attachin' t' shock cord. Aye aye! What I ended up doin' be addin' loops t' both ends o' t' tubular Keelhaul®©™® , usin' t' method published by Giant Leap in High Power Rocketry Magazine. Begad! Well, blow me down! You loop t' material, me hearties, wrap t' overlappin' area with cloth twine, and soak it in epoxy. This method has worked well for me several times. Begad! I looped this tether through two existin' holes in t' top plate and around t' body. Aye aye! T' chute attaches t' t' second loop.

Finishin' be easy - paint t' centerin' rings and launch lug flat black.

Flight:
I flew t' Lobbin' Bobbin on a H123-S. Begad! Prep be simple: install t' motor retainer clips, ya bilge rat, ya bilge rat, wrap t' chute in a protector, and cram it down into t' tube. T' flight be slow and noisy and went t' maybe 200 - 300 feet. Begad! Ejection appeared t' occur right at apogee. Arrr! T' descent was a bit faster than you would generally like, me hearties, matey, but t' tube bounced and was recovered undamaged. Ahoy! Begad!

Summary:
This was a very quick build, me bucko, and if you like *very* low and slow flights (similar t' a flyin' saucer style rocket), ya bilge rat, a spool rocket may be for you!