(by Todd Mullin - 01/26/08)
The Space Ark Jr. is a half-scale low power version of Pemberton
Technologies' (Pem-Tech) mid power Space Ark. It is a single stage, parachute recovery model of the rocket seen in the
sci-fi classic "When Worlds Collide". I got my Space Ark Jr. as a matched signed/numbered edition (#8) at the
time Pem-Tech released their new line of products with their Bucky Jr. kit.
The components came packaged in a heavy, sealed poly bag. All of the components were accounted for and in good
condition. The parts included are:
- Balsa nose cone
- Balsa tail cone
- BT-60 airframe tubing
- 24mm motor mount tubing
- Nose ballast
- 1/8" balsa fin stock sheet
- 1/4" Launch lug
- 1/8" Launch lug
- Screw eyelet
- Wrap around and tail fin alignment guide
- Super groovy fin template sheet
- 1/8" dowel
- 6 page "Destruction" manual
- Supplemental instruction sheet
This was my first kit from Pem-Tech. I had heard in the past about their infamous "Destructions"...
Layne Pemberton obviously has a well developed sense of humor with a writing style similar to Douglas Adams. A very
entertaining read. The manual includes an image of the completed model and only 1 illustration. The lack of
illustrations is not a problem though, as the build really doesn't require more than the one.
The build starts out by sanding and filling the body tube and nose and tail cones and alignment marks are added to
the tube. Next, the nose ballast needs to be added. According to the supplemental instruction sheet, a last minute
snafu, the initial batch of kits did not come with a pre-drilled ballast hole in the nose cone. This was easy to remedy
with a large drill bit. After the freshly drilled hole was drilled and filled with ballast and , I screwed
the eyelet into the rear of the cone and set it aside for the glue to cure.
The fins are next. The modeler must trace and cut the fins by hand for this model. Like the design, the fin
modeling is retro as well. The lack of laser cutting shouldn't discourage even a moderately inexperienced rocketeer.
Next, alignment marks are put onto the tail cone, which is temporarily mated to the body tube. These are used to
cut the "thru-the-tail-cone" fin slots in the tail cone. For a beginner, this might be a challenging step.
The slots need to be cut cleanly, straight and correctly sized.
shock cord is glued to the motor mount and then it is inserted into the tail cone after the slots are cut, and then the
tail cone is permanently glued to the body tube. The fins are glued into the slots on the tail cone.
Next, the gotcha of the kit. The wings are glued to the main body at a different
angle than the fins. This is well illustrated, but if you aren't paying attention, it will ruin the look of the kit.
Also, whereas the manual tells you to glue the wings onto the wing alignment line, it doesn't tell you how far forward
to attach them. I eyeballed them from the photo of the completed kit and decided to put the trailing edge of the wing
just slightly forward of the seam between the tail cone and the body tube.
At this point, I deviated from the "Destructions". The next step is to glue the crossbar on the two
lower fins. As this would make the filleting and sealing of the fins much more difficult, I left the crossbar and the
fin tip dowels off until after I had put on a good, thick coat of Elmer's Fill N' Finish and Kilz onto the model.
After filleting and filling the balsa, I attached the crossbar, 1/8" launch lugs and fin tip dowels.
One step that is notably missing from the instructions is the attachment of the shock cord and parachute to the
nosecone. Probably obvious that this needs to be done to the experienced modeler, but it's omission is noteworthy.
The finishing on the Space Ark Jr. is about as straight forward as it
gets. After careful sanding and priming, a uniform silver paint scheme with no detailing is recommended to match the
rocket from the movie.
For those of you that have not tried to get a "perfect" silver paint job, just a word of caution. Silver
is probably the most difficult paint color to work with. It will show any imperfections in your model, so take your
time and give this beauty the good, smooth sanding it deserves.
out of 5
I was a bit nervous about launching a rocket of this size and weight on a D12 motor on San Diego's Fiesta Island...
Way too much water all around. I ended up bartering a C11 from someone at the launch and felt much better about it.
The Space Ark does not have a thrust ring so that it can fit a variety of different motors, so the rocketeer must
add a wrap of masking tape around the business end of the motor to keep it from sliding up into the model when under
The rocket had a nice, smooth boost with just a slight weathercock to the flight. The ejection was right at
apogee. The C11 is PLENTY of motor for this rocket! I'm glad I didn't go up to the D12...
The shock cord on the Space Ark is an extra long length of Kevlar.
This might sound a little weird...but just a bit too long! Not something you normally hear as a comment with other
manufacturers providing extremely short shock cords with their kits!
The Space Ark ejected perfectly at apogee and came down swinging around itself on the descent. Couldn't figure out
why until the model got to the ground. The shock cord had bound around the shroud lines of the parachute allowing it to
only partially inflate.
Even with a partially opened 'chute, there was not damage on landing.
out of 5
Overall, building and flying Pemberton Technologies Space Ark Jr. has
been a really enjoyable experience. The oversimplified 1950's classic design has been translated into a rocket that
gets attention at a launch.
The materials supplied with the kit are top notch. The "destructions" are a highly entertaining read and
are still easy to follow. There are a few omissions of steps, but in my experience, Pemberton Technologies is extremely
responsive to e-mails.
For my next launch of the Space Ark, I'm planning on adapting the 24mm motor mount down to a 18mm mount. With the
C11 motors becoming harder to come by, I will probably permanently mount the adapter to be able to fly on the smaller
out of 5
Update: I made the 18mm flight with good success. I have glued the mount in permanently. I have forwarded comments on
to Pem Tech about the destructions and they have told me that they will be revised on the next production run.
(Contributed - by Geof Givens - 08/22/08)
The Space Ark Jr. is a of Pemberton Technology's midpower rocket. Layne Pemberton offers a lot of really
cool retro-futuristic designs. He's also a nice guy whose instruction booklets are well known for their humorous
off-beat writing style.
The package arrived with all necessary parts in good condition, except that the balsa nose cone had a couple small
dings. After reading a back-story about the Ruskie commies, Martians, and gung-ho American heroes, it was time to start
First came insertion of lead ballast in the nose cone, and some general sanding and filling. The fins are cut from
stock balsa using paper fin patterns. I had some difficulty because the instructions referred to various fins with
names like "wing" and "horizontal stabilizer", but the patterns/figures had no labels identifying
which was which. By process of elimination, I eventually figured it out.
To attach the fins, alignment lines must be drawn on the. This was a very tricky process. The
installation was made more difficult by the approach of through-the-tail-cone fin installation. It would have been much
easier and surely sufficiently strong to surface mount the wings with an appropriate shape cut along the root edges.
Also, the fin tabs weren't slanted, which was also a bit confusing.
The extra-long Kevlar
shock cord was glued to the outside surface of the motor mount tube, and this assembly was pushed/glued in the tail
cone. Because the cord lay against the exterior of the motor tube, I found it impossible to insert the tube into the
tail cone. I had to cut a trough inside the tail cone to make room for the cord. It was still a snug fit.
The rest of the assembly, including the remaining fins, was straightforward with one exception. I was confused
about how far back along the airframe to mount the wings. I guesstimated it from the picture and adjusted slightly
further back for safety. I skipped the fin-tip pods because these sorts of things tend to snap off so easily.
Finishing was mostly straighforward. I fill and sand before assembly, so all that remained was touchup and then
painting. With this retro-futuristic design, metallic paint is a great way to go, so I chose silver. The only tricky
part is getting the spray into the crevices above the crossbar.
out of 5
My problems occurred during the flight, which was unstable. I was a bit rushed so I quickly looked at the recommended
motors (B6-2 through E18) and chose a B6-4 because it was what I had. Rather than wrap the 18mm motor in duct tape (as
recommended) for friction fitting (the only option), I used a spend 24mm casing as a motor adapter. This works well and
should be lighter than a large quantity of duct tape.
I failed to notice two instruction points about flying. The instructions clearly said to the rocket
before flying. Also, in the middle of construction step three, away from the sections on flight prep, launch, and
recommended motors is a sentence that says that a 48in rod is required for B motors.
Clearly it is my fault for not following the instructions, but I have a couple comments. First, he string test
recommendation is sensible, but I think it is reasonable to believe that any commercially marketed model kit would have
the CG/CP relationship sufficiently above minimum safety margins that modest variations in construction techniques by
various builders should not cause problems for recommended motors. Why flirt so close the edge? Perhaps I placed the
wings too far forward.
Second, I would suggest that the comment about 48in rods be moved to the recommended motor section; it is easy to
overlook in the construction section. Actually, I would omit B motors from the recommended list altogether since most
LPR Estes motor fliers might not have a 48in rod on hand and might not understand the importance of the extra rod
length. I understand it, but I didn't notice the advice.
Anyway, the rocket became unstable after leaving the rod, doing the typical "bumblebee" flight pattern.
Upon crashing, the aft portion of the rudder broke. Repair is possible.
out of 5
Because of my experience, it is unfair to judge flight performance for this rocket. I have rated it on my expected
performance, knowing about PemTech's other kits. Quality of parts was fine, construction was mostly straighforward with
a few difficulties, style was fantastic, and I expect that flight should be good.
½ out of 5