Inaccurate performance data for BOB fighters in COD comparing to RL data

[41Sqn_Banks]

See this post for the relevant pages of AP1565A Vol. I that cover +12 Boost and 100 Octane.

http://forum.1cpublishing.eu/attachm...9&d=1332111633
http://forum.1cpublishing.eu/attachm...0&d=1332111638
http://forum.1cpublishing.eu/attachm...1&d=1332111649
http://forum.1cpublishing.eu/attachm...2&d=1332111659
http://forum.1cpublishing.eu/attachm...3&d=1332111666

Note Sec. 2 Para XII where the increase of boost to +12 is mentioned. Note Sec. 8 Para 7 the use is "authorized" for short period and when 100 octane is used. Also note the "List of Content" of Sec. 8, it shows Sec. 8 was issued with A.L. 6 in July 1940.

Originally Posted by Crumpp

In order to use +12lbs on the Merlin engine, you had to replace the heads with a new design with a increased spigot depth of .020. There were two authorized heads being manufactured to convert engines. One could use the existing rings while the other required a specific set of rings to be installed. Once that was done, the fuel metering system had to be modified. You can figure they would have had a 4 to 1 stock of heads before they started modifying aircraft. They would maintain that ratio even if it limited the size of the force they could convert.

Note that Sec. 8 Para 7 also refers to AP1590B Vol. I (manual of Merlin II and III) for the required modifications. IIRC in this manual only Mod 154 (modification that limits the boost to +12) is mentioned as required and the other modifications are recommended. I will look these pages up later. EDIT: The manual states that both mods are required.

Originally Posted by Crumpp

The July of 1940 Spitfire Mk II manual clears the Merlin III engine for use of 100 Octane fuel and notes +12lbs may be used.

Please correct this statement. It's unlikely that the Spitfire II manual (which has a Merlin XII engine) clears anything for the the Merlin III engine.