M20F cruise performance & service ceiling

[Chris Briley]

I purchased a 1970 M20F last year and have really enjoyed flying it.   I’m wondering if anyone has cruise performance for the mid teens?   In my POH, I have climb performance to 16,000  but the cruise performance figures only go to 12,500.

I’ve run into an issue with flight planning in foreflight as it maxes out the altitude to 12,500 based on the POH.    

My understanding is that the 20F has a service ceiling of 16,900, so not sure why the POH stops at 12,500.

Any info would be great.  

Thanks,
Chris

[gsxrpilot]

Just go up there and work it out. 

These airplanes have been around for so long, and been through many modifications, upgrades, etc, I don't ever take the POH performance charts as the truth. 

With a good engine monitor and maybe a GPS, you'll be able to put together your own performance data based on real world experience in your own aircraft.

[Niko182]

1 hour ago, Chris Briley said:

I purchased a 1970 M20F last year and have really enjoyed flying it.   I’m wondering if anyone has cruise performance for the mid teens?   In my POH, I have climb performance to 16,000  but the cruise performance figures only go to 12,500.

I’ve run into an issue with flight planning in foreflight as it maxes out the altitude to 12,500 based on the POH.    

My understanding is that the 20F has a service ceiling of 16,900, so not sure why the POH stops at 12,500.

Any info would be great.  

Thanks,
Chris

The 20F has a service ceiling of 16,900, but people here have gotten them up to fl230.

[Hank]

25 minutes ago, Niko182 said:

The 20F has a service ceiling of 16,900, but people here have gotten them up to fl230.

No ceiling is published for my 1970 C. Are you sure you found one for your F, or is that just where the Climb Rate chart stopped? My chart goes to 18,000 msl on less power than you have. 

[Niko182]

10 minutes ago, Hank said:

No ceiling is published for my 1970 C. Are you sure you found one for your F, or is that just where the Climb Rate chart stopped? My chart goes to 18,000 msl on less power than you have. 

I just took the number @Chris Briley posted figuring thats what came out of his poh. I figure it seems low. I was just using that as a comparison to what others have made it to. I should have worded my post a bit better.

[carusoam]

Check the most recent version printed for your POH...

There should be a service ceiling in there...

Performance charts printed in the day barely covered most of the flight envelope... on good days...

A modern POH for the same plane would be about 3X as much detail...

Best regards,

-a-

[Hank]

12 minutes ago, carusoam said:

Check the most recent version printed for your POH...

There should be a service ceiling in there...

Performance charts printed in the day barely covered most of the flight envelope... on good days...

A modern POH for the same plane would be about 3X as much detail...

Best regards,

-a-

There are two (2) POHs in the Download section for 1977 M20-F aircraft.

My 1970 M20-C "POH" does not contain the word "ceiling", and all mentions of "Service" refer to MSCs, SBs and other services your Mooney may need, proper intervals for each service task, and service centers to do it for you. My 1977 version is not searchable (now I have work to do . . . .), but many of the charts and tables are the same.

Notice my Climb chart, at light weights still > 200 fpm. Is the definition of "service ceiling" where climb rate drops to 100 fpm or 200 fpm? I don't remember.

[carusoam]

This reliable(?) resource thinks the service ceiling for the M20C is 17,200’

https://www.globalair.com/aircraft-for-sale/Specifications?specid=56

 

Same resource, says M20F SC is 17,900

 

It is under ideal conditions, and may not be really valuable information for every day cruising...

I took my M20C up to 14.5k’ on a west to east flight just to say I did it...

Best regards,

-a-

[kortopates]

Service ceiling is Density Altitude where climb rate drops to 100FPM - not to be confused with absolute ceiling where climb rate drops to 0 FPM and your hanging off the prop or stalling. Service ceiling is based on takeoff at max gross weight, so course you can do a lot better if you get take off significantly below max gross. 

[kortopates]

Just now, carusoam said:

This reliable(?) resource thinks the service ceiling for the M20C is 17,200’

https://www.globalair.com/aircraft-for-sale/Specifications?specid=56

-a-

Except Hank's posted POH table contradict that by A Lot! in fact, Hank's POH post make it look like @Niko182 is right at about FL230 on a ISA or lower than ISA day.

[carusoam]

Now to go read my M20C POH....   

-a-

[Niko182]

3 minutes ago, kortopates said:

Except Hank's posted POH table contradict that by A Lot! in fact, Hank's POH post make it look like @Niko182 is right at about FL230 on a ISA or lower than ISA day.

 

[Hank]

5 minutes ago, carusoam said:

Now to go read my M20C POH....   

"Owners Manual," Anthony . . . . .

[flyer338]

I have taken a 1965 C Model to more than 17,500 and was able to trueOut at 140 knots TAS on about 6 gallons per hour hour. 

[carusoam]

No Hank... POH (1977).  

The OM went with the plane....

I was hoping it would be in a spec sheet... but I didn’t find it...

Got it...

-a-

 

 

Proof....   

[MikeOH]

1 hour ago, kortopates said:

...absolute ceiling where climb rate drops to 0 FPM and your hanging off the prop or stalling.

@kortopates

I probably need re-education but I did not think the plane was anywhere near stalling when at absolute ceiling ( 0 fpm ROC).

My reasoning has been that Vx and Vy converge at some number between their starting values at 0 feet DA.  That is, at an angle of attack near best L/D; not anywhere near stalling AOA.  Pulling back on the stick would increase angle of attack, resulting in more drag and a negative ROC; sinking, but not stalling.  Pushing the nose over would reduce AOA but a shallow dive would ensue.

[Niko182]

5 minutes ago, MikeOH said:

@kortopates

I probably need re-education but I did not think the plane was anywhere near stalling when at absolute ceiling ( 0 fpm ROC).

My reasoning has been that Vx and Vy converge at some number between their starting values at 0 feet DA.  That is, at an angle of attack near best L/D; not anywhere near stalling AOA.  Pulling back on the stick would increase angle of attack, resulting in more drag and a negative ROC; sinking, but not stalling.  Pushing the nose over would reduce AOA but a shallow dive would ensue.

If the plane isnt stalling, doesnt that mean it can continue to climb?

[carusoam]

Essentially the air is so thin...

The AOA to sustain flight... is very high...

At the point you have reached the absolute ceiling you have run out of available AOA...

a simple bump in the air is capable of exceeding the critical AOA...

or trying to climb another foot... again you exceed the AOA limit...

or a small amount of bank... now you have an accelerated stall to avoid... 

Each foot you climb, the %bhp of the engine decreases... requiring the PIC to increase the AOA the slightest amount to hold altitude...

Lots of balance required at the edge... between decreasing HP, and increasing AOA....

Expect to get a feel for what Vy or Vz is while up there...  efficiency is going to be important...  remember you are really low on usable hp up that high...

PP thoughts for discussion only, not a CFI...

Best regards,

-a-

[Mcstealth]

11 hours ago, carusoam said:

No Hank... POH (1977).  

The OM went with the plane....

I was hoping it would be in a spec sheet... but I didn’t find it...

Got it...

-a-

 

 

Proof....   

15 degrees of flaps? Into the flight levels?

[Nokomis449]

I find Globalair info is very... comical with their data.  check out what they say is the max landing weight for my G:

Operating Weights

• Max T/O Weight: 2525 Lb
• Max Landing Weight: 1585 Lb
• ...

[Chris Briley]

15 hours ago, Niko182 said:

I just took the number @Chris Briley posted figuring thats what came out of his poh. I figure it seems low. I was just using that as a comparison to what others have made it to. I should have worded my post a bit better.

I can't find a service ceiling in my POH.   I use Risingup.com for specs on planes, and they actually list the 20F service ceiling as 17,900.  FWIW....   https://www.risingup.com/planespecs/info/airplane481.shtml

[Hank]

13 hours ago, carusoam said:

No Hank... POH (1977).  

The OM went with the plane....

I was hoping it would be in a spec sheet... but I didn’t find it...

Got it...

-a-

 

 

Proof....   

For your R, sure. This is the 1977 C, followed by my 1970 Book:

Surprisingly, the contents are almost identical, except some things have been moved around the panel by 1977 . . . .

Edited January 21, 2021 by Hank

[TTaylor]

The POH is usually pretty optimistic.  With a fully loaded stock  75 20F I fly in the 12,500 to 13,500 range pretty often.  You can climb, but that means you have to give up speed to do it.  I often cross the Sierra and like to be at least 13,500 where I cross just south of Lake Tahoe.  I flight plan for 139 to 140 knots at about 9 gph in cruise at 9,500 to 13,500.  If I need to climb, I increase the RPM to 2650 and fuel flow to about 11 gph, otherwise the climb will be very slow fully loaded.  I have been to 17,500, but used wave on the east side of the Sierra to aid my climb rate and only had two on board that day.

[Hank]

Likewise, I took my C slowly to 15,000 msl one summer afternoon. Did the math later, found DA was 18,800. Handling was mushy. Don't recall other performance, it was simply me, CFI and an oxygen bottle.

[gsxrpilot]

I took my C to 16,500 once, but it was winter and very cold. So I'm sure the DA was lower.