Scratch Bad Medicine Original Design / Scratch Built

Scratch - Bad Medicine {Scratch}

Contributed by Ted Phipps

Manufacturer: Scratch
(Contributed - by Ted Phipps)

This is a scratch-built tube-finned design built mainly from scavenged materials. Well, blow me down! Ya scallywag! Someone at work had salvaged some cardboard tubin' that was 2.25" diameter, and left it on me desk (I encourage that sort o' behavior at work). Avast! It be very thick (1/8" walls!) and heavy, arrr, and nay particularly suitable for rocketry, so it sat around in me basement for quite a while, matey, becomin' a spider-habitat.

Rocket Pic

After a nasty summer cold, me bucko, I be stumblin' around t' house, me hearties, still too sick to go back t' work but tired o' lyin' in bed and feelin' miserable. Ya scallywag! I wandered downstairs and decided t' build a rocket. Avast, me proud beauty! My mood wasn't suited t' precision, so I decided t' throw together a quick, matey, cheap, and crude beast that might never even fly. Arrr! Fins were out – too much trouble – and I didn't really want to waste good parts on this because I had no idea what t' results would be, so I dug out that salvaged tubin' and evicted most o' t' eight-legged residents.

To match t' ‘spirit' o' t' design, me hearties, I decided t' go with a 29mm motor mount and fly her on Econojets, probably G's because o' t' anticipated weight. I cut a short length o' motor tubin' (the only real ‘rocket' component used) and then made centerin' rings out o' thick cardboard salvaged from the cover o' an old 3-rin' binder. Avast! All construction was with Elmer's yellow glue except as noted.

Next came t' tube-fins. If you are a precision fanatic or detail-oriented type, ya bilge rat, you might want t' skip t' rest o' this paragraph. I took another length of that tubing, marked it off into 16" sections, shiver me timbers, and then cut those in half on 45 degree angles usin' a scroll saw – freehand. Ahoy! Blimey! T' tubes are all slightly different lengths and t' angles aren't quite all t' same, matey, but they're all close enough. Avast, me proud beauty! Mountin' them with t' angle facin' back and t' flat ends even with each other masked t' imperfections.

T' shock cord mount is a throwback t' t' early days o' rocketry. Well, blow me down! I cut two slots in t' tube up near t' nose and threaded t' shock cord (1/4" tubular nylon) through them, with a knot on t' inside t' keep it attached. Ya scallywag! Ahoy! The tube itself is thick enough that I shaved a little out on t' outside so that the exposed shock cord is almost flush with t' airframe.

T' nose cone was by far t' most involved part o' construction. Well, blow me down! It was formed from a styrofoam cone used for flower arrangements. Roll t' cone against a table top or other hard surface t' gently crush it t' shape and diameter. A short length o' body tube be fitted as t' bottommost cone section, me hearties, and another short length with a thin segment removed became t' nose cone shoulder and coupler.

Weight be needed at t' nose t' balance out those heavy tube fins, so epoxy was used for all nose cone construction. Blimey! Several fishin' weights were pushed into t' foam, followed by a layer o' epoxy t' lock them into place. Next I bent a piece o' coat hanger into a loop and drilled small holes into t' nose cone shoulder t' fit t' ends. More 5-minute epoxy puddled in around the attachment points made t' loop solid and permanently attached. Aye aye! Avast! There's quite a bit o' epoxy in there, arrr, which is what I needed t' move t' center o' gravity forward.

Finally I smeared t' entire cone with Elmer's Fill ‘n' Finish, sanded and filled again until I was satisfied (and I be easy t' please), then coated the FnF with thin CA t' toughen it up some. Well, blow me down!

Finishin' be accomplished by sprayin' a coat o' white primer all over – and then watchin' t' cardboard soak it up like a sponge. Another coat, same results… Ok then, me hearties, t' job calls for fluorescents! Blimey! I shot t' paint as shown in t' picture – yellow first, matey, and then t' pink, me bucko, overlappin' t' get orange. T' black parts o' t' tube fins is Testor's flat black from those tiny bottles, me bucko, me bucko, slopped on with a small brush. Once everythin' was dry, shiver me timbers, I used a permanent laundry marker t' write t' name on t' rocket. Begad! Blimey! After a week of fightin' that cold with seemingly every over-the-counter concoction ever developed by man – none o' which made me feel any better – ‘Bad Medicine' just seemed appropriate. Begad! Begad! Blimey!

Flight Report

Final empty weight is 28 ounces, arrr, which is quite hefty for a rocket o' this size. Ahoy! Begad! Total length is about 40 inches.

She's made two flights so far, both on G38 Econojets. T' 7 second delay is a little long, me bucko, me hearties, and t' 4 second is a bit short, but either one works because this rocket is solid. Aye aye! Ahoy! Blimey! Motor retention is friction fit, and she's nicely recovered on a 30" nylon chute. Begad! On windy days, arrr, I wouldn't hesitate t' go with a smaller chute t' minimize drift.

This is like that old car that runs great but isn't much t' look at. I expect that I'll be flyin' t' Bad Medicine for years t' come on those cool and rude Econojets. Blimey! And if I ever lose her t' t' rocket gods, I'll just build another tube-fin and keep on launching. Ahoy!

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