Today's Featured Review
Contributed by Chan Stevens
Let me preface this review by pointing out that I have never paid more than $100 for a rocket, and my previous experience with Apogee and the daunting $175 price for this rocket set my expectations outrageously high. That said, this kit has exceeded them in every way. It is a magnificent kit for the serious modeler, though even moderately experienced modelers will not find this an intimidating build thanks to the video instructions. The video instructions and construction techniques are outstanding.
This is a true 1/70 scale kit, with tubes being precisely sized rather than opting for common, commercially available tubing. All components are top quality, with fit and finish being excellent.
The assembly starts with painting the (8) fuel tank tubes. Despite the fact that the spirals in the tube are barely noticeable, the video shows a very effective technique for filling the spirals. Spraying a light base of primer and sanding back down to a bare tube leaves the spirals nicely filled. Two more coats of primer, a little 600 grit wet sanding, and two finishing coats later, the tubes are beautiful, without a trace of spiral. This finish was worth every bit of the time & effort, and should not be rushed.
Next comes the engine mount core. This was quickly and easily built using the 29mm motor mount tube, die-cut cardboard centering rings, and a couple of tube spacers. The components are excellent quality, with everything fitting perfectly. The die-cut cardboard parts break free cleanly with little or no rework. The fuel tank tubes are then glued to the engine mount core with the help of an alignment tool.
After finishing the engine mount core/fuel tank assembly, you're ready for one of the toughest parts of this project: cutting and bonding the vacu-form wraps. My only prior experience with this was the Estes Saturn 5, and after a lengthy struggle I managed to cover up most of my mistakes on that one. The Apogee Saturn 1B makes me wish for a "do-over" on the Estes. The video instructions for this are very detailed, with plenty of close-up shots and tips for lining up the wraps correctly. I was especially impressed with the numerous tips for using trace amounts of CA to avoid premature cracking of the plastic. The wraps are very tight fitting, and getting the edges to line up exactly right is very challenging. The video instructions, though, enabled this "apprentice" to do a very craftsman-like job.
Moving on to the transition section, I had to dig into the wallet a bit for supplies. To do a respectable job on this kit, be prepared to invest in a variety of quality tools and materials. Being primarily an Estes mod-roc builder, I've got basic tools, wood glue, and a bottle of CA, but the transition section on this uses four different glues (overall, you'll use seven glues plus Fix-It epoxy clay). The core of the transition is made with the basic tube & centering ring approach (plus wood glue). Next comes a paper shroud, which is bonded with rubber cement. I've always been frustrated by the flat spots from using wood glue, and the rubber cement is pliable enough that the shroud is perfectly round. Glue #3 is a light application of thin CA to the paper shroud to give it strength. Once that's sanded smooth, a spray matting adhesive (glue #4) is applied to an embossed paper wrap that serves as the outer section of the transition. The dimensions were perfect, and I had a terrific fit.
The escape tower looked like a simple build, much like the capsule from my Mercury Redstone. The parts were tiny enough to call for tweezers, and once again the video instructions turned me into a master craftsman. Not only were there close-ups showing exactly where to cut the parts, and how to remove the sprue, but there were very detailed shots showing where to apply trace amounts of liquid plastic cement which yielded a strong bond without the hairs and seams left behind by the regular tube cement.
The fin assembly starts off with putty-filling the minor blemishes in the resin-cast fins. While I'm sure this is normal for resin cast parts, I was a little disappointed to find any blemishes in what had to this point been a perfect kit with flawless materials. After filling in the fins, you're now facing a choice of "regular" fin alignment, or mounting with a 2° canted alignment. The canted alignment provides a slight amount of spin, helping to stabilize the rocket during flight. This leads to less nose weight for stability, resulting in higher altitude flights. I opted for the canted fins, which is barely noticeable. Fins are bonded to the base with thick CA and to the plastic transition with a tiny wick of thin CA. As usual, everything fit perfectly.
The nozzle assembly was fairly straightforward, and includes a very nicely detailed vacu-form cover for the base. The nozzles have a slight slant to them, though I found the slant a bit less pronounced when bonded to the vacu-form cover.
With the construction just about wrapped up, I'd normally let out a sigh of relief and enjoy the anticipation of an imminent launch. Painting and detailing a Saturn, though, is a very challenging task and takes nearly as much time as the construction itself. There are very helpful tips on filling any blemishes and tube swirls. I deviated a bit from the instructions here, though, and used a very fine steel wool pad (designed for furniture refinishing) to sand down the vacu-form wraps. This took the rough edge off the primer without damaging the wraps. After two very light primer coats, the rocket gets a couple of coats of white. I opted for Krylon flat white, which doesn't hide blemishes as well as gloss, but in my opinion offers a nicer looking overall finish.
After two light coats of white, the masking project begins for the black roll patterns. A sharp edge line along ribbed vacu-form wraps is extremely difficult. The instructions again offer some good tips, starting with using a Sharpie marker to draw a fine edge line, followed by a layer of liquid masking medium, followed by standard masking tape, pressed firmly into the valleys between ribs. I had difficulty getting a satisfactory finish with the Sharpies (note-three different types of Sharpie brand had trouble leaving a consistent finish). First of all, Sharpies leave a glossy finish, which doesn't blend well with my flat black paint. Second, the liquid masking medium tended to pull up some of the Sharpie color, though this could be due to the brand I used (my hobby store doesn't carry the brand recommended in the instructions). After a lot of trial & error, with some touch-ups applied using a microscopic paint brush, I finally got a nice, crisp roll pattern.
After painting, there's minor detailing and application of decals. This is one aspect of the instructions that I found a bit weak. While there are several very sharp photo-like drawings provided, the Saturn depicted in the drawings does not exactly match the one in this kit, and in the drawings it's tough to pick out some of the colors. I'd recommend a secondary resource like one of Peter Always's books before finishing this rocket.
After applying all the finishing touches, final assembly of the modules and prepping of the parachutes. I was very impressed with the chutes, being made of strong nylon, and very brightly colored. To fly the rocket, a bit of nose weight is necessary, and the instructions provide estimated amounts for both the standard and 2° canted fin approach.
Construction Rating: 5
I flew on an Aerotech F25-4 for our local club's sport scale competition, and with winds between 10 & 15 mph at launch, the rocket went completely unstable at about 25 feet, flew roughly horizontal, hit the ground still under propulsion, and popped the chutes in the tall grass.
Damage was pretty heavy-the escape tower was destroyed, a couple of the plastic & resin details were broken, I've completely lost 2 of the 8 fins and recovered 2 others to reattach, the fuel tank housing/shroud was cracked, and I've got a lot of paint touch-up to cover.
For what it's worth, I did manage to win the competition even with zero flight points due to very high marks on construction and craftsmanship.
I'm still working out the root cause(s), but I'm ruling out motor failure, and probably ruling out improper fin alignment (the 2 degree fin cant DID spin fairly well on the way up). My CG was at least 1.5 calibers ahead of the calculated CP, so I'll contact Apogee to see what Tim thinks could have happened.
Flight Rating: 5
Final rocket weighed 17.1 ounces, versus RockSim calculated weight of 13 ounces (the RockSim file was provided with the kit). Part of the increased weight is due to the fact that I went (theoretically) overboard on the clay nose weight, using about 60 grams instead of 20 grams. My real-life CG was 19.25 inches from nose, versus RockSim calculated CG of 21, so all of the normal bases are covered.
My guess is that this had something to do with the 2-degree fin cant. Eyewitnesses tell me it was definitely starting to spin at liftoff (per plan). I was too busy trying to get a shot of the liftoff to see. It seemed to have cleared the rod with awfully low velocity, though, so I'm wondering if the spinning contributed to minor rod drag.
Tim Van Milligan's going to take a look at what's left of the rocket next week at TARC (I'm helping two teams that made the finals), so he might be able to come up with a more definitive answer. Not likely to be a design problem (hundreds of these kits have been built and flown), and I'm too stubborn to claim construction problem (the craftsmanship was top-notch, having built enough of a lead in the contest that I would have won that event even with zero flight points). I'm leaning towards a marginally stable approach with the fin cant, which combined with a little bit of rod drag, slightly heavy winds, and possibly slightly weak motor put this just enough over the edge.
I do plan on repairing/rebuilding and I'll let you know what comes out of it.
I sent the rocket down to the TARC finals with a team I was mentoring, hoping Tim van Milligan could review it and give me some feedback on what might have gone wrong, as well as repair tips. Tim couldn't find anything dramatic, though suggested I add nose weight. I was already about 50 grams over the suggested spec for nose weight with a CG 3.9 inches forward of calculated CP, but following his advice, I added about 50 more grams of nose weight. I also ordered replacement parts from him, and after about 40 hours of diligent repairs, the rocket looks nearly as good as new.
With the added nose weight, the repaired Saturn 1B now weighs in at a hefty 24 ounces including motor, which is right at the limit for an F25, I horse-traded at the pad and went with an F50-4T. There was hardly a trace of wind. The rocket, empty, is now 21 ounces versus the Rocksim file weight of 13 ounces, so nose weight should no longer be a problem. The F50 lit, the rocket raced off the pad, and the 2-degree fin cant resulted in a beautiful spinning motion as the rocket soared upward on a perfectly straight ascent. The 4-second delay was a bit too early, with the rocket still coasting upward at deployment.
Both chutes deployed beautifully, and I watched the two sections drift slowly to the ground. Ordinarily, I'm not impressed by parachutes, but I have to say that watching the rocket slowly descend under the HUGE chutes was really thrilling. The escape tower and SIV-B stage is supported by a bright orange 24" nylon chute, and the lower portion comes down under a fluorescent yellow 36" chute. I had no trouble at all picking these up in the sky or in the very tall grass at our club's field. Everything was recovered in perfect condition, without even a scratch to the escape tower or RCS nozzles.
I would have to agree with Tim's hunch that additional nose weight would help, though after watching the second flight, I think the high winds and low thrust motor were more likely the culprit of the first flight. I'm going to move up to a G for my next flight, then probably retire this rocket to a prominent display location. This is simply the most beautiful rocket I've ever built (or seen), and having proven its mettle in the field, can now safely enjoy its retirement with pride.
Overall Rating: 5
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