<?xml version="1.0" encoding="utf-8"?>
<!--

  Zeppelin LZ 121 "Nordstern" airship flight model for JSBSim.

    Copyright (C) 2010 - 2016  Anders Gidenstam  (anders(at)gidenstam.org)

    This program is free software; you can redistribute it and/or modify
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-->
<piston_engine name="Maybach Mb IVa">
 <documentation>
   Maybach Mb IVa high altitude engine.

   [Vissering:1922:ZS]:
     260 HP above 10000ft
     From engine performance table, assuming that Maybach 1918 is MbIVa:
     260 HP, 1400 RPM, 390 kg, 0.200 kg/(hp hr)

   [PK:1994:LZ120] for Bodensee:
     Side engines had a propeller diameter of 3.2 m
     The aft engine had a propeller diameter of 5.2 m geared down about 2:1.
     4 Maybach Mb IVa-Höhenleistungsmotoren (6 cylinder inline)
       190 kW max above 1800 m
       180 kW max below 1800 m
       2.2 kg/kW (implying an engine weight of 418kg)
       Specific fuel consumption: 270 g/kWh @ 1400 RPM
       Cruise consumption: about 45 kg/h (per engine)

   [Flight:1918:MB, pages 960 - 965]
     Technical description of captured Maybach 300 HP aircraft engine.
     Seems very similar to the Mb IVa so the dimensions may match.

     Bore:              165 mm
     Stroke:            180 mm (Computed from bore, compression ratio
                                and clearance volume)
     Compression ratio: 5.94:1
     Clearance volume:  778.9 cm^3

   [LD:1924:25YOAC, pages 78 - 79]
     Bore:              165 mm
     Stroke:            180 mm
     Compression ratio: 6.08:1
     "The performance of the engine on the ground was limited to 245 hp as at
      this level the carburettor was not yet fully open; full flow was not
      achieved until an altitude of 1800 m had been reached. Performance up to
      this height was consequently maintained at 245 hp. Fuel consumption was
      200 gm/hp hour. When dry the engine weighed 400 kg (1916), later 390 kg."

 </documentation>

 <displacement unit="LTR"> 23.09  </displacement>
 <bore unit="M">            0.165 </bore>
 <stroke unit="M">          0.180 </stroke>
 <compression-ratio>        6.08  </compression-ratio>
 <cylinders>                6.00  </cylinders>
 <cycles>                   4.00  </cycles>

 <minmp unit="INHG">         10.5 </minmp>
 <maxmp unit="INHG">         28.5 </maxmp>

 <maxhp>                   240.00 </maxhp> <!-- Needs to be adjusted so that
                                                full throttle at 1800 m
                                                delivers 240 hp @ 1400 RPM(?).
                                           -->

 <idlerpm>                 250.00 </idlerpm>
 <maxrpm>                 1400.00 </maxrpm>

 <bsfc unit="LBS/HP*HR">    0.443 </bsfc>
 <!-- volumetric_efficiency>          <volumetric_efficiency -->
 <sparkfaildrop>             0.10 </sparkfaildrop>

 <minthrottle> 0.1 </minthrottle>
 <maxthrottle> 1.0 </maxthrottle>

</piston_engine>
