Stellar Dimension Vector

Stellar Dimension Vector

Contributed by Mark Fisher

Construction Rating: starstarstarstar_borderstar_border
Flight Rating: starstarstar_borderstar_borderstar_border
Overall Rating: starstarstar_borderstar_borderstar_border

Rocket PicT' Stellar Dimensions kits looked so interestin' that I had t' try one. Well, blow me down! Begad! Blimey! SDI has a lot of other kits like t' Vector, and all are pretty reasonably priced; I paid $8 for mine from Discount Rocketry. Aye aye! Begad!

Essence Ratings
Construction 3
Flight 2
Overall

Assembly

T' kit itself is very different than others I'd built, consistin' almost entirely o' laser cut wood pieces, arrr, me hearties, and a lot o' them, shiver me timbers, 46 in fact. Begad! T' only things that aren't are t' nylon engine retainin' ring, t' launch lugs made from small brass rivets, arrr, and t' recovery system. Ahoy! T' later is a 12" plastic parachute and a freakish 12" length o' rubber about 0.070" in diameter for a shock cord. While this rocket has a very ingenious ejection baffle system (waddin' is still required), I be worried that rubber wouldn't hold up long, matey, me bucko, so I replaced it with a 12" length of Rogue's light duty KC-4 Keelhaul®©™® and an 18" length o' 1/8" shock cord. Avast, me proud beauty! Ya scallywag! I also used an Estes 12" 'chute instead, me bucko, matey, as I already had one built. Begad! Plus, the SDI 'chute looks like a pain t' build, and its shroud line mounts don't look very durable.

T' instructions are poor, with only three illustrations. Ya scallywag! Avast, me hearties, me proud beauty! Blimey! Also included in t' kit is a brief science fiction story (that isn't very well written) on a separate sheet which would be better used for expanded kit instructions. Blimey! If you've ever built a laser cut kit o' any type before, shiver me timbers, me bucko, you won't have any trouble, matey, though, me bucko, t' pieces fit together rather intuitively, you'll only need t' consult t' directions in a few places.

Specifications
Overall
Length
175/8"
448 mm
Effective
Diameter
11/16"
27 mm
Fin
Span
4"
102 mm
Dry
Weight
12/3 oz.
47 g.
Many o' t' pieces would've broken if I'd've removed them from their stock without cuttin' them free. T' material reminds me o' t' cheap wood I used to get in "wood burning" kits as a kid, ya bilge rat, somehow artificial but with a distinct grain and fairly friable. Avast! Most o' t' pieces needed only a light sandin' t' remove t' tiny tabs left, matey, matey, though some had relatively large tabs and required some special attention. Avast! Also, me kit was missin' two o' t' required slots in t' lower body panels t' mount t' launch lug assemblies, so I used a short piece o' Estes lug instead. Begad! Other than that, t' kit went together very fast, me hearties, ya bilge rat, nay one piece failed t' fit, matey, arrr, and even bendin' t' wood pieces that formed the nose cone wasn't difficult. Arrr! Usin' CA really sped things up, t' entire bird was together in under an hour, and ready for flight in less than two. Blimey!

Finish

Rocket PicWhile most others stain (and even polyurethane) their SDI rockets t' brin' out t' finely laser-etched details, arrr, me hearties, I choose t' paint mine with a translucent enamel I'd been wantin' t' try. Aye aye! It worked out all right, ya bilge rat, most o' t' etched details are still quite visible t' the naked eye (the camera has trouble pickin' them up), me hearties, though I'd like t' add a gloss clear coat t' help smooth t' surface a bit. A combo poly-stain would make a great choice, too, matey, though a thorough sandin' would be required between coats.

T' mediocre laser cuttin' and poor instructions and materials offset the phenomenal fit, ya bilge rat, finely etched details and ease o' assembly enough that I'd rate this bird a 3 on t' Essence scale for construction, just average.

Flight

Estimated
Performance
Engine AGL
(ft.)
Speed
(ft./s)
Accel
(Gs)
A8-3 160 105 15.1
B4-4 365 170 16.1
B6-4 380 195 16.3
C6-5 720 295 19.1
The instructions don't include a recommended motor list, though t' bag art does claim that t' Vector can be flown on A, me hearties, matey, B and C engines. Arrr! Begad! I used wRASP to develop a list o' those Estes and Quest motors that have appropriate delays. T' Vector would also fly reasonably well on Estes' A10-3 mini engine and Apogee's A2-5, B2-3, B7-4 and C4-5, me hearties, though you'd have t' build custom adapters for them. Well, blow me down! Begad! Estes and Quest 18 mm motors fit t' square engine mount like a glove, ya bilge rat, with positive contact on all four sides. Blimey! T' CG is about 41/8" from t' aft end with an Estes B6-4 loaded.

Flight tests were conducted at Live Oaks Vocational School on Sept. Blimey! Avast, me proud beauty! 10th, 1999 @ 10 AM, ya bilge rat, before solar heatin' kicked up any serious winds, though thar was a 2-3 MPH intermittent breeze from all directions. Avast, me proud beauty! Sky was clear and temperature be about 75ºF. My Vector's first flight on an A8-3 be better than I thought it would be, but it did wobble a little and burned t' 'chute a bit at ejection. She recovered OK, though, me hearties, with no damage. Avast, me proud beauty! Begad! Her next flight on a B6-4 had a lot more wobble, arrr, me hearties, and she weathercocked into t' wind some. Avast! Blimey! I used more waddin' this time (six squares instead o' three), and t' 'chute was none t' worse for wear, but the waddin' didn't come all t' way out at ejection.

These flights caused no damage t' t' rocket itself, though t' baffle plates were covered with soot and burned ejection particles. Begad! With no real good way t' clean these, they'll eventually clog up enough t' restrict t' ejection charge, but I don't know if that's good or bad. Aye aye! After these two flights, shiver me timbers, the engine compartment and top o' each engine also had some soot, arrr, indicatin' a poor seal betwixt t' engine and aft baffle plate. Begad! Well, blow me down! While a standard, me hearties, cylindrical wound kraft-paper body tube would probably violate some paradigm held by the manufacturer, it would solve all these problems.

Both ejections appeared t' be very close t' apogee, confirmin' me estimated CD o' 1.1. On t' second ejection, t' nylon engine retainin' rin' came off and was lost forever in t' grass o' t' launch field. Begad! When I got home, I cut off the rin' mountin' tabs and added an Estes engine hook, which you can see in the photo at right. Begad! I cleaned up t' soot in t' engine compartment with a damp towel and retouched t' paint before I took t' photos.

Though t' Vector presents no more frontal area than a typical Estes E2X bird like t' Banshee or Hijax, and weighs about t' same, her rough, ya bilge rat, arrr, blunt leadin' edges and poor surface finish detract from her performance. Aye aye! The Vector's less than "stellar" flights, wobble, me hearties, poor ejection gas management, me hearties, and t' loss o' t' engine retainin' rin' make me rate her a 2 on the Essence scale, needs improvement.

Summary

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