Typical M20C speeds (TAS)

[rwabdu]

Yes, I’m basing that off the poh. Here is my performance at 5000. My Cis a 1968. The key number isn’t listed in my poh but makes a lot of sense. 

6 hours ago, Hank said:

Do you have Performance Tables inyour Owners Manual? I've attached mine for 5000 and 7500 msl. What year is your C? Mine is 1970.

The Key Number for our engines is 46; add your MP and RPM, keep the total 46 or less. For example, I often use 22" / 2400 at 4000-7000 msl, which is below 75% and very leanable.

 

 

[Hank]

@rwabdu, looks like 22"/2300, 22"/2400, amd 22"/2500 all all < 75%, so lean away.

[FlySafe]

Hi All short-body flyers. Here are some recent savvy flight data from a cohort of 77, M20(A-D) for comparison to your personal numbers. Don't laugh or judge me for my lower power/TAS choices.  Best wishes,

k

20230305 Trend Analysis Report N7763M.pdf

[Jcmtl]

On 6/5/2023 at 11:03 PM, rwabdu said:

Question for you all, sounds like some of you are leaning at mixture settings above 75% BHP? ie "Full throttle at 2500 rpm up to 9500 at most and a little over 10 gph"

I always thought settings above 23 x23 I had to keep the mixture in full on an o360 bellow 10,000 msl to stay below 75% bhp. Or, was that because my poh was written pre-engine monitoring technology? 

I lean based exclusively on CHT, which I try to keep in the 340 range (for no particular reason other than it sounds like a good number).  In the winter it means I can fly WOT, 2400 rpm and lean pretty much immediately after takeoff, and even then, the temps struggle to stay above 300.  

In the summer, I am also WOT - 2400 rpm and only start leaning once the CHTs start dropping which really depends on OAT.  

In other words yes, I lean at power settings above 75% without any issues (yet).

[Jim Peace]

my last flight brining it to annual, prob around 50-75 degrees rich of peak.  my FF is a bit higher than book...

my POH says that at 5000 feet I should be at 149 knots and burning 10.9 gallons per hour.

Also says there could be a 3% error.  So I am right in the ball park for a 59 year old plane.

 

 

[rc454]

Flying a box pattern to determine TAS assumes a steady, constant wind for the entire time, (when is the last time that happened?!).  Just plug in the numbers and correct the IAS to TAS. Close enough. And remember that variables like accuracy of IAS, atmospheric stability, (or lack thereof) Mixture setting, DA, GW and CG location also make a difference.   Based on over 1000 hours of flying my M20C I'm pretty confident that the TAS ranges from 130-150+, depending on all the above variables.  Most of the time I fly 7500-9500 at mid weight and that TAS comes in around 140 with the throttle all the way open and the prop at 2350, mixture leaned for economy, (on a standard day that produces 55-60% power).  The fastest I've seen is 153Kts TAS. The slowest - about 133Kts TAS.

This is with a nearly 2000 hour engine that still shows compression checks on all cylinders of 74 or higher.

[Paul Thomas]

On 8/10/2025 at 10:09 PM, rc454 said:

Flying a box pattern to determine TAS assumes a steady, constant wind for the entire time, (when is the last time that happened?!).  Just plug in the numbers and correct the IAS to TAS. Close enough. And remember that variables like accuracy of IAS, atmospheric stability, (or lack thereof) Mixture setting, DA, GW and CG location also make a difference.   Based on over 1000 hours of flying my M20C I'm pretty confident that the TAS ranges from 130-150+, depending on all the above variables.  Most of the time I fly 7500-9500 at mid weight and that TAS comes in around 140 with the throttle all the way open and the prop at 2350, mixture leaned for economy, (on a standard day that produces 55-60% power).  The fastest I've seen is 153Kts TAS. The slowest - about 133Kts TAS.

This is with a nearly 2000 hour engine that still shows compression checks on all cylinders of 74 or higher.

Flying the 3 NTPS pattern is to verify IAS/CAS error. Even though my IAS should be accurate, and all indications are that it is, I do intend to run the pattern and verify it.

[Hank]

2 hours ago, Paul Thomas said:

Flying the 3 NTPS pattern is to verify IAS/CAS error. Even though my IAS should be accurate, and all indications are that it is, I do intend to run the pattern and verify it.

I need to do that. So far I've only used the G430W to calculate TAS and windspeed & direction. My C runs 145-148 KTAS at and above 7500 msl. I'd be interested to see how our 3-way runs compare.