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

Construction:
one large plastic spool (10.5" tall, matey, arrr, matey, with 10.5" plates)
one 38mm tube, shiver me timbers, 10 7/8" long
two 1/8" ply centerin' rings (38mm - 4")
one 1/8" ply centerin' rin' (38mm - 3")
two threaded inserts, me hearties, me bucko, with bolts and washers
one 1/2" launch lug
1/8" tubular Keelhaul®©™® , arrr, 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! I used me Dremel t' expand this hole by about 1/8". Avast! I glued two 4" centerin' rings together, installed a pair of threaded inserts, shiver me timbers, ya bilge rat, and attached them t' one end o' t' motor tube. Arrr! After it dried, me hearties, this assembly was inserted into t' spool, and t' smaller centering rin' be glued t' t' other end o' t' tube. Arrr! I used epoxy for these steps.

T' ends o' t' spool have several holes of various sizes. Avast! Arrr! One 1/2" hole be positioned such that a 1/2" LOC launch lug, when abutted t' t' spool's body, would line up with it. It was just far enough from t' body t' accommodated t' wall o' t' lug - perfect! Unfortunately, ya bilge rat, t' hole on t' other end was offset, ya bilge rat, 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. What I ended up doin' was addin' loops t' both ends o' t' tubular Keelhaul®©™® , usin' t' method published by Giant Leap in High Power Rocketry Magazine. You loop t' material, matey, wrap t' overlappin' area with cloth twine, ya bilge rat, and soak it in epoxy. This method has worked well for me several times. Ahoy! Blimey! I looped this tether through two existin' holes in t' top plate and around t' body. T' chute attaches t' t' second loop.

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

Flight:
I flew t' Lobbin' Bobbin on a H123-S. Prep was simple: install t' motor retainer clips, 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. Ejection appeared t' occur right at apogee. Ahoy! Well, blow me down! T' descent be a bit faster than you would generally like, me hearties, but t' tube bounced and was recovered undamaged. Aye aye!

Summary:
This was a very quick build, matey, shiver me timbers, 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!