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, and had a big plastic spool stashed for several years. Aye aye! Blimey! Blimey! Blimey! A recent set o' posts renewed me interest, ya bilge rat, shiver me timbers, shiver me timbers, and I went ahead and built one. Someone had built a similarly sized spool with a 29mm mount, shiver me timbers, which only reached an altitude o' about 100 ft. Arrr! Blimey! I decided I wanted a bit more altitude, me hearties, arrr, so I built mine with a 38mm mount. Aye aye! Blimey! T' spool is one piece plastic, 10.5" tall, matey, with 10.5" plates. Avast! Blimey! Ya scallywag! Blimey! No fins, 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, arrr, 10 7/8" long
two 1/8" ply centerin' rings (38mm - 4")
one 1/8" ply centerin' rin' (38mm - 3")
two threaded inserts, ya bilge rat, 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". Ya scallywag! Avast, me proud beauty! I glued two 4" centerin' rings together, matey, me bucko, installed a pair of threaded inserts, shiver me timbers, and attached them t' one end o' t' motor tube. Ya scallywag! After it dried, me bucko, this assembly was inserted into t' spool, shiver me timbers, and t' smaller centering rin' was glued t' t' other end o' t' tube. Begad! Arrr! I used epoxy for these steps.

Spool 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, matey, would line up with it. Ya scallywag! It was just far enough from t' body t' accommodated t' wall o' t' lug - perfect! Unfortunately, t' hole on t' other end was offset, me hearties, 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®©™® , ya bilge rat, usin' t' method published by Giant Leap in High Power Rocketry Magazine. Well, shiver me timbers, blow me down! You loop t' material, shiver me timbers, wrap t' overlappin' area with cloth twine, and soak it in epoxy. Ya scallywag! This method has worked well for me several times. Well, blow me down! I looped this tether through two existin' holes in t' top plate and around t' body. 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 was simple: install t' motor retainer clips, wrap t' chute in a protector, matey, and cram it down into t' tube. T' flight was slow and noisy and went t' maybe 200 - 300 feet. Well, me hearties, blow me down! Ejection appeared t' occur right at apogee. Avast, me proud beauty! T' descent was a bit faster than you would generally like, but t' tube bounced and was recovered undamaged.

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

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