(Contributed - by Mike Mistele - 05/01/04)
This is a very basic 4FNC, minimum-diameter, streamer-recovery rocket suitable
for beginners. It's part of Semroc's RetroRepro line and, specifically, the
Micron was originally a Centuri model (#KA-5) first released in 1963. The
RetroRepro line updates these old models with more current technology--in this
case, the upgrades include laser-cut fins and a Kevlar shock-cord.
This kit comes with the following components:
- Body Tube (ST-765)
- Balsa Nose Cone (BC-719)
- Laser-cut Fin Sheet (FV-8)
- Thrust Ring (TR-7)
- Launch Lug (LL-122)
- Screw Eye (SE-10)
- Elastic Cord (EC-118)
- Streamer (RS-36)
- Tape Disc (TD-1)
- Empty Casing (MC-727)
I ordered this kit directly from Semroc's web page. I had gone there to
order a couple Rocket Racks and figured I'd get a kit while I was at it.
The kit comes in a plastic hang-bag just like an Estes or Quest kit. The
"front" of the package, depicting the rocket is actually the front
cover of a 12-page booklet, which includes brief history of both the Micron
model and Centuri Engineering Company, the assembly instructions, an exploded
view of the components, and the NAR safety code.
The instructions were extremely easy to follow, and I saw no need to
deviate from them as I assembled my model.
The parts themselves were generally of very high quality. In particular,
the balsa fin sheet was among the nicest bits of balsa I've ever gotten in a
kit and the laser-cutting was very smooth.
The balsa nose cone was also a nice piece of wood but the shoulder was a
bit too wide for the body tube. A bit of sanding fixed that problem right up
About the only part I would have any complaint with at all was the
streamer--it's a length of orange crepe paper. I'm not sure how long it'll last
(it already has a tear from her first flight), so I'll likely need to replace
it at some point with something a bit more durable.
The illustration of the Micron on the front of the booklet has a fun, early
60's sounding rocket look to it. Unfortunately, the kit doesn't contain any
decals, and it'd be a challenge for a beginning rocketeer to duplicate that
look with paint alone, which includes a roll pattern. As I didn't want to work
that hard, I decided to not recreate that look.
I used Elmer's Fill & Finish to smooth out the nosecone and fins,
followed by a few coats of Krylon grey primer.
For the final finish, I applied a few coats of Testor's Chrome spray paint,
then used Testor's Purple Metalflake spray paint for a "fade" pattern
on the nosecone and top of the rocket.
Once the paint was dry, I put an American flag decal on the body tube (I
got a sheet of flag decals by AutoGraphics at the hobby shop, and put one on
each of my rockets), then finished with a coat of Krylon gloss.
½ out of 5
For the Micron's first flight, I used an Estes A8-3. The delay is a bit shorter
than recommended, but I didn't have any A8-5s handy. The motor is a
friction-fit and one wrap of masking tape around the motor was sufficient to
keep it snug.
The instructions don't recommend a specific amount of recovery wadding; I
used 3 sheets of Estes wadding, and found that the body tube with the wadding,
the shock cord, the streamer, and the nose cone was pretty tightly packed.
Maybe 2 sheets or a little dog-barf would be better.
She took off from the pad very quickly, as you'd expect given the light
weight, and the flight was straight as an arrow. The ejection charge fired a
bit before apogee, though that didn't surprise me, given I was technically not
using the recommended motor.
The Micron uses a combination Kevlar-elastic
shock cord system. The Kevlar
cord is tied around the thrust ring, and extends well beyond the end of the
body tube. The elastic shock cord is then tied to the Kevlar
cord at one end and to the nose cone at the other end.
As I noted above, the streamer is just a length of crepe paper--probably
historically accurate, but it feels a bit flimsy. The streamer is attached to
the elastic shock cord, near the nose cone with a tape disc.
On the first flight, everything deployed nicely, and the streamer fully
unrolled. It seemed like it was coming down a little fast, but drifted only
about 50 yards downwind from the launch pad. Despite the seemingly-quick
descent, she landed with no damage at all.
However, as I was rolling the streamer back up to put the rocket away, I
noticed a long tear in the center of the streamer. It will have to be replaced
at some point.
out of 5
PROs: easy assembly, clear instructions, teaches some basic assembly skills,
CONs: streamer material is cheap, hard to re-create the finish as pictured
½ out of 5
(Contributed - by Chan Stevens - 10/18/04)
Nice little minimum diameter rocket that zips off the pad in a hurry and at $4
retail, makes for a nice little kit for that Cub Scout or school group. This is
also an appealing kit to the nostalgia buff that is based on the 1963 Centuri
kit by the same name.
As is the case with almost every Semroc kit, this one came in a professionally
bagged package along with a certificate of authenticity/production number.
- ST-765 body tube
- Balsa nose cone/screw eye
- 4 laser cut balsa fins
- Thrust ring
- Streamer (crepe paper)
shock cord combo
With laser cut fins, this is definitely somewhere just below a skill level 2
kit. The only challenge is to mask a 2 or 3 color paint scheme.
The instructions were well written and clear; offering some decent
construction tips along the way, such as how to fill grain on the balsa fins.
Being a minimum diameter kit, the body tube acts as a motor tube, so simply
gluing a thrust ring into one end takes care of the motor mount assembly aspect
of the build. Before doing this though, you tie one end of the Kevlar
shock cord to the ring, thereby anchoring it to the thrust ring inside the body
tube. This is a very good and effective technique, one that I wish was more
common in the lower skill level kit range.
Next, sanding the fins, which is easier to do this while still in the balsa
sheet, and removing them from the laser-cut sheet. The instructions call for
bonding them flush with the aft end of the tube, although I'd consider sliding
them forward about 1/8". This won't throw the CP off that much and enables
you to use a band of tape around the motor and body tube for improved motor
Tack on the launch lug, glue the screw eye into the balsa nose cone, and
you're ready for recovery and paint prep.
The streamer for this kit isn't too bad, it is a piece of bright orange
crepe paper roughly 3" x 36", but it's attached using a fairly weak
line and is secured by a single tape disk attached to the center. I don't think
this is likely to hold up very well over repeat flights and would have
preferred to see a chute instead.
I skipped the balsa sealing/filling routine on this one, jumping straight to
primer. Two coats of primer and sanding in between with a 220 grit sponge did a
reasonably good job on the balsa grain, so I moved on to two coats of Krylon
gloss white. I finished up with a blue nose and red fins, matching the
illustration on the package header. The header also depicts some blue accent
stripes (roll pattern), which is possible to paint but would clearly be better
(and easier) if a waterslide decal were supplied for this. I guess for $4 I
shouldn't complain but I'd rather pay $6 and have a decent decal or two.
out of 5
The maiden flight was on a beautiful fall day with low winds, though there was
some cloud cover way up above our club's ceiling. I went with a B6-4, as
I did not have any B6-6s handy. Before I could even blink, this was pushed
almost beyond my sight, well over 800 feet. Apogee might have been a little
early, but not enough early to worry about.
The streamer deployed fine, but it didn't offer much drag for this rocket
and it came down fairly fast. Fortunately, it landed in a large, soft grassy
area undamaged. Still, given the descent rate and weak attachment point, I will
be replacing the streamer with one of my spare chutes just to avoid any
potential damage on the recovery.
combination is a solid, durable method.
CONs: undersized streamer, weak attachment disk/line.
out of 5
This was a terrific value at $4 retail and I'd recommend buying this for a
group build-fly session in the future.
out of 5