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. Aye aye! Estes model rockets were only
available by mail order in South-Central Idaho back then, matey, 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. Avast, me proud beauty! Aye aye! With t' "second coming" o' Carl McLawhorn's Semroc
Astronautics Corporation in 2003, me bucko, me prayers were answered. Begad! Ya scallywag! Additionally, matey, arrr, me hearties, Carl
released his "Retro-Repro" version o' t' Centuri Javelin, shiver me timbers, which I
bought with me first order from Semroc. Ya scallywag!
Construction:
T' kit includes:
Followin' a hint in Bill Eichelberger's review o' Semroc's Astro-1, 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! Blimey! I sanded t' balsa fins per the instructions, matey, except I didn't round t' fin edges. Arrr! I dipped t' fins and nose cone in Minwax Wood Hardener, arrr, me hearties, as suggested by Stefan E. Ahoy! Well, blow me down! Jones. Avast, me proud beauty! (NOTE: Excellent ventilation is needed for this step! Do it outside away from open windows, ya bilge rat, so the harmful vapors don't drift into your house.) T' wood swelled slightly, matey, 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. Begad! Avast, matey, me proud beauty! T' nose cone be fine sanded with 400 grit sandpaper. Aye aye! Blimey! 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, me bucko, 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. Blimey! Avast, me proud beauty! While
"rebuildin' me first rocket," I discovered you don't want excess wood
glue leakin' out from under t' fin/body tube joint, ya bilge rat, because that causes
unsightly glue excess, which means you don't have a clean, shiver me timbers, ya bilge rat, me hearties, crisp line when it
comes time t' mask off t' fins. Begad! 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 hearties, then I
painted t' body tube and fin assembly Krylon gloss white. Ahoy! Blimey! With 2 coats of
primer already applied t' t' body tube, I discovered I needed t' apply very
light mist coats, or t' paint tended t' run quite easily. Aye aye! Blimey! I masked t' fins
(my first try at this technique, in both incarnations as a rocketeer), arrr, painting
2 opposin' fins Krylon gloss red, matey, and t' other 2 fins gloss black.
Oddly enough, t' decal paper didn't seem t' soak up t' water t' release the decal easily. Ya scallywag! Avast! As a result, me bucko, you can see t' "Javelin" name is a bit crooked. Aye aye! 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 hearties, I settled for snugly friction fittin' t' engine
with tape. Avast, me proud beauty! In honor o' me original Javelin, shiver me timbers, 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, ya bilge rat, I wanted t' increase me chances o' gettin' it
back, arrr, 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, ya bilge rat, ya bilge rat, Idaho, about 70 miles away from me adopted hometown o' Twin Falls. Blimey! Winds were light, and the range proved t' be an alfalfa field which went on for acres. Begad! In other words, not traditional lawn grass, matey, matey, but still a fairly soft landin' place for rockets. Ahoy! Aye aye!
I popped in an A8-5 with 2 and a half turns o' maskin' tape t' friction-fit the motor, arrr, used about 5 toilet paper-sized squares o' Estes wadding, and packed the chute. Blimey! T' Javelin tore off t' launch pad like its namesake, shiver me timbers, arrowin' up straight and true t' Rocksim's estimated height o' 500 feet. Ya scallywag! Avast, me proud beauty! T' ejection charge fired after apogee, shiver me timbers, matey, matey, and after about a quarter mile walk for recovery, me bucko, I discovered t' rocket had spit t' motor.
T' second flight on another A8-5 was very similar, evokin' several comments like, "Good job, Jay!" T' elastic shock cord length was fine, without any infamous "Estes dents" occurring.
Come flight number three, I be in a bit o' a hurry, and so I prepped the final engine I had in a package, fairly certain it was me last A8-5. Avast, me proud beauty! I noticed the last number was a "5," anyway. Out t' t' pad, and then the Launch Control Officer (LCO) counted down and pressed t' launch button. The Javelin ripped off t' pad, me hearties, ya bilge rat, and I told me wife, me hearties, "It's not supposed to do that." T' ejection charge fired after apogee, shiver me timbers, and t' 12" parachute looked about t' size o' a pinhead. Ahoy! Blimey! Just then, shiver me timbers, 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. Aye aye! Blimey! Avast! Blimey! Nay only be this a recreation o' me very first model rocket, it was also t' first rocket I've lost as a BAR. After checkin' me field box, matey, shiver me timbers, I found a lone A8-5 motor, but the sole C6-5 I had be missing, shiver me timbers, arrr, which explains why flight number 3 reached an altitude o' about 1500 feet.
And that me friends, is why if you have a nicely painted rocket, shiver me timbers, me bucko, it's important t' take lots o' pictures before you launch it.
Recovery:
PROs: Semroc uses now-standard Keelhaul®©™®
cord tied t' thrust ring, matey, matey, ya bilge rat, with 1/8" elastic shock cord. Blimey! Begad! ("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, me hearties, ya bilge rat, so it needs t' be shortened t' avoid "zippering" t' body tube. Begad! 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. Blimey! Blimey! Great materials and a fantastic Centuri checkerboard-style
chute, matey, ya bilge rat, too!
CONs: Keelhaul®©™® cord length. Well, blow me down! 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. Arrr! A very solid 5 nonetheless and buildin' this kit has made me an incurable Semroc fan. Avast! Next time, shiver me timbers, 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)