Merlin engine limits & failure behaviour

[IvanK]

Good observations Viper.

Mixture issues with both Hurricanes and Spitfires has been reported directly to the Devs.

However in both the Hurricane and Spitfire the Mixtures were non incremental but two position either BACK for RICH and FORWARD for LEAN.
In effect these were AUTO RICH and AUTO LEAN. So in either position they will lean as the aircraft's climbs. In both the Spitfire and Hurricane there is an interconnect (or physical contact) between the throttle and mixture lever such that pulling the throttle back will also drag the Mixture lever BACK to the RICH position. This is all clearly documented in the respective pilots notes and maintenance manuals.* I am happy to provide scans of these if required. It is the reverse of what we have become used to.

Boost limits were placed (+4 on 100 Octane and +2 1/2 for 87 Octane) for LEAN operation .. to prevent Detonation/pre-ignition.

A further complication in COD is that in the case of the Hurricanes it would seem the the effects of mixture control have been reversed in relation to the lever positions.


*Note on some restored aircraft the Mixture controls have been set in a conventional sense (Forward to rich) this as a Flight Safety issue in that the pilots fly multiple types and keeping things standard is a sensible concession to 100% historical accuracy. Though in Peter Vacher's Hurricane I R4118 it has been restored with 100% accuracy in this regard.

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Here are a couple of excepts from Hurricane I pilots notes and Hurricane II maintenance manuals: