1/72 Caudron G.IV, by Stephen Foster

Rene and Gaston Caudron were brothers who were inspired by the efforts of the Wright brothers in America, and who established a company to build aircraft of their own designs in France. After a number of attempts to come to a satisfactory design configuration, they developed the type G in 1913, which was improved to become the type G 3 in 1914. This was a two seat machine with unequal span wings, twin booms holding the horizontal tail surfaces and an 80hp rotary engine. This design was adopted by the French military because it was available in quantity, but it had many limitations, not the least of which was the inadequate view for the crew. The Aviation Militaire called for a more powerful machine which could carry a forward firing machine gun, so the Caudron brothers redesigned the basic G3 by adding a second engine, placing a nacelle between the engines with the observer in the front, and adding two extra fins and rudders to the tail: otherwise the new machine was basically the same. The engines were 80hp Le Rhone or Clerget rotaries and lateral control was by wing warping. 1800 machines would eventually be built in France and 12 were built in Britain as part of a larger order for the RNAS. Caudrons served with French, British, Italian and Russian air arms, and many continued in civilian service in the early post war years. These machines were called Gitterrumpf (lattice tail) by the Germans because of their distinct shapes, but their frail appearance belied their strength: it was able to withstand considerable damage and still return to the airfield with the crew. If the Caudron GIV was flown aggressively it could prove to be a dangerous adversary as shown by a number of successful engagements between French crews and their opponents as they succeeded in downing many enemy machines and several French air aces started their flying careers in Caudrons. It was most widely employed in the unglamorous but important role of reconnaissance, and as a bomber: in RNAS service it was mainly used as a bomber.

Although the Caudron GIII and GIV were both produced and used in large numbers they have been almost forgotten and ignored until relatively recently, which is one reason why this makes it an interesting subject to model. The complexity of construction does not help improve its popularity as a subject for a mass market model but it makes it an interesting challenge for the scratch builder.

CONSTRUCTION

I decided to attempt this on a whim: I had bought the Windsock DataFiles for the Caudron G III and GIV and thought that the latter offered the bigger challenge: besides there is no kit of the G IV. This model was made from plastic card, strip and rod, clear acetate, wire and wood. I did cheat a little because I bought a resin engine from Small Stuff as I could not scratch build one to that standard. The engine under the cowling was scratch built however, but as it is largely concealed it is less important.

Scratch building means that the order in which different components are made is not very important, so I will describe the construction of the major elements first, and then the order of assembly which is much more important, later. I started with the cowlings which were push moulded from 40 thou card, and the nacelle which was moulded from 30 thou card. The cowling mould was the end of an old chair strut as it happened to be almost the exact diameter that I required. The openings at the bottom were cut with a sharp knife and finished with glass paper wrapped around the end of a paintbrush. The fuselage nacelle was moulded so that the sides were deeper than the end product which meant that I could cut the halves to the exact size later. The rear underside was made from 10 thou card and the nose underside from clear acetate as there was a window in the floor in front of the observer. The cockpit openings were cut out from each side, making sure that they matched exactly. The cabane struts were cut from 20 x 30 thou Evergreen strip which was filed to aerofoil shape at one end. I then laid the fuselage halves on to the plan to mark on where the struts were to be inserted and drilled the holes for the struts from underneath in the cockpit sides before inserting and glueing them in place. These formed part of the fuselage structure so they must be added before any other details were put in. The interior detail of the cockpits was based on photos in the DataFile: the observer's seat was made from card and a floor put in beneath it, with the pilot's cockpit having a seat, control column and push rods on the sides of the nacelle for the engine controls. There do not seem to have been any instrument dials in the cockpit so a simple bulkhead of 20 thou card was all that was needed. The pilot's seat filled the whole of the rear of the nacelle and I simulated this with a piece of 40 thou card bent to shape. Fitting the interior detail was a little tricky, but when it was ready the two fuselage halves were joined and the undersides added as previously described. A small hole was also drilled in the top of the nacelle in front of the pilot's cockpit and a small circular window inserted: this was made from clear acetate from a blister pack.

The nacelles were made from a square of 60 thou card for the front with the sides from 20 thou card, and the top and bottom from 30 thou card. I cut the struts from 20 x 30 thou Evergreen strip which had been filed to a streamline shape, and made them a little longer than necessary so that they could be trimmed to the exact size later. I glued the top and bottom of the nacelles to the front plates and laid these on to the plans so that I could mark the correct places for the struts. Small recesses were cut into the top and bottom plates before the struts were cemented to them. I checked that the nacelle struts lined up with the struts in the fuselage as all of these have to be of the same spacing if the model is not to look odd. When I was happy with the strut positions I cemented the nacelle sides on. There was an instrument dial on the insides of the nacelles and a fuel gauge: the former was shaped from small pieces of 20 thou card and the latter from stretched sprue. I drilled a hole on the inside of the nacelles where the control rods would later be fixed and the pipe under the nacelle was made from rod. On top of the nacelles were two filler caps, also made from small pieces of rod.

I made one engine from scrap using a disc of 60 thou and 20 thou card laminated and shaped to form the circular block, and 80 thou rod for the cylinders.The cylinders were scored to simulate the cooling fins, and then pieces of stretched sprue were used for the spark plugs. I added the valve gear on the ends of the engines to two cylinders as only these would be seen. The push rods were thin stretched sprue and the copper inlet pipes were from thin card. Only five sets of spark plugs, rods and inlet pipes were made as the remainder of the engine is concealed beneath the cowling. I used the Small Stuff engine as a model to work from. I put a pin of plastic rod in to the rear of the engine and drilled a hole into the front of one nacelle so that I could mount the engine later. The Small Stuff engine is a wonderful model in its own right and has the crankshaft of exactly the right diameter and length moulded on it so it can be easily glued to the front of the nacelle at a later date. I painted both engines at this stage as they were easy to handle. I used black with a little silver for the crank case and cylinders, copper with a little grey for the intake pipes and silver for the push rods. The propellors were carved from wood - I have some thin hardwood strip which I used for my model. Holes were drilled in the centre to hold a pin for one and represent where the drive shaft would go for the other. The propellor bosses were discs cut from 10 thou card.

The wings were made by cutting a strip of 20 thou card and a wider strip of 10 thou card and gluing them together and holding them in a press while they dried. I then cut a strip of 20 thou card and bevelled it to a triangular cross section to form the trailing edge of the upper wing section. The ribs of the forward part of the upper wing were cut from 10 x 20 thou Evergreen strip held by liquid glue. Similarly the ribs on the underside of the wing were made from the same material. The ribs on the trailing edge of the upper wing were glued into place and then the bevelled card was cut into sections and inserted between the ribs. Any gaps need to be filled with filler and then the ribs were rubbed down to the required thickness both above and below the wings. This was a long and tedious process and required a good deal of patience, but was important as the complex shape of the wings had to be reproduced. Finally the trailing edges of the wings were scalloped using a round file and the tips shaped, using the plans as a guide. On the lower wing the metal plates beneath the nacelles were made from 10 thou card which was glued on with liquid cement and then rubbed down to a thin section. Holes were drilled in top of the lower wing for the various struts, and on the underside for the undercarriage legs. I used the engine nacelle struts as a guide for the distances between the front and rear holes and then laid the wings against the plans to get the correct position for the outer struts. The fuselage struts were used to position the holes for the cabanes.

The tail surfaces were cut from 20 thou card using a tracing from the plans: as with the wings the shapes of the fins and rudders varied on different machines. My model represents a French built RNAS machine, but other aircraft had different shaped rudders and wings. All of the struts were shaped from 20 x 30 thou Evergreen strip. The wheels were made by shaping 4 discs of 60 thou card and the tyres by coiling a length of 40 thou rod around the handle of a file and putting it in boiling water for 10 seconds. The coil of plastic rod was then cut to length and the ends twisted until they lined up. I placed the rod over the discs of card and glued with liquid cement. The axles were cut from wire as were the undercarriage legs. The booms were from 40 x 30 thou Evergreen strip and were made by bending the strip to the correct curve of the front of the boom. The strip was then laid on a plan and the strut locations marked so the holes could be drilled in the correct places. When the holes had been drilled I held the booms on the plan with pins and glued the struts into place.

With all of the sub-assemblies complete the main assembly could begin. I started by gluing the fuselage nacelle to the lower wing and then painted the wings, fuselage nacelle, engine nacelles, tail surfaces and struts as all of these will be difficult to paint later. I used Humbrol enables and mixed the clear doped linen from an old tin of Clear Doped Linen and white. The markings were hand painted except the serial which came from a Pegasus sheet of WW1 RFC/RNAS serials.

I then attached the engine nacelles to the lower wing: first one side which was allowed to dry, and then the other. Alignments of struts had to be carefully checked, as did the level of the nacelles fore-aft and side to side. I had cut the struts to be slightly too long so that I could trim them as required. The wires under the sides and rear of the nacelles, and struts under the front were added at this stage, as were the control rods between the fuselage and engine nacelles. The strut location holes for the cabanes and engine nacelles under the top wing were measured by placing the top wing upside down and placing the lower wing assembly on to it. Then the strut positions could be marked and drilled. The outer wing strut locations were marked from the holes in the lower wing. Glue was dropped into the holes in the top wing for the engine nacelle and cabane struts and the top wing placed on the lower wing assembly, carefully aligned and supported, and allowed to dry out. When the assembly was dry I added the outer wing struts and rigged the top of the nacelles and cabanes. The inner wing struts were added next and the rear struts rigged, as were the fore aft wires between the struts. The struts supporting the wing overhangs and the bracing were added last.

The front ends of the booms were chamfered slightly so that the leading edges were almost flat against the top wing - the front tapered in line with the wing surface. The wing sub-assembly was placed over a copy of the plans and the booms placed so that their leading edges were on the top wing. The model was mounted on a small block during this operation to give the necessary clearance under the lower wing. The booms were glued into place and held with clips while they dried. The undercarriage legs were cut from the wire from a length of telephone extension cable which had been rolled flat on a block of wood, and held in place with CA. When the undercarriage was complete I glued the horizontal tail surface to the rear of the booms, having first drilled holes where the rear posts would go. As I glued the tail unit to the booms I added the vertical struts, also from wire and held in place with CA - this reinforced the rear and held it in place. Care was needed with alignments at all stages of the boom assembly because even small errors would show up on the finished model. The fins and rudders were added after the horizontal surface was dry. The axles were added to the front of the booms followed by the axle covers which had been cut and shaped from an aluminium drink can.

The remaining rigging of the model was fairly straightforward. I finished the wings and rigged part of the tail before adding the control column in the pilot's cockpit, also from wire, and the pilots windscreen, bomb racks from scrap thin strip, release levers and cables (wire). Only then did I attempt the control cables to the elevator and rudder, and the undercarriage. The wheels were finally put on to the axles and the sit of the model checked - some very small adjustments were necessary to get the booms to rest properly. The model could now stand upright while the engines were glued to the front of the nacelles and one of the cowlings placed over the scratch built engine. A windscreen for the observer and brackets for the cowling on the nacelle without a cowling, plus the propeller, completed the model. Figures from WD Models were added to the base to give more interest.

CONCLUSIONS

Copper State Models make a resin kit of this aircraft in 1/48 scale, but for some reason nobody makes one in the Gentlemens’ Scale so I had no option but to scratch build my own. This was one of the more complex projects that I have attempted, the bigger problems being aligning the struts for the engine and fuselage nacelles and the booms at the rear. Once these issues had been resolved the model was no more difficult than assembling any other kit, except that I had to make most of the parts first. The Small Stuff engine meant that I could leave one engine exposed, otherwise I would have had to cover both with cowlings. This fills another gap in my collection of early military aircraft that served in considerable numbers.

REFERENCES

KIT #:
PRICE:
DECALS:	Pegasus sheet of WW1 RFC/RNAS serials
REVIEWER:	Stephen Foster
NOTES:	Made from plastic sheet, rod and strut, an engine from Small Stuff, and figures from W D Model