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Questions tagged [mixture]

The mixture ratio of an engine is the amount of air used for burning a given quantity of fuel; spark-ignition piston engines use different mixture ratios for different phases of flight.

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4 answers
365 views

Engine performance under best economy vs best power mixtures and how it relates to TAS on a fixed pitch propeller?

I am currently training on a very basic PA-28-161 (it has a single reciprocating air-cooled engine with fixed pitch propeller). I have a rather involved question on mixture as it relates to power as ...
22 votes
3 answers
10k views

Carbureted Rotax engines have no mixture control, how do they handle less dense air?

Rotax engines have no mixture control, yet they don't seem to have any more problems than other engines at altitude. How do they handle the lower air density in order to not get a too rich a mixture?
0 votes
1 answer
717 views

What is the purpose of mixture control? [duplicate]

What's the purpose of mixture control? Is it to control the amount of fuel provided to the engine with which it is associated? If that's the case, what's the purpose of throttle lever then?
0 votes
1 answer
315 views

Cessna 182Q (parachute operation) - climb leaning with CHT

for a 182Q the POH specifies for maximum climb to use 2400 RPM and full power with given speeds (78 KIAS for Sea Level, reducing to 72 at FL100). It specifies that the mixture may be leaned at 5000ft ...
4 votes
1 answer
394 views

What happens if you change power setting with constant mixture setting?

For a given Cruise Setting: Manifold set / RPM set / Mixture set according to P.O.H. values: what happens to the Mixture if you were to reduce power or increase Power by varying throttle? Does a ...
9 votes
2 answers
2k views

Why does a fuel-injected engine have a mixture control?

For example, in a C172S fuel injected type, what does the mixture control lever control exactly in the fuel system? They have a fuel air control unit which regulates fuel flow based on air passing ...
4 votes
1 answer
1k views

On the G1000 lean assist page, what does a positive delta EGT mean?

When leaning the fuel mixture on a C172 using the lean assist feature on the G1000, the hottest cylinder's EGT will be displayed, along with a reading showing the difference between the current ...
21 votes
3 answers
43k views

How does the mixture of an engine affect the engine's operation?

I know that in most piston aircraft that there is a mixture control for the engine. My question is, how does the mixture control affect the engine's operation and what type of situations dictate a ...
28 votes
2 answers
7k views

Why does the mixture knob spin?

On my first intro flight. I noticed the instructor twisting the mixture knob. I didn't think of asking, but now Im curious.
7 votes
4 answers
3k views

Why does enriching the mixture ratio beyond stoichiometry give more power?

In other words, in a piston engine, the best-power mixture is richer than that producing the EGT peak that signals stoichiometric combustion. Why is that, physically?
1 vote
2 answers
3k views

Why is the fuel:air ratio of a turbojet engine not around ~1:15 (the stoichiometric ratio)? [closed]

Also, what is the maximum fuel:air ratio possible in a combustion chamber of a jet engine?
4 votes
2 answers
1k views

What is the relationship between fuel mixture, throttle setting and engine temperature?

I'm trying to understand the relationship between mixture, throttle, and engine temp. In this article from AOPA, it states ... a lean mixture of 16 to 1 is not going to burn as hot as a rich mixture ...
1 vote
1 answer
2k views

What is the air/fuel mixture ratio in a turbojet engine?

How does it relates to stoichiometry ? What are the possible extinction accidents related to air/fuel mixture ratio ?
0 votes
1 answer
352 views

Does the DA-42 automatically lean to clean fouled spark plugs?

The DA-42 has an automatic run-up method. Specifically, the pilot in command is to hold two buttons (one for each engine) until the run-up is complete. Since the DA-42 has no manual mixture control, ...
2 votes
1 answer
592 views

Does a lean mixture result in a higher cylinder temperature for a given power setting?

From what I know over rich mixture help cools the engine due to evaporation process and lean mixture do the opposite. So why this graph showing when reaching around peak EGT the opposite happens:
10 votes
4 answers
5k views

How does the DA 40 NG automatically control the mixture, pitch and power by just providing one throttle?

I'm a student pilot and here at my school we have the older gen DA40s which have individual lever for mixture, pitch and power. I was looking at this video of the DA40 NG, and got quite curious as ...
8 votes
1 answer
1k views

Does the mixture and throttle setting affect the quality of priming of fuel prior to start?

This question is a generality. For airplanes with small reciprocating engines, does the mixture and throttle setting at the time of priming affect the quality of the priming or the engine start, or ...
2 votes
1 answer
5k views

How do you lean mixture using only the instruments on a C172 Skyhawk?

POH manuals always tells to use the voice of the engine as a reference. (Which complicates things a little bit since carbs and fuel injected planes have different "reaction times" for each cylinder) ...
1 vote
1 answer
2k views

How to lean with constant speed prop on multi-engine aircraft without EGT

This question is more about the indication of engine roughness. The procedure for leaning without an EGT is clear in the POH and Lycoming documentation which basically states as follows: Best power: ...
5 votes
2 answers
1k views

Do Diesel engines have a mixture option?

Consider the DA-42, it has no mixture control. Is that because it is run on Jet-A/diesel? Or is the mixture control automated?
1 vote
0 answers
270 views

What variables is an engine's AFR based on?

Maybe this is a bit too technical for an aviation forum, but it specifically concerns a flight engine.(Rotax 912 iS) Road vehicle engines will probably have different behavior. As you may know, the ...