Scratch SLS Vector V Original Design / Scratch Built

Scratch - SLS Vector V {Scratch}

Contributed by Bill Eichelberger

Manufacturer: Scratch
(Contributed - by Bill Eichelberger - 02/01/06) (Scratch) SLS Vector V

Brief:
This is an upscaled version o' t' Centuri Vector V made entirely with Semroc parts, hence t' SLS designation. Blimey! Blimey! While nay an official Semroc release, shiver me timbers, it would seem t' fit in well with t' current trend toward upscales o' Centuri classics (the SLS Laser X bein' a perfect example).

Construction:
T' parts list:

  • LT-22580 lower body tube
  • ST-13180 main body tube
  • 5.0" ST-9 engine tube
  • CR-2050 engine block
  • BC-1354 balsa nose cone
  • 2 CR-913 centerin' rings
  • 2 CR-9225P centerin' rings
  • 1/8" balsa fin stock
  • long engine hook
  • large screw eye
  • metal washer for nose weight
  • 2 large snap swivels

T' first thin' I had t' do when startin' this project was figure out the upped scale dimensions. (Since this involves math, it's never easy for me.) With two completely different sizes o' tubes used in t' original Vector V, I figured that I be goin' t' have two wildly different scales betwixt t' top and bottom sections, but I lucked out. Blimey! T' ST-13 is roughly 1.765 times as big in diameter as t' ST-7, while t' LT-225 is 1.746 times as big in diameter as the ST-13. Aye aye! While nay exact, shiver me timbers, they were close enough for me personal tolerances.

(Scratch) SLS Vector V I started on t' fin can first by markin' off t' locations for t' five fins. Ahoy! Avast! I had upscaled t' fin pattern by 175% usin' a work copier, and t' me surprise, the fins came out sized perfectly. Avast, me proud beauty! After shapin' them, shiver me timbers, shiver me timbers, I attached them t' t' fin can usin' Loc Tite Gel CA then double filleted them with Elmer's Wood Glue.

Under t' skin, t' SLS Vector V is a mass o' centerin' rings. Avast! Some of them, which thar was no call for them, arrr, didn't exist when this project started. Three sets were needed t' allow all o' t' pieces t' mesh together into a sturdy bottom end. Blimey! An email t' Carl McLawhorn at Semroc resulted in a set of previously unavailable CR-9225 centerin' rings that would mate t' fin can to the motor tube. They slid together like they were made for each other, which they were. Ahoy! A second set o' CR-913 rings mated t' motor tube t' t' main body tube, and a third connected t' LT-225 fin can and t' ST-13 main body tube. Ya scallywag!

T' recovery system be secured by tyin' 150# Keelhaul®©™® to t' motor tube and passin' it through t' centerin' rings, knottin' it, arrr, and gluin' it along t' way. Begad! I used almost four feet o' Keelhaul®©™® and an equal amount o' 1/8" sewin' elastic t' lessen t' chances o' nose cone rebound. Begad! Arrr! (Next time I'll use five feet.) T' nose cone be attached with a heavy duty screw eye and a large washer t' better distribute t' weight.

(Scratch) SLS Vector V(Scratch) SLS Vector V

T' shroud was created usin' a template widget and was printed on heavy paper. Begad! It came nowhere close t' fitting. Avast, me proud beauty! A second shroud was then made by upscalin' t' original by 175%. Aye aye! It fit perfectly. T' be fair, shiver me timbers, me bucko, this be probably more luck than anything, matey, and t' chances that I screwed up with t' template widget are high. Well, blow me down! Well, blow me down! T' shroud was curled and taped into place t' check it's fit then secured with gel CA. Well, blow me down! Once it be glued in place, ya bilge rat, t' entire structure was coated liberally with thin CA t' allow it t' better withstand t' sandin' and sealin' t' come. Ya scallywag!

Finishing:
After t' fill, finish, matey, shiver me timbers, and sand process, t' nose cone be painted gloss black and t' main body tube was coasted in gloss white. Arrr! T' lower section was then painted florescent orange, which I (correctly) thought might come in handy durin' t' post-flight searches that would come later. Ya scallywag! Before t' decal process began, shiver me timbers, matey, t' entire rocket was sprayed with a coat o' gloss clear. Aye aye! Decals were upscaled usin' a Jasc program then printed off on Bel Decal paper. Arrr! Ahoy! After they were applied, t' entire structure be again sprayed with gloss clear for protection.

Flight:
To begin with, I wasn't entirely convinced that this rocket would be stable without gobs o' nose weight, mainly because o' t' heavy aft section. Avast! Well, blow me down! For this reason I decided t' start t' flight day with a C11-5 motor, figurin' that the less powerful motor might cause less damage in t' event o' an event during flight. Blimey! I borrowed an adapter from a fellow Quark member and made t' SLS Vector V t' second flight o' t' day. Aye aye! It turns out I had no reason t' worry.

Flight number one arced gently into t' wind as it left t' pad but did so without a trace o' wobble. Ya scallywag! It maxed out at a respectable height, ya bilge rat, arrr, me bucko, ejected at apogee, and then gave me a scare by recoverin' way too close t' the access road for me personal comfort. Like many o' t' rockets flown on that Saturday, matey, it bounced when it hit t' ground but suffered no damage.

T' second flight be on a D12-5, t' next motor up t' scale. Aye aye! Boosting surprisingly straight durin' a rare lull in t' gales, shiver me timbers, t' Vector V again ejected right at apogee then recovered safely in t' grass, arrr, and nowhere near the access road.

Flight #3 be t' real adventure and was t' flight I had in mind when I started construction. Ya scallywag! Loaded on an E9-6, t' Vector V shot off t' pad into the wind, me hearties, shiver me timbers, noticeably higher than t' previous two flights. Begad! Ejection was once again perfect, but it be immediately obvious that t' recovery walk was goin' t' be a killer. Well, blow me down! Arrr! I watched it descend, shiver me timbers, mentally marked t' spot, then saddled up the van for t' drive. Begad! (I'm no fool.) Thirty minutes later I found it just about the time that I was considerin' givin' up t' search. I had greatly misjudged the distance but had t' line right. Begad! T' bright orange paint be what allowed me t' spot t' rocket, arrr, which had landed in a large, me bucko, me hearties, newly cut prairie. Ahoy! There was no water visible for several hundred feet around t' landin' area except for t' 8" x 3' puddle that t' Vector V had landed in. Ahoy! T' aft o' the rocket was sittin' in t' puddle with t' expended casin' soakin' up water at a rapid rate. I managed t' bite t' casin' out, which was when I noticed the broken fin. Well, blow me down! I found t' missin' piece floatin' in t' puddle, but after studyin' t' break, matey, arrr, shiver me timbers, I believe it happened when t' nose cone rebounded, shiver me timbers, nay on impact with t' ground. T' piece just happened t' hold on until landing. In that case, me hearties, I was lucky. Begad! T' break is fairly clean and looks like it will be a quick and easy fix, me hearties, but t' big Vector will never again have that "fresh from t' factory" look t' it.

Recovery:
Recovery be handled by a Thrustline 18" nylon chute and a piece of Perma-Wadding. Ya scallywag! Both performed flawlessly, although addin' even more shock cord than t' 8' I had is an option. Aye aye! Avast, arrr, me proud beauty! (That ejection charge is a killer.)

Summary:
PROs: Semroc parts and service. A much more satisfyin' project than t' 1:1 Vector V, arrr, although I need t' build another one o' those just for t' sake of scale.

CONs: Nose cone rebound with eight feet o' shock cord.

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