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.

MAIN BODY

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.

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!)