Power Settings?

[MBDiagMan]

I am brand new not only to my Mooney, but also to controllable pitch propellers.  I am still trying to find my way to the best power settings.  I printed and laminated the POH pages with climb and cruise settings, but I am really just experimenting at this point.  So far I have flown with three basic settings; Takeoff, Everything Forward, after gear up, power back to 24/25 for climb out, Cruise 23/25.

My goal is to find good speed and reasonable fuel economy without straining the engine.  I feel like cruising at 23/25 at about 4,000' is easy on the engine, but I don't quite make it into the yellow with this power setting and a cleaned up plane.

If anyone can point me toward any information taking into consideration engine health/speed/fuel economy and how the different parameters relate and interact I would be appreciative.  I also would enjoy simply reading your own favorite power settings for different conditions.

[jetdriven]

Don't pull the power back for climb. There's no benefit to that. Iran been beat to death and there's two camps. People who believe data and the other kind. For everything else run at full throttle and 24 or 2500 RPM.. unless you need to stretch the range a little. Then something between 20-23" and 2400 rpm. 

Edited April 9, 2017 by jetdriven

[carusoam]

If you have a few dollars for training Mapa has a good book and can set you up with a lot of detail for Mooney specific things.

Best regards,

-a-

[gsxrpilot]

First of all, cruise higher than 4000.  The higher you fly, the easier it is on your engine and your fuel bill. If I was ever going two or more hours anywhere, I'd cruise at 12,500 or 13,500. The C just sips the gas at about 60% power. WOT, 2450, 7gph, 150 knots. That engine will run forever at those low power settings.

[MBDiagMan]

Thanks for the replies.  I am learning from all of them.

I have yet to go more than about 100NM in one trip, so I haven't bothered to go to higher altitudes yet.  I go to Europe for three weeks beginning next week.  I am planning on some long distance Mooney trips after that and will definitely be climbing out and trying her up where she is happy.

please keep the replies coming.  They are greatly appreciated!

[Hank]

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.

[Bob - S50]

We fly a J, but the same principals apply.

For short flights (less than about 250 miles), for saving gas, it doesn't really matter what altitude you choose.  The fuel you save with a higher TAS at altitude will be wasted climbing to get to altitude.  Probably less than a gallon difference no matter what altitude you pick.

Ride matters.  Pick a smooth altitude and enjoy the ride instead of bumping along.  In the summer, somewhere around 5 or 6 thousand AGL will usually do it.

Winds matter.  If you can find an altitude that is more favorable wind wise by even 5 knots, it's worth changing altitude.  I'm becoming a believer in windytv.com to help me with those decisions.

I'll leave it to MAPA and guys that own a C to tell you about power settings.

[Steve65E-NC]

Do you have a fuel flow indicator?  More important, do you have an all cylinder monitor?  If you have both, or especially if you have the monitor, suggest you go to GAMI and read about LOP.  For your aircraft you do not necessarily need to install GAMI injectors to make their techniques work.  Stay out of the RED BOX!  If you are always in a hurry, just ignore this suggestion.  I only use these techniques below about 70% power.

[Stetson20]

7 hours ago, gsxrpilot said:

First of all, cruise higher than 4000.  The higher you fly, the easier it is on your engine and your fuel bill. If I was ever going two or more hours anywhere, I'd cruise at 12,500 or 13,500. The C just sips the gas at about 60% power. WOT, 2450, 7gph, 150 knots. That engine will run forever at those low power settings.

Paul, just curious- do you have portable or onboard O2?

[gsxrpilot]

1 hour ago, Stetson20 said:

Paul, just curious- do you have portable or onboard O2?

I carried portable O2 in the C... (I need to list the bottle, and other stuff here for sale) Of course now in the 252 I have built in O2.

I never used O2 unless above 12,500.

[Hank]

9 hours ago, Steve65E-NC said:

Do you have a fuel flow indicator?  More important, do you have an all cylinder monitor?  If you have both, or especially if you have the monitor, suggest you go to GAMI and read about LOP.  For your aircraft you do not necessarily need to install GAMI injectors to make their techniques work.  Stay out of the RED BOX!  If you are always in a hurry, just ignore this suggestion.  I only use these techniques below about 70% power.

Don't worry about GAMIjecfors,  those are for fuel injected engines. Us folks with carburetors just gotta make the best of it.

Speaking of LOP . . .   It helps to reduce the throttle below WOT, as the cooked throttle body helps to create turbulence in the carburetor, leading to better fuel atomization. Sometimes adding a little carb heat helps, too.

I could never run smoothly LOP until I spent two annuals resurrecting my doghouse and rebuilding the carb heat flapper and box. Now I can run ~25°LOP pretty smoothly, but I dont cruise there because it's kind of slow and I don't (yet) have an engine monitor (but my recent magneto issues are making getting one more important!).

Most importantly, have fun and fly safe! And no more partial power climbs, full power puts more cooling air through the engine and gets you to altitude quicker. Watch your oil temp, and climb at higher airspeed if it gets too high for your comfort instead of reducing power.

[Hank]

Sorry, Diagonal Man. Sometimes I get a little verbose . . . . Especially when I care about the subject.

[rbridges]

I follow hanks advice with my c. Usually getting up in altitude keeps the manifold down low enough that it keeps me out of the red box. 

[Raptor05121]

Hank's advice is spot on

[MBDiagMan]

^{Some great stuff in this thread!  Thanks guys!}

Hank, I read nothing verbose at all.  (Headed to Germany next week so I need to start getting verbose into my German vernacular.)

 

[Hank]

4 hours ago, MBDiagMan said:

^{Some great stuff in this thread!  Thanks guys!}

Hank, I read nothing verbose at all.  (Headed to Germany next week so I need to start getting verbose into my German vernacular.)

 

I find "sprechen zie englisch?" to be beneficial . . . .    But I've spent 5 whole days in Germany, compared to 3 years in Japan. Can't help much with the language.

[MBDiagMan]

I lived in Germany two years as a young Army Radar Repairman ca., 1969 to 1971.  Then worked quite a lot in Western Europe in the early 2000's.  Germany is my favorite country over there, but we will be making a pretty wide tour from Belgium through Germany to Prague, Vienna, Switzerland, Italy and the South of France.   Looking forward to some good runs on the Autobahn among many other things.  

I have never been to Asia.  That is a very unusual thing to be said by someone who was in the Army ca. 1958 to 1971.

[jetdriven]

On 4/9/2017 at 3:54 AM, gsxrpilot said:

First of all, cruise higher than 4000.  The higher you fly, the easier it is on your engine and your fuel bill. If I was ever going two or more hours anywhere, I'd cruise at 12,500 or 13,500. The C just sips the gas at about 60% power. WOT, 2450, 7gph, 150 knots. That engine will run forever at those low power settings.

Range is pretty much independent of altitude. Winds affect it. But climbing higercto burn less fuel isn't such a sure bet 

[gsxrpilot]

Of course both of you are correct. But altitude has other benefits such as running the engine at much lower power, gliding range, less traffic, and often a smoother ride. But you certainly won't find me leaving a tail wind at 6000 for a headwind at 12000.

[rbridges]

31 minutes ago, gsxrpilot said:

Of course both of you are correct. But altitude has other benefits such as running the engine at much lower power, gliding range, less traffic, and often a smoother ride. But you certainly won't find me leaving a tail wind at 6000 for a headwind at 12000.

lower power setting is a big thing, but smoother ride is number one.  I'll generally fly higher and slower (stronger headwind) if the air is smoother.  

[MBDiagMan]

How does speed work out at higher altitudes.   I have been disappointed with the speed of my Cmodel so far.  I haven't worried about it yet because I am expecting better speed at higher altitudes where I can run higher power settings.  I see 150MPH air speed at 23/25 ar 4,000 feet or so.

[jetdriven]

1 hour ago, MBDiagMan said:

How does speed work out at higher altitudes.   I have been disappointed with the speed of my Cmodel so far.  I haven't worried about it yet because I am expecting better speed at higher altitudes where I can run higher power settings.  I see 150MPH air speed at 23/25 ar 4,000 feet or so.

speed is also rather unaffected by altitude, at least below about 8-10K feet.  You can run the same 75% of power at sea level, up to about 6500'.  pulling the throttle back in a carbureted plane is slightly less efficient than cruising at WOT, but its a small difference. But you can still do 145-150 KTAS on 10 GPH al all those altitudes from sea level to 6500'.  A inefficient climb profile such at Vy 25/25 will give away all the gains of cruising at high altitude, because you gave up so much fuel, time, and distance to climb to get to the altitude.

then % of power reduces with altitude. drag comes down too, but its a wash. At least, in a J model, 13K you better be cruising at 2600 RPM or even 2700, because the TAS ends up in the 145 KT range as well, a ten knot loss, but higher RPM gets most of that back. the NMPG (and trip burn) actually gets better at higher RPM.

[MyNameIsNobody]

Biggest benefit in going high is comfort.  Summer temps down low are awful.  Cooler up high means passenger and pilot happy.

[Hank]

2 hours ago, MBDiagMan said:

How does speed work out at higher altitudes.   I have been disappointed with the speed of my Cmodel so far.  I haven't worried about it yet because I am expecting better speed at higher altitudes where I can run higher power settings.  I see 150MPH air speed at 23/25 ar 4,000 feet or so.

I generally indicate around 145-150 mph at 3000 msl, 23/2300. But I only fly that low for short trips. The Performance Tables show 154 mph at 2200 lbs for 2500 msl, and 160 mph at 5000 msl for 23/2300.

In my manual from 1970, at 5000 msl, 23"/2500 is 78.5% power and should give 160-163 mph Full Rich depending on weight; at 2500 msl, you should be at 75.9% power and get 155-157 mph leaned out.

Remember, the accuracy of your ASI falls off 2% per 1000 feet, so 150 mphi at 4000 = 150 + 8% = 162 mph. You're there. Are you flying Full Rich?

[MBDiagMan]

Hank,

Thanks!  I had forgotten about the ASI altitude correction.  Having putt-putted around in a Cessna 140 over the years, speed is not something I have been calculating or concerned about.  In fact with a Cessna 140, when you are thinking speed you are thinking about getting in the air and waiting for the Earth to rotate underneath.

Anyway, I have not been running full rich, but have not been leaning while concentrating on EGT.  This is something I need to start working on.  I probably won't have any distance flights until after my vacation.  I will start working on leaning scientifically then.  I will begin using your recommended power settings next time I fly.  Thanks very much for spoon feeding me.  This is helping a lot. Your information will be easy to remember and apply.

Everyone,

Thanks to everyone for the excellent feedback here.  It has helped me wrap my head around the variables involved and how they interact.  You guys are great!