Construction Rating: | starstarstarstarstar_border |
Flight Rating: | starstarstarstarstar_border |
Overall Rating: | starstarstarstarstar_border |
Manufacturer: | U.S. Rockets |
Background:
Nick at EMRR sent me this kit when I became a Featured Reviewer for EMRR. This
was my first experience doing a staged rocket, as well as my first experience
building a US Rockets kit.
The kit is packed in a standard clear plastic bag with a paper hang tag.
Parts List
The tubes are thicker than Estes BT-50, and have a smooth white glassine finish
with minimal spiral. The pre-cut plywood fins had some fuzzy edges that clean
up easily with a little sandpaper. The tube couplers are not standard brown
kraft paper; they have the same white glassine coating as the body tubes. The
shock cord is a very generous 55 inches long.
My kit was missing the Shock Cord Mount (easily re-created from a piece of
paper), and I got an extra launch lug.
The instructions are printed on four 8.5x11-inch pages on orange paper. The directions have lots of text and a goodly number of computer-generated illustrations.
Construction is relatively straight-forward, and this would probably be a
Skill Level 1 kit if not for the staging.
The first step is to taper the edges of the precut plywood fins with
sandpaper. Next, the body tubes are marked using a marking guide (not the
wrap-around kind, though), and the lines are extended using a door jamb. Then
the fins are glued to the body using wood glue. I used the G. Harry Stine
double-glue method with Titebond-II wood glue. To ensure that the upper fins
lined up with the lower ones, I temporarily connected the two stages using the
stage coupler and a used engine, then used a straightedge clamped to one fin to
align the other fin.
After the fin joints have dried, the launch lug is cut in half and glued
against the base of the fins.
Motor mounts are built for each stage using BT-20-size tubes along with two
centering rings each. The spacing of the rings is somewhat non-standard and
must be done correctly to allow the stages to mate properly later. The
directions explain this clearly.
The motor mounts are glued into the body tubes and a stage coupler is glued
into the lower body tube with 1 inch protruding out the top.
A standard tri-fold paper shock cord mount is used to anchor the shock cord
to the bottom half of the sustainer. It is important that it be inserted at
least 1.5" deep into the tube, since the upper stage shoulder is at least
that long. I recommend inserting it even deeper than that to make it easier for
the streamer to deploy cleanly.
The payload section is constructed from a 5-inch piece of body tube, a
plywood bulkhead, screw eye, and a tube coupler. A pink plastic streamer (looks
like construction site ribbon, 3" x 45" x 0.004") is taped to
the shock cord between the sections. (I glued and stapled mine to ensure that
it stayed attached.)
Finishing:
Finishing is pretty standard: Sand, seal, sand, seal, sand, prime, sand,
paint. I skipped the sealer and used a single thick coat of Kilz primer to fill
the grain and spirals, sanded most of it off, then a light coat of Rustoleum
Painters Choice white primer.
The directions recommend painting the booster flat black and the sustainer
fluorescent colors. I used a Rustoleum Fluorescent Red-Orange on most of the
model, and Rustoleum Painters Choice Flat Black on the nose, one fin of each
stage, and a band on the payload bay.
Recommended Motors
Booster |
Sustainer |
---|---|
A8-0* B4-0* B6-0 C6-0 |
A8-5 B4-6 B6-6 C6-7 |
Engine Combinations |
Max Alt
(feet) |
B6-0/A6-4 | 542 |
B6-0/A8-5 | 572 |
B6-0/B4-6 | 859 |
B6-0/B6-6 | 867 |
C6-0/B6-6 |
1297 |
B6-0/C6-7 | 1458 |
C6-0/C6-7 | 1809 |
Here are the steps for flight preparation:
The next two flights occurred on a breezy day late in July, with winds from 5 to 10 MPH. Flight #2 used a B6-0/B6-6 combination. After a straight takeoff, it angled into the wind a little bit. There was a brief wiggle when the second stage lit, then the upper stage angled into the wind a bit more. Ejection was a bit after apogee. The large streamer deployed well and carried it downwind across two soccer fields and nearly into a men's soccer game in progress.
To prevent the wrath of a few dozen sweaty soccer players, I decided to
angle flight #3 into the wind about 5 degrees when I moved up to a C6-0/B6-6
combo. The longer burn of the C6-0 was much more satisfying than a B6-0, and
the B6-6 lit perfectly. It did quite a bit of weathercocking and headed out of
the soccer field and over some apartments on the upwind side of the field.
Fortunately, the wind carried it back over the apartments to the grass at the
edge of the field.
On both flights the booster landed on the same fin and on both flights the
fin-body joint got cracked, even though the grass was quite soft. For flying
over hard surfaces, it might be a good idea to replace the streamer with a
parachute.
Flight Rating:4 ½ out of 5
OVERALL:
A good solid performer that should be able to handle a lot more impulse than I
dared to feed it.
Overall Rating: 4 ½ out of 5
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