Mercedes D.IV
1915 - 1916
Description
The Mercedes D.IV is an 8-inline-cylinder aircraft engine manufactured by the German company Daimler Motoren Gesellschaft during the First World War. The D.IV was the first mass-produced German engine equipped with a propeller reduction drive. Its construction scheme derived from the previous and very successful D.III, from which it differed for the larger number of cylinders (from 6 to 8). The engine overcame the acceptance test in December of 1915, but it was produced in only 429 copies because of its poor reliability, mainly due to the fragility of the crankshaft for its excessive length. Because of this the D.IV was soon replaced by a completely redesigned engine, the D.IVa with 6 cylinders. The designation similar between the two engines is due to the rigid classification then in use in Germany, based on groups of power output by (I to VI), in which the first letter indicates the manufacturer.
Technical specifications
| Manufacturer | Daimler Motoren Gesellschaft, Stuttgart-Untertürkheim, Germany, 1915 |
| Type | Mercedes D.IV |
| Description | aircraft engine with 8-inlne cylinders, aluminium alloy crankcase with 9 main bearings, stell-made cylinder and heads, cooling jackets in thin-walled welded steel, steel-made pistons from of two part (top and skirt) screwed and welded |
| Stroke | 160 mm |
| Bore | 140 mm |
| Displacement | 19770 cm³ |
| Compression ratio | 4.6 |
| Power | 232 hp at 1440 rpm (maximum output at sea level); 210 hp at 1300 rpm (max. service output at sea level) |
| Specific consumption | 230 g/hp/h |
| Specific power | 12.1 hp/litre |
| Valvetrain system | 2 overhead valves per cylinder controlled by an overhead gear-driven camshaft |
| Fuel feeding system | with two single-barrel gasoline carburetors |
| Ignition system | two spark plugs per cylinder fed by two high voltage magneto distributors Bosch HL8 |
| Cooling system | liquid-fed by a centrifugal pump |
| Lubrication system | forced by means of a 4-cylinder reciprocating pump |
| Length | 1990 mm |
| Width | 600 mm |
| Height | 1040 mm |
| Weight | 410 kg |
| Mass-to-power ratio | 1.71 kg/hp |
| Propeller transmission ratio | 1.38:1 by means of a reduction drive with a pair of spur gears |
Application
AEG C.V (reconnaissance aircraft)
AEG G.III (bombardier)
AEG G.IV (bombardier)
AEG G.V (bombardier)
AEG R.I (bombardier)
AGO C.II (reconnaissance aircraft)
AGO C.VIII (reconnaissance aircraft)
Albatros C.V (reconnaissance aircraft)
Gotha G.II (bombardier)
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