Scratch Lobbin' Bobbin Original Design / Scratch Built

Scratch - Lobbin' Bobbin {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
Rating
(Contributed - by Dick Stafford - 10/01/02)

SpoolBrief: I've been readin' about spool rockets on r.m.r for a long time, shiver me timbers, 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. Well, blow me down! Ahoy! Blimey! Someone had built a similarly sized spool with a 29mm mount, which only reached an altitude o' about 100 ft. Arrr! I decided I wanted a bit more altitude, shiver me timbers, so I built mine with a 38mm mount. T' spool is one piece plastic, 10.5" tall, shiver me timbers, with 10.5" plates. Ya scallywag! No fins, arrr, no finishing...this thin' is a skill level-0 HPR rocket!

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

Spool T' ends o' t' spool have several holes of various sizes. Avast, me proud beauty! Blimey! One 1/2" hole be positioned such that a 1/2" LOC launch lug, when abutted t' t' spool's body, shiver me timbers, ya bilge rat, 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, ya bilge rat, matey, t' hole on t' other end be offset, arrr, 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. Arrr! What I ended up doin' was addin' loops t' both ends o' t' tubular Keelhaul®©™® , me bucko, usin' t' method published by Giant Leap in High Power Rocketry Magazine. Begad! Blimey! Aye aye! Blimey! You loop t' material, wrap t' overlappin' area with cloth twine, and soak it in epoxy. This method has worked well for me several times. Blimey! 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. Arrr! Prep be simple: install t' motor retainer clips, shiver me timbers, shiver me timbers, wrap t' chute in a protector, me bucko, ya bilge rat, and cram it down into t' tube. T' flight was slow and noisy and went t' maybe 200 - 300 feet. Begad! Avast, me proud beauty! Ejection appeared t' occur right at apogee. Begad! T' descent was a bit faster than you would generally like, ya bilge rat, me hearties, but t' tube bounced and was recovered undamaged. Blimey! Ahoy!

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), arrr, a spool rocket may be for you!

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