Renault 90 hp
Renault 90 hp fitted to a Maurice Farman biplane
Type Air-cooled V12 aero engine
National origin France
Manufacturer Renault
First run 1911
Number built 130
Developed from Renault 70 hp
Developed into Renault 100 hp

The Renault 90 hp, or 12A, was the world’s first V12 aircraft engine. The engine was developed in 1911 from Renault’s earlier V8 engines and used the same air-cooled design.[1][2][3]

Design and development

By 1911, V12 engines had already been built for boats and automobiles.[1] As with other V12s and straight-six engines, Renault's design had the inherent advantage of primary and secondary engine balance. The 60 deg angle between two rows of 6-cylinders resulted in even firing intervals for smooth power delivery and gave the engine a narrower profile than Renault's 90 deg V8s thereby reducing aerodynamic drag.[1][2]

The 90 hp model featured articulated master-and-slave connecting rods allowing corresponding cylinders in each row to be arranged directly opposite each other which improved dynamic balance. This arrangement also made the engine crankcase shorter than would have been the case if the "side by side" connecting rods (found on the earlier V8 Renault 70 hp) had been used.[1]

As with Renault's V8 air-cooled models, engines intended for pusher aircraft were fitted with a centrifugal blower while those engines intended for tractor aircraft used a cowl mounted air scoop to feed cooling air over the large finned cast iron cylinders.[4]

Another feature inherited from earlier Renault air-cooled V8 engines was the form of reduction gearing where the propeller was fixed to the end of the camshaft allowing it to turn at half engine speed. This method of gearing allowed the engine and propeller to be run close to their optimum speeds without the additional weight penalty of a gearbox[1][4] while the reverse rotation of the crankshaft and propeller reduced gyroscopic forces improving aircraft handling.[5]

Renault aircraft engine advert c.1912 showing the 5 available models

The Renault 90 hp was first exhibited at the 1911 Salon de l’Aéronautique at the Grand Palais in Paris. The engine was offered at a price of 17,000 Francs (the 70 hp V8 model was priced at 12,500 Francs).[6] By mid 1912 the engine had been fitted to aircraft manufactured by Astra, Farman[7] and Bréguet.[8]

The 90 hp engine was quickly followed by a 100 hp model in the summer of 1912.[3]

Applications

Specifications

Data from Angle[4] and L'Aéro[5]

General characteristics

  • Type: Air–cooled, upright, 60-degree, V-12 piston engine
  • Bore: 90 mm (3.54 in)
  • Stroke: 140 mm (5.51 in)
  • Displacement: 10.66 L (650.76 cu in)
  • Dry weight: 289.4 kg (638 lb)

Components

  • Valvetrain: One exhaust valve and one inlet valve per cylinder. Both valves located in a lateral pocket with the exhaust on top and the intake on the bottom.
  • Fuel system: Carburetor mounted on the left side of the engine block.
  • Fuel type: 40–50 octane petrol
  • Oil system: Wet sump. Internal oil pump.
  • Cooling system: Air-cooled
  • Reduction gear: 0.5:1, left hand tractor (there is no reduction gear as such; The reduction was achieved by mounting the propeller on the camshaft).
  • Rotation (looking end on at the propellor hub): Engine crankshaft, 1800 rpm counter-clockwise. Camshaft and propeller, 900 rpm clockwise

Performance

  • Power output: 90 hp (67 kW) - Nominal
  • Power-to-weight ratio: 0.232 kW/kg (0.141 hp/lb) at nominal power output

See also

References

  1. 1 2 3 4 5 Ludvigsen, Karl (2005). The V-12 Engine. Haynes. pp. 18–19. ISBN 1844250040.
  2. 1 2 Eppelsheimer, Frederick (13 November 1915). "Twin-Six Engines for Aeroplanes". Scientific American. United States.
  3. 1 2 Hartmann, Gerard (2005). "Les moteurs d'aviation Renault" [Renault aviation engines] (PDF) (in French). Retrieved 10 December 2023.
  4. 1 2 3 Angle, Glenn D. (1921). Airplane Engine Encyclopedia. Dayton, Ohio, USA: The Otterbein Press. pp. 412–414.
  5. 1 2 "Les Moteurs d'aviation Renault" [Renault aircraft engines]. L'Aéro (in French). France. 18 June 1912.
  6. ↑ "Engines at the Paris Show". The Aeroplane. United Kingdom. 4 January 1912.
  7. 1 2 3 "The Grand Prix of the Aero Club de France". The Aeroplane. United Kingdom. 20 June 1912.
  8. 1 2 "French Military Aviation". The Aeroplane. United Kingdom. 11 July 1912.
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