Mercedes D.IVa

D.IVa
	Mercedes D.IVa at the Deutsches Museum. The prominent black piping is the inlet manifold from the carburetor
Type	Inline piston engine
Manufacturer	Daimler Motoren Gesellschaft (DMG)
First run	1917

The Mercedes D.IVa was a German six-cylinder, water-cooled, inline engine developed in 1917 for use in aircraft and built by Daimler Motoren Gesellschaft (DMG).^[1]

Design and development[edit]

The D.IVa replaced the failed Mercedes D.IV inline eight-cylinder engine. The D.IVa was primarily used to power bombers and large reconnaissance aircraft. Unlike most German designs, the D.IVa was relatively advanced, including four valves per cylinder actuated by a SOHC valvetrain, the same "single-camshaft" arrangement that had also been used on the earlier two-valve per cylinder D.I through D.IIIa powerplants.

Designed specifically to be installed in the fuselage, the engine featured a number of design elements intended to reduce its width. For instance, the carburetor was placed behind the engine, feeding fuel to the cylinders via a long tubular intake manifold. This had the disadvantage of poor fuel distribution. Two versions of the engine were produced in mirror copies, running in opposite directions.

Applications[edit]

Engines on display[edit]

A Mercedes D.IVa recently restored by the Museum's Friends ASSN. is on public display at the Museo Nacional de Aeronautica (MORON-Argentina).

Specifications (D.IVa)[edit]

Data from Jane's all the World's Aircraft 1918,^[2] Jane's Fighting Aircraft of World War One^[3]^[4]

General characteristics

Type: 6-cylinder, inline piston engine
Bore: 160 mm (6.30 in)
Stroke: 180 mm (7.09 in)
Displacement: 21.72 L (1,325 cu in)
Length: 1,168.4 mm (46 in) approx.
Height: 1,968.5 mm (77.5 in)
Dry weight: 498.50 kg (1,099 lb)

Components

Valvetrain: Shaft driven SOHC operating twin exhaust and inlet valves with a half compression setting for starting
Fuel system: Twin jet Mercedes carburettor with automatic mixture control
Fuel type: Gasoline
Oil system: Forced feed to bearings and camshaft
Cooling system: Water-cooled
Reduction gear: Direct drive, left-hand tractor

Performance

Power output: 187.92 kW (252 hp) at 1,400 rpm
Compression ratio: 4.94:1
Fuel consumption: 125 pints per hour
Specific fuel consumption: 0.329 kg/kWh (0.541 lb/(hp⋅h)) / 0.461 L/kWh (0.605 imp pt/(hp⋅h))
Oil consumption: 0.024 L/kWh (0.032 imp pt/(hp⋅h))
Power-to-weight ratio: 0.376 kW/kg (0.229 hp/lb)
Bmep: 741.19 kPa (107.5 psi)

References[edit]

Notes[edit]

^ Gunston 1989, p.101.
^ Grey, C.G., ed. (1968). Jane's all the World's Aircraft 1918 (facsimile ed.). New York Pages=46d-56d: Arno Press Inc.{{cite book}}: CS1 maint: location (link)
^ Jane's 1993, p. 299
^ Figures were derived from a British bench test of a captured engine.

Bibliography[edit]

Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
Jane's Fighting Aircraft of World War I. London. Studio Editions Ltd, 1993. ISBN 1-85170-347-0

External links[edit]

Tests of the Daimler D-IVa engine at a high altitude test bench (October 1, 1920)

[1] Gunston 1989, p.101.

[JAWA1918-2] Grey, C.G., ed. (1968). Jane's all the World's Aircraft 1918 (facsimile ed.). New York Pages=46d-56d: Arno Press Inc.{{cite book}}: CS1 maint: location (link)

[3] Jane's 1993, p. 299

[4] Figures were derived from a British bench test of a captured engine.

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