Power Settings?

[Browncbr1]

If I am down low and want to go fast, I find that higher MAP and low RPM (2200-2300) nets higher airspeed with lower fuel burn and lower temps, especially oil temp.

[MBDiagMan]

Thanks Brown!  I will try that on my next short jump.

[Hank]

3 hours ago, Browncbr1 said:

If I am down low and want to go fast, I find that higher MAP and low RPM (2200-2300) nets higher airspeed with lower fuel burn and lower temps, especially oil temp.

 Just watch the Tach Redlines--his F is different than our Cs. Mine is red from 2000-2250, so I generally run 2300. Then I can set MP anywhere up to 47 - 23 = 24".

Edited April 11, 2017 by Hank

[MBDiagMan]

Thanks Hank!

[Browncbr1]

45 minutes ago, Hank said:

 Just watch the Tach Redlines--his F is different than our Cs. Mine is red from 2000-2250, so I generally run 2300. Then I can set MP anywhere up to 47 - 23 = 24".

good point and correct... I also have a different tach restriction because of the Top prop.

[Hoeschen]

When folks are talking about running LOP with a carb; are you referring to running LOP on the first cylinder to peak only?


Sent from my iPhone using Tapatalk

[carusoam]

LOP is the last cylinder to peak by definition...

The reason for this is... if the first to peak came significantly before the last, you could possibly set up with the last cylinder still in the red box.

Realistically, you want the GAMI spread to be very close.  It wouldn't matter much which peaked first if they all peak together...

Unfortunately, O360 there isn't a tuned set of FIs to work with.  A good engine monitor will tell you if one cylinder is straggling far behind the others... 

So, at least be aware of this logic.  There are some maintenance things to do that may improve a crummy GAMI spread in an O360.  None that are easy to identify.

PP thoughts only.  Check my logic for accuracy.

Best regards,

-a-

 

Edited April 12, 2017 by carusoam

[sdflysurf]

On 4/9/2017 at 7:29 AM, Hank said:

I am believer in the MAPA Key Numbers (I've been to two PPPs). Using what's printed on the MP and Tach dials:  MP + RPM <= 47 for our Cs.

Using this and the Performance tables in the Owners Manual, I've settled pretty much on three Combinations:

• Low level--23" 2300 (short trips, lunch runs, etc, generally 3000 msl)
• Mid level--22" 2400 (Generally 4000-6500ish; also good for when ATC levels me off or descends me)
• Travel Cruise--2500, and I back the throttle off enough to make the MP needle just start to move.

I leave the WOT stuff to the injected guys. Tried it on a trip once, got an extra knot or two for an extra gallon or two per hour. I pull back some just to close off the WOT Fuel Enrichment circuit in the carb.

Other easy stuff:

• Takeoff--WOT, 2700
• Climb--WOT, 2700 to altitude, generally Vy to Vy + 5 mph, a little higher speed in hot weather for cooling (watch your Oil Temp).
• Level off and let the plane accelerate until ASI stops moving, then set power. Yesterday at 8500 msl, this was at 140 mph. As you lean the engine, you will accelerate a little more even with reduced RPM. 
• Descend at cruise settings. As you come down, MP will increase so every now and then pull it back to your cruise setting, then advance mixture to restore cruise EGT value. I generally use 500 fpm, which gives 170 mph. 
• Level off a couple of miles from the airport at TPA, and work on slowing down. Enter pattern with Takeoff Flaps, generally still slowing towards 90 mph pattern speed.
• I use 90 mph downwind and base, 85 mph on final, and by 50 agl or so I shoot for 70-75 mph (70 if light, 75 if heavy; technically it's 75 mph minus 5 mph for every 300 lb below gross, but 70 light / 75 heavy covers about everything).

Have a good trip, and remember, your Mooney will still be here when you get back.

Hey All, I found this thread while researching best-practices for power settings.  I am about to go out on a cross-country trip about 250miles in our fuel injected M20F.  Altitude will be 9500 or 11500.  It is just about 10 degrees F over standard temp at sea level tomorrow, and we are about 50lbs shy of gross weight.  I plan on using the advice that I am quoting from Hank like this:

1. Climb at WOT 2700RPM with cowl flaps open at a little over VY watching oil temp.
2. Cruise - Level off at altitude and do nothing except gain speed for 2 minutes, then close cowl flaps, pull throttle back just enough to see MP needle move, then set Prop at 2500RPM and lean mixture until I feel it get a bit rough then 2 screws forward (CFI taught about feeling the mixture lean - please comment if this is ok - I do not have an engine monitor yet!)
3. Descent - Descend at 500ft/m, reducing throttle as necessary to keep MP number where it was in cruise, and advancing mixture slowly over the descent.

Besides that, when I start to level off to slow down close to the airport, is there any other trick to slowing down besides reducing throttle further and extending gear/flaps down when appropriate?

 

 

[jetdriven]

 

You have an FI airplane need different technique.

1. climb at 120-140 MPH IAS. better cooling.

2. dont touch the throttle. leave full.  set prop then lean.

3. if you have the 200 MPH IAS redline you may need to reduce MP to keep at 23-25" ish to keep the descent going without busting redline airspeed.

[Hank]

He's right, your F has a different Key Number and performs better at Full Throttle [WOT].

While many vinntage Mooneys do not have engine monitors, do you at least have an EGT Gage? It's quite handy for leaning and takes the worry out of "lean to rough, richen to smooth" for many. You will also cruise faster than my C, although I could keep a friend's F in sight on trips up to an hour or so.

Slowing down, especially after a power-on descent. The only thing I've found that works is to level off and reduce the throttle, then wait . . . It takes time and a couple of miles to reach flap speed, the  tbey help slow me the rest of the way to pattern entry. Early in the game, give yourself 4-5 nm after descent gto slow down; as you get used to it, and see how it works for your plane, adjust your descent point to match your slow-down results.

Have a great trip! And fly safe!

[Shiny moose]

As others stated, wide open all the way up and until you descend , if your traveling more than 50 miles, get some altitude!  in summer months 6K will get you cooled off ( I like altitude) level off, cowl flaps closed, when speed has increased and stabilized don’t rush it, set prop to your desired RPM (I like 2500 or 2600 if high) , lean As desired ROP,LOP. Plan your decent for 500FPM (GS here) , push nose over, trim AS  for top of green, that will get you aprox 500FPM, reduce your power slowly 1” per 1K keeping speed up,increase mixture slowly during descent as needed,  plan  for 14-15” MP 5 miles from destination,  level off at TPA, a minute later you will be at gear speed. 

[MBDiagMan]

This is weird, but I am going to hijack my own thread.

I no longer have the C that prompted me to ask the question in my OP.  I now have an F with a JPI.  From one of Hanks posts, I get the idea that there may be a red line on the tach somewhere below 2700.  IIRC the C was redlined below 1800.  So, what low RPM redline would have been on the original tach in my F?

[jaylw314]

4 hours ago, MBDiagMan said:

This is weird, but I am going to hijack my own thread.

I no longer have the C that prompted me to ask the question in my OP.  I now have an F with a JPI.  From one of Hanks posts, I get the idea that there may be a red line on the tach somewhere below 2700.  IIRC the C was redlined below 1800.  So, what low RPM redline would have been on the original tach in my F?

IIRC, on some engine/prop combinations, there's are caution RPM/MP settings that need to be placarded.  I don't recall if the tach actually is REQUIRED to have a yellow or red area that corresponds to that

 

On 10/4/2018 at 12:15 AM, sdflysurf said:

Hey All, I found this thread while researching best-practices for power settings.  I am about to go out on a cross-country trip about 250miles in our fuel injected M20F.  Altitude will be 9500 or 11500.  It is just about 10 degrees F over standard temp at sea level tomorrow, and we are about 50lbs shy of gross weight.  I plan on using the advice that I am quoting from Hank like this:

1. Climb at WOT 2700RPM with cowl flaps open at a little over VY watching oil temp.
2. Cruise - Level off at altitude and do nothing except gain speed for 2 minutes, then close cowl flaps, pull throttle back just enough to see MP needle move, then set Prop at 2500RPM and lean mixture until I feel it get a bit rough then 2 screws forward (CFI taught about feeling the mixture lean - please comment if this is ok - I do not have an engine monitor yet!)
3. Descent - Descend at 500ft/m, reducing throttle as necessary to keep MP number where it was in cruise, and advancing mixture slowly over the descent.

Besides that, when I start to level off to slow down close to the airport, is there any other trick to slowing down besides reducing throttle further and extending gear/flaps down when appropriate?

Like @jetdriven and @Hank said, climbing at 100 KIAS or so gives you better cooling, and you're covering more ground so you'll save time.  Sometimes I'll climb near Vy (90 KIAS) until about 5000', and then lower the nose to 100 KIAS and lean the mixture.  That saves a little fuel, but I don't have problems with high CHT's.

Incidentally, oil temp should not be the issue during climb, it's your CHT's you have to watch.  I usually put my cowl flaps in trail once I'm climbing above 3000' or so to save a little drag and stress on the mechanism, but obviously don't do that if your motor runs hot.

As said before, leave the throttle full open.  If you're cruising above 7-8000', there's no point in reducing throttle anyway.  The "throttle cocking" is intended for carb engines to make the intake air turbulent help distribute the fuel better.  Not an issue with fuel injection.

Leaning to rough and then increasing until the roughness is gone (not 2 turns) is recommended by Lycoming for those without an EGT gauge, and I think it makes complete sense for those without an engine monitor.  I would not suggest using your the "2 turns" method below 5000', since at high power you will have no idea if that puts you in the "red box" (something around 50^o ROP).  Cruising above 5000', there's nothing bad you can do with your mixture, so knock yourself out--enrichening more will give you more power, so if you don't care about gas or range, twist that puppy to the right.  Obviously, you could also increase RPM to 2600 or even 2700 instead of enrichening (or both) to go faster, but some people don't like the noise.  At 9000' and up, I find the noise actually is significantly less, though

For descent, don't just reduce throttle.  Reduce throttle by 4" MP or so first, then I reduce  RPM to 2200.  If necessary, after a minute or so, I reduce the MP down to about 20" and RPM down to 2000 (or whatever is within any MP/RPM limits you have).  The slower RPM's and higher MP keep more heat in the engine for any given power setting and cools the engine slower than reducing MP alone.

During descent, keep decreasing throttle (you don't have to hold a precise MP, just stay in the ballpark), but don't bother increasing the mixture unless the engine starts running rough.  At your descent power setting, the engine usually runs fine very lean, and you have enough things on your mind during this phase of flight.  Just make sure you increase mixture if you have to level off or climb again.

Take the above with a grain of salt, since every motor is different.  Mine has very good cooling, and pretty good fuel distribution, and I have no motor/prop RPM limits.  Don't make life too complicated either, you don't need to be exact on any settings, just your altitude and heading.

[KLRDMD]

6 hours ago, Shiny moose said:

As others stated, wide open all the way up and until you descend , if your traveling more than 50 miles, get some altitude!  in summer months 6K will get you cooled off.

That kinda depends one where you are. In AZ in the summer you often have to get above 15,000 ft to be cool and smooth.

[N6018Q]

6 hours ago, MBDiagMan said:

This is weird, but I am going to hijack my own thread.

I no longer have the C that prompted me to ask the question in my OP.  I now have an F with a JPI.  From one of Hanks posts, I get the idea that there may be a red line on the tach somewhere below 2700.  IIRC the C was redlined below 1800.  So, what low RPM redline would have been on the original tach in my F?

My '66 E (IO360) tach is redlined from 2100-2350

[Hank]

Boy, @jaylw314  that's a complicated descent profile! I just push on the yoke for 500 fpm and trim the forces away. Every now and then I'll reduce the throttle to whatever my cruise setting was, and richen up to mixture to my cruise EGT. Airspeed builds nicely to about 170 mph, making up for the slow climb at the beginning.

My goal is to level off 3-4 nm from the field and use that distance to slow down below 125 mph and get Takeoff Flaps in. Then the rest of the landing is easy. If I'm still a little fast dropping Flaps in downwind, I'll extend another 1/4 mile or so (making a total increase of 1/2 mile traveled), and that's always been plenty.

[gsxrpilot]

I’m with@hank. Descending into KHOT yesterday there was a Southern Airways Grand Caravan at 9 o’clock and 5 miles. Memphis Center pointed out the Mooney at 3 o’clock and said, it’s got 20 knots on you so plan on landing #2 behind the Mooney.
We were descending out of 11,500 by just pushing the nose over. Consequently we were 190 knots over the ground.
We were on the ramp shutting down as the Caravan landed.

[Hank]

Pulling power is for pu . . . . Nope, can't say that. Keep power on for the descent, make up for your slow climb, land normally. Fuel burn stays pretty constant, but watch the change in your block time!  

[Shiny moose]

4 hours ago, KLRDMD said:

That kinda depends one where you are. In AZ in the summer you often have to get above 15,000 ft to be cool and smooth.

Not today, temp at 6K over Pheniox 14C or a mere 57F. Of course its only 87 on the ground so it must be wintertime 

[Hank]

10 minutes ago, Shiny moose said:

Not today, temp at 6K over Pheniox 14C or a mere 57F. Of course its only 87 on the ground so it must be wintertime 

Last week in the sunny south, ground temps were in the 90s. At 8500 midafternoon, I was running partial cabin heat . . .

Altitude is the best air conditioning!

[jaylw314]

22 hours ago, Hank said:

Boy, @jaylw314  that's a complicated descent profile! I just push on the yoke for 500 fpm and trim the forces away. Every now and then I'll reduce the throttle to whatever my cruise setting was, and richen up to mixture to my cruise EGT. Airspeed builds nicely to about 170 mph, making up for the slow climb at the beginning.

My goal is to level off 3-4 nm from the field and use that distance to slow down below 125 mph and get Takeoff Flaps in. Then the rest of the landing is easy. If I'm still a little fast dropping Flaps in downwind, I'll extend another 1/4 mile or so (making a total increase of 1/2 mile traveled), and that's always been plenty.

True, it's simpler to just go fast.  I have three reasons to keep speed down in descent, so I've just made a routine of it

• It's easy for me to get behind an IFR approach at 160 KIAS
• I have a psychological thing about flying efficiently
• My wife hates bumps

Obviously, those don't apply to everyone, but I hate the OWT of "reduce MP by 2 every minute for descent".  

[Shiny moose]

On 10/6/2018 at 1:05 PM, KLRDMD said:

That kinda depends one where you are. In AZ in the summer you often have to get above 15,000 ft to be cool and smooth.

I would assume ( big word)  the adiabatic lapse rate is the same for you as it is for me. 3.5 degrees per 1K and being in dry air would most likely be more, so if your having a 100 degree day in PHX at 1K , at 6K it will, should be comfortable for you 83 (5X3.5) I would emagine at 15K the temp would be (14X3.5) in that 50 degree range(Maine summertime temps). Now as far as smooth air ??? 

[KLRDMD]

3 hours ago, Shiny moose said:

I would assume ( big word)  the adiabatic lapse rate is the same for you as it is for me. 3.5 degrees per 1K and being in dry air would most likely be more, so if your having a 100 degree day in PHX at 1K , at 6K it will, should be comfortable for you 83 (5X3.5) I would emagine at 15K the temp would be (14X3.5) in that 50 degree range(Maine summertime temps). Now as far as smooth air ??? 

We get 100º days starting in May and going through October. There are often more than 100 days of 100º or more each year. I'm more interested in the 115-120º days.

[0TreeLemur]

I love the article by former Mooney test pilot Bob Kromer regarding climb power settings.  To me, his article definitively answers the question regarding climb power settings. click here.

[gsxrpilot]

26 minutes ago, Fred_2O said:

I love the article by former Mooney test pilot Bob Kromer regarding climb power settings.  To me, his article definitively answers the question regarding climb power settings. click here.

It might be sacrilege but I'd differ just a bit for the turbo Mooneys. We don't lean at all in the climb. But it's a good article.