Mixture setting for landing

[pinerunner]

One of the things that Busch and Deakins reccomend that I haven't seen discussed here is setting the mixture for maximum power during the low-power, landing phase of flight. After some agonizing I've incorporated that advice, along with some practice at altitude for advancing mixture first, then power for go-around; it didn't seem too complicated. Basicly as I approach entry into downwind I drop the power until the prop comes out of governance with the prop full forward and then set it to 2500 RPM. Then mixture comes back until slight decrease of RPM and move back ahead until it maximizes. Then I leave it (the mixture) alone for the rest of the landing, treating it like a fixed-pitch prop and controlling everything with just the throttle. 

 

I practiced once at altitude giving it full throttle with the mixture set like this to be sure the engine wouldn't quit like it does when aggresively leaned for idle; that wouldn't do if I reverted to just going for the throttle in a go-around situation 10 feet off the runway. It gave power fine; I didn't leave it like that but gave full mixture after a couple seconds of course.

 

The point is to help keep the temperatures up and minimize lead and carbon deposits. It is obviously in the low-power regime where detonation isn't an issue. The only criticism for it I can think of is what might happen in a go-around if I forget to go full rich.

 

While I was trained 40 years ago to basicly ignore the mixture control, I've been implementing newer leaning procedures cautiously since I purchased my M20E two years ago. As a chemist Busch and Deakins made sense to me and they were quoting a lot of good data. It also made sense things were done the way they were "back in the day" when we didn't have such good engine monitors so I can see where two separate "churchs" have evolved around leaning.  For me a big question mark was "What about my habits and training".  Its one thing to understand something and another to implement it. I've slowly convinced myself to trust myself and these day use of the mixture is part of my SOP in all phases of flight (full rich for take-off at sea level where I live).

 

Dave 

[Jamie]

I've kind of been ignoring this, because I can get away with it. I lean in cruise climb and in cruise of course. But when it comes time to land, I've been leaving the mixture alone until I'm in the pattern and then going full rich. I can "get away with it" because my home field elevation is ~630 ft.

 

Do you have a link or two to articles where they discuss this technique?

[DS1980]

I think you're making it too complicated. Set mixture in the pattern for go around. This mixture setting will be ROP and based on your altitude to stay out of the red fin. Deposits will not be a concern.

 

 

Remember, what has to happen with the mixture for a go around if not already configured? The mixture must be advanced. You will remember to do this 98% of the time. It's the 2% that will get you into trouble and bend your airplane.

 

One of the best things I learned about the GUMP check is to say the words "go around" during the check. So my check sounds like this:

"Gas on correct tank and pump on, Undercarriage down, Mixture and Prop set for go around."

 

By saying the words "go around," it activates that part of the brain and keeps it there as a real option, instead of just using it as a last resort.

 

This differs in the advise that Mr. Busch gives because he is a better mechanic and pilot than I am. If you never forget to advance the mixture, no problem 

 

Of course, do what you are comfortable with. I will be the first to admit there are many ways to correctly fly an airplane. Do what keeps you safe and in your comfort zone.

[Bob - S50]

I agree with DS1980.  Since I don't go around very often I will have a hard time establishing the habit of mixture, prop, throttle for a go around.  I want to avoid the 2% as much as possible.  Here's what I've been doing:

 

1.  Leave it LOP all the way to the pattern, using 2200 RPM and 17" to be at about 100k on downwind.

2.  Some time after turning base I'll need to come back almost to idle to keep my airspeed and glidepath where I want them.  When that happens, I go full rich, full forward on the prop, and boost pump on with no resultant change in power.

3.  I then use just the throttle through touchdown.

4.  As soon as I clear the runway I lean the engine again.

 

I'm only full rich for less than 2 minutes.

 

When I finally fly to Colorado to visit my brother, I'll have to figure out some other setting for the mixture.  Since I lean during the climb to 1250 -1300 EGT, I'll probably take a look at the mixture position when I'm passing 5000' and try to get some type of feel for what that looks like.

 

Bob

[midlifeflyer]

I agree with DS1980 also. Yes, you want to configure the mixture for go-around power but no, I'm not that crazy about the idea of doing much more than guesstimating the mixture setting that will accomplish this. Especially during the workload of the landing phase. My thought is that, while it's nice to be super precise, there' same lot of room between too rich and too lean -about 3000 feet of density altitude according to many manufacturers.

I've personally never done more than a guesstimate of the setting for landing, even during 20 years of flying in Colorado. Go-a rounds have never been a problem

[Bob - S50]

I agree with DS1980 also. Yes, you want to configure the mixture for go-around power but no, I'm not that crazy about the idea of doing much more than guesstimating the mixture setting that will accomplish this. Especially during the workload of the landing phase. My thought is that, while it's nice to be super precise, there' same lot of room between too rich and too lean -about 3000 feet of density altitude according to many manufacturers.

I've personally never done more than a guesstimate of the setting for landing, even during 20 years of flying in Colorado. Go-a rounds have never been a problem

Thanks for the input.

 

And when I think about it, we really only need to worry (even if just a little) about detonation and pre-ignition at high power settings.  Supposedly once you get down to 75% power the chances of that happening are about nil.  By the time we get to 7500' there is only enough air to generate 75% power at full throttle.  Since Boulder is at 5288', I'm almost that high.  If I happen to get the mixture just a bit too lean, it probably isn't going to hurt anything.  As a matter of fact, it will probably put me closer to max power.  Even if I look at John Deakin's red box, it disappears at 7500'  At 5000' in looks like it runs from a few degrees LOP to about 100 ROP.

[DS1980]

 

Supposedly once you get down to 75% power the chances of that happening are about nil. 

Think more along the lines of 60-65% power and you got all bases covered. You're right 98% of the time when at 75%, but as from my previous posts, I'm not a fan of the 2%. (except milk, 2% is great)

[pinerunner]

Dave,

I watched those Mike Busch webinars too, after the guys posted the link here on Mooneyspace. I thought it was a great video and very educational, especially the part about running 50f rich of peak being the worst place to run your engine - knowing my other Mooney driver friends who tell me they run 50f rich of peak all the time? I was totally on board with his techniques and his rationale for those techniques ... until he got to that one technique.

Like these other guys are doing, I think I'll still just go full rich on downwind or base ... So I don't ever miss it on a go-around, you're not there (full rich) but a minute or so ... But the other techniques were right on. MKes me want to watch them again - just for review. Great videos!

 

Thanks. Just to review, by leaning it at 2500 RPM I,m not in danger of the engine coughing, sputtering, and hesitating just when i want power the most. The concern then is detonation. First of all I am working hard to train in Deakin's admonition to adjust Mixture, Prop, then Power for all major power changes. More complicated for sure than my original training but hey, I wanted a complex airplane. 2nd, I'm not in as bad a setup for detonation as taking off with it leaned into the red box since I have flying airspeed and reasonable cooling in play instead of a dead start. The engine will also have cooled down during decent. So I decided to take their advice. My approach came from listening to Busch's advice (haven't been able to find which video) to simple fixed pitch props with no engine monitor. Throughout the pattern I keep the prop out of governance just for simplicity. (I think I'll use lower RPM's in the winter though to keep the CHT's up)  Both D and B talk about staying lean in the descent and right on though the landing. Busch makes the admonition to go full rich only for cold starts and max power below 3000 feet. But as many are pointing out here the big and personal issue is training. What have you been trained to do and what can you trust yourself to do in a pinch if you try to retool that training. A very personal question and not so easy to answer honestly. I'm confidant that I'll do the mixture first 90% of the time when doing a go around (2 so far in the last 40 years) and in the other 10% bells will go off in my head if I forget and I'll hit the mixture one second later. A very personal decision and it does include a commitment to retrain my procedures hard.

[Shadrach]

I shoot for 200 ROP at whatever my descent throttle setting is. I don't really sweat it that much. A go around does not need to be a dramatic operation, nor does it require 100% of available power right now. So many pilots have a hard time getting the airplane to land with the throttle closed. A Mooney is not going to sink into the abyss if you don't get the balls to the wall in a split second during most go-around situations, even at a high DA. There will be time to fiddle with the mixture after the power is added and the descent has been arrested. 

[fantom]

Makes me wonder about how many pilots bend metal or die over managing momentary engine settings

[Shadrach]

Makes me wonder about how many pilots bend metal or die over managing momentary engine settings

I doubt setting the engine has killed many...but "over" managing things depending on your definition might cause some pretty lousy reactions. 

[pinerunner]

I doubt setting the engine has killed many...but "over" managing things depending on your definition might cause some pretty lousy reactions. 

Its actually pretty simple to do so I don't consider it overmanagement. Obviously I believe that job one around an airport and in the pattern is looking out the window.

 

Dave