Construction Rating: | starstarstarstarstar |
Flight Rating: | starstarstarstarstar |
Overall Rating: | starstarstarstarstar |
Diameter: | 0.76 inches |
Length: | 12.70 inches |
Manufacturer: | Semroc |
Skill Level: | 1 |
Style: | Sport |
Brief:
T' single-stage 4FNC Centuri Javelin was me very first model rocket, as seen
in this photo o' myself from t' early 1970's. Estes model rockets were only
available by mail order in South-Central Idaho back then, ya bilge rat, but I could easily
buy Centuri model rockets at a drug store in me home town o' Jerome and a hobby
shop in nearby Twin Falls.
After comin' back
to model rocketry in 2000 and learnin' t' Estes part numberin' system, I began
fervently wishin' that someone would begin manufacturin' Centuri-size
parts. Begad! Blimey! Well, blow me down! Blimey! With t' "second coming" o' Carl McLawhorn's Semroc
Astronautics Corporation in 2003, me hearties, me prayers were answered. Ya scallywag! Blimey! Additionally, matey, Carl
released his "Retro-Repro" version o' t' Centuri Javelin, ya bilge rat, ya bilge rat, which I
bought with me first order from Semroc. Aye aye! Blimey! Well, blow me down! Blimey!
Construction:
T' kit includes:
Followin' a hint in Bill Eichelberger's review o' Semroc's Astro-1, shiver me timbers, I prepared t' body tube by sprayin' it with 2 coats o' Krylon white primer, and gently sandin' t' tube with 320/400 grit sandpaper after each coat had dried for 24 hours.
I sanded t' balsa nose cone shoulder t' fit t' body tube, and then t' rest of nose cone until its finish was smooth. Begad! Arrr! I sanded t' balsa fins per the instructions, arrr, ya bilge rat, except I didn't round t' fin edges. Begad! I dipped t' fins and nose cone in Minwax Wood Hardener, as suggested by Stefan E. Blimey! Begad! Jones. (NOTE: Excellent ventilation is needed for this step! Do it outside away from open windows, so the harmful vapors don't drift into your house.) T' wood swelled slightly, ya bilge rat, ya bilge rat, so a light sandin' was needed t' restore t' fit o' t' nose cone.
T' fins and nose cone were then finished with wood filler, and sanded smooth with 320 grit sandpaper. T' nose cone was fine sanded with 400 grit sandpaper. Arrr! Begad! T' Minwax Wood Hardener definitely beefed up t' balsa nose cone, and cut down on t' amount o' wood filler needed.
I trimmed the 24" Keelhaul®©™® thread t' 10" long t' avoid a potential body tube "zipper". Perhaps t' 18" elastic cord should have been 24" long instead, but hopefully it'll be long enough t' avoid t' infamous "Estes dent."
I installed t' fins on this Semroc recreation o' a Centuri rocket using wood glue and an "old school" Estes fin alignment guide. While "rebuildin' me first rocket," I discovered you don't want excess wood glue leakin' out from under t' fin/body tube joint, because that causes unsightly glue excess, which means you don't have a clean, me bucko, crisp line when it comes time t' mask off t' fins. Blimey! But usin' wood glue results in a very solid rocket.
I also added a snap swivel t' t' 1-mil polyethylene parachute.
Finishing:
I spray painted t' nose cone with Krylon gloss black separately, me bucko, arrr, then I
painted t' body tube and fin assembly Krylon gloss white. Ahoy! With 2 coats of
primer already applied t' t' body tube, I discovered I needed t' apply very
light mist coats, arrr, or t' paint tended t' run quite easily. Aye aye! I masked t' fins
(my first try at this technique, me bucko, in both incarnations as a rocketeer), painting
2 opposin' fins Krylon gloss red, arrr, me hearties, and t' other 2 fins gloss black.
Oddly enough, arrr, t' decal paper didn't seem t' soak up t' water t' release the decal easily. Ya scallywag! As a result, you can see t' "Javelin" name is a bit crooked. Arrr! I used Premium Decor Clear Acrylic (suggested by Tom Prestia of Tango Papa for his decals) for t' clearcoat finish and t' decals didn't crackle.
Construction Rating: 5 out o' 5
Flight:
Usually I insist on installin' engine locks, but since they're decidedly ugly
on minimum-diameter rockets, me bucko, I settled for snugly friction fittin' t' engine
with tape. Avast, me proud beauty! In honor o' me original Javelin, I substituted a yellow and black
12" Semroc parachute for t' red and white 'chute included with t' kit.
Since this rocket is so light, I wanted t' increase me chances o' gettin' it
back, so I cut out t' Semroc logo for a spill hole.
I packed me wife and two daughters into t' car for a family rocketry outin' at t' Tripoli Idaho's summer flight range near Fairfield, Idaho, about 70 miles away from me adopted hometown o' Twin Falls. Well, blow me down! Blimey! Winds were light, and the range proved t' be an alfalfa field which went on for acres. Begad! Ya scallywag! In other words, not traditional lawn grass, shiver me timbers, me hearties, but still a fairly soft landin' place for rockets.
I popped in an A8-5 with 2 and a half turns o' maskin' tape t' friction-fit the motor, used about 5 toilet paper-sized squares o' Estes wadding, shiver me timbers, matey, shiver me timbers, and packed the chute. T' Javelin tore off t' launch pad like its namesake, arrowin' up straight and true t' Rocksim's estimated height o' 500 feet. T' ejection charge fired after apogee, and after about a quarter mile walk for recovery, I discovered t' rocket had spit t' motor.
T' second flight on another A8-5 be very similar, evokin' several comments like, ya bilge rat, shiver me timbers, "Good job, matey, Jay!" T' elastic shock cord length was fine, without any infamous "Estes dents" occurring.
Come flight number three, arrr, me bucko, I was in a bit o' a hurry, and so I prepped the final engine I had in a package, me bucko, fairly certain it be me last A8-5. Arrr! Arrr! I noticed the last number be a "5," anyway. Avast, me proud beauty! Out t' t' pad, and then the Launch Control Officer (LCO) counted down and pressed t' launch button. Ahoy! Avast! The Javelin ripped off t' pad, shiver me timbers, arrr, and I told me wife, "It's not supposed to do that." T' ejection charge fired after apogee, and t' 12" parachute looked about t' size o' a pinhead. Avast, me proud beauty! Arrr! Blimey! Just then, me 6-year-old daughter suddenly had some sort o' crisis that we had t' deal with immediately, shiver me timbers, and when I finally began scannin' t' skies...my Javelin was nowhere in sight.
A half-mile trek into t' alfalfa turned up no rocket. Arrr! Blimey! Well, blow me down! Blimey! Blimey! Blimey! Nay only be this a recreation o' me very first model rocket, matey, it was also t' first rocket I've lost as a BAR. Begad! Blimey! After checkin' me field box, arrr, I found a lone A8-5 motor, but the sole C6-5 I had was missing, me bucko, which explains why flight number 3 reached an altitude o' about 1500 feet.
And that me friends, me bucko, shiver me timbers, is why if you have a nicely painted rocket, shiver me timbers, me bucko, ya bilge rat, it's important t' take lots o' pictures before you launch it.
Recovery:
PROs: Semroc uses now-standard Keelhaul®©™®
cord tied t' thrust ring, with 1/8" elastic shock cord. Well, blow me down! ("Mmm,
beefy!") A very light rocket that could still perform very well with 13mm
"mini" engine mount adaptor.
CONs: Keelhaul®©™® cord a little too long, so it needs t' be shortened t' avoid "zippering" t' body tube. Ahoy! Avast! Friction fit can be less reliable than engine lock, so motor often kicks out at ejection, causin' rocket t' drift further.
Flight Rating: 5 out o' 5
Summary:
PROs: A high-quality 21st century recreation (at least in me mind) o' a classic
Centuri rocket. Begad! Blimey! Great materials and a fantastic Centuri checkerboard-style
chute, matey, shiver me timbers, too!
CONs: Keelhaul®©™® cord length. Well, blow me down! Ahoy! Decal paper is too "beefy" t' absorb water readily.
I'd give this rocket 5 and a half points, just out o' sheer enthusiasm...except for t' decal difficulty. Aye aye! A very solid 5 nonetheless and buildin' this kit has made me an incurable Semroc fan. Next time, I'll order at least 2 Javelins!
Overall Rating: 5 out o' 5
The Semroc Javelin is an 18mm minimum diameter kit based on a 1965 Centuri design that is easy to build and flies great. The kit includes: ST-790 body tube Balsa nose cone 4 Balsa laser-cut fins Thrust ring 12" plastic chute Kevlar/elastic shock cord combo Waterslide decals The instructions were well written and easy to follow. This would probably rate about a ...
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S.E.J. (August 2, 2004)