Gakken Kit #35, V-2 Steam Engine

Gakken has been either reissuing, reusing or revamping their Otona no Kagaku kit ideas for quite a while now.  A case in point for revamping is the camera, which started out as the pinhole camera, morphed into the stereo pinhole camera and ended up as the dual lens camera.  For reusing, there’s the Jansen linkage which started with the Theo Jansen Mini Beest, and turned into the Mini Rhino.  And, for reissuing, we have the Edison Gramophone, the Premium Gramophone and the Edison Cup Cylinder Recorder (version one used a styrofoam cup, version 2 uses a clear plastic cup).  Kit #36, due out in September, will be another cylinder recorder, this time apparently using a wax candle.  My sense for these reissues is that as the older kits go out of print, Gakken updates them to appeal to new fans of the series.  I’m not sure how the older long-time fans feel about paying more money for something they’ve already built, but the completists will buy the new kits regardless, and the more casual hobbyists will get only those kits that really appeal to them.

(All rights belong to their owners.  Cover image used for review purposes only.)

Kit #35, V-2 Steam Engine, 3,150 yen.
Kit #35 revisits kit #7, the 1-cylinder steam car last seen in 2005.  One big difference is that the V-2 kit only consists of the engine, lamp and boiler.  If you want to have it drive something, it’s up to you to build that separately.  The theory is very straight forward.  You put a couple ounces of water into the boiler with an eye dropper, then light the burner (using heating fuel). Steam pressure builds up in the boiler, pushing the steam up the silicone tubing and to the T-joint.  The steam is applied evenly to both cylinders.  You’ll probably have to start the engine spinning with your finger.  Then, the steam will push one piston forward until it reaches the end of its stroke and opens the path to the exit vent. Through momentum, the other piston will reach the top of its stroke and the steam pressure will push it down, etc.  The exiting steam will condense and you’ll get water dripping onto your table.  Eventually, you’ll either run out of fuel, or water in the boiler.  It’s best to put the fire out early to avoid damaging the boiler.  The cylinder frame is designed with a snap pin-notch combination so that you can rotate the cylinders to 72, 90, 120 and 180 degree angles.

Gakken suggests 40 minutes for assembling the kit, and even with the extra time taken to double-check my work, I finished in 35.  This is a very simple kit, with 13 pieces, not including the screws and springs.  The first step is to fill the boiler with water, connect the tubing to one connector, and blow the water out of the boiler in order to remove any oil that may remain after assembly (wash the tubing first with soap and water).  The assembly instructions are pretty easy to follow, just refer back to the photos to check your work.  When you attach the cylinders to the frame with the two long bolts, just tighten the bolts down enough so that the red spring caps go about halfway into the cylinder housings.  Clip off 1 cm of tubing and use that on the bolt ends to keep them from unscrewing during operation.  If you cut the tubing as shown in the instructions diagram, the remaining piece that connects the 2 cylinders to the T-joint will be too long.  I trimmed it by 2-3 inches and that seems to be good enough to remove slack while avoiding pinching.  When you mount the boiler to the tray, the instructions state to hold the boiler legs in place by bending the middle finger of each leg down at the bottom side of the tray.  The wick for the burner is just a piece of tissue folded into squares and pulled through the burner mouth.  The instructions say that you should use “heating alcohol” and not gasoline, by which I take it to mean the fuel used in portable cooking stoves, or possibly kerosene.

I started out trying lighter fluid, but the resulting flame engulfed the boiler and left soot all over everything.  I made the wick shorter, but that didn’t make any difference in the size of the flame.  The burner reservoir dried out within a minute or so, and the boiler ran out of water pretty fast as well, but the engine did run during this time. Which brings me to the first problem: if you put in more than 2 squeeze bulbs of water into the boiler, it’s going to take longer to heat and you’ll run out of fuel first.  Use less water, and the engine will start running faster but also run out of water faster.  I’d suggest that your first mod be to increase the burner reservoir size, or mount the engine over a bunsen burner or a can of sterno.  I also tried rubbing alcohol, but while the fuel burned clean and lasted a good 5 minutes, the steam pressure never really built up enough to get the engine running for more than a few seconds.  Regardless of the fuel, the engine spit water out of the tray and onto the table.

The mook has a great selection of photos this time, starting with a look at a couple shops that build bikes and restore old cars.  This is followed by an illustrated history of steam, diesel and gas engines, a sampling of old cars, and pictures of BMW, Harley and Ducati motorcycle engines.  There’s an illustrated chapter on thermodynamics and an explanation of torque and the carnot cycle.  Other articles include an interview with the designer of the kit, a Q&A with three of the engineers at Subaru, and photos of the fab process for a BMW engine.  Mods for the kit include connecting a belt to the engine pulley to drive a car made with Lego parts; connecting a motor to generate electricity for a lamp, by Mathrax; and adding a “super-heater” (a length of metal tubing to put directly over the burner to heat the steam further). You can also add a small disc to the pulley, and use an LED with a photocell connected to the Japanino to measure the engine’s RPMs.  There’s then an article on steam locomotives, a spotlight on a guy that made a scale model of the grounds around Himeji castle, and a demonstration of 1-cut kirikami (you fold a sheet of paper, cut it once, and unfold it to reveal full words or kanji characters).  There’s a 6-page section with satellite photos, an article on iPS (induced pluripotent stem cells), and chapter 2 of Asari’s Manga Science series (“Telescopes and Sunspots”).

Summary: If you like those brass models of vacuum and sterling engines, but can’t afford them, then you’ll love this V-2 steam engine.  If you have pets or small children, then you may want to avoid this kit like the plague.  It’s a fun party piece, but unless you connect it to a car body or a DC generator to power an LED, there may not be a whole lot of replay value. And, there’s that whole “semi-controlled flame inside your house” issue, combined with “spitting water over your table”.  Still, it’s very impressive for being so simple to build.

Next Up: Edison Cylinder Recorder, tentatively scheduled for the end of September.  No price yet.


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