Red Fin for M20J

[Wojciech Kacprzyński]

Hi,

I'm sorry if it is somewhere in the forum, but I haven't found it for the past hour. Do any of you have the up-to-date leaning red fin for this Mooney? If someone directs me to that info somewhere around here I would really appreciate it and delete this topic because then it becomes useless.

Thank yall!

WK

[carusoam]

49 minutes ago, Wojciech Kacprzyński said:

Hi,

I'm sorry if it is somewhere in the forum, but I haven't found it for the past hour. Do any of you have the up-to-date leaning red fin for this Mooney? If someone directs me to that info somewhere around here I would really appreciate it and delete this topic because then it becomes useless.

Thank yall!

WK

The source of the red fin / red box and leaning….

Can probably be attributed to Mike Busch, the patron saint of aviation mechanics…

Find savvy.com https://resources.savvyaviation.com

Tell them Paul @kortopates sent you…

Best regards,

-a-

[Fly Boomer]

2 hours ago, Wojciech Kacprzyński said:

up-to-date leaning red fin for this Mooney?

Not sure about "up-to-date", and this is a bit of a long-winded potpourri, but it may give some pointers to other sources:

https://mooneyspace.com/topic/11639-red-box/

EDIT:  and from Mike Busch:

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2012-12_red-box-red-fin.pdf

[201er]

1 hour ago, carusoam said:

The source of the red fin / red box and leaning….

Can probably be attributed to Mike Busch, the patron saint of aviation mechanics…

Find savvy.com https://resources.savvyaviation.com

Tell them Paul @kortopates sent you…

Best regards,

-a-

I’m pretty sure Mike Busch is the one who doesn’t believe in Red Box concept.

Here’s the skinny of it, 8GPH or less, you can be at peak or any mixture. 8-10gph you want to be progressively leaner on the LOP side from 0 at 8GPH to about 25LOP by 10gph.

[elimansour]

A few years back, I extrapolated the information and created the following red fin profile/ LOP fuel flow.  I am not sure how accurate it is.  Maybe someone smarter can take a look and let me know?

RedFinM20J.docx RedBoxM20J.docx

[Fly Boomer]

1 hour ago, 201er said:

Mike Busch is the one who doesn’t believe in Red Box concept

see above

[kortopates]

I recommend the following from the Gami folks to all. To "all" because  it's good conservative advice for all our piston engines, simplest to implement/follow and approved FAA data to boot. Further, it doesn't matter if Gami injectors aren't installed (an engine just won't be able to run LOP smoothly without good mixture distribution). The vast majority of Lyc IO-360's have very good mixture but most big bore and turbo engines do need tuned injectors to run LOP smoothly. 

https://gami.com/gamijectors/AFMS - GAMIjectors Rev IR.pdf

Especially heed the important caveats to any leaning, ROP or LOP, to keep CHTs cool and keep from exceeding ~400F  (lean more LOP or Enrich ROP) and TIT within Limits and more conservatively below 1600F for better exhaust component longevity.

All that a pilot needs to do not in the document is calculate % percent power based on either FF using the appropriate multiplier for their CR Or for ROP settings look up their performance tables for % power MAP/RPM/FF; then lean ROP or LOP  per the attached guidance. But remember for any power setting below 65% there is no red box/fin and you can leave the mixture anywhere you want, but why not use the NMPG field on your engine monitor to lean for best efficiency/mileage (which will be LOP).

Common LOP Multipliers:

LOP % Power = FF(GPH) * Multiplier/max HP

Multiplier			CR:1
13.5			7.3		Turbo's
13.7			7.5		Most Turbo's
14.3			8		Bravo
14.4			8.1
14.9			8.5		Most NA high compression engines
15.1			8.7		Mooney J
15.4			8.9
15.5			9
16.8			10.1

Edited April 7, 2022 by kortopates

[Fly Boomer]

19 minutes ago, kortopates said:

Common LOP Multipliers:

Thanks, Paul @kortopates

[Ragsf15e]

5 hours ago, Fly Boomer said:

Thanks, Paul @kortopates

So for the J with the above numbers, 65% is at 8.6gph.  It’s certainly possible to run safe and efficient at higher ff and higher power settings but 65% is always safe from a mixture perspective.

8.6gph x 15.1 = 130hp

130hp/200hp = 65%

[carusoam]

11 hours ago, 201er said:

I’m pretty sure Mike Busch is the one who doesn’t believe in Red Box concept.

Here’s the skinny of it, 8GPH or less, you can be at peak or any mixture. 8-10gph you want to be progressively leaner on the LOP side from 0 at 8GPH to about 25LOP by 10gph.

Help me with this one…

He may not believe in it, but it looks like he covers it one way or another….

i need to work on my memory of the key people in modern aviation… Busch, Deakin, and the other guy… 

-a-

In this follow-on to his "Leaning Basics" webinar, A&P/IA and CFI Mike Busch discusses lean-of-peak operation and the "red box/red fin" concept. Savvy Aviation offers Professional Maintenance Services to owners of General Aviation aircraft, such as: Savvy Mx

 

[PT20J]

If you set power at or below 65% (per Continental recommendations) or 75% (per Lycoming recommendations) you can do whatever you want with the red knob. In other words there is no red box. So where does the red box come from? If you set the power to say 65% and then pull the mixture back to whatever LOP setting you prefer (based on EGT), you will be running well below 65%. To get the power back to 65%, you have to increase the MAP. Now you have created a red box because if you enrich the mixture from this point, the power will increase but the mixture may be too lean. The red box was originally meant to be more of a guideline than a rule. John Deakin was clear about that.  What's most important is to keep the CHTs in check. Deakin used to cruise his turbonormalized Bonanza at 80+% power LOP with the CHTs well below 400F to no apparent detriment. I believe some of the Cirrus crowd is doing the same thing. But you have to know what you are doing. There are fewer options to run LOP with a NA IO-360 because the power falls off as you climb and you run out of throttle.

Skip

[carusoam]

Avoiding the red box is easy with an NA engine….

So… defining the end of the red box as 65%bhp…

There is an altitude where your MP is less than 65% of max….

Roughly 65% of 29.92”… about 19.4” of MP… (rough is close enough, lots of wiggle room given for pilots… and max MP is always short of the ideal sea level atmospheric pressure))

That altitude is around 8k’…

Outside of the red box… lean any way you like… detonation can’t be a problem…

Keep in mind… CHTs can still be a problem…

The Red Box is about avoiding detonation….

 

Now extending this idea to lower altitudes….

You can pull the throttle back to simulate being at altitude, outside the red box…

Again, lean any way you like…

Going Rich of peak helps with cooling, but throws some fuel out the exhaust…

Going LOP helps with cooling, but speed drops off the further LOP you go….

Some people are happy a few degrees LOP… knowing 100% of the gasoline is getting burned while producing max power… 

+1 for controlling %bhp using the fuel flow guidance for LOP that 201er outlined above…

Flying above 10k’… is really good for improved gliding distances…

 

PP thoughts only, not a CFI…

Best regards,

-a-

[Ragsf15e]

Exactly what @PT20J said… I live in Washington, so by the time I climb to my normal cruise altitudes of 8500-10500, my NA engine is around 65% even at full throttle.  If I want efficiency, I then set mixture just barely lop.  There’s really no red fin up there.  Now if you live in Florida and cruise at 4500’, you might want to look at it a little more closely because your full throttle mp is much higher and there’s probably some ff range where you could cause excessive heat/pressure.