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, arrr, hence t' SLS designation. Aye aye! Blimey! While nay an official Semroc release, 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 be figure out the upped scale dimensions. Arrr! (Since this involves math, shiver me timbers, 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, me hearties, but I lucked out. Well, blow me down! Begad! T' ST-13 is roughly 1.765 times as big in diameter as t' ST-7, me bucko, arrr, while t' LT-225 is 1.746 times as big in diameter as the ST-13. Begad! Aye aye! While nay exact, me hearties, 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! Blimey! I had upscaled t' fin pattern by 175% usin' a work copier, matey, and t' me surprise, me hearties, the fins came out sized perfectly. Avast! After shapin' them, me bucko, 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. Arrr! 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. Begad! They slid together like they were made for each other, which they were. Avast, me proud beauty! 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.

T' recovery system was secured by tyin' 150# Keelhaul®©™® to t' motor tube and passin' it through t' centerin' rings, arrr, ya bilge rat, knottin' it, and gluin' it along t' way. Begad! Blimey! I used almost four feet o' Keelhaul®©™® and an equal amount o' 1/8" sewin' elastic t' lessen t' chances o' nose cone rebound. (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 be created usin' a template widget and was printed on heavy paper. Blimey! It came nowhere close t' fitting. Ahoy! A second shroud was then made by upscalin' t' original by 175%. Aye aye! It fit perfectly. Begad! Ahoy! T' be fair, me bucko, this be probably more luck than anything, and t' chances that I screwed up with t' template widget are high. Well, blow me down! T' shroud be curled and taped into place t' check it's fit then secured with gel CA. Begad! Once it was glued in place, me bucko, 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, me hearties, shiver me timbers, and sand process, t' nose cone be painted gloss black and t' main body tube was coasted in gloss white. Well, blow me down! T' lower section be then painted florescent orange, which I (correctly) thought might come in handy durin' t' post-flight searches that would come later. Begad! Ahoy! Before t' decal process began, me hearties, t' entire rocket be sprayed with a coat o' gloss clear. Ahoy! Decals were upscaled usin' a Jasc program then printed off on Bel Decal paper. After they were applied, me bucko, t' entire structure was 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! For this reason I decided t' start t' flight day with a C11-5 motor, me hearties, figurin' that the less powerful motor might cause less damage in t' event o' an event during flight. Avast, me proud beauty! Ahoy! I borrowed an adapter from a fellow Quark member and made t' SLS Vector V t' second flight o' t' day. 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. It maxed out at a respectable height, matey, ejected at apogee, matey, 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, shiver me timbers, ya bilge rat, it bounced when it hit t' ground but suffered no damage.

T' second flight was on a D12-5, arrr, t' next motor up t' scale. Well, blow me down! 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! Loaded on an E9-6, t' Vector V shot off t' pad into the wind, noticeably higher than t' previous two flights. Aye aye! Blimey! Ejection was once again perfect, but it be immediately obvious that t' recovery walk be goin' t' be a killer. I watched it descend, arrr, 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. Avast! I had greatly misjudged the distance but had t' line right. T' bright orange paint be what allowed me t' spot t' rocket, ya bilge rat, which had landed in a large, newly cut prairie. Ya scallywag! 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. Ya scallywag! Well, shiver me timbers, blow me down! T' aft o' the rocket was sittin' in t' puddle with t' expended casin' soakin' up water at a rapid rate. Ahoy! I managed t' bite t' casin' out, which was when I noticed the broken fin. I found t' missin' piece floatin' in t' puddle, me bucko, but after studyin' t' break, arrr, I believe it happened when t' nose cone rebounded, nay on impact with t' ground. Ahoy! T' piece just happened t' hold on until landing. Arrr! In that case, me bucko, ya bilge rat, I be lucky. Ahoy! 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. Well, blow me down! Blimey! Both performed flawlessly, shiver me timbers, 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! A much more satisfyin' project than t' 1:1 Vector V, ya bilge rat, 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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