Hi Debonair,
>I was read in a US test document about Kommandogerat (tm) that it ran over-rich at high power settings & was wondering if this was as an aid to cooling, how much it affected fuel economy
It's my impression that the BMW801D did not increase its specific fuel consumption as rapidly when going to emergency power as for example the R-2800. That's from memory only :-) I'm not sure whether this is due to the command device or simply due to the use of direct fuel injection. (The modest consumption increase seems to be a trend for German engines, so it might be the latter.)
>if it was common practice to override Komandogerat (tm) in this instance for the performance boost & fuel saving.
I'm not even sure it could be overridden.
One comparative US report report on the FW190 expresses doubt on whether the command device would allow to get the best performance and economy from the engine. On the other hand, there is a detailed NACA report showing that it handled non-linear relationships of some half dozen parameters, and I believe it would be hard for a human operator to manage the engine with similar effectiveness.
However, after WW2 additional sensors were installed in piston-engined aircraft that provided the flight engineers with more data than available before (stuff like brake mean effective power gauges and exhaust temperature thermometers), and from what I've read, that really took engine management a step beyond what was possible during WW2, command device or not.
The command device, by the way, was not unique. The Jumo 213 for example had a "single lever control device" that was even more advanced than its BMW counterpart, regulating charge mass instead of boost pressure to get higher power below full throttle height.
The Allies, too, had single lever control devices. The French had employed one for the Dewoitine D. 520 even before the war, but apparently it still had some issues, judging by Eric Brown's test flight impressions. The late-war Spitfires had an "interconnected control levers" operation mode, too, which apparently worked just like a command device, at least when the engine was operating at maximum power. For normal climb and cruise situations, the pilot could override this system for better efficiency.
An interesting topic, though (or because? :-) it's hard to find detailed information. Thanks for bringing it up! :-)
Regards,
Henning (HoHun)
