Recreating the Zero-X from Gerry Andersons Thunderbirds Are Go

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When International Rescue made the leap from black & white television to the large cinema screen it wasn't the colourful Thunderbird machines that took centre stage but a large metallic blue spacecraft called the Zero-X.
This multi-winged space plane took a crew of four to the Rock-Snake covered plains of Mars before crashing back to Earth in a blazing fireball.

Picture left: My model on display at RAF Cosford 2013.

However this wasn't the end for the Zero-X as the detachable front section, the MEV, was filmed again for the opening episode of 'Captain Scarlet and the Mysterons' where it accidentally blasted the Mysteron Complex to ruin. Then more importantly the Zero-X appeared each week in the classic TV21 comic with a full colour two-page strip inside and regular photographs on the cover.

This strip enjoyed a continuous run for three years until the comic's demise, which was surprising considering it was the only one without a TV series to support it. At the time this comic strip quickly became my favourite and was the first story I looked for each week. Now I can say its easily my all time favourite and that's because it was often drawn by Mike Noble (example left) who's attention to detail and realistic approach made him, in my opinion, the best artist working on the publication.

On the silver screen the giant craft was represented by two complete models. The largest version, used for close-up scenes, reportedly cost 3000 and measured 7 feet long and was supplemented by a half scale copy used for wide-angle takeoff and flying shots. There also seem to be at least two larger scale MEV's constructed for scenes on the Martian planet.

Unfortunately the climax of the movie revolved around the Zero-X crashing into a small city, a sequence that ended up having to be filmed twice due to the first attempt not being considered spectacular enough. As a result of all this pyrotechnic work the large Zero-X model was completely destroyed, but the smaller version did survive and was later photographed for the comic.

The Build

by David Sisson

The Zero-X was one of the first models I ever tried to scratchbuild due partly to the fact that it has a lot of flat areas that I could easily make with sheet plastic. Unfortunately this first attempt in 1983 wasn't that impressive and so later in 1993 I decided to have another go. Little did I know that I wouldn't finish the model until late in 2006 which was somewhat longer than I was expecting.

My first task was to draw up a blueprint and I collected as many photographs of the original models as I could together with the video and later the DVD that came in very handy. The two main models were generally similar in shape and overall proportions to each other but like all models differed in certain areas. The biggest difference is normally caused by the curves put onto the edges of the two models as they are usually done to a similar degree, which means that when you take scale into account the smaller model often ends up looking rounder, or less square. Personally I prefer the larger model but the all important profile pictures were of the smaller version, so I would be working mostly from that model but then using publicity photos to adapt key areas to reflect the larger crafts appearence.

Size wise I usually like to build my replicas to the same scale as a studio model, often because of any model kit parts that have been used. However on this kit part free design I decided to choose a size and ended up with a model around 53 inches long with a 43 inch wingspan (I'm not sure now how I came to pick that!) which makes it rather big and probably the largest model I'll ever make.


At the beginning it all seemed very easy, as again I quickly assembled the main body using flat sheets of plastic. This time the standard 'Plasticard', modellers plastic sheeting, was clearly not going to be up to the job so I went to my local DIY store and bought a very large sheet of 4mm Perspex. The main pieces were cut from this and assembled using internal Plasticard bulkheads to create the shape. Coarse wet & dry paper was then used to rub it all down and round off the edges. .

You can't use flat plastic sheets for everything though - a mistake made by a lot of scratchbuilders who usually end up with very square looking models. The more curvy rear engine section had to be blocked out in two separate sections using Balsa wood.

The lower piece was a hollow box made from 1/2inch thick sheets and moulded in two halves, using plaster of Paris, resulting in this somewhat rough fibreglass casting. Car filler fixed all of the larger holes, then knifing putty and spray filler sorted out the minor imperfections. More resin and fibreglass matting was applied to the inside to create a strong join while some internal supports held the parts level during the process.

The upper rear section was carved from several layers of Balsa assembled into a block, then cast in one piece. The masters for this area of the model were all solid shapes with the many openings being cut from the final castings. The two large inlets were formed at the end of the process by building up the shape in layers of P38 car filler on an inner plastic support frame..

So far so good, but as I was just working on the central main body I decided to push ahead and finish the MEV first. Here the basic shape was formed in 4mm Perspex and thinner Plastic sheet. The edges required a lot of work to get the required curves so the structure was strengthened with internal bulkheads and by smearing car filler along the inside joints.
The cockpit section, done as a separate piece, was cast in fibreglass with clear resin windows.

Unfortunately after completing the MEV I found that the sprayed on paint began to peel off the surface of the Perspex especially when I drew on the panels lines with a biro - as the pressure of the nib caused the paint to buckle!
This set back with just the small front section made me realise what a disaster I would have with the rest of the large Perspex model as the main body would need to be handled a great deal and the paint would be forever chipping off whenever the model got a knock. Put off by the thought I dumped the model in the loft for a while and the whole project stalled at this point for a few years.

After a good deal of thought, involving the possibility of restarting from scratch, I decided to continue with the parts I had already made but just use the Perspex shapes as master patterns and produce fibreglass copies from a set of plaster moulds. This was a better idea anyway as the rear section had to be fibreglass and so I would get a much better connection using the same materials.

For those that haven't read any of the other articles here's a brief description of my very simple fibre glassing technique.

1. I always use moulds made from plaster of Paris apart from small multiple items where a rubber mould is needed. After the mould has been pulled off the master pattern it has to be left for a week or two to properly dry out, you can tell when this has happened as it suddenly stops feeling cold to the touch. If this isn't done then it can stop the fibreglass resin from properly curing and creating a very rough pitted surface finish.

2. I spray the inside of the plaster mould with gloss paint, from my large collection of almost empty spray cans, which seals the porous plaster surface and I then rub this over with household wax. If you don't do this resin will bond with the plaster and you will never get your casting out of the mould!

3. I just use resin and Fibreglass tissue & matting from my local motorcar accessory shop together with a dozen or so very cheap paintbrush's that are thrown away during the process as the bristles gunk up with the reacting resin mixture.

4. All the fibreglass matting is pre-cut into differing sizes and shapes and then spread out in an open box for me to grab easily during the frantic casting process. Advice - cut up far more than you think you will need and in very odd shapes because you'll probably need them.

5. The first layer that I apply to the mould is usually a sloppy mixture of car filler and resin that will become the surface of the final part. Fibreglass tissue is then added over this followed by more resin, then fibreglass matting and even more resin.

6. After its all set I remove the casting by breaking the plaster mould as with my limited prevention measures the resin will still be sticking to the plaster quite well in places. The plaster can be knocked off with a hammer or prised off with tools and then finally all removed by immersing the part in water and rubbing it off. I don't actually mind all this too much because as fibreglass sets it can often distort and pull away from the surface of the mould - but if its slightly sticking to the mould then it should end up being exactly the same shape and not a shrunken version. I actually had more problems with big rubber moulds because of movement!

7. I always use a good quality dust mask/respirator during the process, work in well ventilated areas and I don't wear clothes that I'm particularly fond of and wish to wear again - as its a very smelly messy business. Gloves are best worn although I find it better to only wear one as it can be a bit tricky getting hold of some of the parts. I then clean any resin off my hand with a rag dipped in cellulose thinners before washing well with soap and water. Also beware of the edges of the finished fibreglass castings as they can be ultra-sharp. I suggest that you don't try any of this if you are under 16 years of age - or clumsy.

Back to the model again.

Two plaster moulds were made of the main hull, top and bottom, as there is a seam down the sides that happily covers the join line. The front wheel well was created in the casting process by isolating the area using plastic strips..Similarly the recessed band that goes around the front section could also be done by gluing lengths of plastic into the plaster mould (see white bit) beforehand that would transfer into the fibreglass and could then be later removed.

The series of groves, along the hull, were now cut and filed into the smooth moulded surface. .

The lower rear section was now attached to the main fuselage. The biggest problem here was just keeping everything flat and straight. The access hole cut in the top provided a way to apply the extra fibreglass to strengthen the connection point and to build up the inside lining of the adjoining air-inlets..

The engine inlet vents took a great deal of effort to shape, building the parts up using plastic and filler whilst modifying the surrounding fibreglass area. It this stage of the project I was just applying spray filler (the yellow bits) and rubbing it down with wet & dry paper for weeks trying to get the contours I wanted.

In the photo (above right) the concave curved opening has been created by applying filler between two plastic temporary pre-shaped supports and pushing a piece of plastic tube into the filler as it sets. As I was mostly working from profile pictures of the small studio model I failed to notice that the big version that I preferred is actually different in this area, instead of the angular wedge shape it actually curves round...

The tail fin was a fairly complex series of shapes and I finally decided to build it in layers, the bottom two being formed in car filler around a 1.5mm Plasticard outline, the exposed edges of which had to be cut away and filled at the end of the process. The thinner top piece was shaped from several layers of plastic sheeting. On the original studio models this fin could retract but it was a feature that was never used - and as a result I certainly didn't want to have it on mine.

The model was given several coats of spray filler and rubbed down with wet & dry paper with any minor pinholes or surface blemish's being filled. It was then painted using cellulose motorcar spray paint.
The larger red bands were also sprayed on whilst the thinner ones are Letraset Letraline tapes. Chrome finish for the air inlets using self-adhesive metal foil (exhaust pipe repair tape). Like on the original models, this has to be applied in thin strips due to the curvy nature of the area and as a result gives it a more realistic panel effect finish.

The rear engine block was built from plastic with an outer layer of corrugated plastic sheeting. Again this had to be covered in metal foil, a tricky process which had to be done slowly, as I had to get it on smoothly whilst also pushing it into all the groves.

The five small engine bells were thinly cast in a P38/resin mix with the three larger ones being formed from highly modified kit-parts. All of them were then outfitted with smooth internal plastic cores that I heat-formed from 0.75mm Plasticard.

One of the many delays to this project was the need to find nearly a hundred decent wheels because the plan had always been to have the Zero-X displayed with its landing gear in the down position.
Luckily I eventually came across a chap who supplies replacement parts for various toy and model cars (Steve Flowers - Leicester, UK) and he had a metal wheel with a rubber tyre that was just about perfect.
The wheels were mounted on brass rod axles held in plastic frames on a brass tube support struts. The wheels are held in place by hammering small metal washers onto the ends of the axles. The front wheel bay was built as a separate unit, inserted into the hole in the hull and secured with a screw. It should therefore be possible to remove all the wheels and supports if I decide to show the model with its landing gear in the retracted position.

The MEV is secured to the main body with two threaded rods that pass through the engine tubes. Access to these is via a detachable cabin section held in place with magnets. This section was cast in fibreglass, it's window areas cut out and then back-filled with clear resin. Built in 1994 its actually the oldest part on the model and I'm planning on changing it soon for one with rounder edges and clearer windows. Internal detail is fairly basic as not much can be glimpsed through the small windows; I fixed metal foil to the rear bulkhead to help backlight the figures.

The internal cabin layout is somewhat confusing. The film presents the pilot cabin behind just one set of the four small windows, cut-away drawings from the sixties pinpoint it behind both sets whilst the comic often shows it extending right across the whole frontal area!
Personally I think that the film presentation was either the result of a mistake in the set building plans or a practical consideration, so I've decided to put mine behind both small sets of windows as this makes far more sense to me.

Another change from the film was the shape of the two main engines. The originals were cone shaped designs with small tubes extending from the centre, although in a repeat of the Thunderbird 2 bungle the actual special effects rockets came out of a different place!! As a fan of the comic strip I never really liked this odd design so I went for the bigger, more powerful looking, TV21 versions. (Note - at the beginning of the film the MEV butt's up against the Mainbody and slides into position, an impossible move for a craft sporting any exhaust tubes!)



One of the reasons for the delay in completing this model was that I was unsure of how to construct the large wings; I was also worried that after building them they would both end up drooping!
My basic technical knowledge told me that several layers of materials glued together, in a composite, are stronger than one thick material as they act against each other. So I decided to build up the shape of each wing using layers of different materials starting with the basic outline cut from thin MDF.

This MDF sheet became the horizontal centre of the wing with sheets of Balsa added above and below to create the aerofoil shape. As the wing thickness also reduces towards the wing tip I glued plastic tapering strips into place behind the leading edge in order to act as guide markers for sanding down the Balsa to the desired angles. Weights were placed on the sheets of wood to keep them compressed while the glue set, after which I could then begin shaping the wings by firstly trimming off the obvious surplus wood with a knife. The pictures here show the front wing which was easier to work on as both wingtips were made separately. Later in the process I removed the rear protruding engine area and the two front inlets..

The next stage was to spend a great deal of time sanding the wings down to the correct shape - and then to take them down even further, as the wood needed to be given a fibreglass coating which would add to the overall thickness.
When they were ready I gave the wings a coat of SP113 laminating resin, this is a two-part epoxy resin (used by radio controlled model aircraft and boat builders) that depending on the mixture and temperature takes up to a day or more to set properly. This initial coating sinks into the wood and when set leaves a rough surface finish that needs cutting back with wet & dry abrasive paper. I then checked over the wing for any major imperfections that needed correcting with car filler before applying another coating of the resin. This next application also included fibreglass tissue, to give the wings extra strength, and it had to be applied very carefully to prevent any lumps appearing. Again it was all left for several days to thoroughly set before being sanded down and a final topcoat of resin to finish it all off. Then the wings were then treated with several coats of spray filler and sanding began again with any uneven areas and holes being fixed with car filler.

Picture right; shows the rear wing, with the areas for the undercarriage being cut out. There isn't really enough room in the wing for the wheels to fit but I preferred to cut a semi-recess than just fix the undercarriage to the wing surface (which is often seen on models that appeared in Gerry Anderson TV shows).

A master pattern for the bullet shaped front end was sculpted, moulded in plaster and then two copies cast up in a resin/car filler mix. These were then secured to the MDF core of each wing, with the surrounding air-intake areas formed in plastic sheeting which was all blended into the wing with more filler..The rear triangular engine sections were made in a mixture of plastic and filler.

For the outer wing fairings I made a master pattern of only half the shape then cast up eight copies and paired them off.

See the Thunderbird 3 build for details on making this type of shape.

The areas for the undercarriage hatch covers were pencilled into position and drilled out. Slots were also drilled out to allow the fairings to be embedded onto the wingtips, superglue held them in position whilst car filler was smeared around the parts to securely lock everything together..

The vertical fins on the wings were formed from MDF. A centre line was drawn around the edges of each fin and then they were sanded down to an aerofoil shape, coated in resin and sanded smooth. Cardboard versions were used to test the final shape and position. The fins are one of the items that are very different on the two studio models.
Slots were cut into both the fins and wings allowing them the lock into each other. Then the parts were glued and filler used to blend them together.

The next problem was building 16 engines!
Repetitive jobs are something that I hate doing, as I'm usually very bored by the time I've made the fifth identical part! Although the engines look like square boxy shapes they do have very round edges so making them from plastic sheeting would not only require a lot of pieces but then a lot of hard sanding.
The answer, again, was to cast the parts in a car filler/resin mixture using some sort of mould.

For speed I decided against making a rubber mould and opted for a solid plastic one that could be taken apart to release the castings. Here a centre core forms the main shape with the sides, strengthened with metal rods, simply held in place with elastic bands.
As the mixture dissolves styrene plastic I had to cover the parts in adhesive metal foil that I waxed to help prevent the filler from adhering.

The aerofoil shape of the wing was cut from the sides of each engine using two templates as a rough quick guide. Then each engine was carefully adjusted to its correct position and numbered so I didn't mix them up. To create a perfect join a small amount of filler was applied to each edge and then the engine bodies were pushed into place against the wings surface.
The surplus filler that squeezed out of the sides was trimmed off as it began to set, whilst the wings paint surface was protected during the process by temporarily covering it with clear adhesive tape.
Note - The tape is first applied to either my skin or trousers to kill off some of its adhesive strength and stop it from lifting the paint when it is removed. .

Because of the tape all 16 engine bodies could then be easily prised off, sanded smooth, painted, then reattached using clear 2-part epoxy glue. More detailed multiple parts had to be produced using rubber moulds. These were all painted prior to being fixed in position.

There are no reference photos of the inside of the wheel housings so I just had to invent something that looked good. The hatch covers were vac-formed in 0.75mm plastic sheet over the master pattern.
The large inlet cones were temporarily glued into position whilst the series of small plastic vanes were applied around the base, each one having to be trimmed to perfectly match the gap, then the finished part could be snapped free and painted before being permanently attached.

The large numbers were spray painted on using masking tape outlines. Letraset numbers were enlarged to the right size and used as a guide to cut out the shape from the masking tape. These numbers were placed on the model and moved about until they were in the right position, then the surrounding tape was placed back over it and the number removed. The edges of the tape were carefully pressed down, to stop any paint from bleeding under it, and then the paint applied in a series of light coats, again to prevent bleed through and get a sharp edge..

More sets of wheels were now assembled. Luckily the front wing only has two sets but the rear wing features five, which includes a small steering unit. The two main centre sets were soldered to Brass plates that were glued into the wing recesses.

Left; In this unused SFX shot the front Lifting Body takes off to rendezvous with the Zero-X mainbody. Note that there are no wheels on the ends of the wings due to the folding design - so why does the rear wing need them?

The engine exhausts were the final details to be added to the wings. The two studio models seem to differ here, with the small model having large empty square outlets and the big version having round holes with rocket tubes protruding. I didn't fancy the empty space or tube look so I used a metal mesh to blank off the holes.

All the panel lines now had to be added using a black ballpoint pen. Weathering was applied just using black powder paint rubbed on by hand against masking tapes, whilst chipped paint highlights were added to the edges of the panels using silver enamel paint. The large White band on the wings is in a different position on the two original models so I compromised and picked a position between the two, allowing it to just clear the outer engine.

Paint colour can always be a problem decision and the Zero-X was no exception here. While there's no question over it having a metallic Blue paint finish the puzzle is how Blue should it be?
The original studio models appear to have a rather pale colour at times, and if you watch the film they do look to have an almost 'washed-out' appearance in many scenes. But having looked at photographs of the models published in books, magazines and comics, together with toys and models made over the last 40 years they all tend to look very much darker! So we are again faced with the problem of making something the way it actually was - or how it is perceived to be!

I have spent much of the last 25 years attempting to be super-accurate in my model making, but now I'm trying to relax over certain issues and accept that somethings either can't be done to a 'totally' accurate level or they don't really want to be done that way.
As my viewpoint is from watching the programs I'm inclined to have the model look more like I expect it to be rather than perhaps how it originally was, and so with this in mind I felt free to go for a slightly darker/richer shade of Blue.
I should also mention that this view was heavily influenced by my 25-year-old memories of seeing a very large Zero-X replica that had a lighter colour scheme and I remember thinking that the ship's design looked poorer for it, because without a strong colour the craft seemed to loose some of its presence!

Again I used motorcar spray paints and I had to visit numerous shops before initially deciding to paint the Mainbody using a colour called Miami Blue. However after displaying this part of the model at the Fanderson 2004 Convention I decided that it was just too dark. So when I came to complete the wings I decided to repaint the whole model using a lighter colour called Cosmos Blue. (The colour has to be light enough for you to clearly see the drawn on panel lines.)

But at the Fanderson 2006 Convention the completed model was displayed next to other versions including a Martin Bower MEV that I believe uses a colour called Kingfisher Blue. They were all very similar in appearance, but Mike Trim walked in took one look at them all and said - 'Wrong colour'!

And no I haven't made the chrome nosecone, as I don't really like it, especially as it covers the front of the MEV - which I think is one of the best features on the model. I'll probably end up making it at some point in the future but I'll probably be building another bigger version of the MEV before that, possibly the Mike Noble comic version.


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