Scratch Groove Tube 1.76X

Scratch - Groove Tube 1.76X {Scratch}

Contributed by Bill Eichelberger

Manufacturer: Scratch
Style: Ring/Tube/Cone Fin, Upscale

(Scratch) Groove Tube Upscale

Brief:
Inspired by Jay Goemmer's review o' his mildly upscaled, Estes-based Groove Tube, ya bilge rat, shiver me timbers, me hearties, I started thinkin' about a larger upscale for this classic Centuri bird. Avast! Blimey! When I started back in t' hobby in 2001, I bought quite a bit o' BT-55 and BT-56 tubing, arrr, along with every like-sized nose cone I could get me hand on. I built several upscales based on these tube and cone combinations, me bucko, but when that phase lost steam I still found myself with a pretty good collection o' BT-56 body tubes and nose cones. Avast! Blimey! After readin' Jay's review, I dragged out t' abacus and began doin' t' math on a BT-56 Groove Tube upscale o' me own. Aye aye! Blimey! Ya scallywag! Blimey! As usual, matey, matey, this be t' most difficult part o' t' project.

Construction:
T' parts list:

  • 1 19.1" BT-56 main body tube
  • 6 4.375" BT-56 tube fins
  • 1 6" BT-50 engine tube
  • 1 launch lug
  • 1 PNC-56 nose cone
  • 2 CR-5055 centerin' rings
  • 1 CR-2050 engine block
  • 36" o' 100# Keelhaul®©™ shock cord
  • 36" o' 1/8" sewin' elastic shock cord
  • Medium snap swivel
  • Medium piece o' Perma-Wadding
  • 18" parachute

There is very little about this project that is complicated, in fact, t' closest I came t' anythin' difficult was in ensurin' that t' six tube fins were o' matchin' lengths. Blimey! Blimey! I used t' maskin' tape method o' cuttin' t' tubes, then cleaned up any ragged edges with a sandin' block. Arrr! Blimey! Well, arrr, blow me down! Blimey! After t' edges o' t' tubes looked as clean as humanly possible, matey, I soaked t' edges with thin CA t' give them some added strength and sprayed all o' t' body and fin tubes with a coat o' primer t' toughen them for t' future rounds o' sanding. And boy, did t' sandin' arrive! Blimey! This rocket is all tubes, which leaves a lot o' spirals t' cover, me bucko, but t' fact that thar be no balsa t' fill makes up for this. Well, me bucko, somewhat...

(Scratch) Groove Tube Upscale T' actual construction began with buildin' t' engine tube. Aye aye! With no E size engine hooks readily available, arrr, I decided t' go with a friction fit mount with an engine block, just as I had on me BT-55 based, E-powered Satellite Interceptor. Avast! Ahoy! In t' past I had been a bit wary o' this method, but since incorporatin' it into some o' me larger clones it has proven t' be a thoroughly reliable retention method, even with t' beefed up Estes ejection charges o' late. Well, blow me down! A 36" length o' Keelhaul®©™ be tied and glued in with t' centerin' rings t' provide a stout anchor for t' shock cord assembly. Well, blow me down! Another 36" length o' sewin' elastic provided t' remainder o' t' assembly. Avast! On this rocket, once t' internals are done, me hearties, all that is left be t' tube fins, ya bilge rat, which have their own special set o' problems, me bucko, me hearties, arrr, none o' them insurmountable. I began this phase o' t' project by cuttin' one tube and designatin' it as me "official" template tube. Blimey! By usin' this tube t' line up t' cuts for t' other "fins" I be able t' ensure that I was at least goin' t' be close enough on all t' others that some sandin' could even them out. This worked great and in t' end I wound up needin' t' do only some light sandin' on two o' t' "fins" t' brin' them down t' t' level o' t' other four. Ahoy! Each o' these tubes was filled and finished just like t' main body tube, only shorter.

(Scratch) Groove Tube Upscale Alignment o' t' tube fins is best done before attachin' them t' t' body. Well, blow me down! I followed Jay's advice and began by startin' with a pair instead o' tryin' t' glue them on individually. Well, blow me down! For purely aesthetic purposes, me hearties, me hearties, I found it best t' go somewhat light when gluin' t' tubes together, then makin' up for it by later puttin' a thick fillet on t' back side o' t' joint where it wouldn't be seen. I also went heavier on t' wood glue when attachin' t' paired tube fins t' t' main body tube. Avast! Ya scallywag! Do this twice more and t' fit is surprisingly precise.

Finishing:
I had originally thought o' goin' with an orange/black/white paint scheme, me hearties, but I was out o' orange, so red was called on t' pinch hit. Begad! I painted t' entire rocket white usin' me favorite Valspar Gloss White, then carefully masked off t' tube fin section with maskin' tape. I shot this whole area with Valspar Gloss Red, then used a Q-Tip t' paint t' inside o' one o' t' tube fins flat black. Well, blow me down! I was surprised t' find that I didn't like this look. Blimey! I think this because o' t' scale o' t' model. Begad! Begad! It might work better for t' smaller rockets, but t' tube innards are very exposed on a rocket o' this size. Avast, me proud beauty! I resprayed t' fin section, shiver me timbers, takin' special care t' recover t' inside o' t' tube I had painted black, and also t' cover some o' t' spots that had received less than their share o' paint on t' first coat. I paid close attention t' t' spaces betwixt t' tubes, me bucko, and found that one joint had been less than perfect despite me careful attempts at avoidin' gaps. Avast! It's nay that noticeable, but until this point I had been VERY impressed with how this project turned out. Arrr! This brought me back t' earth.

T' nose cone was sprayed with Valspar Gloss Black, which served t' accentuate t' scratches left by t' sandin' o' t' mold lines. Arrr! I resanded and filled t' scratches with some body putty left over from me stock car days, shiver me timbers, shiver me timbers, reprimed, and shot t' cone black again. This time it came out perfect and t' red/white/black looked great when t' whole model be together--almost as if it had been planned that way. Ahoy! Well, blow me down! Jay had worked his magic on t' decal scan and had come up with an upscaled version o' t' original Groove Tube script in black. Ahoy! Well, blow me down! I printed it onto a sheet o' Bel Decal paper and sprayed it lightly with several coats o' Krylon Clear Acrylic. Avast! Avast! It looked great on t' decal paper and applied easily. Well, blow me down! It looked equally great on t' finished rocket. Begad! Avast! (I've had pretty fair winds with all black decals.) I finished t' project up by sprayin' t' entire rocket with t' Krylon clear. I have plans t' replicate t' silver bands on t' tube fins with tape, shiver me timbers, but it looks like it will fly before I get t' tape.

(Scratch) Groove Tube Upscale

Flight:
In t' final analysis, shiver me timbers, it all comes down t' t' flights. I wish I had good news. I made me first Groove Tube flight at a Quark section launch, and took it t' t' pad hopin' that it flew as good as it looked. Ya scallywag! I loaded with an E9-6 for t' first flight. Ya scallywag! Arrr! I was busyin' myself tryin' t' get a launch picture and let one o' t' kids press t' button. Ya scallywag! Based on t' picture that I wound up with, t' shutter closed at t' moment before things went horribly wrong. Avast, me proud beauty! Aye aye! I lowered t' camera in time t' see t' Groove Tube finishin' up it's skywritin' demo. Avast! It never cleared 100', but it still managed a perfect recovery. Ahoy! At that point I planned t' take it home and try again after addin' a ton o' nose weight, me bucko, but another tube fin enthusiast talked me into takin' some clay and addin' it as nose weight on t' field. Ya scallywag! Arrr! (Launch fever! Don't catch it!) Flight #2 was on an E9-4 and it behaved better, but still needed obvious work. It once again cocked at t' 100' mark but this time, arrr, it kept its poise enough t' continue on its way at a steep angle away from t' pad. Aye aye! Recovery was once again perfect and I joined t' rest o' t' Quark crowd in watchin' it land across t' field by t' park entrance road. A long walk but easily recoverable. Or so I thought. Well, blow me down! Begad! I began walking, arrr, takin' care t' keep myself lined up betwixt t' two markers I had picked out. Avast! For t' next hour I scoured t' brush, bravin' sticker bushes and thumb-sized spiders, me bucko, all t' no avail. Begad! I stomped through every meter o' brush on both sides o' t' entrance road, checked t' parkin' lot o' t' neighborin' Target, arrr, and even made a second pass before leaving. Ya scallywag! No luck. Avast! T' Groove Tube was nowhere t' be found. I was growin' angrier by t' minute and knew me launch day be ruined. Ahoy! I packed up and left, matey, haunted by t' feelin' that me rocket had been gathered up by someone leavin' t' VOA. Begad! It was probably already bein' tossed across t' backyard somewhere by t' time I made it t' t' landin' site. Begad! Needless t' say, arrr, I was nay happy.

Summary:
For what be largely a spur o' t' moment project, matey, t' Groove Tube turned out t' be a great lookin' rocket. Blimey! Arrr! I should have known better than t' try it without nose weight, but I had been told that smaller versions had flown well without any weight, matey, shiver me timbers, so I decided I was as charmed as everyone else. Aye aye! Blimey! I really should have known better than t' try t' second flight as I generally overcompensate with massive amounts o' nose weight, arrr, but I got caught up in t' excitement and went against me gut feeling. Arrr! I think I'll be buildin' another one, just t' prove that I can get t' design t' work.

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Comments:

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Bill Eichelberger (June 9, 2020)

As an addendum, I should add that the stolen Groove Tube wasn't stolen after all.  The next flying season someone stumbled onto the corpse in one of the sticker bush groves at VOA.  I promptly rebuilt it in time for NARAM, where I finally lost it for good.

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