14.26 Can anybody tell me about propeller/mixture settings?
From FlightSim
I WANT TO UP MY SIM REALISM YET ANOTHER NOTCH, AND WOULD APPRECIATE IT IF ANYBODY CAN GIVE ME SOME ADVICE ON TYPICAL SETTINGS AT DIFFERENT TIMES (TAKEOFF, LANDING, APPROACH, CRUISE, ETC.) FOR THE PROPELLER AND MIXTURE WITH THE CESSNA 182 AND RG.
The mixture control on light a/c is normally set a full rich for takeoff at sea level under standard conditions (15 deg. C, 29.92 altimeter setting, 0 percent humidity). Propeller is normally set to full forward (max RPM).
At higher altitudes (and even very high temperatures) the engine is leaned prior to takeoff. There are various techniques, but the most common one is, during the runup (1800 or so RPM), lean to max RPM, then make it just a touch richer. Some a/c (the Bonanza, for example) will give a specific fuel flow setting for given conditions in the handbook, but I still use this technique for the initial setting and only make a change after getting some altitude.
At altitudes less than about 3,000 ft, many suggest no need to lean, but I find that you can usually improve fuel efficiency (and power) by doing so anyway, especially if the temperature is above standard.
Leaning at cruise with a constant speed prop (like the 182) is not as easy as with a fixed pitch prop (use max RPM again), unless the a/c is equipped with an EGT (Exhaust Gas Temperature gauge). Then, depending on engine and a/c manufacturers' recommendations, you lean to peak EGT for economy or 50 degrees rich of peak for max power. There are some that let you go as much as 50 degrees lean of peak at lower power settings; and there are other variations.
Leaning in the climb is a bit different, as you must allow for engine cooling, as well as performance. Fuel flow is used for cooling in most aircooled engines (most a/c), including the 182. When at full throttle, it's not quite as much of a concern, as there is an automatic enrichment provided, but as soon as you reduce the throttle (which you do at lower altitudes shortly after takeoff), the auto-enrich goes away, so you MUST keep the mixture a bit rich. I'd go about 100-150 degres rich of peak on the EGT.
On the Cessna 182 models that have a max RPM of 2400, you can just leave the prop full forward all the time if you wish, but can improve economy at cruise by coming back to 2100-2300 RPM. Just remember to go full forward again before landing, to allow max power for a go-around. Also, if you have leaned for cruise at altitude, you'll need to gradually enrich the mixture during letdown, such that at pattern altitude at sea level airports you're back to full rich. Don't go full rich landing somewhere like Denver or Albuquerque, though, as the density altitude will leave you way short of max power.
Larry N.
