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, matey, hence t' SLS designation. While nay an official Semroc release, me hearties, arrr, 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, shiver me timbers, arrr, 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. Begad! T' ST-13 is roughly 1.765 times as big in diameter as t' ST-7, matey, while t' LT-225 is 1.746 times as big in diameter as the ST-13. While nay exact, 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. I had upscaled t' fin pattern by 175% usin' a work copier, and t' me surprise, the fins came out sized perfectly. Ya scallywag! After shapin' them, arrr, I attached them t' t' fin can usin' Loc Tite Gel CA then double filleted them with Elmer's Wood Glue.

Under t' skin, ya bilge rat, t' SLS Vector V is a mass o' centerin' rings. Blimey! Some of them, arrr, which thar be no call for them, shiver me timbers, ya bilge rat, 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. Ahoy! Avast, me proud beauty! 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, arrr, which they were. Begad! Begad! 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. Blimey!

T' recovery system was secured by tyin' 150# Keelhaul®©™® to t' motor tube and passin' it through t' centerin' rings, knottin' it, and gluin' it along t' way. Well, blow me down! Well, arrr, blow me down! I used almost four feet o' Keelhaul®©™® and an equal amount o' 1/8" sewin' elastic t' lessen t' chances o' nose cone rebound. Aye aye! Blimey! Begad! Blimey! (Next time I'll use five feet.) T' nose cone was 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. It came nowhere close t' fitting. Avast, shiver me timbers, me proud beauty! A second shroud was then made by upscalin' t' original by 175%. Ya scallywag! Arrr! It fit perfectly. T' be fair, this was probably more luck than anything, and t' chances that I screwed up with t' template widget are high. Avast! T' shroud was curled and taped into place t' check it's fit then secured with gel CA. Blimey! Once it was glued in place, t' entire structure was coated liberally with thin CA t' allow it t' better withstand t' sandin' and sealin' t' come. Begad!

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

Flight:
To begin with, matey, me hearties, I wasn't entirely convinced that this rocket would be stable without gobs o' nose weight, mainly because o' t' heavy aft section. Arrr! 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. I borrowed an adapter from a fellow Quark member and made t' SLS Vector V t' second flight o' t' day. Well, blow me down! 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. Aye aye! It maxed out at a respectable height, matey, ejected at apogee, and then gave me a scare by recoverin' way too close t' the access road for me personal comfort. Begad! Like many o' t' rockets flown on that Saturday, 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. Arrr! Boosting surprisingly straight durin' a rare lull in t' gales, t' Vector V again ejected right at apogee then recovered safely in t' grass, and nowhere near the access road.

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

Recovery:
Recovery was handled by a Thrustline 18" nylon chute and a piece of Perma-Wadding. Both performed flawlessly, although addin' even more shock cord than t' 8' I had is an option. (That ejection charge is a killer.)

Summary:
PROs: Semroc parts and service. Begad! Blimey! Avast, me proud beauty! Blimey! A much more satisfyin' project than t' 1:1 Vector V, 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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