Star Trek's Son'A Drone

Scratchbuilt model 'how-to'. Caution - 30 medium jpegs!

The Son'A drone appeared in Star Trek "Insurrection" as an autonomous device for tagging the fleeing planet inhabitants for transport off the surface. The drones were about half a meter across and consisted of a small dart throwing body about the size of an orange, and two curved A4-sized wings, presumably related to some field-control manoeuvring system. My drone model was going to be a display piece at the Contagion 2000 Star Trek convention, and I was looking forward to building it as it was both a full scale replica and a really cool looking device. There were also no lights in it, so the bank account could sit this one out!

No doubt the Insurrection movie will have a dedicated "art of..." book in the fullness of time, but for now my reference material was the film and the articles in edition 34 of SF&F. There were two distinctly different versions of the drone: a pre-production test and the final version. Although very similar in size and shape, the pre-production test had plain elliptical copper banded wings, while the final movie version had lots of surface panelling and a metallic green and silver finish. The hardest part was going to be getting the wing angle right from the available pictures. The wing support structures were simple oleo struts, and the central 'business area' looked to be a petelled sphere opened at the front, and didn't look too difficult.



the real thing (© Sci-Fi & Fantasy Models, Issue 34, p30)


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This is just about all that's needed, although the detailed shape of the boomerang bit at the top has to be precise: if it's not, the wings won't automatically emerge from the bulkheads at the right angle.


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I decided to try a card model first (1mm card), to give me some kind of handle on the wing angles. The plans, measurements and templates I refined on the model would be transferred directly to the plastic sheet for the replica. It would have taken a month of Sundays to cut-and-try, so I decided to get a bit of graph paper and try to do the job right first time. There are two main components in the wing assembly: the wings and the front bulkhead, split into to halves, that the wings attach to. The front bulkhead halves lean forward with a separation of 120, and the wings sweep backwards at 120 from these bulkheads. The front bulkheads looked to be elliptical, and at first I thought that this was because of the angle, but they were in fact elliptical. For the maths fans, the primary and secondary dimensions of the ellipse were 13cm and 19cm, with a central cut-out of 9.6 and 8cm, respectively. Now, the problem here is that these elliptical bulkheads meet with the wings at an angle of 120, and this changes the geometry considerably. Dredging the dusty reference section of my bookcase, I found my old maths books and worked out the equation of the next curve &endash; this is what the front of the wings will have to be cut to, to meet with the bulkheads. I cut the bulkheads as a single piece of card (they meet in the middle anyway) and folded it in the middle, and cut a 'W' shaped card support with all angles at 120 to keep all the angles right, and with the length of the 'arms' 9.5cm (+ an extra 1mm to allow for the thickness of the card when bending) to make a rib for the wings to sit on. I stuck the bulkhead to the support with PrittStick, then started cutting wings out of paper and trying them for size. I had pretty well tied down the wing angle; the front of the wing (where it meets the bulkhead) was the right shape already (thanks to my maths book), and the overall length I could get from relative measurements, but the plan form of the wings I had to make guestimates of &endash; I reckon I got it to within 1cm either way of the key points, and just kept cutting out different variations until they matched the photos. The one thing I couldn't change was the curve on the front of each attempt &endash; this was crucial in making the wings sit right on the bulkheads. This left me with a cardboard and paper mock-up of the wing assembly, and it looked pretty good so far &endash; this was certainly the biggest hurdle. I had nothing on the spine or wing supports yet though &endash; no problem, I'll do them as I come to them, I thought…….


Which is the job that presented itself next. I couldn't fix the wings once I'd made them without the central 'axle' and the spine, so it was of to the stationers for some A3 graph paper. After some quick sketches with the plan of the wings as a starting point, I had figured out the principle dimensions of the axle and spine: The next questions would be on materials selection and construction, and this would largely depend on whether I wanted the thing to dismantle, bearing in mind that it had to be transported to a convention along with some other bits & pieces.


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Since I was happy with the cardboard and paper templates for the wings, I decided to get them out of the way first. The detailing was simple &endash; a raised outline and centre piece about 1cm broad, and double the thickness of the wing itself, which looked to be of the order of a few millimetres. I selected 2mm plasticard for the job, but not the sheets available at modelling outlets &endash; they're too small: I bought a large sheet from a plastics fabricator (wow &endash; what a price difference: about 20% of the shop price!). I cut out 2 wings, by printing a template on paper then sticking the paper to the plasticard with SprayMount aerosol glue (health & safety &endash; use a respirator with appropriate filter): this scrubs off easily later. These wings were solid, and would be overlain by the cut-out wings for detail as this was easier than trimming lots of 1cm-wide strip, but there is a bigger advantage as you'll read about shortly. I also cut out the oval bulkheads at this point, again with a stick-down template. I marked out radial lines on the paper template every 7.5 - 12 per quarter &endash; and marked each one top and bottom with a hole punch. These would help me place the rib details on the bulkhead later. Since the wings would meet the bulkhead at a 120 angle, I knew it was going to be a difficult glue-up, so I made a mounting tool in the form of a bulkhead half supported at 60 by a big rib and with a toe-plate to hold the real bulkhead. I used masking tape to hold the wing at the right shape, then held the real bulkhead against the mounting tool, then tried a test fit with the wing &endash; did you spot the problem? The masking tape holding the wing in the correct curved shape was fouling on the rib. Now, everything was fine with this procedure apart from that, so I decided to cut slots in the rib where I wanted the tape to pass through. This means that the assembly will be taped up until it's dry, but I was close to a working solution here, so I persevered. With a few tape slots cut, I glued the nicely formed wing onto the bulkhead with the big rib holding it horizontal along it's midline, just like I wanted &endash; lovely job.



Now, the spring in the 2mm plasticard would have popped the glue off as soon as I released the tape, I'm sure. No problem &endash; that's where the overlay cut-out wing comes in. Glued into place on the curved under-wing, the overlay would act as a cantilever, holding the curve that the tape had given me until now. I held a sheet of paper over the wing and traced it, and found that the surface had grown by about 6mm overall because of being on the outside of the curve, so I adjusted the template accordingly and cut out 2 more wings, then cut out the panels to form the overlay. I glued one into place over the curved under wing, and held it in place with clothes-pegs. I re-positioned the tapes one-by-one as I glued it up, so that the tape wouldn't be trapped and do that the curve would be maintained. I gave it a good few hours to dry, cut the tape &endash; perfect result! Wing undersurface detail was stuck on as for the top, adding some more strength into the bargain. The second wing was a repeat of this process. I stuck a good bead of Milliput on the back of the joins with the bulkhead just for good measure. The under wing and overlay edges were tidied up with w&d paper.


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The hinge looked to be a simple rhomboid box with the dart throwing 'orange' in front and the spine sticking out of the back with the wings stuck on the top and bottom. I was concerned about two factors: keeping the whole assembly rigid (the wings were weighing at just under 1kg by now), and keeping the angles at either 60, 90 or 120. I decided to make the spine out of brass tube, with cast resin detail, and to make the rhomboid box out of resin filled plasticard offering strength with easy fixing later.


The symmetry of the rhomboid box is important, as it defines the angle of the spine relative to the wings. I cut the basic shape from plasticard sheet with a couple of ribs to help to form the sides, then stuck the front and back plates together with SprayMount so that I could guarantee drilling a hole in the same place in each with a drill and press, forming the horizontal (long) axis. I did the same with the top and bottom plates for the vertical (short) axis. I glued the ribs, top and bottom plates and sides onto the backplate with the plastic pipe running through the vertical axis holes to line everything up. That's as far as I could go before the step below....


Apart from the rhomboid box the most prominent aspect of the hinge is the disk assembly at the top and bottom. I found a plastic milk bottle top and a spice jar top that had the right properties, and took casts with condensing silicone compound (403 866 from Tiranti), then moulded them with resin (405 500 from Tiranti). The bases of the disks were finished by grinding on a bit of w&d paper. I drilled a 9mm hole centrally in the larger discs, and filed each hole to be a tight fit for 1cm plastic tube. I drilled a 1mm hole centrally in one of the smaller disks &endash; you'll see why in a minute. The tube was cut to match the height of the wing bulkheads + the 2x5mm of the larger discs into which the pipe would slide. Now I glued each small resin disk to each larger one with a blob of resin, then pushed the plastic tube through the vertical axis of the rhombus then into one of the disk assemblies (the one without the 1mm hole). This blocks off the horizontal axis hole in the rhombus &endash; don't panic! This whole disk/pipe/rhombus assembly was held vertical and resin poured in to fill the plastic tube and leave a slight meniscus, and the other disk assembly (the one with the 1mm hole) pushed on top &endash; the hole allowed air to escape and squeezed a drop of resin out &endash; this was wiped off and I knew I had a good join. At this stage, I could spin the rhombus freely about the vertical plastic pipe.


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Now for the brass tube of the spine. After centring the rhomboid on the vertical plastic pipe, and using a mini drill, I burred away enough of the resin filled plastic pipe to clear the horizontal axis rhombus hole (health & safety &endash; use a respirator with appropriate filter), then passed the brass tube through &endash; leave 5cm in front of the rhombus for the 'orange', and cut the other end to be 5cm proud of the box: the spine and 'orange' will be in 0.9cm brass tube, and will plug into the 5cm sockets. I mixed up several batches of resin to fill the rhombus in several goes, as it might have generated enough curing heat to melt the plastic of the rhombus otherwise &endash; could have used longer set stuff but once I'm on a roll I keep going! For the first pour, I popped the backplate into place to fix the brass tube at 90 to the rhombus until the resin set and could hold it. With the last pour, I stuck the backplate in place. I now had something resembling a WW1 gun carriage, completely symmetrical and solid as a rock &endash; just the job!

A box

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The spine supports a backward 'A' shaped box in the middle holding the two wing positioning rams. The box emerges from a central bulge on the spine, comprised of a cylinder with a bullet shaped nose and tail, and a similar bullet shaped fairing where it emerges from the hinge rhomboid. I decided to make three identical bullet shapes for the spine detail, and to make the 'A' shaped box from plastic sheet to save weight &endash; it was getting a bit on the heavy side.

Looking around the house I found a 20W candle bulb with just the right profile for the bullet fairings. I made a cast by mixing some condensing silicone which was pushed into a small glass, then shoving the bulb into the silicone to half of the bulbs depth. To help pull the set silicone plug from the glass, I first dropped a plastic disk into the glass with nylon string at the back and trailing over the glass sides. By pulling on the string, the disk helped to pull the plug out of the glass, and the bulb was eased out in turn to leave a clean mould. I cut a 9mm hole at the apex of the mould by carefully twisting a 0.9cm brass tube section into it &endash; this allowed me to push the mould onto the 0.9cm brass tube section that formed the spine &endash; all I had to do now was hold it vertical and pour in resin to make a bullet-shaped fairing for the front of the 'A' box, then invert it and do the same for the back. The mould just slides off the brass tube, leaning the resin behind. My measurements showed the bullet casts had to be 8cm apart. I used the same technique for the third bullet, this time using a 4.5cm long, 1.1cm diameter brass section &endash; this would simply sit over the 5cm long socket emerging from the rhomboid box.

I cut top and bottom plastic templates for the 'A' box, and arranged them to fit between the resin bullets and held apart by the brass tube. The central cylinder was made from two half-cylinders in pre-bent plastic sheet, formed over the bullet rims and super-glued into place. The wings on my model were fixed, although the real ones articulated, but the positioning rams would add a lot of welcome support. The rams emerged from the 'feet' of the 'A' and headed out towards the trailing edges of the wings where they slotted into larger diameter sockets, about 5cm long. I used 6mm plastic tube for the ram and 8mm (next size up: good tight fit) for the sockets. The rams emerge from the apex of the 'A' box and point forward to the wings at about 20 so an elliptical hole (9mm by about 1.5cm) has to be cut on each side of the 'A' frame for this. I had to stop here &endash; I'd have to finalise the socket's exact location and angle after the wings were attached to the hinge.


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The 'orange' was made with another piece of 1.1cm diameter plastic pipe, 10cm long, with a 9cm diameter plastic disk attached. Next was 12 petals glued into a strip, then formed into a circle round the disk &endash; to get this right, I divided the circumference of the disk and carefully spaced a paper template as a test. Just before gluing I curled the ends of the petals inward over the edge of a table. At this point, the 'orange' could be pushed onto the front of the WW1 gun carriage, and the spine with it's 'A' box could be pushed onto the back: wing fixing and the rams were the next and final steps.

wing fixing

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Thanks to the template and the hinge design, the wings would pretty much only go together the right way &endash; all I had to worry about was the 120 angle, and I solved that with 2 small formers which were glued to the back of the wings, and which ran the full span of the bulkhead. The formers were cut with a 1cm diameter, three-quarter circle bite out of the inside angle which was a nice tight fit over the hinge axle and forced the wings to sit slightly apart, duplicating the original. A quick run of glue and one wing, both formers and the axle came together &endash; hence the reason for the resin-filled plastic rather than brass for the axle. The second wing went on shortly after when the first had dried.


The wings had a band running round the front edge where they join the bulkhead &endash; this wouldn't be structural on my replica, but it looked as if it was from the photo's in issue 34 of SF&F. I made it with a length of 8mmx3mm plastic U beam, sharply curved by pulling it over the edge of a table. This was superglued to the hinge disks and liquid poly'd to the front of the wings with lots of clothes pegs and tape to hold it as it dried.


Last step &endash; the wing rams. I slid the spine into place in the WW1 socket, then slipped the ram sockets onto the rams, then slid them down until they touched the wings, then cut the exact slope to meet the wings at the same point on each side. This leaves a 1cm overlap between the rams and sockets &endash; there is enough flexibility in the structure to allow the rams to be bent into these sockets when the sockets are fixed to the wings. At this point, the thing was basically complete and could be disassembled into three parts: the 'orange', the wings and the spine with 'A' box and two rams. Assembly was fiddly but easy, and the thing was reasonably robust and, more importantly, symmetrical. Victory!


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Detailing involved a few minor additions. There was the spike at the end &endash; an old sharpened brush handle, heavily primed and sanded, and stuck into the brass tail pipe. The front bulkheads had some 1.5mmx1.5mm plastic I beam strips glued on along the radial dents, and two raised 'boxes', one on each side, made with 8mm plastic pipe, capped at the ends and squared off with plastic sheet: the pipes must be in line with each other when fixed. The plastic pipe in the 'orange' was terminated by a lid from a detergent bottle. The wing panels have a ribbed section in the middle &endash; some 0.5mm sheet cut into strips and stuck in place does the job nicely. The hinge disks were capped with some washers and plastic lock-nuts. There are four triangular fins, I used 2mm plastic sheet, just forward of the 'A' box &endash; easily attached to the brass pipe with superglue &endash; this was my only metal-plastic join.


templatesmaquetteswingshinge spine'A'-boxwing fixingdetailingpaintingreal thinghome

Always a tricky one! The detail painting patterns were easy &endash; it was the colour blend that took the time. Fortunately, the drone only has two main colours: green and grey. It turned out that the grey was almost identical to auto primer. Now I think that, statistically, the chances of almost every grey I have to use on a model looking like auto primer must be zero, unless all the SFX guys out there also happen to use it! I've written a few SF&F reviews now, and saying 'looks like grey auto primer' is getting to sound a bit like 'tastes like chicken'! Still &endash; don't look a gift horse in the mouth &endash; slap auto primer all over. The green was a complex blend in Humbrol enamels as follows: 6 parts green 101, 3 parts white, 2 parts black, 2 parts metallic blue 52 and 1 part silver 191. If you don't fancy that, Halfords version of Nissan Leaf Green is a fast and very close alternative &endash; I almost went for this myself, but the blend I came up with has just a hint of blue in there that helps to get the right look in most light conditions. I used red-brown 100 for the spine fins and highlights on the ram sockets and tail, and gave the whole thing a coat of lacquer, as the studio model had a gloss finish.

the real thing

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