Recommended Cruise Settings

[Cwalsh7997]

Hey guys some of you know I just bought my M20F, since I have to pay for the gas myself I want to optimize the range and endurance of the plane while still getting a good cruise speed out of it. I was wondering what your guys recommended settings would be for that??

[Bob - S50]

I've got a J, but supposedly the best speed uses "Carson's" (?) factor.  If I remember, that is about 1.3 times L/D max.  So about 1.3 times your best glide speed.  In the J that would be about 90 x 1.3 = 117 KIAS.  The higher you go, the higher the TAS will be for any given IAS.  So... for whatever altitude you pick, theorectically, pick a power setting that will give you the desired indicated airspeed.

 

Bob

[TTaylor]

There is optimum and there is practical.  Mooney's are designed to get there fast and efficiently.  Carson speed does not take engine and prop costs in to account.  Practical flying most find the sweet spot for an F (and J) is in the 8 to 9 gallons per hour range.  I fly mostly at 9 to 12K feet in the west and set my fuel flow at 8.6 gallons per hour and get an average ground speed of 139 knots with a mostly stock, three bladed, 1975 F.   I find this is my balance point for speed and efficiency. We didn't buy Mooney's to fly around like Piper's and Cessna's   .

[aaronk25]

If your GAMI spread is good (if it isn't call GAMI) 7.2gph at 2200-2300rpn, peak egt is best efficient cruise, 8.2gph 2,400rpm at 20lop is really good compromise or 9.2gph 2,400rpm at 20lop.

Don't run more than 20lop as the mileage falls off.

Pick a prop RPM that is smooth.

Higher is always better as long as trip length makes sense.

[yvesg]

My best settings is 23 squared when I want to go fast and keep the fuel flow reasonable (8.5 gallons per hour).

Yves

[Guest]

23 square, 16 GPH at 170-175 KTAS, economy cruise.

Clarence

[cujet]

Also, there is a great iPhone app called IO360. It contains all engine settings for power or economy at all possible altitudes, temperatures and RPM settings. 

 

I use it to confirm that I have it right. 

 

I'm not a fan of flying slow to save a few dollars of gas and waste a hundred dollars of my time. While accumulating unnecessary engine/prop hours. 

 

I do prefer to go as fast as practical, without running overly rich and wasting fuel. For me this means 7500 feet, 65% and 11 gallons per hour or higher w lower fuel flows. Such as 9500, 9.5/10GPH. 

 

In my case, I could save 3 gallons fuel on a 4 hour trip, by going slower. Adding nearly an hour to my trip and my engine. I don't see the sense in that. 

[ShermAv8tor]

Will the IO360 app give about the same ballpark for the O360? I flew my 65C for the first time yesterday and have a list of questions and this is one of them...Thanks

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[ArtVandelay]

Will the IO360 app give about the same ballpark for the O360? I flew my 65C for the first time yesterday and have a list of questions and this is one of them...Thanks

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It specifically states it does not, now how far off it is I don't know

Also, it doesn't match the POH tables for the J anyway

[Cwalsh7997]

Also, there is a great iPhone app called IO360. It contains all engine settings for power or economy at all possible altitudes, temperatures and RPM settings.

I use it to confirm that I have it right.

I'm not a fan of flying slow to save a few dollars of gas and waste a hundred dollars of my time. While accumulating unnecessary engine/prop hours.

I do prefer to go as fast as practical, without running overly rich and wasting fuel. For me this means 7500 feet, 65% and 11 gallons per hour or higher w lower fuel flows. Such as 9500, 9.5/10GPH.

In my case, I could save 3 gallons fuel on a 4 hour trip, by going slower. Adding nearly an hour to my trip and my engine. I don't see the sense in that.

That's kinda the whole point is for me to build hours since I'm 17 haha

[EDNR-Cruiser]

Well, I believe that tastes are varying greatly here... - I guess that most prefer a fast-efficient power setting which keeps the flight time short without sacrificing too much gas, some others are the "pedal to the metal" types but very few here are really trying to reduce their consumption to the minimum while flying... - but I go this route for sure...

I am a Newbie too, earned my wings in July 2011 and bought my M20F in March 2013. In Germany, where I live, 100LL is extremely expensive (not less than USD 10 per gallon) and I just love to be up there in the air... - I often fly just for fun, doing some airwork, enjoy the view, build hours and fly circles around my homebase. With such a profile there is little to win going fast, especially if you fly rather low for sightseeing and photos (2000 - 3000 AGL).
I usually cruise around 6 - 6,5 gallon/h, depending on altitude. My RPM is redlined between 2100 and 2350, so I usually fly 2000 RPM / 21" or 2400 RPM / 18" (always LOP) which is good for 115 - 120 kts TAS, that is PA28 Warrior top speed at C152 consumption...   
When I go somewhere, I fly much faster however... - usually 2400 RPM / 22", burning roughly 8.5 gal/h at 129 - 133 kts IAS, that is about 145 - 150 kts TAS in 6.500 AMSL.    

[bonal]

As we were flying home 2500/23 at 6500 my friend / CFI asked me why I pull out a couple inches of MP and I tried to explain the optimum pressure thing and he asked who the hell came up with that. I explained it was something I read but really did not know the answer. I think all the red box and other examples of proper power management have made me fly more conservative which is not a bad thing but I wonder if I'm really saving anything by reducing my power at that altitude and to be honest I have not seen much improvement in fuel consumption. And to defend my friends comment he has more flying experience than I can even begin to describe including hundreds of hours flying just about every Mooney type ever made. I asked him once if he had any idea how many hours he has flow and he said he really stopped keeping track after 10,000

[aaronk25]

He is right your not saving anything other than maybe some gas.

I ran my last set of cylinders really hard like 25-27" at peak egt or even slightly rich whatever have the best speed with littler fuel. Now with that I never got CHTs above 380. I spent a considerable amount of time improving baffles and ensuring cowl flaps were adjusted perfectly. After 1800 hours at overhaul due to failed cam; the cylinder barrels still met new specs, not service limits actually new limits!

Now operation under same conditions at 450chts and your asking for a head to barrel separation along with cracked cylinder heads.

Temperature weakens steel, that there is the main factor, in my opinion.

Oh and the detonation argument doesn't hold water when operated on 100ll. It's really good stuff.

[ArtVandelay]

Temperature weakens steel, that there is the main factor, in my opinion.

Not to mention aluminum, which the pistons are made of

[bonal]

My oil temp is 175 to 185 CHT runs between 360 to 370 in cruise of course this is from an old original gauge pack so who knows. I just make sure my numbers are consistent for my airplane not much more one can do with the tools I have. Sometimes reading all the posts about temp readings obtained from those real precise monitors may be giving you guys more grey hair than you need. I don't know if there is such a thing as too much information.

[Sabremech]

I typically fly my C at 2500/25 or whatever manifold pressure I can get at my cruise altitude, but almost never less than 2500 rpm. I want to get where I'm going and the little I save on gas isn't the reason I purchased a Mooney.

Just my thoughts.

David

[ArtVandelay]

I typically fly my C at 2500/25 or whatever manifold pressure I can get at my cruise altitude, but almost never less than 2500 rpm. I want to get where I'm going and the little I save on gas isn't the reason I purchased a Mooney.

Just my thoughts.

David

Take example of a 600nm trip, at 150k it's a 4 hour trip, at 140k, it takes 17 minutes longer, not really a huge difference.

[aaronk25]

Take example of a 600nm trip, at 150k it's a 4 hour trip, at 140k, it takes 17 minutes longer, not really a huge difference.

17 mins is along time if the wife's sister in back has to pee.....

[EDNR-Cruiser]

Sure, there is not much disadvantage flying our Mooneys fast!!! That is not what I am saying... - but sometimes it doesn't make sense to fly fast and in some areas of the world it is not even a great idea...
Sure, you can do a 600 miles trip an hour faster and burn almost the same amount of fuel on the trip as someone flying very slow but then if the aim is not to fly anywhere but log flight time, then this practice becomes VERY handy because you learn a lot of things, that you won't learn elsewhere... - managing fuel, managing energy, managing speed... - that is all good practice in managing an aircraft...

...and going fast in a Mooney is really NOT a challenge... - that's what our birds were made to!
Managing energy and speed - especially during descent and approach - are the challenges of flying a Mooney... - nothing spectacular, just some practice and discipline is all it takes to enjoy this wonderful aircraft...

[TTaylor]

Also, there is a great iPhone app called IO360. It contains all engine settings for power or economy at all possible altitudes, temperatures and RPM settings. 

 

I use it to confirm that I have it right. 

 

I'm not a fan of flying slow to save a few dollars of gas and waste a hundred dollars of my time. While accumulating unnecessary engine/prop hours. 

 

I do prefer to go as fast as practical, without running overly rich and wasting fuel. For me this means 7500 feet, 65% and 11 gallons per hour or higher w lower fuel flows. Such as 9500, 9.5/10GPH. 

 

In my case, I could save 3 gallons fuel on a 4 hour trip, by going slower. Adding nearly an hour to my trip and my engine. I don't see the sense in that. 

 

 

My "Back of the envelope" calculations show that with a Mooney 20F that you save 9 minutes on a 576 nautical mile flight and burn 6 gallons of fuel more by running at 10.5 gallons per hour and 144 knots versus 8.6 gallons per hour and 139 knots.  I will take the $3 extra engine cost to save the $30 of fuel. Real numbers are likley even closer because I did not run the climb and desend profiles for the estimate.

[carusoam]

Tp

[carusoam]

Dp

[carusoam]

So, if maximizing your time and minimizing the FF is the driving force...

Bone up on carson's speed, LOP and G bottle dimensions...

Carson will get you the furthest distance on the least amount of fuel...

LOP will get the most energy out of the fuel you burn...

Experiment with low power settings around approach speeds. This gets lowest fuel burned for hour of flight, while maintaining operation in a useful, safe flight regime...

Keep an eye on temps and fuel levels...

http://www.gatorade.com

Bernd,

How are fuel prices in your part of Europe doing lately?

Auto fuel in NJ is down near $2.00 per US gal...

Best regards,

-a-

[Hank]

Dig through your Performance Tables, see what will get you the longest duration. For my C, Max range is 20"/1900, but I don't like the control feel there. Your IO-360 will be different than my O-360, so hit the books. Carson's Speed is another possibility, then see how far LOP you can go.

Giving rides on Airport Day, I have to throttle way back to play nicely with the 172s also giving rides, so I set 2300 and pull the throttle back around 14-15" to hold Cessna speeds. It's not quite as bad as driving the Jaguar V12 in parades and keeping my foot on the brake because idle is too fast.

[Oscar Avalle]

Will the IO360 app give about the same ballpark for the O360? I flew my 65C for the first time yesterday and have a list of questions and this is one of them...Thanks

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In the POH there are some power tables. I also believe that there is a course book somewhere in this www side that gives you the power settings for the O360