(Contributed - by Chan Stevens - 07/04/05)
This review is for the beta version of the not-yet-released Thrustline kit. Not
to tease you readers too much but this will be a wonderful kit and when it's
released, I'd highly recommend it. It's futuristic design is influenced by the
Mars Snooper, and it is large, graceful, and flies magnificently on E9s. It's
jumped onto my top-ten list of favorite kits.
[Note: Because this is a beta, I'm including a few gotchas along the way
that are extremely unlikely to occur in the finished product, as the build was
coordinated with Thrustline every step of the way.]
This kit has a fairly extensive parts list:
- Balsa nose cone, NC-55 Honest John style
- 3 BNC-5 cones
- 3 BT-5 inner pod tubes
- 3 BT-20 outer pod tubes
- 2 BT-55 body tubes 12.25" each
- BT-70 body tube
- BT-50 motor tube
- E-sized metal clip
- Assorted plywood, fiber, and cardboard/paper centering rings
- 1/8" and 3/32" Balsa fin stock sheets
- Mylar chute
- D/E motor adaptor kit
Parts were all very good quality although the balsa stock is a bit soft. The
instructions were generally very good but contained a few beta-related typos.
They were packed with lots of color photos, including an indexed parts photo to
help you sort out the bag of stuff as you go along. Overall, I'd rate this
about a skill level 3 kit as there are some slightly challenging techniques
involved and a potentially complex paint scheme.
Motor mount construction is fairly straightforward, however, this kit
included an unusual reinforcement method. Most kits use either masking tape or
a centering ring to hold the metal clip in place. This kit includes a BT-50
sleeve which is slit and then slid over the BT-50 motor tube and glued in
place. This is definitely going to outlast masking tape, but I found it to be
slightly overkill (and ironically, my motor mount blew out on flight #3 after a
very violent ejection charge).
Next up is construction of the side pods. These are actually somewhat
intricate assemblies, not ordinary BT-20 pods tacked onto the fins. The
assembly consists of a center BT-5 tube, which has a couple of CR5-20 centering
rings attached. A BNC-5 cone is then glued into place and the BT-5 assembly is
then glued into a BT-20 tube. This leaves a part of the BT-5 sticking out the
aft end and the BNC-5 sticking out the forward end for a nice layered look. The
look is finished off with a boat tail shroud cut from a paper pattern. There
are extra patterns printed, so there's plenty of recovery room for goofs. (In
fact, my kit had more than double the required amount.) My shrouds fit fine but
they had goofy and unnecessary tabs on both ends. One tip I'd offer for these
(and for paper shrouds in general) is to use only rubber cement or white glue
for bonding and then paint them with a thin CA for firmness.
The main body tube is actually a 2-piece assembly of BT-55s with
a coupler. At 12.25" apiece, I had suggested that this be switched to a
single piece tube, eliminating an unsightly seam on the main sight line. This
makes the bag bigger and shipping more difficult, but this request is being
considered. The current design with the coupler, also includes a centering ring
at the base of the coupler which is used to anchor the Kevlar
shock cord line. That's very helpful, and keeps the Kevlar
a foot above the motor, saving it from some of the ejection charge stress.
There is a larger BT-70 "outer tube" that slips over the main
BT-55 tube, towards the aft end. This is pretty basic, aided by a pair of fiber
centering rings in the BT-70. [Note: Any external fillets, as the rings are
flush mounted, should be minimal since there are trim fins that butt up against
the centering rings.
Next in the build comes the tube marking for the BT-55s, BT-20 side pods,
and the BT-70. I suggest doing this before they're bonded together, but
bonding afterwards is still possible. My kit had a whoopsie on the larger
marking guide--it was sized for a BT-60, not a BT-70--but I was able to whip
one up very quickly using RockSim.
Depending on how you look at it, cutting out the fins is either
a pain or a pleasant mini-project (if you consider yourself old school and
prefer slicing your own). There are 30 different fins/pieces to cut on this and
all from pre-printed patterns. While it might add a buck or two to the cost of
this kit, this really might be a nice application for laser-cutting, especially
given the numerous curves and angles involved. Many of the pieces are not
symmetrical and therefore can't be cut back to back with a common line. Six of
these fins go aft of the BT-70 outer tube and six go forward of the tube. I
wound up deferring the bonding, wanting to paint them first. (I took the time
to mask off a line for bonding too).
The main body fins are a somewhat complex 4-piece assembly. Pay careful
attention to the pattern sheets and you'll have no problem, but one of the
triangular sections is a bit easy to orient the wrong way. With 3 seams and
grain going in all sorts of different directions, these were a real pain to
sand and fill. Even after 3 coats of Elmer's Fill 'n' Finish, I still have
visible grain, but it's only noticeable upon very close examination. I would
also note that the stacked root length of the fin patterns was about 1/4"
too long and will no doubt be corrected before the final release.
Last up on the fins are a set of 3 dorsal fin/canards and a set of 3 very
small pod trim fins. Pay careful attention when bonding these fins as the main
body fins look like they're on backwards and they look this way on purpose. I
bonded all my various fins using CA to tack them in place and then used yellow
glue for fillets. Once the main fins are attached, the side pods get tacked to
the main fins then trim fins to the side pods.
The nose cone is attached using a screw eye and elastic shock cord, which
is tied to the Kevlar
just inside the body tube for a zipper-free design.
John and I debated several different paint schemes before I ultimately cheated
and went off to paint it on my own. I was delighted with the appearance of my
Squirrel Works Astrid and wanted to use a similar scheme on this one. So after
applying 3 very light coats of primer (be careful to avoid runs--there are lots
of nooks and crannies on this), I went with a base of Rustoleum Silver
Metallic. I'm not talking about the solid/mirror finish, but the stuff that has
a flaky/glittered look to it. I then trimmed most of the fins using a similar
red metallic flake paint. All six aft trim fins were painted gloss black, as
were the BT-70 and BT-55 centering rings. Finally, the BT-5 nose cones were
painted orange. I'm not sure I like the orange, but I had no idea what else to
go with at the time.
As noted previously, I painted the trim fins before bonding and wound up
bonding them using a tiny amount of CA followed by a fillet of Elmer's white
glue, which dries clear.
Decals are not currently available for this, although a design is in the
works. I'd like to see something adding a royal blue to this along with a
couple of long trim lines and possibly some type of cockpit detail.
out of 5
The recommended motors are D12-5 and E9-4. For the first flight, I chose to
jump straight to the E9-4. The flight was unstable and it crashed still under
impulse. Fortunately, there was virtually no damage. After a couple of email
exchanges, we decided to add some nose weight. I wound up attaching about 1.5
ounces of washers to the nose cone (by replacing the screw eye). I also scaled
back down to a D12-5 and tried again the following weekend. This time in
heavier winds of about 10-12 mph, it flew fine and deployment was right at
apogee. After slipping off into contest flights for a couple months, I got
another chance to fly this on an E9-4 twice. Each flight was wonderful--long,
slow, and straight as an arrow (not even a hint of spin on the way up) with
deployment right at the top. The nose weight made all the difference.
The beta kit included both an 18" and 20" mylar chute, asking me for
feedback on which to use. I mainly used the 18", but I fly on a field with
very tall (2-3 feet) grass and even when I completely forgot to pack a chute
one time, soft landings are the norm. For short grass flying, I'd probably go
with the larger 20 or 24" chute, as the large fins could be prone to
breaking with the mixed grain directions.
out of 5
I found this to be a beautiful rocket with awesome flights on my favorite
motor, the Estes E9. It's definitely an unusual and appealing design and a
break from the typical commercial fare. The main PROs are design, performance,
and quality of instructions and materials.
The only CONs would include soft balsa with lots of hand cutting, the
two-piece body tube, and (beta only) lack of decals.
½ out of 5