Scratch USS Moebius Original Design / Scratch Built

Scratch - USS Moebius {Scratch}

Contributed by Todd Mullin

Manufacturer: Scratch

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I loved EMRR's new "Spaceship Design Contest", but in t' beginning, I wasn't excited by any o' t' designs. Avast! But, over t' weeks that followed, matey, I rotated t' pictures on me desktop wallpaper and studied each for a few days and finally settled on this design. Begad! I thought that t' outboard motors would be an interestin' challenge that I had nay tried before. This design reminds me o' t' look o' t' ships o' Star Trek, ya bilge rat, ya bilge rat, though somewhat "lower tech" looking. Ahoy! Begad! Probably around t' time o' t' "Enterprise" series and an early Star Fleet tug or supply ship from its looks. Well, blow me down! Well, blow me down! Workin' with that line o' thought, me hearties, as many o' t' ships in t' Star Trek universe are named after famous scientists and scholars, me hearties, I decided t' name this rocket t' USS Moebius.

I started out t' design process by firin' up me handy-dandy copy o' Rocksim. Begad! Arrr! I got t' basic model built and lookin' pretty good, I thought. Begad! However, me hearties, thar was one little problem... Arrr! Rocksim said it be totally unstable even with several ounces o' nose weight! At this point, I decided t' go ahead and build t' rocket that, with me many years o' experience, I was pretty sure would be stable.

I decided that I would use an old Estes Fat Boy nose cone that I had kickin' around after me last Fat Boy lost it's match with gravity. Ya scallywag! This provided t' scale for t' design and t' rest be scaled t' look proportional t' t' picture. I decided t' keep t' design as simple as possible and pop t' nose cone on each nacelle instead o' tryin' t' passport t' ejection charge t' push out t' main nose cone. Due t' t' naggin' feelin' in t' back o' me head created by Rocksim, matey, I decided t' go with 13mm motors instead o' t' larger 18mm t' cut back t' weight on t' tail end as much as possible.

Right side

This rocket provided me with an interestin' new challenge as well. Ahoy! Ahoy! T' get t' nose cones for t' nacelles t' look right, me bucko, I would either need t' use a BT-5 stuffer tube inside o' t' BT-20 nacelles t' get t' correct look, matey, or try t' turn t' cones. Blimey! I up until this point had been highly intimidated by t' though o' tryin' t' turn cones for myself. For some reason, t' process seemed much more dauntin' than it actually (if you'll pardon t' pun) "turned" out t' be! I cut a chunk o' balsa t' 1"x1"x1" and CA'd a piece o' hard wood dowel into one end. I chucked this into me drill after it cured and locked t' drill in t' "on" position. Ahoy! I let t' drill rest on t' ground and held t' dowel as it turned (I'd recommend gloves for this...friction burns are nasty...) and used some 80 grit paper t' slowly round t' balsa into shape. Begad! Blimey! T' first one came out amazingly perfect! I was floored! T' came t' harder part.... Begad! Makin' three more that were identical.... Arrr! Heady with me initial success, ya bilge rat, it took a couple extras t' get four that were suitably close enough for use. If you have nay tried this because it seems t' "scary", give it a shot. T' process is reasonalby simple t' grasp, but it is definitely an artform. Avast! Begad! Give it a little practice and it is really rewarding!

I also had t' turn t' tailcone for t' Moebius as well. This was somewhat easier as I was able t' trim t' diameter o' t' balsa t' match t' tube before I started turning. Begad! After turning, ya bilge rat, I glued t' cone flush without it havin' a shoulder. It seems t' be sturdy enough t' survive without t' extra weight that t' shoulder would have added.

Tall

T' rest o' t' build was fairly straight forward. Avast! Begad! Blimey! I tacked t' fins t' t' nacelles with CA and Tite-bond, arrr, me bucko, filletin' after t' root bond had cured. Well, blow me down! Blimey! Blimey! I eyeballed t' alignment o' t' fins onto t' main airframe since me fin alignment guide wouldn't fit under t' outboard pods, matey, usin' t' same gluin' technique. Arrr! I finished up where I normally start, buildin' and insertin' t' mini-motor mounts into t' pods.

At this point, I decided it would be a good time for a swin' test t' make sure that I was goin' t' have a rocket t' flew in straight lines instead o' loops! With a couple o' ounces o' sand glued into t' front o' t' Fat Boy cone, ya bilge rat, ya bilge rat, t' rocket seemed stable enough for flight! Nice t' see that I haven't lost me eye for stability, shiver me timbers, even though t' software said otherwise....

I took a page from t' Master o' t' Dark Art o' Rocketry, Shrox, shiver me timbers, t' add t' details t' t' nose...Pin' pong balls! I cut t' ends off a couple o' balls, as a full half o' a ball was much too large for t' look o' t' design. Well, blow me down! I had a couple o' old Alpha III cones in me parts box, shiver me timbers, so I halved them and trimmed them down t' about a third o' t' length so that they would match up nicely with t' pin' pong balls. Aye aye! Gluin' these t' t' airframe helped disguise t' seam betwixt t' body and t' nose somewhat.

I filled t' seams with Elmer's Fill-n-finish, ya bilge rat, sanded and primed with Kilz and sanded again. Arrr! T' tailcone got a coat o' Rust-o-leum Metallic Blue and t' airframe got a coat o' gloss grey. Ya scallywag! After maskin' t' grey stripes, I sprayed t' whole model with Rust-o-leum Metallic Black. T' design for t' contest had a bit o' a pixelated pattern t' t' lighter grey areas, so I laid a piece o' loose weave fiberglass over t' grey areas and sprayed them with t' metallic black t' give them a little bit o' t' texture from t' image.

Back side

T' day o' t' launch, me bucko, I had decided t' nay tempt t' wrath o' t' Rocket Gods and didn't want t' fly t' rocket in it's finished paint. Aye aye! Well, blow me down! It flew in primer only... Pretty rockets make ugly flights!

My initial flight be on 4 A10-3T's. I loaded t' motors up and installed t' igniters with and borrowed a whipclip from a buddy. Begad! All four motors lid and it jumped into t' sky perfectly thanks t' t' high initial thrust spike o' t' A10's. All four nosecones popped in series, much t' t' delight o' several children who were lookin' on. Begad! I had installed two streamers and a parachute, leavin' one o' t' cones t' just pop. Avast! Avast! This brought t' model down reasonably quickly, but with no damage as t' flight was nay very high and our launch field here in San Diego is sand.

Lift-offI waited until another day t' get me additional flight in. Both me second and third flights were near disasters. Only 2 or 3 o' t' 4 motor lit on these flights. Avast! With t' reduction in thrust, me hearties, matey, t' model be terribly underpowered, matey, barely clearin' t' rod on t' 2 motor burn. Ya scallywag! Avast, me proud beauty! At this point, shiver me timbers, shiver me timbers, I had burned through most o' me supply o' A10-3t's, so I loaded only two on t' next flight as well as 2 A-10PT's! This one lit perfectly, but seemed t' nay fly quite as high as t' first flight had. Ya scallywag! After another failled flight, with this motor combination, matey, shiver me timbers, ya bilge rat, I switched t' me final flight configuration, matey, me bucko, 2 A10-3T's and 2 A3-4T's. Ya scallywag! Luckily, arrr, as these were t' last mini-motors that were left in me flight box, all t' motors lit. Begad! This combination be again underpowered. Ahoy! Begad! My thought had been that it would get more altitude because o' t' longer burn o' t' A3's, me bucko, but without t' initial thrust spike from 4 A10's, t' flight barely ejected before impact.

I enjoyed t' experience o' buildin' this rocket because o' t' challenge o' it's outboard cluster and havin' t' learn t' new skill o' turnin' cones. Aye aye! Begad! Overall a very satisfyin' experience. Begad! Begad! I am goin' t' continue flyin' t' Meobius after t' contest, shiver me timbers, me hearties, matey, but in a modified configuration. Aye aye! Begad! I am goin' t' glue in t' nacelle nose cones. Lightin' all 4 motors is more o' a challenge than I would rather deal with every time I want t' fly it. Avast! Aye aye! Since t' tail cone is only surface glued t' t' end o' t' main airframe, it should be easy t' remove. Begad! Avast, me proud beauty! I'm goin' t' install a central 24mm motor mount that will aft eject, as t' nose details are glued securly over t' seam at t' front, makin' a standard ejection impossible.

 

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