Leaning quadrant vs vernier

[Bartman]

In another thread @kortopates mentioned that it was harder to lean slowly with the quadrant mixture control like I have in my bird.  Sometimes I overshoot and go too far and end up repeating the procedure.  If I overshoot and try just enrichen slightly then I end up pushing the mixture much farther than I would expect, like you have to take up the slack in the cable is the best I can describe. I get more consistent results when I approach from high to low, but trying to tweak that quadrant mixture control can be challenging especially if you add in a little turbulence. 

Any suggestions on technique or maintenance of the system for those of us who are blessed with the quadrant controls ?

[Hank]

I don't generally have a problem with it, but I also don't try to manage it to 1° increments. You'll get used to how far you needed to move, so approximate that position then make small adjustments. I sometimes drop my hand down to rest on the quadrant and hold the lever not the knob, makes all of them easier to adjust. I especially do this to the throttle in the pattern.

[kortopates]

Just as@Hank described, with AP flying or another pilot flying, grab the lever an inch or two above the quadrant and move it as slowly as possible with gentle pressure.
Hah for getting 1F accuracy! What we're trying to do is get resolution of 0.1 GPH changes but sometimes that's just impossible as it jumps by 0.2 GPH.
One of the reasons it's definitely easier from the rich to lean is that when you jump too lean you'll trigger misfire in a plug, now you have erratic EGT and won't clear it up till you enriched again significantly- so once you know where that is try to avoid getting that lean and hopefully you won't have misfire right by peak. If you do, you'll have to note the mag and cyl and fix the plug to get pass that.


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[carusoam]

It may also help to know if you have the quick acting sensors or the older slower to react sensors....

heavy shielded EGT sensors take a while to heat or cool when the mixture is changed...

Thinner quick acting EGTs sensors are less robust in construction...

Best regards,

-a-

[xcrmckenna]

You also might try adjusting the tension on the quadrant. You might find being able to move the levers easier when setting up the leaning easier then tighten it up after you have it set. Big black knob on the right side of the quadrant.


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[Ron McBride]

I grab the mixture lever next to the quadrant, with my hand resting on the quadrant. Just move it as little as you want.

I usually only grab the throttle or the prop by the knob when making big power changes. 

On takeoff and landing, my hand rests on the quadrant, with my fingers wrapped around the controls and can make fine adjustments as needed, I can also operate my flaps from this position at any time.   On takeoff, my hand only leaved the quadrant for gear retraction and to turn the fuel pump off.  On landing I do not need to remove my hand from the quadrant until after leaving the runway to set power for taxi.

Just practice.

Ron

[Bob_Belville]

On my '66 model the mixture control is "non-standard", between the throttle and the prop. Sure glad I do not have a quadrant with that arrangement!

[gsxrpilot]

@Bob_Belville your whole panel is "non-standard" 

[Bob_Belville]

Just now, gsxrpilot said:

@Bob_Belville your whole panel is "non-standard" 

I'll take that as a compliment. 

[bradp]

You'll also figure out a target EGT for a given altitude - i.e. my #1 peaks last and I know where it lands at my typical cruise of 7-8k feet.  You really want smooth movement of the quadrant during the rich to lean sweap around your target temperatures.  Increasing the sampling rate on your engine monitor may help with your quadrant mixture lever as well. 

[Bob_Belville]

4 minutes ago, bradp said:

You'll also figure out a target EGT for a given altitude - i.e. my #1 peaks last and I know where it lands at my typical cruise of 7-8k feet.  You really want smooth movement of the quadrant during the rich to lean sweap around your target temperatures.  Increasing the sampling rate on your engine monitor may help with your quadrant mixture lever as well. 

I prefer to target fuel flow rather that EGT temp. With my 200hp IO360 I know that 8.2-8.3 gph (~ 62% power LOP) is a setting that works great for maximizing range/economy. Deakin (or Busch?) would call that the Big Pull, I think. 

[bradp]

Bob makes a great point. My target EGT ~20-LOP just happens to coincide with 8.4 gph sixty something %HP at cruising altitude.   

I just calculated that since my engine monitor was installed and I started doing LOP I saved 1300 gal of gas. Not bad.  

[Bartman]

I use several of the above techniques depending on altitude and my attitude. Climb at target EGT 1250 until about 9-10K and then go to peak or a few degrees ROP for best power. I usually fly at least 8,000 - 10,000 if going any significant distance and at that altitude I don't want to be very much LOP so 8.4 to 8.5 GPH is good.  If I'm higher than 10,000 I'll shoot for peak and that's where I want to be most accurate to get the most power available. Last week I climbed to 15,000 to stay clear to watch for towering CB's so I ran just a few degrees ROP, but she ran smooth even a few degrees LOP. If I'm lower than 6,000 I sometimes just do the BMP and go for 8.3 GPH and watch CHTs for anything over 360 beccause I know that's where she runs when about 15-20 LOP.  Options are my friend.  

[midlifeflyer]

Truthfully, I've never noticed that much of a difference. Yeah, a vernier allows for a wee bit more fine tuning, but not so much as to make a substantial operational difference.

[211º]

Crazy clear and smooth skies in Ohio River Valley (and 50% of the US).

Went to 2500 'and to 5500' to get some numbers of LOP fuel flow when under 65% power. I was quite surprised that I could go down from the book value of 9.3 gph to the 6s while the motor still sounded good. Roughness began around 5.7gph.

Does that seem reasonable?


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[nels]

20 hours ago, 211º said:

Crazy clear and smooth skies in Ohio River Valley (and 50% of the US).

Went to 2500 'and to 5500' to get some numbers of LOP fuel flow when under 65% power. I was quite surprised that I could go down from the book value of 9.3 gph to the 6s while the motor still sounded good. Roughness began around 5.7gph.

Does that seem reasonable?


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Dave, what did 6 gph do to the airspeed. That's a huge change in fuel flow. I just started playing with fuel flow u at 7000 ft but I seem to remember engine roughness about .7 to 1.0 gal under book . I didn't record anything so shooting from the hip on those numbers.

[gsxrpilot]

22 hours ago, 211º said:

Went to 2500 'and to 5500' to get some numbers of LOP fuel flow when under 65% power. I was quite surprised that I could go down from the book value of 9.3 gph to the 6s while the motor still sounded good. Roughness began around 5.7gph.

Does that seem reasonable?

It sounds like a well balanced fuel injection system.  If the injectors are exactly balanced, the engine should run smooth all the way to cut off. So this is really good.  Be happy you have a well balanced engine.

[211º]

Data and more data...

Not sure if this is of interest to anyone, but thought that it might be. I've put the POH data into a spreadsheet and compared it to actual book values for my 66E.  Two items popped out at me.  First, my airplane's ability to come closer to the POH book values occurs (at least in the limited-to-date tests a higher altitude.  Second, I can save about 15 minutes time on a 300sm XC when flying at 24/2400 vs. 22/2350 at 5,500 ft at a cost of about 1.8 gallons.  And Second-prime, if the ceiling is lower and I'm going to stay down low, I can cruise way low of peak at 6.2 gph and arrive about 10 minutes later at the savings of about 6 gallons of gas.

I'm curious to try this data at higher altitudes in the not-too-distant future.

[carusoam]

Data like that, is always appreciated! 

Best regards,

-a-