Type of improvement: Spit II Mixture Operation
Key points:
1. Currently impossible to use +2.5 boost on lean mixture at 2650 RPM (maximum cruising value specified in manual for 87 octane). Maximum possible is currently +1.1 boost.
2. Mixture should have a direct effect on the temperature of the oil and coolant - at present it has no effect.
3. Smooth engine operation is possible at extreme boost levels +5 upwards. These are way above the maximum permissable on a weak mixture and from what I've read should result in severe detonation - rough running and eventual engine damage.
Explanation of proposals: I've been experimenting with the auto-rich / auto-lean mixture settings on the Spit II. My original Mark II manual states that auto-lean cruising should be possible at 2650 RPM up to +2.5 boost on 87 octane and up to +4 boost on 100 octane fuel.
I'm not sure which fuel is being modelled for the Spit II but I guess 87 octane since boost only registers up to +8 and not +12 as mentioned in the manual.
I'm finding that I can't use more than +1.1 boost without the engine starting to miss. This is at sea level. As you climb the boost must be backed off to keep the engine running smoothly - I'm no pilot but this seems logical enough - higher altitudes = less air so mixture becomes richer and starts choking the engine.
I'd like to request that mixture is tweaked to allow me to operate according to the manual please.
I'd also like to see an effect on oil and coolant temperatures when switching between rich and lean mixtures.
It is also possible to operate very high boost settings on lean mixture (way above the maximums in the manual) without any signs of detonation or engine trouble.
Benefits: More accurate mixture behaviour allowing user to fly by the manual and obtain higher boost settings in a lean cruise. Introducing effects of mixture on engine temps would make engine management more interesting and varied.
Thanks
