Fokker Spinne (Spider)
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I have started work on this scratch build by doing the engine first. This is an Argus 50hp four cylinder water cooled engine. I started by turning an aluminium rod down to 8.0mm, I also added the prop shaft extension and the casing at the rear for the gear drive. The cylinders are cut from 4.0mm aluminium rod, they will be sanded to 7.0mm long. The heads are made from four layers of 1.0mm styrene sheet glued together then cut and sanded to shape. The cylinder plate is also made from styrene sheet and four 4.0mm holes drilled in the appropriate position. I received an email from Robert Karr with drawings of the Argus engine, these drawings where very good and allowed me to scale them to 1:32 scale, this helped tremendously in getting the dimensions needed to make the engine. I glued the cylinder plate onto the crank case using CA, then I filled the gap with epoxy filler. The bolts are Grantd Line railway accessories and are fitted by drilling a 0.4mm hole then inserting the bolts, they are fixed with a very small drop of CA.

Once the two heads were sanded to shape I drilled four 2.0mm holes in each for the valve covers, the centre ones also hold the spark plugs. There will also be two primer taps on top of each cylinder. I inserted short lengths of 2.0mm brass tube into each of the holes and used CA to hold them in place. On the outside of the heads I glued three flanges on each, these came from left over cylinders from previous kits. The outer flanges will hold the exhaust pipes while the centre flange holds the intake manifold. I drill 4.0mm holes into the bottom of each cylinder head to accept the cylinders, these are a very snug fit.

After positioning the cylinders in the plate on the crank case making sure they were square in all directions I applied CA around the base of each cylinder. Once dry I refitted the heads and again making sure they were sitting square I applied CA around the cylinders, this made for a very strong assembly.

The push rods are made from 0.4mm brass tube with a small spring placed over each one. I drill 0.6mm holes into the crank case to take the bottom of the push rods and to allow a good solid mounting point for them, once in position a drop of CA holds them firmly. The intake manifold is made from spares from my spare parts box, at this stage it still needs some more work but this gives a general idea of what it will look like. I still need to add the crank case join flange which will run along the centre line of the crank case, also the mounts need to be made and added. The match gives you and idea of the size of this engine, it is not huge.

The engine is nearly finished, still need to add the plug leads and some plumbing. I added the four primer taps to the top of each cylinder, also the spark plugs, all these items were hand made. The cylinders and heads have been painted with Mr Metal Colour Iron, when dry it was lightly buffed. The push rods and plumbing was painted with Mr Metal Colour Stainless and buffed. The magneto was made from left over bits and pieces from my spares box as was the water pump. The match and hand photos gives a good size comparison of this engine, it is not huge.

The crank case flanges were added by cutting strips of styrene, they were cut to the appropriate length and shape and drilled with a 0.4mm drill bit to take the bolts, the flanges were glued to the crank case with CA. The engine mounts were also made from styrene sheet, cut and sanded to shape, these were glued to the crank case with 5 minute epoxy. I made the magneto from bits and pieces from my spares box, things I couldn’t find I made. I sampled some iron colour to give me an idea of what it was going to look like, I like it.

Frame construction is fairly straight forward, the two engine bearers are also the fuselage, all that will be added is a seat for the pilot. I made most of the frame from brass tube with the undercarriage legs being 1.0mm in diameter. The two main undercarriage beams are made from 1.6mm square solid brass with the front bent to the required shape. The whole assembly is held together with CA but it is quite flimsy at this stage, there will be a mass of rigging which will add the required strength to the assembly.

I have made and added the seat to the airframe, as can be seen it is a very simple metal frame and wood slat seat fixed to the timber beams, the flying position for the pilot is quite precarious and a seat belt would be essential.

The engine, like the pilot, sits very precariously on the two wood bearers fully exposed to the elements. Once the engine is fixed in position I will add the plumbing for the cooling system and the fuel  lines.

I added a few rigging lines to strengthen the frame assembly, it is now quite solid and easier to handle. I made the rigging attachment plates and fitted them to the top of each mast, they are made from brass sheet. I also made the fuel tank, this is made from two left over bombs in my spares box, they were cut in half then joined. The straps around the fuel tank are thin strips of styrene sheet.

I also made the control wheel, the wheel was made from 0.65mm copper wire bent to a circle then the spokes added from brass tube. The wheel was wrapped in 0.18mm copper wire. As per an original photo I have a small button and electrical wire was added to the wheel, I am presuming that this is an engine kill button.

These pictures show the fuel tank painted and sitting in position. The control wheel has been fitted. I have started to paint the frames, these will be done in Mr Metal Colour Stainless and when dry buffed to a medium sheen, the seat slats will be a light wood colour.

The seat has been painted using artist oils, once dry it will be given a coat of clear orange. The close-up shows the engine in detail and the fuel tank, it also demonstrates the excellence that Doug Craner put into making the laminated propeller.

I made the two radiators by first starting with styrene sheet cut to size, I then cut lengths of guitar string and glued each one onto the styrene using CA. The guitar string is phosphor bronze wrapped around stainless steel wire so hard wire cutters are needed to cut the lengths, the diameter of the string I used is 0.65mm. The second photo shows a trial fit of the two rediators.

The radiators have now been painted and fitted to the frame. I painted them using Humbrol Metal Cote Steel, once dry, about 20 minutes, I buffed the paint with a soft cloth to give a polished steel appearance. I now need to add the plumbing from the radiators to the engine.

The wheels are from John Vojtech, Scale Spokes at umm-usa and are fitted with white O Rings for the tyres. The rims and spokes have been painted with Mr Metal Color Stainless. The axle is 1.5mm brass tube which is the correct size for the hubs in the wheels. I have also started to add some of the rigging to the top mast, each rigging line has a turnbuckle so rigging takes a bit of time. Close examination will reveal that the plumbing has been added to the radiators and to the engine.

These three photos show the landing skid added, it is connected to the rear of the axle and drags behind under the seat. There is a support which runs up behind the seat with bungee cords, a pretty crude set up but functional.

The tail surface is made from 1.0mm styrene sheet cut to size from the plans. The ribs are simulated by gluing lengths of 1.0mm half round styrene strips to the tail. The set up here is only a temporary arrangement just to show roughly how it will look.

I’ve used a mixture of tan and off-white for the CDL colour, it is from the Gunze acrylic range. The reinforcing patches where the warping cables will fix to the tail and also on the ends of each strut have been painted using Humbrol No.62 Leather. The leather padding at the front of the tail plane is also painted with Humbrol No.62 Leather, the padding was formed using putty. The rudder support rod and the rigging cross bar are 1.0mm brass tube, they are only sitting loose just for the photo. The whole tail assembly will only be supported by two small U bolts which mount to the frame just behind the seat, the rest of the support will come from the rigging which will be fixed to the rear rigging mast. There will be eight cables on top and below the elevator to control the warping.

I have commenced the rigging on the tail, I am using 0.12mm monofilament as the rigging lines and once fitted they are painted with Mr Metal Color Stainless. The turnbuckles are of the one ended type with the tail fitted directly to the tail. The rudder support bar is also fitted, this is 1.0mm brass tube and the stays are 0.8mm brass tube

The rudder is made from styrene sheet cut and sanded to shape, I made the Fokker decal on my drawing program and printed it out on clear water slide decal paper. The font is French Script but I had to reshape the F to conform with the photo I have. The warping rigging is attached to the elevator, the connection for the cables are two 3.0mm x 3.0mm x 3.0mm triangles of brass sheet with the rigging lines sandwiched between then and super glued. I still need to add a rudder to the underside of the tail and also the warping rigging lines.

The bottom rudder is now fitted, no decals on this rudder. The tail rigging is now complete, the eight warping wires for the bottom of the elevator are now fitted as are the control cables for the two rudders. The next step in construction are the wings, these will be a bit of a worry.

The wings are made up of two layers of 0.25mm styrene sheet, they are cut to shape then glued together, a length of 10.0mm brass rod was used to create the curved leading edge of the wing, the remainder of the wing is just a big flat section. I used 1.0mm half round styrene strips to simulate the ribs on top of the wing and I.0mm styrene round rod to show the ribs on the underside of the wing. The front end of each rib was given a bend to coincide with the shape of the leading edge of the wing, I did this with my fingers. After the ribs were glued in place the wings were painted and the reinforcing leather patches applied with Humbrol No.62 leather paint. The wings are extremely light and should mount easily onto the wing support rods through the two wing spars (not fitted at this stage)   

I have used two lengths of 0.85mm steel wire for the wing mountings. These have been bent to shape as per the plans with dihedral and back sweep. I fixed them to the undercarriage legs by using CA, then I twisted some 0.13mm copper wire around each leg and to the wing mounting wire, more CA was added which resulted in a strong join. I will be fitting four lengths of 1.2mm brass tube (spars) over the wing mounting wires, this tube has a 0.95mm hole so it fits over the steel wire very well. The brass tube will be cut to the correct length to reach the tip of each wing then fastened to the wings using CA and 5 minute epoxy. The close-up photos show the neat attachment of the wing mounting wires to the undercarriage legs, using stell wire has given me quite a strong assembly.

This photo shows the wings sitting on the bench beside the plane, as can be seen the wings are not huge but they do sweep rearward and they have a fairly big dihedral. As with most of this aeroplane the strength for the wings will come from the rigging, 16 wires with turnbuckles on each wing.

The wings are now fitted, it was a very simple matter to glue a length of 1.2mm brass tube just under the leading edge of each wing, once dry the wing was slipped onto the stell wire wing mounts. I also slipped a length of 1.2mm brass tube onto the rear wing mounts and allowed the wing to rest on the brass tube, glue was then added at each rib where it came in contact with the spar, once it was all dry it became a fairly solid assemble. The dihedral is quite pronounced as is the wing sweep, both these features help aircraft stability in flight. All that is left to do now is the wing rigging.

COMPLETED MODEL

This has been a very enjoyable build, it is a unique aircraft and was the forerunner to a lot of the early type aircraft. Anthony Fokker was ahead of his time in aeroplane design by incorporating dihedral and wing sweep into this very early model. It may appear to be very fragile but the model is quite sturdy, the wing rigging has made the wings quite a strong assembly. I really like the early aircraft, their bare bones and rustic design offer a lot of appeal.

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