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

Contributed by Peter Davidson

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

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 put together with no "gotchas" and such. The components are top quality and the instructions come in the form of a detailed booklet in color. These instructions were very well written and easy enough for even the most inexperienced novice to understand well.

The motor assembly is constructed by inserting the motor hook into the pre-cut slot in the motor tube. After gluing in the thrust ring, the two cardstock centering rings are then glued into place. I then used white glue to add fillets around the edges of the centering rings where they slide over the motor tube. Once that is done, the completed motor assembly is glued into place in the body tube. Although I had my reservations about Semroc's recommendation to loop and tie off the Kevlar® cord to the motor hook, I nonetheless went ahead and did that anyway. Time will tell if the Kevlar® will hold up under such an arrangement.

Fin marking is provided by a fin guide in the instructions consisting of a circle with hash marks by which the end of the body tube is placed on the circle and the hash marks used as a guide for fin position markings. I had no problems using this although personally I would have preferred to use a wraparound fin marking guide. I then tacked the fins on with medium CA and followed this up with white glue for multiple fin fillets. Following on from this, the launch lug was added.

With the exception of using CA to tack on the fins, I used Selleys PVA (white glue) throughout the construction process.

Finishing:
This rocket was a cinch to finish. I filled in the balsa fin grain and the lovely balsa nose cone with two applications of Micro-Fill model sealer and after having initially slightly roughened up the body tube with 360 grit sandpaper, I gave the rocket two coats of Tamiya Fine White primer with light sanding in between and followed this up with two coats of Tamiya Pure White enamel gloss for the upper body tube, Black gloss for the nose cone and Italian Red gloss for the lower body tube and fins. I opted not to use a clear coat finishing paint to try keeping down the rocket's weight.

After having allowed the paint to cure for a full week, the striped roll waterslide decals were then carefully applied. I found these to be quite durable and easy to apply.

Construction Rating: 4 out of 5

Semroc Astrobee 350

Flight:
Motor retention is by use of a short and springy motor hook which has shown itself to be quite durable.

The first flight was with an A8-5 motor with three squares of recovery wadding due to the small field that I was launching from. The rocket immediately went unstable upon launch and cartwheeled back down to the ground where ejection subsequently happened although there was no damage. Not to be deterred, I loaded up with another A8-5 and this time the flight was perfect with a lovely straight boost to around 270-280 feet.

Since then I have only used the A8-5 motor as the B6-6 and C6-7 motors could quite easily make for an out of sight flight!

Recovery:
The Kevlar®/elastic recovery system has proven to be very reliable and has held up to repeated flights without problems. The Semroc-supplied 12" plastic parachute is of excellent quality and has also proved to be very durable. I also applied thin CA to the top of the body tube before painting so as to lessen the chances of the Kevlar® causing any denting during recovery.

Flight Rating: 5 out of 5

Summary:
This is an excellent skill level one rocket for a rocketry novice. The excellent Semroc components ensure that a novice will be able to put together a nicely detailed scale rocket that should prove to very durable and robust with the potential for hours of fun.

Overall Rating: 5 out of 5

Other Reviews
  • Semroc - Astrobee 350 {Kit} (KV-13) By Chan Stevens

    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 ...

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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