Spitfire mixture/throttle lever interlocking device

[gecko]

Hi all,

In each version of the Spitfire pilot's notes from Mk.I up to Mk.VI the following line appears in the section describing the throttle and mixture controls:

"...an interlocking device between the levers prevents the engine from being run on an unsuitable mixture."

Does anyone have any references for how this device was rigged? At what point in the throttle's travel would it move the mixture control? I assume at the point where manifold pressure began to exceed the maximum for WEAK mixture the throttle would push the mixture lever from the WEAK position to the NORMAL position, but this would be a different position in the throttle travel depending on if you were above full throttle height if I understand how the boost controller worked correctly. To muddy the waters, the only place I've seen this represented is the IL-2 Cliffs of Dover flight simulator, and they have the throttle moving the mixture from the WEAK position to the NORMAL position when the throttle is brought towards idle and allowing WEAK mixture to be selected with full throttle. Normally I have a lot of respect for IL-2's attention to detail, but this seems like exactly what you WOULDN'T want the interlocking device to do. (Note, this isn't about if they are right or wrong, I don't play their sim, just mentioning the only other place I've seen this feature noted.) Any technical details are greatly appreciated. Thanks,

Dan

 

[Crimea_River]

Daryl (user name Tony Hill) may know but I have not seen him here for a while. He's building a PR I cockpit simulator in this thread and there may be some reference to the throttle workings there.

 

[gecko]

Thanks, didn't find anything there. I did come across a Spitfire Mk.II manual that described the interlock device, but not with much detail. It did work as it is modeled in the IL-2 simulator, but I can't figure out why they designed it that way or what it was trying to accomplish? It allows you to run WEAK mixture at full throttle, and forces you to run NORMAL mixture at low power and idle throttle settings. You never want to do the former, and sometimes being able to do the latter would be very useful. It makes no sense to me.

 

[Spits2]

Its a linkage at the back of the Merlin off memory.

 

[lest we forget]

bit late to the party but was just reading an Airfix blog on their website regarding the new 1/24 Mk IX Spitfire instructions which included reference to 'the mixer control' not being required on scheme B of 4 and to cut it off, presumably the graphic shown pre-dates the 5th scheme being added which are not showing any A B C D E reference on their website anyway so I can't say which one is B without delving deeper.

As far as i'm aware after reading one or two mentions of the mixture control lever the pilot could only make the mixture richer from any throttle position so the lever was forward moving of the throttle position only, it couldn't be moved back past the throttle lever without re-engaging with the throttle and so was only fully independent on the richer side, the interlocking mechanism you mentioned probably mechanically prevented the lean / full throttle scenario.

Hope that's of some use even if it only confirms any more up to date knowledge you now have, Airfix may have corrected their typo or are still showing a slight lack of correct fuel/air mixture terminology on the instructions for their new superkit.