> And as I got to know the airplane, I could estimate the fuel burned on a trip within a gallon. Leaning was done by pulling out the mixture until the engine go

> And as I got to know the airplane, I could estimate the fuel burned on a trip within a gallon. Leaning was done by pulling out the mixture until the engine got rough. It was much later when the fancier planes got EGT gauges, and decades after that with EGT readouts for each cylinder Correctly leaning a piston engine to balance the power output, manifold pressure, EGT (Exhaust Gas Temperature), CHT (Cylinder Head Temperature), Peak Pressure Point and RPM is a fascinating subject. After a series of mysterious spontaneous combustion events in my home flight simulator, I found a 1999 article by John Deakin of AVweb, and was finally able to investigate and resolve the issue and take my Constellation up to FL220 - and back down again - with all four engines intact! https://www.avweb.com/features_old/pelicans-perch-18mixture-magic/ https://www.avweb.com/features_old/pelicans-perch-18mixture-... I've found no other more informative article on the topic! Particularly interesting to me is that the 'engine getting rough' behaviour that the C172 author describes is actually due to the variation of fuel flow to the different cylinders. When you lean the engine, the fuel flow isn't reduced identically to all the cylinders, causing the power output to become unbalanced. John Deakin points out that "virtually all factory big bore engines suffer from this uneven power distribution, which sets an artificial limit on just how lean we can run." Radial engines have superior fuel flow, because the fuel is driven by centrifugal force into each cylinder equally from a central pipe! The Lockheed Super Constellation in my flight simulator shows no roughness when leaned, because it has radial engines. However, it's still susceptible to detonation due to the higher combustion speed when leaned. That's what was causing the fires. Interestingly, one feature which my flight simulator doesn't replicate - but was present on the Super Constellations in real life - is a 'spark retard' control. That would allow power to be squeezed out of the engines even more efficiently by letting the engines run leaner without detonation, artificially delaying the spark to compensate for the more violent combustion.