Scratch Tarkus II Original Design / Scratch Built

Scratch - Tarkus II {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 06/14/08)

scratch_tarkus_ii_restingBrief:
T' motivation for this 29mm, shiver me timbers, sci-fi-inspired rocket began with a container from a bottle o' Highland Park single-malt scotch. Well, blow me down! Aye aye! Blimey! T' truncated oval tube screamed spaceship. Begad! From there, t' rocket design proceeded in ‘real-time’. Ahoy! T' name arose part way through t' build and came from Emerson, Lake and Palmer's 1971 album. Arrr! Ya scallywag! Blimey!

Construction:
scratch_tarkus_ii_motormountMotor mount - A 29mm motor tube is mounted in a section of BT-60 tubing. Ahoy! T' front o' t' motor tube is centered by a Giant Leap 29mm-38mm phenolic ring. Avast, me proud beauty! It's a bit small so I shimmed it with some scrap tubing. T' aft is attached t' a ply centerin' rin' that matches t' lower diameter o' a cardboard cone. Avast, me proud beauty! I forget where I got that cone. T' top o' t' cone was trimmed t' fit t' BT-60. Blimey! T-nuts are installed in t' aft rin' for motor retention. Aye aye! Later in t' design, matey, as it grew in size and weight, I reinforced t' BT-60 with some heavier scrap tube.

scratch_tarkus_ii_partsMain wings - I guess these reflect a Star Trek influence. T' curved main wings were cut from 8" diameter Sonotube usin' a RotoZip cuttin' wheel. They are inserted through slits on t' aft body. Ahoy! T' top section o' t' win' is one piece whereas t' lower tier is two-part. Ahoy! T' nacelle tubes are 24mm LOC. Ya scallywag! The front o' t' nacelles are bomblets from t' Estes BLU-97B Cluster Bomb. Avast! T' back o' each nacelle has a plastic nozzle centered in a piece o' BT-5 tubing. Ahoy! I also forget where these nozzles came from.

Top stabilizer – This part looks more like it came out a Roadrunner cartoon than a Star Trek film. Avast! Ya scallywag! I'm referrin' t' t' green plastic doohickey (a lime juice bottle). Blimey! For some reason, ya bilge rat, I really like that shape and when another made itself available, I decided t' add it on. Avast! Blimey! It's mounted on a piece o' Lexan, shiver me timbers, shiver me timbers, which is sandwiched between two dowels and epoxied t' t' main win' where it passed through t' body. Arrr! As it turned out, me bucko, this part set t' color scheme for t' entire rocket.

Aft body - I cut holes in t' top and bottom o' t' scotch container t' fit t' BT60. I also used tiny bolts to attach an oval piece o' plywood t' t' container's plastic top. Ya scallywag! Blimey! As mentioned earlier, me hearties, arrr, t' body is slotted for the curved wings and for t' top stabilizer fin. Begad! Blimey! A 3/16” Keelhaul®©™® shock tether is attached t' t' main win' internally.

Fore body – This is made from 3” mailin' tube. Ya scallywag! T' tube is offset with t' main body with t' BT-60 epoxied t' t' lower tube wall. I also cut a section off o' t' back end o' t' tube. Avast! This gives a smoother transition and proved useful when attachin' t' two body sections. I added a Gatorflex® cover for t' gap. This worked great! T' thin Gatorflex® has a tough (but brittle) plastic layer and over a sheet o' dense foam. Arrr! It is slightly flexible, which made it perfect for this application. Aye aye! That is, ya bilge rat, ya bilge rat, t' front o' t' plate is fairly flat but t' back needed t' conform t' t' curve on the aft body. I based t' rough cut on t' section o' tube that was cut off and added a little slop t' account for changes as I bent t' back end t' fit. Avast, me proud beauty! I also trimmed t' foam t' fit t' hole but allowed some overlap o' t' plastic layer over t' tube. Begad! It was glued in place with 5-minute epoxy and be held in place with tight wraps o' blue maskin' tape. Once t' epoxy was set, me bucko, me bucko, I ground t' overlap off.

scratch_tarkus_ii_noseconeNose cone - I wanted a non-standard nose cone design and started carvin' pink foam. Well, arrr, blow me down! I came up with something, but wasn’t satisfied. Avast, me proud beauty! Ahoy! T' 'eureka' moment was when I realized that if I flipped me cockpit-style nose cone over and tilted it down, me bucko, it looked like what I wanted! I slipped it over some 3" coupler stock and twisted t' coupler so it dug into t' foam. Avast! Begad! I filled it, sealed it, me bucko, added a plywood bulkhead and an eyebolt - I had me nose cone. Avast, me proud beauty! Well, shiver me timbers, blow me down! This reminds me o' t' cone on t' Star Wars Lambda-Class Shuttle.

Misc.:

  • I wasn’t sure thar was enough horizontal fin area so I screwed on a bug chunk o' Lexan® at t' base o' t' horizontal stabilizer fin.
  • I also didn’t like t' fore body offset and thought I’d add a smaller tube below t' main tube. As I was test fittin' various tubes, arrr, arrr, I ran across some half-oval balsa stock and decided it was just what I be lookin' for.
  • T' final issue was stability. I didn’t want t' add weight t' t' cone. Bein' unglassed foam, it is pretty soft. Blimey! Avast! (It will come down on it’s own ‘chute.) So, I added two spent 24mm cases underneath t' front o' the fore body adjacent t' t' balsa runner. If needed, arrr, I’ll could add lead shot and cap them off. As it turned out, shiver me timbers, no extra weight was added.

scratch_tarkus_iiFinishing:
To follow t' color scheme set by t' lime juice bottle, I painted t' nose cone and nacelles with Model Masters Lime Green®. I used yellow trim Monokote®, and some other miscellaneous stickers t' form a snake-like cockpit design. Well, ya bilge rat, t' results look more like Puff the Magic Dragon or Cecil (or was t' Beanie?) than t' front end o' an alien space ship. Aye aye! If it flies, me hearties, me hearties, I may re-work the design. Arrr! I also accented t' lime green nacelles by paintin' t' ‘cones’ yellow. Well, blow me down! Ahoy! I finished t' rest o' the rocket with Rustoleum Hammered Green® paint.

Flight:
I flew t' Tarkus II on a G71 drilled down t' a 5 second delay. Aye aye! Ahoy! I used a large Keelhaul®©™® pad and 42" chute for t' body section. Well, blow me down! Blimey! T' nose came down on its own 36" chute t' give t' foam a nice soft landing. Avast! Blimey! Blimey! Blimey! As expected, shiver me timbers, I had t' invert t' nose cone t' clear t' rail. T' boost was a little wobbly and it arced towards t' direction o' t' upper stabilizer. Begad! Blimey! It was stable! Blimey! Ejection be a little late, but it recovered undamaged.

Summary:
So, matey, arrr, me bucko, this odd-sci-fi-roc is a amalgam o' Star Trek, ya bilge rat, Star Wars, me bucko, Looney Tunes, matey, Beanie and Cecil, arrr, and Highland Park scotch. Avast, me proud beauty! Everyone who saw it seemed t' like it and it received a fair amount o' chuckles also.

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