Maybach Mb.IVa

Mb IVa
	Mb IVa at the National Air and Space Museum
Type	6-cyl water-cooled in-line piston engine
National origin	Germany
Manufacturer	Maybach-Motorenbau GmbH
Designer	Karl Maybach
Major applications	Zeppelin airships (LZ 105 to 114)
Produced	1916 - 1918

The Maybach Mb IVa was a water-cooled aircraft and airship straight-six engine developed in Germany during World War I by Maybach-Motorenbau GmbH, a subsidiary of Zeppelin. It was one of the world's first series-produced engines designed specifically for high-altitude use. It was quite different engine design than the previous Maybach Mb.IV, not just a simple modification.

Design and development

Like all engines of that time, the previous Maybach design, the Mb IV, lost as much as half of the nominal power of 240 horsepower at high altitude. The new Maybach Mb IVa of 1916 was the first engine designed to overcome this limitation.^[1] It did not use a supercharger, but a much more primitive solution. The engine had purposely "oversized" cylinders, and a significantly higher 6.08:1 compression ratio. It was tested on Wendelstein (mountain)^[2] at an altitude of 1800 m and rated there at 245 hp.^[3] This would theoretically correspond to rating of about 300 hp at sea level; however, the engine was not designed to withstand such power^[4] - it needed to be carefully throttled down at low altitude, so it would not exceed the safe level of 245 hp. It had three carburettor settings, to be changed during the flight depending on the altitude.

The engine was falsely given a rating of 260 hp (190 kW) at sea level, so it would not appear inferior to the engines it replaced.^[4]

Applications

During the First World War

Friedrichshafen G.V (one built)
Gotha G.VIII (one built)
Gotha G.IX
Gotha WD.8
Hansa-Brandenburg W.29
LFG Roland G.I
Rumpler C.VII
Sablatnig C.III
Zeppelin airships, beginning with LZ 105 up to LZ 114^[1]
Zeppelin-Lindau Rs.III
Zeppelin-Lindau Rs.IV
Zeppelin-Staaken R.VI
Zeppelin-Staaken R.XIV
Zeppelin-Staaken R.XV

After the First World War

Other Maybach engines

The earlier Maybach engines were:

Maybach AZ of 1909: 140 hp (100 kW)^[3]
Maybach CX of 1915: 210 hp (160 kW)^[3]
Maybach DW and IR of 1914: 160 hp (120 kW)^[3]
Maybach HS (there was a variant HSLu, known also as HS-Lu) of 1915: 240 hp (180 kW)^[3]
Maybach Mb III - a new designation for the existing Maybach IR engine^[5]
Maybach Mb IV - a new designation for the existing Maybach HS engine^[5]

The power ratings for these older engines are at sea level, unlike the rating of the Mb IVa.

Specifications (Mb.IVa)

Data from Kleinheins.^[1]

General characteristics

Type: 6-cylinder inline liquid-cooled aircraft engine
Bore: 165 mm (6.6 in)
Stroke: 180 mm (7.2 in)
Displacement: 23.096 l
Dry weight: 400 kg (881 lb) (later variant with aluminium pistons 390 kg (859 lb))
Designer: Karl Maybach

Components

Cooling system: water-cooled

Performance

Power output: 245 hp
Compression ratio: 6.08:1
Specific fuel consumption: 200g/PS/h

References

^ ^a ^b ^c ^d Kleinheins, Peter (2005). Die grossen Zeppeline : die Geschichte des Luftschiffbaus (in German). Berlin [u.a.]: Springer. pp. 91–93. ISBN 3-540-21170-5.
^ Ernst Heinrich Hirschel; Horst Prem; Gero Madelung (2004). Aeronautical research in Germany : from Lilienthal until today. Berlin: Springer. pp. 217–218. ISBN 3-540-40645-X.
^ ^a ^b ^c ^d ^e Wilhelm Treue; Stefan Zima; Gustav Burr (1992). Hochleistungsmotoren : Karl Maybach und sein Werk (in German). Düsseldorf: VDI Verlag. p. 290. ISBN 978-3-18-400905-2.
^ ^a ^b George William Haddow; Peter Michael Grosz (1962). The German giants. Putnam.
^ ^a ^b Kyrill von Gersdorff; Kurt Grasmann; Karl Prestel; Helmut Schubert (1985). Flugmotoren und Strahltriebwerke : Entwicklungsgeschichte der deutschen Luftfahrtantriebe von den Anfängen bis zu den internationalen Gemeinschaftsentwicklungen (in German) (2. erg. und erw. Aufl. ed.). Koblenz: Bernard & Graefe. p. 26. ISBN 3-7637-5283-8.