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REV 2.4 - Thu Jan 13 02:35:41 2011

Pemberton
Space Ark Jr
2330 HWY 321 N
Ward, AR 72176
 
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SPECS: 16.35" x 1.64" - 3 oz
ROCKSIM FILE: Right Click to Download
SpaceCAD FILE: MISSING - please submit here
REC'D MOTORS: B6-2, C6-3, D12-5, D15, E15, E18

Rating
(by Todd Mullin [Who's Who Page] - 01/26/08)

Brief:
pem_space_ark_lackluster 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 low power line of products with their Bucky Jr. kit.

Construction:
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
  • Kevlar shock cord
  • Parachute
  • 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 Gorilla Glue, 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.

The Kevlar 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.

pem_space_ark_tailNext, 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.

Finishing:
pem_space_ark_allsystemsgoThe 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.

Construction Rating: 4 out of 5

Flight:
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 thrust.

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...

Recovery:
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.

Flight Rating: 4 out of 5

Summary:
pem_space_ark_wehaveignitionOverall, 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 motors.

Overall Rating: 4 out of 5

Other:
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.


Rating
(Contributed - by Geof Givens [Who's Who Page] - 08/22/08)

pemberton_space-arkBrief:
The Space Ark Jr. is a downscale 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.

Construction:
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 the build.

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 tailcone. 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:
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.

Construction Rating: 3 out of 5

Flight:
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 string test 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.

Flight Rating: 4 out of 5

Summary:
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.

Overall Rating: 3 ½ out of 5

[Submit your Opinion]

GUEST's OPINION:
09/08 - "I really enjoyed building this rocket! The instructions were funny and well presented. I was worried about the thru the tailcone fin mounting, but found it much easier than I expected. The fins are VERY strong with this method. I had no trouble attaching the Kevlar shock cord to the motor tube on mine. I did install a 24mm motor block in mine and I flew it on a C11, it flew very nice and high. A D12 would really send this rocket into orbit. PemTech has a winner here." (M.A.)

GUEST's OPINION:
09/08 - "After reading my review, Layne immediately wrote to me, thanking me for my honesty and offering a replacement kit "out the door today". In my opinion, this shows excellent customer service and it is not the first time I have had such good service from Pemberton Tech. I didn't need another kit, but my experience with the Space Ark won't deter me from buying another PT kit in the future. Layne also mentioned that the instructions were updated at some point." (G.H.G.)

GUEST's OPINION:
09/08 - "Geof has given a very fair and accurate review of our Space Ark Jr. kit. I personally apologize for the kit being sold with the old Destruction Manual, which was reported to have all the deficiencies listed and supposed to have been replaced. The updated manual has: grain directions and names on the fin templates, mounting position of the wings and improved descriptions of steps. The suggestion about moving the comment concerning 48in rods to the recommended motor section will be implemented as well as a reevaluation of minimum motors. We would be glad to replace all parts broken during an unstable flight, free of charge. Please contact us at: ooppss@pembertontechnologies.com" (P.T.)

[Enter Rocket Specific Tip]

SPECIFIC ROCKET TIP:
09/08 - "For those looking for a good silver paint, try Dupli-Color Arctic Silver, my preference, or Dupli-Color Millenium Silver. The Millenium has a grayish tint to it while the Arctic is more true to a silver color. Both are "sparkly" silver rather than "chrome-looking" and both look great on the "sci-fi" models." (J.R.G. )

[Enter Flight Log]
Date Name Motor Ejection/
Altitude
Wind Notes
10-06-2007 Mark Alterio Est SU C11-5 Apogee - NC Down 0-5 mph winds - Nice flight! ejection perfect, smooth recovery. Est about 400-500 ft.A great rocket.
12-30-2007 Todd Mullin Est SU C11-3 Just Before 5-10 mph winds Event: Fiesta Island
- Nice maiden flight. Was concerned about wind coming up. Shroud lines slightly tangled in shock cord. Spiraled down to soft landing.
01-13-2008 Todd Mullin Est SU C6-3 Apogee - NC Down 0-5 mph winds Event: Fiesta Island
-
01-13-2008 Todd Mullin Est SU B6-2 Apogee - NC Down 0-5 mph winds Event: Fiesta Island
-
02-10-2008 Todd Mullin Apo SU C6-3 Apogee - NC Up 0-5 mph winds Event: Fiesta Island
-
05-24-2008 Todd Mullin Est SU C6-5 Apogee - NC Up 10+ mph winds Event: Fiesta Island
-
08-30-2008 Todd Mullin Est SU C6-3 Just Before 5-10 mph winds Event: Fiesta Island
-
01-11-2009 Todd Mullin Est SU C6-5 Just Before 0-5 mph winds Event: Fiesta Island
-

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