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, I started thinkin' about a larger upscale for this classic Centuri bird. Well, blow me down! When I started back in t' hobby in 2001, I bought quite a bit o' BT-55 and BT-56 tubing, along with every like-sized nose cone I could get me hand on. I built several upscales based on these tube and cone combinations, arrr, but when that phase lost steam I still found myself with a pretty good collection o' BT-56 body tubes and nose cones. Begad! Avast! After readin' Jay's review, me hearties, shiver me timbers, me hearties, I dragged out t' abacus and began doin' t' math on a BT-56 Groove Tube upscale o' me own. Arrr! Aye aye! As usual, me bucko, this was 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, me hearties, me hearties, matey, in fact, ya bilge rat, t' closest I came t' anythin' difficult was in ensurin' that t' six tube fins were o' matchin' lengths. I used t' maskin' tape method o' cuttin' t' tubes, then cleaned up any ragged edges with a sandin' block. After t' edges o' t' tubes looked as clean as humanly possible, 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, arrr, matey, did t' sandin' arrive! This rocket is all tubes, matey, me hearties, which leaves a lot o' spirals t' cover, but t' fact that thar be no balsa t' fill makes up for this. Ahoy! Arrr! Well, shiver me timbers, somewhat...

(Scratch) Groove Tube Upscale T' actual construction began with buildin' t' engine tube. With no E size engine hooks readily available, shiver me timbers, arrr, I decided t' go with a friction fit mount with an engine block, matey, just as I had on me BT-55 based, E-powered Satellite Interceptor. 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. A 36" length o' Keelhaul®©™ was tied and glued in with t' centerin' rings t' provide a stout anchor for t' shock cord assembly. Well, blow me down! Blimey! Ya scallywag! Blimey! Another 36" length o' sewin' elastic provided t' remainder o' t' assembly. Begad! Blimey! Well, blow me down! Blimey! On this rocket, arrr, me bucko, once t' internals are done, me hearties, all that is left be t' tube fins, shiver me timbers, which have their own special set o' problems, none o' them insurmountable. I began this phase o' t' project by cuttin' one tube and designatin' it as me "official" template tube. 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. Arrr! Blimey! 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. Arrr! Blimey! Blimey! Blimey! 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. Blimey! Begad! I followed Jay's advice and began by startin' with a pair instead o' tryin' t' glue them on individually. Ahoy! Ahoy! For purely aesthetic purposes, me bucko, shiver me timbers, 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. Ahoy! I also went heavier on t' wood glue when attachin' t' paired tube fins t' t' main body tube. Aye aye! Arrr! Do this twice more and t' fit is surprisingly precise.

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

T' nose cone be sprayed with Valspar Gloss Black, which served t' accentuate t' scratches left by t' sandin' o' t' mold lines. Arrr! Blimey! I resanded and filled t' scratches with some body putty left over from me stock car days, me bucko, reprimed, me bucko, shiver me timbers, and shot t' cone black again. This time it came out perfect and t' red/white/black looked great when t' whole model was together--almost as if it had been planned that way. Begad! 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. Well, me hearties, 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, me proud beauty! Avast, ya bilge rat, me proud beauty! It looked great on t' decal paper and applied easily. It looked equally great on t' finished rocket. (I've had pretty fair winds with all black decals.) I finished t' project up by sprayin' t' entire rocket with t' Krylon clear. Avast, me proud beauty! I have plans t' replicate t' silver bands on t' tube fins with tape, ya bilge rat, but it looks like it will fly before I get t' tape.

(Scratch) Groove Tube Upscale

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

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