(05/29/99) The WAC Corporal is
one of the most popular kits from Aerospace Speciality Products and now comes
with the Tiny Tim Booster to make a 2-stage, sport- scale rocket. My kit is the
18/18mm version, however, it also comes in a 24/18mm version.
CONSTRUCTION:
This was
really the first scale kit that I have put together. It is approximately 1/12th
scale.
The instructions had 11 pages. There is a brief summary
about the real WAC Corporal, two pages of interesting "Notes on
Adhesives" which you should review since you do use different glues for
different assembly steps. The assembly instructions were broken down into three
sections: the Tiny Tim Booster, the WAC Corporal upper stage, and final
construction. I found the the instructions to be clear with a lot of text
explanation and and appropriate number of reference drawings.
The Tiny Tim Booster has a body tube, motor mount,
1/16" dowels to attach to the upper and lower telescoping tubes, 4 strips
of styrene and 3 precut fins as its main components.
Assembly required some patience and finesse. Rubber bands
(supplied) were needed to hold the dowels in place for gluing and it was
necessary to really check for alignment.
The four styrene strips are used to add detail to the
Tiny Tim booster and are evenly spaced at the lower end of the booster, all of
which go under the three fins. Gluing these on also required rubber bands and
CA glue. You also have to mark and groove the to accommodate the strips.
The WAC Corporal's main components are a body tube, motor
mount, Kevlar® shock cord, elastic shock cord, balsa nose cone with 2 nose
weights (washers) and an eye-screw, 3 pre-cut balsa fins, a square balsa stick
and a mylar parachute.
Assembly of the WAC Corporal is relatively easy and
doesn't require any special techniques.
The instructions include nice illustrations for the
shaping of the fins. I like how the instructions say, "If you want a
slightly less scale fin, simply round all edges of the fins except the root
edge." I didn't. I worked hard at getting the shape like the
illustrations. Shaping is required for both the Tiny Tim and the WAC
Corporal.
The launch lugs are mounted on a thin basswood strip
before being glued to the body. This little offset is nice to prevent the rod
from rubbing the rocket body, however, its functional value is to allow the rod
to clear the 4 styrene strips on the booster.
The motor mounts include engine blocks and are set up for
stand 18mm motors. They do not have retaining hardware. The WAC Corporal's
motor mount has the Kevlar® shock cord tied around it and then the upper
centering ring placed over the shock cord.
The remaining portion of the recovery system includes a
piece of elastic which is tied to the Kevlar® shock cord and to the nose cone's
eye-screw. A swivel and 12" mylar parachute finish the recovery
system.
I could go on, because there was actually quite a lot to
building this kit. I'm not saying anything was too difficult but there are
quite a few techniques used that I have not come across in other builds.
Aerospace Speciality Products has made the claim that they offer "Kits YOU
Build!". I agree and encourage others to give one of their kits a try. If
for no other reason but to pick up on some of the various techniques used. You
may apply them to other kit builds or for scratch building.
For finishing I always rely on several good coats of
Plasti-Kote primer. I then followed
the color scheme described in the instructions. I had one issue when my black
reacted with my yellow. I had to re-sand and clean it up then repaint. Happens
every now and then when you mix brands and types of paint. I guess I should
always test . . .
Overall, for CONSTRUCTION I would rate this kit
4.5
points. Take your time and read all of the text. It would have been
good to have some wrap-around type of fin marking guides although this was not
a big issue. Motor retention would have been nice but would take some away from
the scale look.
FLIGHT/RECOVERY:
The
recommended motors for the WAC Corporal as a single-stage are A8-3, B4-4, B6-4,
and C6-5 (or 7). The recommended motors for the two-stage are B6-0, C6-0 with
an A8-3 (or 5), B6-6, or C6-7.
I first flew my kit as a single stage on an A8-3. Being
able to observe the whole flight I was able to see that it was still climbing
fast at ejection. At ejection the nose cone separated with the parachute and
the main body fell to the ground. Upon inspection the elastic had broke just
above where it is tied to the Kevlar®.
This doesn't surprise me too much since the nose cone has
two heavy washers as nose weight attached to it. This puts a lot of extra mass
in motion which in turns puts a lot of stress on the shock cord at the
"snap" point. It, no doubt, didn't help that it was still traveling
upward. I reassembled everything but had to use a method
since I could no longer reach the Kevlar® loop inside the tube.
I then flew it on a B6-0/B6-6 combination. The second
stage ignited and took off, while the booster turned and "flew"
straight and stable downward into the ground. This impact broke one of the
dowels that hold the telescoping tube. It should be repairable.
I didn't see ejection, however, after recovery it was
obvious that it wasn't at apogee. My guess is that it was still going upward
based on my observation on the A8-3 and a later observation on a C6-7. The
obvious indicator was the 1/2" tear (zipper) at the upper section of the
WAC Corporal.
After putting a single piece of tape around the top, I
flew the WAC Corporal again as a single stage on a C6-7. It was still going up
at ejection and upon recovery the upper portion of the body tube was badly
damaged.
On the positive side, Aerospace Speciality Products has
made an excellent gap-boost design. There is a 6" space between the top of
the booster motor and the bottom of the sustainer motor. With the removable
staging tube, it can look realistic on the stand and still function in
flight.
For FLIGHT/RECOVERY, I would rate this kit
2.5
points. I think motor selection is critical on this one and I would
also recommend doubling or even tripling the length of the shock cord,
especially due to the nose cone weights. It was certainly a straight a fast
flier, but use the longer delays. I don't know what to say about the Booster
coming back down like a rocket but I can not see this as being terribly durable
unless it lands in the grass.
Overall, the WAC Corporal with Tiny Tim Booster was a
challenging kit to build utilizing many build techniques. It was fun to be able
to learn them and see the results in a sharp looking sport-scale model. I give
the kit an OVERALL rating of
3.5
points.