The Gnome-Rhône 14K Mistral Major was a 14-cylinder, two-row, air-cooled radial engine. It was Gnome-Rhône's major aircraft engine prior to World War II, and matured into a highly sought-after design that would see licensed production throughout Europe and Japan. Thousands of Mistral Major engines were produced, used on a wide variety of aircraft.
Design and development
In 1921 Gnome-Rhône purchased a license for the highly successful Bristol Jupiter engine and produced it until about 1930, alongside the smaller Bristol Titan. Starting in 1926, however, they used the basic design of the Titan to produce a family of new engines, the so-called "K series". These started with the 5K Titan, followed by the 7K Titan Major and 9K Mistral. By 1930, 6,000 of these engines had been delivered.
However, the aircraft industry at that time was rapidly evolving and producing much larger aircraft that demanded larger engines to power them. Gnome-Rhône responded by developing the 7K into a two-row version that became the 14K Mistral Major. The first test examples were running in 1929.
As the Jupiter had set the pattern for one-row radials in the 1920s, the Mistal Major became a canonical design for twin-row radials of the 1930s. It was widely licensed and formed the basis for many successful designs. Among the licensees were Industria Aeronautică Română, Manfred Weiss in Hungary, Alvis of the UK, Tumansky in the USSR, Walter of Czechoslovakia, Isotta-Fraschini and Piaggio in Italy. Nakajima in Japan also licensed it, but did not put it into production, developing their own designs based on features taken from the Mistral and other designs.
KbrKbrsKdrun-supercharged with reduction gearing
Kdsdirect drive with supercharger
Kdrssupercharged with reduction gearing
KesKirsKnrsKrsd?
Korsopposite rotation to Kors
Manfred Weiss WM K.14Piaggio P.XIIAR 14KTumansky M-87ИАМ K.14Isotta-Fraschini K.14Amiot 143Aero A.102Bloch MB.200Bloch MB.210Breguet 274Breguet 460Breguet 462Breguet 470Breguet 521Breguet 670Dornier Do 17KFarman F.222Loire 46 C1Makhonine Mak-101PZL P.24PZL P.43Potez 501Potez 506Potez 62Potez 651Aero A.102Breda Ba.65Breda Ba.88CANT Z.1007CANT Z.1011Caproni Ca.135Caproni Ca.161Heinkel He 70IAR 37IAR 80Ilyushin DB-3MÁVAG HéjaReggiane Re.2000Saab 17Savoia-Marchetti SM.79Savoia-Marchetti SM.84Sukhoi Su-2Weiss WM-21 SólyomData from
Type: Fourteen-cylinder two-row air-cooled radial engineBore: 146 mm (5.748 in)Stroke: 165 mm (6.496 in)Displacement: 38.673 l (2,360.0 cu in)Length: Kds - 1,317 mm (51.85 in)Kdr - 0.5 reduction gear - 1,528 mm (60.16 in)Kdr - 0.666· reduction gear - 1,530 mm (60.24 in)Kdrs - 0.5 reduction gear - 1,554 mm (61.18 in)Kdrs - 0.666· reduction gear - 1,556 mm (61.26 in)Diameter: 1,288 mm (50.71 in)Dry weight: Kdr 0.5 reduction gear - 503 kg (1,109 lb)Kdr 0.666· reduction gear - 508 kg (1,120 lb)Kdrs 0.5 reduction gear - 523 kg (1,153 lb)Kdrs 0.666· reduction gear - 528 kg (1,164 lb)Kds 502 kg (1,107 lb)Valvetrain: Two Overhead valves per cylinder operated by pushrodsSupercharger: (Kds / Kdrs - Single-speed centrifugal type supercharger)Fuel system: Stromberg carburetorFuel type: 87 octane rating gasolineCooling system: Air-cooledReduction gear: Direct drive, 0.5:1 or 0.666·:1Power output: Kdr - 600 kW (800 hp) at sea levelKdrs - 580 kW (780 hp) at 1,500 m (4,900 ft) at 2,400 rpmKdrs - 510 kW (680 hp) at 4,000 m (13,000 ft) at 2,400 rpmKds - 560 kW (750 hp) at 1,500 m (4,900 ft) at 2,300 rpmKds - 480 kW (650 hp) at 4,000 m (13,000 ft) at 2,300 rpmSpecific power: Kdr 15.5 kW/l (0.34 hp/in³)Compression ratio: 5.5:1Specific fuel consumption: 328 g/(kW•h) (0.54 lb/(hp•h))Oil consumption: 20 g/(kW•h) (0.53 oz/(hp•h))Power-to-weight ratio: 1.52 kW/kg (0.92 hp/lb)
