Macchi M.39

{{Short description|Racing seaplane}} {{Use dmy dates|date=September 2016}}  {{Infobox aircraft |name = M.39 |image = Macchi M.39.jpg |caption = |type = Racing seaplane |manufacturer = Aeronautica Macchi |designer = Mario Castoldi |first_flight = 6 July 1926 |introduction = |retired = |status = |primary_user = Regia Aeronautica |more_users = |produced = |number_built = Five (two trainers and three racers), plus one static-test airframe |unit cost = |variants = }}

The '''Macchi M.39''' was a racing seaplane designed and built by the Italian aircraft manufacturer Aeronautica Macchi. The type is most remembered for its settings of multiple world speed records during the mid-1920s, as well as for winning the Schneider Trophy, for which the M.39 had been specifically developed.

Designed by Mario Castoldi and constructed in Varese, north-western Lombardy, the M.39 was a considerable departure from the company's preceding racing flying boat, the Macchi M.33. It was a single-seat twin-float seaplane with an open cockpit, tightly-braced monoplane wing, and a streamlined fuselage. Two-thirds of the wing's upper surfaces functioned as surface radiators, providing relatively low drag cooling for the engine. It was powered by a Fiat AS.2 V-12 piston engine with an exceptionally high power-to-weight ratio for the era.

Two versions of the M.39, a trainer version and a racer, were produced. On 6 July 1926, the first aircraft, the trainer model MM.72, performed the type's maiden flight. On 13 November 1926, three M.39s participated in the 1926 Schneider Trophy contest, held at Hampton Roads, Virginia, in the United States; one aircraft, MM.76, piloted by Mario de Bernardi, took first place with an average speed of {{convert|396.698|km/h|mph}}, setting a new world speed record for seaplanes, while MM.74, flown by Adriano Bacula, came in third place.

==Design and development== The M.39 was designed by the Italian aeronautical engineer Mario Castoldi to represent Italy in the 1926 Schneider Trophy competition. It represented a considerable departure from his prior designs, being the first low-wing monoplane that Castoldi would design for Macchi, virtually nothing of the company's preceding racing flying boat, the Macchi M.33, was present in its design.<ref name = "naca 1"/> It had been determined that the prior aircraft's basic configuration, which was built around a central hull, while affording great stability upon the water, would unavoidably present a great obstacle to penetration and thus was substituted for a pair of braced floats that formed a rigid support. Construction of the aircraft was performed at the company's factory in Varese, north-western Lombardy.<ref name = "naca 1">NACA 1927, p. 1.</ref>

It was a single-seat twin-float seaplane of mixed (metal and wooden) construction. The pilot sat in an open cockpit above the trailing edge of the wing; the cockpit{{'}}s windscreen was profiled into the fuselage decking to reduce drag.<ref name="Donald, p. 594">Donald 1997, p. 594.</ref> This fuselage was streamlined and intentionally avoided angularity.<ref name = "naca 1"/> The horizontal empennage consisted of a sizable stabiliser and an unbalanced two-part elevator while the vertical empennage consisted of two fins, one above and one below the fuselage, and an unbalanced rudder, lacking any external bracing.<ref name = "naca 1"/>

The monoplane wing, which was situated underneath the fuselage, was rigidly braced using steel cables.<ref name = "naca 1"/> One feature of particular note about these wings, which were composed of wood, was that two-thirds of the wing's upper surfaces functioned as low drag surface radiators.<ref>{{cite journal |journal=Skyways |title=Details: Macchi M.39 Racer |page=37 |date=July 2001}}</ref> The adoption of such a radiator arrangement, which avoided the drag that would have otherwise been generated through the use of traditional honeycomb or fin-type radiators, was considered to be a key innovation of the aircraft. The oil radiator was incorporated in the bottom of the fuselage in a relatively exposed position to achieve effective cooling.<ref name = "naca 12">NACA 1927, pp. 1-2.</ref>

thumb|An M.39 undergoing engine tests, {{circa|1926}} The M.39 was powered by a Fiat AS.2 water-cooled V-12 piston engine, which was directly drove the propeller.<ref name = "naca 2">NACA 1927, p. 2.</ref> This engine, which was installed within the aircraft's nose, was equipped with three double carburetors, one for every four cylinders, that were specifically designed as to enable them to operate normally at practically any orientation of the aircraft.<ref name = "naca 23">NACA 1927, pp. 2-3.</ref> The power-to-weight ratio achieved by this engine, inclusive of the water in the cylinder jackets and tubing, the residual oil, the starter apparatus and the fuel pump, was exceptionally low (467 grams (1.03 lb.) per hp); it was reportedly lighter that any other powerplant in its power range in production with any other manufacturer in the world at that time.<ref name = "naca 3">NACA 1927, p. 3.</ref>

The M.39 was specifically built to compete for the Schneider Trophy; accordingly, its design had specialised features to aid it in this exact purpose. As the course circuit required left turns, the left wing of the aircraft had a slightly greater span than the right wing, which permitted the aircraft to make tighter left-hand turns. To counteract propeller torque reaction, the floats had unequal buoyancy.<ref name="Donald, p. 594"/> Furthermore, fuel was stored within these floats.<ref name="Donald, p. 594"/>

Macchi produced two versions of the M.39, a trainer version and a racer. The trainer version had an increased wingspan of 10.23 metres (33 ft 7in) -compared to the 9.26m (30 ft 4.5in) of the racers-<ref>James 1981, p. 114.</ref> and was powered by a 447-kilowatt (600-horsepower) Fiat AS.2 liquid-cooled V12 engine, while the racing version had a 597-kilowatt (800-horsepower) Fiat AS.2. Macchi built two trainers, three racers, and one non-flying static-test airframe. The first M.39, a trainer with serial number MM.72, was built in only a few months. It was soon followed by the second trainer (MM.73), the three racers (MM.74, MM.75, and MM.76), and the static-test airframe.<ref name="Donald, p. 594"/>

==Operational history== thumb [[File:Macchi M.39 front 2009-06-06.jpg|thumb|Preserved Macchi M.39 in Italy at the ''Museo storico dell'Aeronautica Militare di Vigna di Valle'', photographed on 6 June 2009. This aircraft, MM.76, piloted by Major Mario de Bernardi, won the 1926 Schneider Trophy race and set two world speed records that year.]] On 6 July 1926, the trainer MM.72 performed its maiden flight, becoming the first M.39 to fly. On 16 September 1926, the Italian Schneider team captain was killed when the MM.72 trainer over that he was flying stalled over Lake Varese and plunged into the lake itself. Development of the M.39 proceeded undaunted.<ref name="Donald, p. 594"/>

On 13 November 1926, the three M.39 racers took part in the 1926 Schneider Trophy contest at Hampton Roads, Virginia, in the United States. MM.75 suffered a burst pipe and had to leave the race early, but MM.76, piloted by Mario de Bernardi, took first place with an average speed of {{convert|396.698|km/h|mph}}, setting a new world speed record for seaplanes. MM.74, flown by Adriano Bacula, came in third place.<ref name="Donald, p. 594"/><ref name = "naca 25">NACA 1927, pp. 2, 5.</ref><ref>{{cite web |url = https://www.bbc.co.uk/dna/mb6music/A86205396 |title = h2g2: The Schneider Cup |publisher = BBC |date = 26 September 2011}}</ref>

Four days later, on 17 November 1926, de Bernardi used MM.76 to achieve a new world speed record of {{convert|416.618|km/h|mph}} over a {{convert|3|km|mi}} course at Hampton Roads.<ref name="Donald, p. 594"/>

Castoldi based the design of his next racing seaplane, the Macchi M.52, on that of the M.39.<ref name="Donald, p. 594"/>

==Surviving aircraft== MM76, the aircraft flown by de Bernadi to win the Schneider Trophy and set a new world speed record, is on display in the Museo Storico Aeronautica Militare in Bracciano.<ref>{{cite web |url = https://www.aeronautica.difesa.it/en-home/historical-museum/ |title = Italian Air Force Museum, Vigna di Valle |website = aeronautica.difesa.it |access-date = 25 May 2024}}</ref>

==Operators== ;{{flag|Kingdom of Italy}} * Regia Aeronautica

==Specifications (M.39 racer)== thumb|Macchi M.39 {{Aircraft specs |ref= ''World Encyclopedia of Civil Aircraft'',<ref name="Angelucci civil p149">Angelucci 1984, p. 149.</ref> ''The Complete Encyclopedia of World Aircraft''<ref name="Donald, p. 594"/> |prime units?= met  |crew= 1 |length m= 7.77 |length note= including floats :::{{cvt|6.73|m}} fuselage length |span m= 9.26 |height m= 2.97 |wing area sqm= |aspect ratio= |airfoil= |empty weight kg= 1,257 |gross weight kg= 1,572 |max takeoff weight kg= 1,575 |fuel capacity= |more general=  |eng1 number= 1 |eng1 name= Fiat AS.2 |eng1 type= V-12 liquid-cooled piston engine |eng1 kw= 597

|more performance= }}

==See also== {{aircontent  |related= * Macchi M.52 * Macchi M.67 |similar aircraft= * Curtiss CR-3  |lists= * List of seaplanes and flying boats |see also= }}

==References==

===Citations=== {{reflist}}

===Bibliography=== * Angelucci, Enzo. ''World Encyclopedia of Civil Aircraft''. London, UK: Willow Books, 1984. {{ISBN|0-00-218148-7}}. * Donald, David, ed. ''The Complete Encyclopedia of World Aircraft''. New York, US: Barnes & Noble Books, 1997. {{ISBN|0-7607-0592-5}}. * Eves, Edward. ''The Schneider Trophy Story''. Shrewsbury, UK. Airlife Publishing Ltd., 2001. {{ISBN|1-84037-257-5}}. * James, Derek. ''Schneider Trophy Aircraft''. London, UK: Putnam, 1981. ISBN 0370303288 * {{cite journal |last1=Lefèbvre |first1=Jean-Michel |last2=Foxworthy |first2=Thomas |name-list-style=amp |title=Vitesse à la italienne: Macchi M.39, partie 1 |journal=Le Fana de l'Aviation |date=May 1978 |issue=102 |pages=8–11 |issn=0757-4169 |language=fr |trans-title=Italian Speed: The Macchi M.39, Part One }} * {{cite journal |last1=Lefèbvre |first1=Jean-Michel |last2=Foxworthy |first2=Thomas |name-list-style=amp |title=Vitesse à la italienne: Macchi M.39, partie 2 |journal=Le Fana de l'Aviation |date=June 1978 |issue=103 |pages=8–11 |issn=0757-4169 |language=fr |trans-title=Italian Speed: The Macchi M.39, Part Two }} * [https://ntrs.nasa.gov/citations/19930089533 "Macchi M. 39 Seaplane: Single-Seat Racer with an 800 HP. Fiat "A-S2" Engine"] ''National Advisory Committee for Aeronautics'', 1 March 1927. NACA-AC-32, 93R18823.

==External links== {{commons category|Macchi M.39}} * [http://www.britishpathe.com/record.php?id=14985 Newsreel footage of Macchi M.39 MM.76 and Major Mario de Bernardi after winning the 1926 Schneider Trophy race] {{Webarchive|url=https://web.archive.org/web/20110611044431/http://www.britishpathe.com/record.php?id=14985 |date=11 June 2011 }}

Category:Schneider Trophy Category:Floatplanes Category:1920s Italian experimental aircraft Category:Racing aircraft M.39 Category:Low-wing aircraft Category:Single-engined tractor aircraft Category:Aircraft first flown in 1926