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  #11  
Old 07-09-2017, 04:42 AM
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Beam Catcher:



The fuselage with all its folds and cutouts looks pretty scary, but it went together quite well. Be sure to laminate sides and ceiling where the wings attach. It's good to attach rear landing skid after the wings because you can punch holes in the white rectangle under it and push against the wings from within.

Wedge-shaped cutouts in the "prong" on the vertical wing need to get rid of tabs and be cut wider because the leading edge bloated by two layers of real paper and one tab since leaving virtual space:



This is how I did the antenna dish:



Worked well, recommendable. Those cardboard-laminated circles weigh something and my model tends to topple to the right, but a connecting magnet (which I didn't install) should be enough to keep it upright.
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  #12  
Old 07-09-2017, 04:43 AM
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And finally, the shots we were all waiting for:



BC and the refinery will need to find their exact positions between bows of SE and NL, Orca's side winglets and RL's wings (easy with magnets alone, but I'll need shape locks and electric connectors too). Opalia doesn't fit very well: the two cargo pods are too far apart to fit within the recess in its stern while the engines are too close together to fit around the wingtips easily - looks like paper thickness was ignored during construction. But I don't mind, that connection node is going to be HUBAR (hacked up beyond all recognition) anyway :-).
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  #13  
Old 07-17-2017, 01:53 PM
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Now it would be handy to know how big the "real" ships are. It determines the size of decks, hatches and other things I might need to build. I tried 1/1000 and voila, it looks perfectly plausible:



So 1 mm on the model corresponds to 1 m in real - great, I love simple math. Numbers of people on board also seem to match. The Jumbo jet and the bus can carry lots of passengers while being small and light, but you can't live in there for long. Marine ships offer more living space, but they're just hollow shells with some little machinery below the waterline, while a nuclear spaceship is full of machinery and fuel. So 602 people plus some recreational facilities, gardens, hydroponics etc. (as mentioned in the official backstory) look pretty realistic. My guess at Neucom's mass is in the order of tens of thousand metric tons. For comparison: Boeing 747 weighs cca 400 t, Titanic 52310 and Bismarck 50300 (Neucom doesn't look very big on the picture, but she's wider than the two sea ships combined).

Scale comparison says that shuttle number 8, which docks at Neucom's back, is so big that a whole family could comfortably live in it. Given how crowded the Robinson is, they certainly would be living there, so the windows would be lit up during the flight. There is no choice but to light up the tiny model too:



Given the window placement, I'll use three miniature SMD LEDs. The windows are "glazed" by cigarette paper (with an interesting square grid texture) and the inside of the hull is covered with aluminium tape to prevent light leaks. The LEDs will be wired in parallel with one limiting resistor (more of those wouldn't fit inside), supply voltage will be probably 5 V, landing gear will double as power connector. Nice theory, I hope it's going to work.

I'm not going to build the wreck of shuttle 8 (I aim for the middle of acceleration phase when it has already been recycled for parts), so its wings will make vertical rudders for shuttle 7. They were not included in the kit, but a rudderless plane is sort of... incomplete .

To be continued next week when I get my bag of cables home and measure how hungry the LEDs are (they are salvaged from an old phone, so I don't have their datasheet).
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  #14  
Old 07-24-2017, 12:15 PM
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Let there be light!

An example of a LED testing circuit:




Exact values don't matter; I used 12V power source and 10kiloohm variable resistor just because they were at hand.

We're building a cozy living room, not a lighthouse. Therefore we don't need much light. These diodes produce sufficient amount at 2.78 V and 0.96 mA each (plus or minus manufacturing tolerances, multimeter inaccuracy, contact resistances etc.). The lighting circuit will look like this:



These LEDs can't go in series because their combined voltages would exceed the 5 V supply I'm going to use. So the only remaining question is how big the limiting resistor needs to be:
Voltage across the resistor = supply voltage - LED voltage = 5 V - 2.78 V = 2.22 V.
We want current of 3*0.96 mA = 2.88 mA running through the resistor at this voltage.
Ohm's law: I=U/R or R = U/I = 2.22 V / 2.88 mA = 2.22 V / 0.00288 A = 770.8 ohms (careful with the units: only use plain volts, ampers and ohms, no mili or kilo).
The closest available resistor values are 750R and 820R. I found one 750 in my electronic scrapbox, so it was easy. An ohmmeter says it is only 736 ohms, so the resulting current will be 2.22 V / 736 ohms = 3.0 mA which means 1 mA for each LED. Perfect, let's go soldering:



The scale of the picture deceives a little. The gray-insluated wires come from computer IDE ribbon cable and the two thick rods are stripped wires from an ethernet cable. Black smudges mark negative pole of the LEDs because they were originally unmarked (detection procedure: connect the diode over a resistor to harmless 3 V and see which polarity lights it up). The shiny stuff in the hull is aluminium sticky tape, the black one is electric insulation tape which prevents short circuits on the aluminium.

After some fixing and insulating:



White glue would take too long to cure and would dissolve the surrounding paper. Solvent-based glue wouldn't be much faster and would make bubbles with poor insulating properties. Hot glue gun is clumsy for miniatures like this, but still usable.

Coming next: hull final assembly.
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  #15  
Old 07-24-2017, 05:41 PM
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Very interesting. Thanks for walking us through the process
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  #16  
Old 07-30-2017, 05:01 AM
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Huzzah and hurrah, first shuttle is finished:




Now just six more plus eight ships and Bob's yer uncle :-D.

Originally a simple two-part box, now there are over thirty parts (not counting the electronics). I'm not very happy with the result. Port hull side got glued by almost a millimetre too far forward, so the whole structure twisted like a propeller blade and had to be brutally forced into shape. The undercarriage is best viewed from afar from where one can't see how each panel is of different size and each leg of different crookedness. Atmo engine cowling on the bottom is hollow (except of the docking magnet). I should have swapped the striped halves of the rudders, they would look better. The windows got crumpled and the front left one spoilt by red paint. And the light is stronger than expected and leaks through the cockpit sidewalls:



It doesn't look that bad in real, but I must put another limiting resistor under the mothership's docking pad. Lesson learned: all paper parts with light source behind need to be at least painted with a black marker on the back, ideally laminated with black paper or aluminium tape. I'm glad this is the only shuttle which needs lighting.

To be continued somewhere in the second half of August, too many other things are interfering now.
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  #17  
Old 08-01-2017, 03:00 PM
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I d/l'd this some time back and have been following your build with interest. I really thought there'd be more interest in it. I find your approaches to problems and their solutions to be elegant and appreciate your honest appraisals of its strong and weak points. Very much looking forward to the resumption of this thread in a couple of weeks.
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  #18  
Old 08-01-2017, 04:02 PM
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Its very hard. I am going to run the back side thru and print black on the whole sheet. I guess I might need sharper scissors too.Great Job!!!!
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  #19  
Old 08-15-2017, 10:49 AM
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->Spaceagent: good idea with the black print at the back. There might be a problem of glue not sticking properly to the toner layer, but that's solvable.

->Elliott: lack of interest? Well, the kit is quite new and not based on any famous movie or book. So build threads are the only advertisements it can get .

All right, let's go spoil Jan's backstory with a bit of science .

First: who built the Robinson? The official story suggests some unspecified aliens (blue sun, unknown location names etc.), the ships themselves suggest earthlings (latin script, English words, five-fingered hand in Beam catcher's logo, two lovely nose arts and also the name of the complex). Now what? I applied a universal bipolar determinator (a.k.a. coin flip) and decided for the second variant. And I've already read two books about aliens escaping from supernovas, so it wouldn't be very original anyway .

So it's our own civilization in an unspecified future. We haven't invented faster-than-light travel at that time, because otherwise a) we wouldn't be travelling in a sublight ark and b) we would already have colonies in other star systems, so one exploded sun wouldn't be such a trouble. But interplanetary flights are no problem.

Second: what energy sources do we have? It doesn't matter whether we can annihilate antimatter or not, because antimatter first needs to be made from energy made from something else. Neutronium annihilation and other comic book inventions are probably beyond our reach, so let's stay with nuclear fusion. Fission is too weak for practical space travel.

Third: what kind of propulsion do our spaceships use? The unoverlookable nozzles say good old reactive drive. That means we haven't yet discovered how to control gravity, otherwise our ships would look different. Therefore we need some non-gravitational device which a) creates an illusion of gravity on ships' decks (those hulls don't look like having been designed to accommodate centrifuges), and b) allows the ships to land on planets even with their lack of streamlining. This could be repulsors: something that doesn't exist even in theory, but appears in sci-fi quite often. In our case, it might be a device emitting some unspecified force field which freely overlaps with matter and repulses it away from its focal point. Emitor's geometry determines focus and shape of the field - see fig. 1 and 2:



Fig. 3 shows what happens when a repulsor approaches a large solid mass, like ground: the field pushes against the mass and an equal reactive force pushes back on the emitter, creating thrust. Of course, the volume of air molecules between emitter and ground gets blown away too, so repulsion hovercrafts make the same dusty mess as today's propeller-driven ones (they have it all wrong in Star wars ). If we apply more power, we rise higher, ultimately hovering in the air like a helicopter. It needs more power (Froude efficiency: the more kinetic energy lost in vortices behind an aircraft, the less of it remains to propel us forward), but it's possible. Repulsive field has nothing to push against in vacuum, but that's no problem: just squirt some fluid through the focal point, the field accelerates it and you get a rocket. And artificial gravity? Line your ceilings with low-power wide-field repulsors and they will push you against the floor. They will also blow the surrounding air around you, but if the field is homogenous enough, it should be no worse than the usual draft from ventilation ducts.

But repulsion drive has a big disadvantage in space: it needs reaction mass. Not very much because it can theoretically accelerate it to very high relativistic velocities, but eventually it will run out of it. Long-range cargo ships need something better: photon drive. A photon is a nonmaterial particle whose mass is non-zero only because it travels at the speed of light (zero gets multiplied by infinity in some equation, accidentally giving something real and positive). Energy consumption is high, but we can replenish hydrogen for fusion reactors in interstellar space (that's exactly what our ion refinery does) and recycle the fused helium in repulsion thrusters.

In case of Robinson, let's assume the two long-range freighters, Solar explorer and Next liner, have photon engines. Neucom (which looks like repulsor-only tourist vessel) also had to be equipped with some improvised variant because she is located above the axis of thrust of the two main engines and if she didn't balance it with her own drive, the complex would fly in circles.

Fourth: what is the usual lifespan of a spaceship in Robinson's era? I think it might be quite long. "Consumables" like personal electronics or cars become obsolete and are replaced faster and faster these days, but complex and expensive nuclear machinery stays in service for decades (for example: carrier ship USS Enterprise had clocked over 55 years). If a spaceship doesn't lose parts on takeoff, can be reused without a complete overhaul after each flight and is economically profitable, why couldn't it fly around for a century? So it's worth building it tough to actually survive that century. Of course, some scientific breakthrough might happen and make all contemporary spacecraft obsolete, but it looks like it hasn't happened yet (we all know how long it took (resp. will take) to get to first practical fusion reactor). This is not going to affect the model much, but at least it explains all the wear marks we can see on most of the surfaces.


I hope next time there will be something to take pictures of.
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  #20  
Old 09-11-2017, 11:20 AM
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The exercise continues with another shuttle:



Originally just two parts, but they proliferated to over thirty again and this is the result:



Lesson learned: when photographing black things on white background, set the exposimeter so that it only measures brightness of the target, not the whole field.

The stern got new engines and also a rudder which makes the plane look sexier. It's black because it doubles as heat radiator, and as we all know, blackbody radiates best (and also because it was cut from the bottom side of wings from the second print, but no one needs to know that). Wing roots and fuselage bottom are rounded; I'm not happy with spoiling the nice curves with landing gear, but the plane needs to park somehow. The parking is going to be interesting anyway, because I totally forgot to install any magnetic anchor. So either I'll stuff some wire chips in the remaining holes, or the shuttle will be glued to the ship permanently.

Last thing to figure out is how passengers get into the plane, and scratchbuild some connecting tunnel or catwalk. Let's pick the tall windowed sections on hull sides, some of the panes might be openable. Air intakes just a step away look scary, but repulsion impellors have no spinning turbines, so they are easy to shut down anytime and don't ingest anybody.

Next time I'll probably build sibling number 5, before I forget all dimensions and tricks used on this one.
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