The Hispano-Suiza 18R was an eighteen cylinder high performance water-cooled piston engine, in an 80° W or broad arrow layout, for use in racing aircraft, built in France during the latter half of the 1920s.
|Hispano-Suiza 18Sbr W-18 engine on display in the Musée de l’Air et de l’Espace in Le Bourget, France.|
|Type||W-18 high performance Aeor-engine|
|Developed from||Hispano-Suiza 12N|
Design and development
After failing to enter the Schneider Trophy seaplane race for several years, the French Ministère de l’Air decided to enter the 1929 competition. Two companies were tasked with designing and building floatplane racers to compete with the entries from Italy and Great Britain, resulting in the Nieuport-Delage NiD-450 and Bernard H.V.120, both of which were powered by the specially designed Hispano-Suiza 18R engines.
To power the racers Hispano-Suiza married three six cylinder blocks from the Hispano-Suiza 12Nb to a common crankshaft / crankcase, set at 80° to each other. Retaining the 150 mm (5.91 in) bore and 170 mm (6.69 in) stroke of the 12Nb, the 18R had the compression ratio increased from 6.25:1 to 10:1 with a total displacement of 54.075L (3,299.8ci). Each cylinder aspirated through two valves operated by single overhead cam-shafts with ignition from two spark plugs set on opposite sides of the combustion chamber supplied by magnetos at the rear of the engine. Fuel metering was carried out by nine carburetors each supplying two cylinders.
Construction of the 18R was largely of Elektron magnesium alloy for body components with high strength steels for highly loaded parts such as the crankshaft. In common with many multiple bank and radial engines the pistons were connected to the crankshaft via master and slave connecting rods; the central vertical bank was served by the master rod which housed the big-end bearing with connecting rods articulating from this to the other two banks. The 18R was available with or without a Farman (bevel planetary) reduction gear.
Development issues delayed production of the engine, with the first geared drive engine delivered to Nieuport-Delage in October 1929, a month after the 1929 Schneider Trophy race. Despite the effort put into its development the 18R proved to be unreliable and unable to achieve the expected power output. The poor performance of the 18R prompted the development of the 18S, a de-rated version intended for commercial use. Reducing the compression ratio to 6.2:1 at a maximum rpm of 2,000 and replacing the Elektron with aluminium alloy, the 18S was available with or without the Farman reduction gear, but was not a success, only powering the Ford 14A in the pylon mounted central nacelle.
The 18R and 18S did not have successful careers, only powering four aircraft types in very small production numbers, proving to be totally outclassed by contemporary racing engines, such as the Rolls-Royce R which powered the Supermarine S.6 family of floatplane racers.
- The original racing engine with 10:1 compression ratio, available with or without the Farman reduction gearing.
- The de-rated. 6.2:1 compression ratio, commercial version without the Farman reduction gearing.
- The 18Sb with the Farman reduction gearing.
Engines on display
- Type: W-18 80° water-cooled in-line engine
- Bore: 150 mm (5.91 in)
- Stroke: 170 mm (6.69 in)
- Displacement: 54.1 l (3,301.38 cu in)
- Length: 1,640 mm (64.57 in) without reduction gear, 1,990 mm (78.35 in) with reduction gear
- Width: 1,330 mm (52.36 in)
- Height: 1,170 mm (46.06 in)
- Dry weight: 540 kg (1,190 lb) 18R without reduction gear, 600 kg (1,300 lb) 18R with reduction gear
- 516 kg (1,138 lb) 18Sb without reduction gear, 590 kg (1,300 lb) 18Sbr with reduction gear
- Valvetrain: single shaft driven overhead camshaft with one exhaust and one inlet valve per cylinder
- Fuel system: nine carburretors feeding two cylinders each
- Fuel type: gasoline
- Oil system: pressure fed
- Cooling system: water-cooled
- Reduction gear: optional Farman (bevel planetary) geared drive, which weighed 60 kg (130 lb).
- Power output: 1,253 kW (1,680 hp) at 2,400 rpm (18S – 745 kW (999 hp) at 2,000 rpm)
- Compression ratio: 10:1 (18S – 6.2:1)
- Pearce, William. "Hispano-Suiza 18R and 18Sb Aircraft Engines". oldmachinepress. Retrieved 14 September 2013.
- Schneider Trophy Seaplanes and Flying Boats by Ralph Pegram (2012)
- Hispano Suiza in Aeronautics by Manuel Lage (2004)
- Aerosphere 1939 by Glenn Angle (1940)
- Jane's All the World's Aircraft 1931–1933 by C.G. Grey
- Beyond the Model T: The Other Ventures of Henry Ford by Ford Bryan (1997)