Macchi-Castoli MC 72

From designers to great pilots, through specialists, Schneider Cup has so much heroes to feed a lot of tales.

A vivid portrait of Eng. Mario Castoldi, Macchi's designer, has been drawn by his successor, Ermanno Bazzocchi: "Misogynous, good wine loving, he had the hobby of rice growing. His huge and heavy complexion was the most improbable for a man devoted to catch for the speed. We believe he flew only once".

His irascible character is reported in an exclamation "In FIAT, power is measured in donkey-power", pronounced after the 1927 defeat. Not casually, perhaps, before Venice race, Maria Vittoria De Bernardi had been warned by Castoldi not to leave her husband fly on such aircraft.

For Subofficer Francesco Agello it0's sufficient to say that he reached the record only when, after death of Lt. Ariosto Nari, he remained the only pilot endorsed for MC-72. Heavy responsibility on his shoulders must be paired with the constant memory of the killed colleagues but also, we believe, with the sense of revenge of a man damned to be an eternal reserve.

About De Bernardi, Baldassarre Catalanotto remembers when, talking about his secret technique to turn around the pylon, he answered: "When I first flew Macchi 39, it had no intention to turn at all, to lower the wing. So, I kicked in the pedals, ripped the stick and the aircraft turned very well. Since then, I ever did so". Behind his simple words, one of the best natural talents of pilot ever seen in Italy was hidden, one in which technical ability was glued with instinct to form an unbeatable champion.

Besides those strong personalities, were peoples like Armand Palanca, chief civil technician in RAV workshop and last to disappear among Schneider's protagonists. After studying the problem of turbulence around air intakes, Palanca studied and patented a special carburettor, RAV.26, to solve the heavy breathing failures of AS-6.

Macchi MC-72 after his record flight (107Kb)

The decision to trust in a single type for 1931 edition mobilised resources never available before, allowing to build sophisticated devices to test the tricky FIAT AS-6 engine, conceived by Eng. Tranquillo Serbi. To avoid the problems created by huge propeller torque, Zerbi decided to adopt a double, counter-rotating fixed-pitch propeller. Not only efficiency was some 15% higher, but rear propeller was immediately flooded by aur flow and was efficient even during take off.

In the difficult floating phase, torque absence should allow to have a balanced load on the floats: an important aspect, considering that, with 1800HP engine, the left float was loaded 23% more than right one. In 1931 Supermarine S-6B with 2650HP was 32% overloaded, while MC-72 barely reached 3% even with 3000HP. Behind this propeller stand a singular twin engine, obtained coupling on the same axle two 12V, 60 degrees engines directly derived from AS-5, each moving a propeller through two coaxial crankshafts passing through forward engine banks. Air intakes were in the centre, between both engines, while breathing system, composed by a centrifugal compressor and a bank of 8 aspirated carburettors, was single for the whole plant.

The plates "Front Engine" and "Back Engine", still in the cockpit, show that semi-engines were independent, as confirmed by run-up scene in the famous movie of the record. It seemed the simplest solution, but, as often happens, AS-6 promises were harder to win than expected.

Onde defined the engine solution, airframe realization proceeded rapidly and without problems. Design base was conditioned by the 4m of the engine, and aircraft emerged as a steel tube frame, acting both as engine mount and forward fuselage, completed with mounts for wing, floats and rear fuselage. Wing structure was also metal, with rectangular shape, covered with flat surface radiators, while tail unit, with empennages and cockpit, was a monocoque wooden structure. Under the tail a further radiating element was foreseen.

The floats, used as fuel tanks and also covered with flat radiators, were initially metal but were eventually changed with wooded, lighter and smaller ones. All above gave a very nice and sleek aircraft, whose main section was lower than MC-67 one, giving no flight problems even if control surfaces were not dynamically balanced as surprisingly happened in all Schneider's planes.

What let the participation to 1931 Schneider Cup to be abandoned was finally AS-6 tuning, which emerged as difficult beyond any prevision: 18 months tests first on loose parts, then on subassemblies, finally on the whole engine, running for one hour on April 20, 1931. It offered 2200HP only and burned two valves.

problem solution required two months, twelve different valves combinations and 1000 valves in 10 different steels. Reached at the end of May the 2400HP, an AS-6 was mounted on the first MC-72: optimism of the tests were frozen on June 22th, shortly after first take off. Detonations and flameouts, so strong to crack the compressor, obliged Monti to land immediately.

FIAT AS-6 engine, producing 2500/3000HP (103Kb)

While the test flights continued, the necessary modifications were implemented. Then on August 2nd, 1931, Monti crashed on take off and died. Ltn Ariosto Neri and Stanislao Bellini took over with the second MC-72: only 40 days were left before the race, but no solution for the troubles was in sight.

On September 3rd, Ministres of Aeronautics of Italy and France asked British Royal Aero Club to postpone the race one year: the Britons refused, without fair play but pragmatically, because their participation was only paid by sponsors, and retiring that year could mean forever. Thus, on September 12th the British Supermarine flew alone. A record attempt was held also in Desenzano, on September 10th, but concluded dramatically: flameouts, detonations and MC-72 exploded in flight. No escape for Bellini.

In two months, RAV had been shocked and humiliated, but remained alive to gain the world speed record and the 100Km one. To resolve the carburration troubles a third engine test bed was set up, filling a whole hangar where two 400- and 700HP engines simulated wind up to 750Km/h. The device was used to verify proper functioning of Palanca's RAV-26, fitted with transparent elements to observe fuel flow.

On February 26, 1932, a 2400HP AS-6 simulated on the test bed a record flight on 3Km basis: to get an ideal fuel "Rod" Banks, the British wizard of fuel mixtures, was enrolled. He created a mix of 55% gasoline, 22% benzol, 23% alcohol and 0,15% lead. Engines were prepared with 3000HP for record runs and with 2500HP for endurance, working mainly on supercharging.

Neri and Agello, eternal reserve, restarted flying in June: On 15th Neri had the first flutter experience, landing safely only thanks to his skill. Unfortunately, Neri died three months later on a training flight on a CR-20.

Only Agello was left, having scored an unofficial record of 664,078Km/h: a third attempt was interrupted on June 4th after only 8 minutes. The final assault to 700Km/h was finally decided, with Agello as pilot. After several aborts, a first attempt was held on May 13th, interrupted for flameouts. Second attempt on June 22th, aborted for compressor failure. Third try on July 4th, with strong vibrations insurging. Then, long stop until autumn.

Here's another unsuccessful flight on October 1st. On October 13th, other flameouts and further delay. On October 23rd, take off at 14,56: 64 seconds floating, light mist, then the four official passes. Landing at 15,11, with Agello unaware to have beaten his own record. After the calculations, average resulted of 709,209Km/h, with the third, fastest pass at 711,462Km/h. Finally, decorations, promotions, celebrations came, with the immediate storage in a museum of the three MC-72 left, which perhaps never flew again.

In December 1938 RAV command was handed over to Agello, now Lieutenant, which disbanded the remaining of the wing on May 6th, 1940: 61 men, including two officers and two pilots. Agello's record resisted four years and a half, then was beaten two times in a month: by Hans Dieterle on Heinkel 100V8 at 746,450Km/h on March 30th, 1939 and by Fritz Wendel on Messerschmitt Me-209V1 at 755,1Km/h on April 26.

In seaplanes category the record was overcome only on August 7th, 1961 when soviet jet plane Beriev M.10 of Nikolau Andrjewski flew at 912Km/h.