Macchi Castoldi MC 72 by SBS

1/72 scale
Kit No. 7015
Price: $39.99
Decals: One version
Comments: Injection molded resin with photo-etch detail parts; bracing wires sold separately by SBS

History

The Macchi Castoldi M.C. 72 is the aircraft that set the absolute world speed record of 440 mph for racing seaplanes in 1934, a record which stands to this day, nearly ninety years later. First flown on July 16, 1931, the M.C. 72 was specifically designed to beat the British Supermarine S.6B in the 1931 Schneider Cup race. But its new thoroughbred engine, a revolutionary liquid-cooled Fiat AS-6 V-24 cylinder engine which produced an extraordinary 2,850 hp, was considered almost too hot to handle and had bugs to be worked out. It ran perfectly on the testing stand, but had a tendency to backfire and explode in flight.

The high-powered but temperamental engine would force Italy to withdraw from the 1931 Schneider Cup race, ceding the Schneider Cup to Britain for all time. In the wake of this disappointment, the Italians redoubled their efforts to break the world speed record set by the S.6B. If it couldn’t be beaten in a race, it could still be bested in terms of pure speed.  During the next two years, Macchi’s engineers worked to perfect the Fiat V-24 in anticipation of the attempt to break the world speed record, but before it finally set the new record it would kill two test pilots.

On October 23, 1934, just over three years later, an MC 72 piloted by Francesco Agello set the absolute world speed record for a piston-powered seaplane of 440 mph — a record which still stands nearly 90 years later.  To put this achievement into perspective, no combat aircraft would achieve such a speed for another ten years.  The M.C.72 was built by Macchi Aeronautica and operated mainly by the Regia Aeronautica (Royal (Italian) Air Force). The “MC” model designation reflects the fact that Macchi built the design by Mario Castoldi. Five M.C.72’s were built, with two being destroyed during test flights. For two years prior to Agello’s success with the M.C. 72, it suffered from many mechanical defects, and two test pilots had died trying to coax world class speed out of it (first Captain Giovanni Monti, and then Lt. Stansislao Bellini). The final design of M.C. 72 used contra-rotating propellers powered by a modified FIAT AS.6 supercharged V24 engine generating some 1,900-2,300 kW (2,500-3,100 hp), and wooden floats in place of metal ones fitted to earlier designs. The counter-rotating blades cancelled the engine’s torque effect.

The MC 72 was powered by a 50.256 liter (3,067 cubic inch) liquid-cooled, supercharged Fiat S.p.A. AS.6 24-cylinder 60° dual overhead cam (DOHC) V-24 engine with 4 valves per cylinder. Reports vary as to the engine’s output: it has alternately been cited as 2,850hp or 3,100hp, but regardless it was likely the most powerful aircraft engine of its day.  The M.C. 72 was an amalgamation of all the latest technology, and it rode the ragged edge of what was possible. As powerful as it was, it was a delicate balance to get it all to work reliably. Unfortunately, the new engine suffered from serious problems caused by dangerous back fires, which led to two fatal accidents involving pilots Monti and Bellini in the run-up to the 1931 Schneider Cup race.

On August 2, 1931, an engine backfire caused the fuel mixture in the intake manifold to ignite, and the engine exploded, killing test pilot Monti when the plane hit the water. On September 10, 1931, two days before the race, Lt. Bellini set a record of 394 mph, but near the end of the flight crashed into a hillside and was killed on impact. Subsequent investigation revealed another engine backfire which crippled the plane. These tragedies resulted in an Italian request to postpone the Schneider competition, but with permanent possession of the trophy at stake, the British refused to budge, so the Regia Aeronautica felt compelled to pull out of the 1931 races. With the American team having dropped out previously, only the British ended up flying the race with their Supermarine S.6As and S.6Bs.

In the coming months the engineers worked furiously to further increase the performance of the Macchi M.C. 72 and its engine, but the attempts on the record were foiled by additional technical problems. Finally, on October 23rd, 1934 Agello was ready to try again. Taking off smoothly, Agello completed the four laps over Lake Garda at an average of 709.202 km/h (440mph). The FAI team recorded the lap speeds as follows: 1st lap 705.882 km/h (438mph)—2nd lap 710.433 km/h (440mph)—3rd lap 711.426 km/h (441mph) and the 4th lap 709.034 km/h (440mph). The record was subsequently verified by the FAI for the seaplane with internal combustion engine category (subclass C-2, Group 1).

Despite this, neither Col. Bernasconi nor Agello were completely satisfied, as they were convinced that with better weather conditions, it would be possible to achieve an even better result. In fact, in the course of an earlier, unofficial flight, the M.C. 72 had recorded speeds greater than 730 km/h (453mph). Unfortunately, the arrival of winter and the high costs of embarking on yet another record attempt, what would be the eleventh, compelled the two men to accept their already excellent result with good grace.

For an in-depth history of the MC 72, please see the preview of this kit here.

Building the Macchi Castoldi MC 72

The Macchi Castoldi MC 72 is a beautifully detailed kit with an economy of parts (30 resin and 16 photo-etch). However, the bracing wires, purchased separately, make for an additional 16 photo-etch parts. The two-part fuselage has a remarkably detailed cockpit for the scale, with a control console, floor, seat, control yoke, and forward bulkhead/firewall, and photo-etch detail parts for the instrument panel face (with an acetate insert), seat straps, and individual control levers. The fit for the most part is excellent and with the cockpit assembled you move quickly to sealing the fuselage up. At this point the kit’s only real flaw became evident; the fuselage was slightly curved between the mid-section immediately aft of the cockpit and the tail. I was only able to partially cure this by exposing it to hot water for short periods and bending it to the limit of the stress I estimated the fuselage could take.

The vertical tail consists of two separate parts, and here is the only place where the fit was less than perfect. The larger dorsal section of the tail cemented onto the fuselage easily and fit flush with it. For the ventral portion of the tail there was a visible gap. The wings fortunately had pins which aligned perfectly with holes in the fuselage for a virtually seamless appearance, as did the horizontal stabilizers, which had separately mounted parts for what on the actual aircraft was the movable portion of their control surfaces.

The airscrew with its separately mounted propeller blades, while a nicely detailed assembly, does not correspond to the images in the kit instructions. The instructions would have you believe that the airscrew itself minus the blades consists of two parts (numbered 24 and 25). In fact, the conical airscrew consists of three (3) parts, the largest of which I lost and replaced with an identical part from the much older Delta 2 Macchi Castoldi MC 72 kit, sanded to more perfectly fit the newer kit’s dimensions. Cementing the individual propeller blades on was a bit challenging since these are small and fiddly parts that are also easy to lose if you are not careful. Knowing that the propellers are rather delicate and that I would be handling the kit a lot while attaching its support wires, I set the completed airscrew aside once I had painted and assembled it, waiting until the very end to attach it to the fuselage.

The floats and their support struts are beautifully engineered, although each of the support struts required a bit of sanding at their attachment points to fit flush into the floats. While the prospect of assembling and mounting them was a bit intimidating (they had to be painted in advance), once assembly began their fit was surprisingly precise with only a little effort. I used cyanoacrylate glue throughout, to allow a few seconds’ flexibility to reposition the parts as needed. I highly recommend buying the separate SBS kit containing the MC 72’s bracing wires, along with a high quality nipper that will cut photo-etch parts cleanly. They are worth the investment, both for the headache they will save you in putting the finishing touches on the kit, and in terms of its final appearance. The stage of attaching the wires took patience, since they vary in length and are all long enough to reach their attachment points, but they require incremental nipping to get the individual lengths just right. I took my time and did it over the course of three sessions.

The windscreen was my first encounter with clear resin, and while separating it from the block a small crack developed on one side. While this is a small, fiddly part, I was quite delicate and careful in my handling of it, so I cannot say for certain that the damage was avoidable. Modelers should know that this part will require extra care. That said, the part had a very clearly delineated frame which made painting easy.

Painting

The MC 72 is airbrushed mostly in acrylics, Gunze Sangyo Super Italian Red and Tamiya Brass. The airscrew is airbrushed in AK Interactive’s Polished Aluminum and Tamiya Flat Black for the rear side of the propeller blades. Touch up painting on the airscrew, and detailed natural metal painting on the fuselage was done with a Humbrol enamel, Polished Aluminum Metalcote. The underside of the floats were airbrushed in a base coat of Tamiya Gloss White, with touch-up painting done by hand using a Model Master enamel, Semi-Gloss White.

Conclusion

This is a very crisply detailed model that assembles almost with the ease of an old Airfix kit, and offers loads more detail. Its engineering is well above average in what for me is the relatively new medium of injection molded resin. The finished product looks extremely close to the original. Very Highly Recommended.

References

• warbirdnews.com ~ “Macchi Castoldi MC 72, The World’s Fastest Piston-Powered Seaplane,” by Luigino Caliaro
• fly.historicwings.com ~ “Agello and the MC 72”