Semroc - Astrobee 350 {Kit} (KV-13)

Contributed by Chan Stevens

Construction Rating: starstarstarstarstar_border
Flight Rating: starstarstarstar_borderstar_border
Overall Rating: starstarstarstarstar_border
Diameter: 1.04 inches
Length: 16.20 inches
Manufacturer: Semroc
Skill Level: 1
Style: Scale
Semroc Astrobee 350

Brief:
Another Semroc retro-repro kit, the Semroc Astrobee 350 is a modernized version of the Centuri 1965 kit that also is a quick, easy scale project.

Construction:
The kit includes:

  • ST-1010 body tube
  • Balsa nose cone
  • 18mm x 2.75 motor tube pack
  • 4 Laser-cut balsa fins
  • 12" plastic chute
  • Waterslide decal

Parts are excellent quality, and come in a sealed plastic bag complete with individual production number.

Semroc instructions are clear and easy to follow. This kit begins with basic motor mount assembly consisting of 2 centering rings, an 18mm tube, motor block, and metal retaining hook. A nice upgrade to the Centuri kit is the Kevlar® cord mounted to the motor mount with an elastic extension. The instructions call for tying a loop and placing the metal hook through the loop, which struck me as a potential weakness, so I wrapped mine around the tube instead and brought it out under the centering ring.

Fin prep is very easy with these kits as they're pre-cut using a laser. The fins are mounted on 90-degree angles around the tube. The instructions include a basic circle with hashmarks for a marking guide, which is quicker than cutting out a template but easier to goof up on. I tacked on my fins with a medium CA, then applied fillets using yellow glue.

This kit included a very nice balsa nose cone, which is secured via a good old-fashioned screw eye. My cone was a bit tight in the tube and took just a little bit of sanding for proper fit.

Construction wraps up with making the parachute, which is a basic plastic cutout with tape disks to attach the shroud lines.

I was in a bit of a hurry on this one (building a batch of 7 different Semroc kits at once), so skipped my usual spiral fill/grain fill application of Elmer's Fill 'n' Finish. This brought the total construction time down to about 30 minutes, at which point it was ready for paint.

Finishing:
I applied a couple of coats of primer, which did a reasonable job of filling the spirals once I sanded it back down a bit. After that, I followed up with two coats of Krylon gloss white. I then masked off the white (after allowing a couple of days to fully cure) and painted the fins red and the nose cone black per the standard paint scheme.

This kit comes with a very nice waterslide decal for a striped roll pattern at the top and a pair of thin stripes to trim the bottom. I found the decals very easy to work with and they add a nice accent.

Construction Rating: 4 out of 5

Flight:
First flight was on a beautiful day of light winds. I went with a C6-7, which should have carried it to an estimated 1250 feet. Unfortunately, once it left the rod, it went into a bizarre loop then straightened out and took off at about a 40 degree angle. This clearly indicated that the rocket was unstable with the weight of the C6, and as the propelant burned down (and the CG moved forward), it became more stable. With this flight path, ejection was 3-4 seconds late, though the model landed gently, and I avoided any damage (not even a zipper).

Second flight was on a B6-6, which flew straight up without any problems, though I think it was only around 500 feet versus the estimated 650 on the kit header card.

Recovery:
The Kevlar®/elastic recovery is an excellent combination, and this is exactly the way modrocs should come. The plastic chute worked fine though this rocket needs plenty of wadding or dog barf to hold up over repeated flights.

Flight Rating: 3 out of 5

Summary:
This is a fairly nice looking rocket that's very easy to build using excellent components. I would recommend a couple of washers for nose weight though, to take care of the stability problem using C motors.

Overall Rating: 4 out of 5

Other Reviews
  • Semroc - Astrobee 350 {Kit} (KV-13) By Peter Davidson

    Brief: A Semroc retro-repro version (KV-13)of Centuri's 1965 Astrobee 350 (KC-5)and incorporating updated technology like laser-cut fins and Kevlar ® -mounted shock cord. Construction: The parts list is covered in Chan's review so I won't elaborate here. This being my first Semroc build, I found the Astrobee 350 to be a nice and easy skill level one kit to p ...

Flights

Comments:

avatar
J.G. (October 22, 2004)
When I was examining the Astrobee 350 on the Semroc website, I was struck by the thought, "Those fins *don't* look big enough for that rocket!" I was intrigued to discover that it seemed to fly stably without any nose weight -- until a "C" motor was used. Even if this *is* an accurate "RetroRepro" of an original Centuri design, I can't seem to shake my initial impression regarding the apparently undersized fins.

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