Brief:
The single-stage 4FNC Centuri Javelin was my very first model rocket, as seen in this photo of myself from the early 1970's. Estes model rockets were only available by mail order in South-Central Idaho back then, but I could easily buy Centuri model rockets at a drug store in my home town of Jerome and a hobby shop in nearby Twin Falls.

After coming back to model rocketry in 2000 and learning the Estes part numbering system, I began fervently wishing that someone would begin manufacturing Centuri-size parts. With the "second coming" of Carl McLawhorn's Semroc Astronautics Corporation in 2003, my prayers were answered. Additionally, Carl released his "Retro-Repro" version of the Centuri Javelin, which I bought with my first order from Semroc.

Construction:
The kit includes:

• Body Tube ST-790
• Balsa Nose Cone BC-735
• Laser Cut Fins FV-16
• Thrust Ring TR-7
• Launch Lug LL-122
• Screw Eye SE-10
• Elastic Cord EC-118
• Kevlar® Thread SCK-24
• Plastic Parachute RC-12
• Tape Discs TD-6
• Shroud Line SLT-6
• Decal DKV-16
• Empty Casing MC-727
• Snap swivel (not included)

Following a hint in Bill Eichelberger's review of Semroc's Astro-1, I prepared the body tube by spraying it with 2 coats of Krylon white primer, and gently sanding the tube with 320/400 grit sandpaper after each coat had dried for 24 hours.

I sanded the balsa nose cone shoulder to fit the body tube, and then the rest of nose cone until its finish was smooth. I sanded the balsa fins per the instructions, except I didn't round the fin edges. I dipped the fins and nose cone in Minwax Wood Hardener, as suggested by Stefan E. 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.) The wood swelled slightly, so a light sanding was needed to restore the fit of the nose cone.

The fins and nose cone were then finished with wood filler, and sanded smooth with 320 grit sandpaper. The nose cone was fine sanded with 400 grit sandpaper. The Minwax Wood Hardener definitely beefed up the balsa nose cone, and cut down on the amount of wood filler needed.

I trimmed the 24" Kevlar® thread to 10" long to avoid a potential body tube "zipper". Perhaps the 18" elastic cord should have been 24" long instead, but hopefully it'll be long enough to avoid the infamous "Estes dent."

I installed the fins on this Semroc recreation of a Centuri rocket using wood glue and an "old school" Estes fin alignment guide. While "rebuilding my first rocket," I discovered you don't want excess wood glue leaking out from under the fin/body tube joint, because that causes unsightly glue excess, which means you don't have a clean, crisp line when it comes time to mask off the fins. But using wood glue results in a very solid rocket.

I also added a snap swivel to the 1-mil polyethylene parachute.

Finishing:
I spray painted the nose cone with Krylon gloss black separately, then I painted the body tube and fin assembly Krylon gloss white. With 2 coats of primer already applied to the body tube, I discovered I needed to apply very light mist coats, or the paint tended to run quite easily. I masked the fins (my first try at this technique, in both incarnations as a rocketeer), painting 2 opposing fins Krylon gloss red, and the other 2 fins gloss black.

Oddly enough, the decal paper didn't seem to soak up the water to release the decal easily. As a result, you can see the "Javelin" name is a bit crooked. I used Premium Decor Clear Acrylic (suggested by Tom Prestia of Tango Papa for his decals) for the clearcoat finish and the decals didn't crackle.

Construction Rating: 5 out of 5

Flight:
Usually I insist on installing engine locks, but since they're decidedly ugly on minimum-diameter rockets, I settled for snugly friction fitting the engine with tape. In honor of my original Javelin, I substituted a yellow and black 12" Semroc parachute for the red and white 'chute included with the kit. Since this rocket is so light, I wanted to increase my chances of getting it back, so I cut out the Semroc logo for a spill hole.

I packed my wife and two daughters into the car for a family rocketry outing at the Tripoli Idaho's summer flight range near Fairfield, Idaho, about 70 miles away from my adopted hometown of Twin Falls. Winds were light, and the range proved to be an alfalfa field which went on for acres. In other words, not traditional lawn grass, but still a fairly soft landing place for rockets.

I popped in an A8-5 with 2 and a half turns of masking tape to friction-fit the motor, used about 5 toilet paper-sized squares of Estes wadding, and packed the chute. The Javelin tore off the launch pad like its namesake, arrowing up straight and true to Rocksim's estimated height of 500 feet. The ejection charge fired after apogee, and after about a quarter mile walk for recovery, I discovered the rocket had spit the motor.

The second flight on another A8-5 was very similar, evoking several comments like, "Good job, Jay!" The elastic shock cord length was fine, without any infamous "Estes dents" occurring.

Come flight number three, I was in a bit of a hurry, and so I prepped the final engine I had in a package, fairly certain it was my last A8-5. I noticed the last number was a "5," anyway. Out to the pad, and then the Launch Control Officer (LCO) counted down and pressed the launch button. The Javelin ripped off the pad, and I told my wife, "It's not supposed to do that." The ejection charge fired after apogee, and the 12" parachute looked about the size of a pinhead. Just then, my 6-year-old daughter suddenly had some sort of crisis that we had to deal with immediately, and when I finally began scanning the skies...my Javelin was nowhere in sight.

A half-mile trek into the alfalfa turned up no rocket. Not only was this a recreation of my very first model rocket, it was also the first rocket I've lost as a BAR. After checking my field box, I found a lone A8-5 motor, but the sole C6-5 I had was missing, which explains why flight number 3 reached an altitude of about 1500 feet.

And that my friends, is why if you have a nicely painted rocket, it's important to take lots of pictures before you launch it.

Recovery:
PROs: Semroc uses now-standard Kevlar® cord tied to thrust ring, with 1/8" elastic shock cord. ("Mmm, beefy!") A very light rocket that could still perform very well with 13mm "mini" engine mount adaptor.

CONs: Kevlar® cord a little too long, so it needs to be shortened to avoid "zippering" the body tube. Friction fit can be less reliable than engine lock, so motor often kicks out at ejection, causing rocket to drift further.

Flight Rating: 5 out of 5

Summary:
PROs: A high-quality 21st century recreation (at least in my mind) of a classic Centuri rocket. Great materials and a fantastic Centuri checkerboard-style chute, too!

CONs: Kevlar® cord length. Decal paper is too "beefy" to absorb water readily.

I'd give this rocket 5 and a half points, just out of sheer enthusiasm...except for the decal difficulty. A very solid 5 nonetheless and building this kit has made me an incurable Semroc fan. Next time, I'll order at least 2 Javelins!

Overall Rating: 5 out of 5

Brief:
The Semroc Javelin is an 18mm minimum diameter kit based on a 1965 Centuri design that is easy to build and flies great.

Construction:
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 skill level 1 to 1.5 and was a quick build.

Construction starts by tying the Kevlar® shock cord to the thrust ring, which anchors it nicely. The thrust ring is then glued into the body tube.

The fins are laser cut and are attached based on a fin guide template at 90-degree orientation.

The balsa nose cone uses a screw eye for attaching the shock cord. My cone was slightly tight and needed a light sanding for proper fit.

The chute is a basic plastic cut-out chute, using tape disks to attach the shroud lines.

Finishing:
I painted following the stock color scheme, starting with a couple of coats of primer to fill most of the grain and spirals, followed by two coats of gloss white. I then painted the nose cone bright red, and the fins a nice yellow. There's also a pretty nice waterslide decal to top things off.

Construction Rating: 5 out of 5

Flight:
First flight went up on a B6-4. This rocket raced off the pad and went to the very limits of my middle-aged eyesight before deploying the chute. The recommended delay of 6 would have been much better as my 4 second delay was a bit early.

Second flight was on an A8-5, with perfect deployment.

Considering how high I went on a B, I'm waiting for perfect conditions to fly on a C (or else I'll swap out the chute for a streamer).

Recovery:
Excellent Kevlar®/elastic combo. The 12" chute is overkill though, resulting in long, slow decent. A streamer would work just fine on this lightweight rocket.

Flight Rating: 4 out of 5

Summary:
Excellent reproduction and a good value (the kit retails for $6, can usually be found around $5).

Overall Rating: 4 ½ out of 5