Will a plane fly faster at specific RPM leaned / full rich?

[Karbonkid]

ok, not sure why I am second guessing myself on this but figure there are many with answers here.

When you fly at 2400 RPM full rich will you fly slower than you will at 2400 leaned for max power?

some reason I feel there is more to this than 2400 puts x ammt of power to the air which makes y speed.... but I may be off

[jrs14855]

Fuel injection will definitely gain a couple knots at best power. Carb depends on the individual setup. A pressure carb has no significant change at low altitude. Float carb depends on the individual setup. Most POH's call for leaning for takeoff above 4-5000', again this may not hold true for some unique installations.

[RV7A Flyer]

Originally Posted by Karbonkid

ok, not sure why I am second guessing myself on this but figure there are many with answers here.

When you fly at 2400 RPM full rich will you fly slower than you will at 2400 leaned for max power?

some reason I feel there is more to this than 2400 puts x ammt of power to the air which makes y speed.... but I may be off

It's not called "Best Power" for no reason

[rjbob]

2,400 RPM...fixed pitch prop...same speed no matter what the mixture (all else being equal).

2,400 RPM...constant speed prop...more power=more speed. If leaning gets you more power, speed will increase because the propeller pitch will increase. (all else being equal).

[RV6_flyer]

At 2,300 RPM, I can see 10 KIAS, 10 Kts Ground Speed change with only a mixture change. The mixture change cost me 1.5 GPH fuel flow for the extra fuel burn to get 10 Knots.

Best Power mixture or Best Economy mixture is what I typically run.

Full Rich and Max Power can be the same thing at standard sea level but at altitude, Full Rich may be less power than Max Power mixture setting. The answer to your question depends on altitude.

[rzbill]

If you lean towards best power in the climb, you can see the climb rate go up. Watch CHT of course.

[N941WR]

With a FP prop, starting at 2400 RPM, the RPM's will increase as the plane accelerates with leaning because you are producing more power.

Full rich is too rich, thus you are not optimizing your fuel to air ratio for maximum power. Leaning it to the proper stoichiometric mixture ratio produces the best power. However, depending on your CHT's you might want to run it a little rich to keep your temps down.

[RV10inOz]

Study this graph, the answers are all there including many to questions you have not asked.

(Courtesy Advanced Pilot Seminars)

At around 75dF ROP is where the "peak power" is found, and while you can fly there for periods of time at high power settings, without destroying or causing significant harm that is not what the maker intended. And hence you have a mixture knob.

If you want to get the most out of your engine while maintaining stress levels on the engine (induced from Internal Cylinder Pressure ICP) then use the appropriate amount either LOP or ROP as your mission requires.

Take a look here at this interactive. http://www.advancedpilot.com/redbox.html

[Mike S]

Originally Posted by rjbob

2,400 RPM...fixed pitch prop...same speed no matter what the mixture (all else being equal).

2,400 RPM...constant speed prop...more power=more speed. If leaning gets you more power, speed will increase because the propeller pitch will increase. (all else being equal).

Agree totally.

[flyingriki]

Originally Posted by Mike S

Agree totally.

Then why, while testing a new FP prop, did I get max speed out of leaning for max RPM?