M20C late model POH on PDF?

[Urs_Wildermuth]

A question if I may.

 

I heard that the later model M20C POH have a much improved perfomance section over the 1966 Manual I have. We are currently preparing a performance course for our pilots and I would really have liked to see what the later manual pages look like. I am well aware that the figures themselfs will probably not match the 1966 model, but I would really be interested to see what Mooney has done with the later manuals.

 

Has anyone here got a PDF version of the later year manuals, 1977 or 76, in particular the performance part they might be able to let me have a look at?

 

Many thanks.

 

Best regards

Urs

 

 

[Hank]

Urs--

 

There are several C-model POHs in the Download section. My 1970 is there, along with an undated one. I've heard good things about the 75? 77? version, but even mine has decent performance tables.

 

Maybe someone will upload the "good" one for us.

[DXB]

My '68C POH is sparse- what is really lacking are emergency procedures and short field/soft field procedures. And the takeoff/ landing performance charts are a bit rudimentary.  Also nothing on max crosswind component, but in '69 the rudder got longer, so I doubt any later data would apply.  

 

I did download the '74C POH (I think from this site?), and to my surprise it was not much better.  Maybe someone has a '77 or '78 POH to upload?   This is when the C model briefly extended into the "modern" era that started with the J.  I assume the POHs for the first Js were better?   If so, it may be worth the trouble to track down the same years for the C.

[Mooneymite]

My '68C POH is sparse- what is really lacking are emergency procedures and short field/soft field procedures. And the takeoff/ landing performance charts are a bit rudimentary.  Also nothing on max crosswind component, but in '69 the rudder got longer, so I doubt any later data would apply.  

 

I did download the '74C POH (I think from this site?), and to my surprise it was not much better.  Maybe someone has a '77 or '78 POH to upload?   This is when the C model briefly extended into the "modern" era that started with the J.  I assume the POHs for the first Js were better?   If so, it may be worth the trouble to track down the same years for the C.

 

Actually, I've been looking for a '74C POH.  This site doesn't have it (that I could find).  Can you tell me where you found it?  I can buy a paper replacement, but not for my serial number.

[Shadrach]

DXB,

 

There is no such thing as max crosswind component; there is only max demonstrated crosswind, which is a function of what the manufacture was able to document, not what the airplane is capable of.  I am not sure what the "full length" rudder did for the airframe. The more I think about it, the more I think it was to simplify manufacturing...less gaps to close and compound curves to match.  Maybe we have an aerodynamicist that can ring in?  I think that when the tail is at higher AOAs (slow speeds, a la approach and landing), the bottom part of the rudder is likely in a turbulent low pressure area. 

 

I agree that the early POHs leave a lot to be desired, though the lack of demonstrated Xwind component is not something that I am particularly concerned with. 

[Shadrach]

My '68C POH is sparse- what is really lacking are emergency procedures and short field/soft field procedures. And the takeoff/ landing performance charts are a bit rudimentary.  Also nothing on max crosswind component, but in '69 the rudder got longer, so I doubt any later data would apply.  

 

I did download the '74C POH (I think from this site?), and to my surprise it was not much better.  Maybe someone has a '77 or '78 POH to upload?   This is when the C model briefly extended into the "modern" era that started with the J.  I assume the POHs for the first Js were better?   If so, it may be worth the trouble to track down the same years for the C.

 

Many pilots would be terrified of a true Mooney short field procedure, and the factory probably did not want to encourage the operation.

 

1.1 Vso, (calculated by weight) full flaps with the wing unloaded in descent. no round out, just a very smooth and direct up elevator input as the plane enters ground effect.  If don't have full up elevator at touchdown, you've left performance on the table. 

 

I enjoy short field work when I feel really current.  I uploaded a spreadsheet that I put together for calculating threshold speeds.

[DXB]

Actually, I've been looking for a '74C POH.  This site doesn't have it (that I could find).  Can you tell me where you found it?  I can buy a paper replacement, but not for my serial number.

Not sure where I found the PDF online.  I just tried to upload here but it wouldn't let me-  file is too big (8mb).  PM me your email and I will send to you, and maybe someone more clever than me can tell me how to reduce the file size.

[ryoder]

Many pilots would be terrified of a true Mooney short field procedure, and the factory probably did not want to encourage the operation.

 

1.1 Vso, (calculated by weight) full flaps with the wing unloaded in descent. no round out, just a very smooth and direct up elevator input as the plane enters ground effect.  If don't have full up elevator at touchdown, you've left performance on the table. 

 

I enjoy short field work when I feel really current.  I uploaded a spreadsheet that I put together for calculating threshold speeds.

Wow. If I make the first turnoff I call that a short field

[Urs_Wildermuth]

I did look at the POH's available here, they don't have much better data than the one I do have.

 

If anyone has one of the very late POH's on the C Model, I'd be really grateful.

[Weston]

Does anyone have a PDF for a 66’ M20-C that they could share?  Many thanks in advance, Weston

Westondavisdvm@gmail.com

 

[Jpravi8tor]

I uploaded the 1974 M20C POH its in the download section @Urs_Wildermuth

 

[0TreeLemur]

Yes the early model manuals are pretty thin.  Following the sage advice of @carusoamI made a pdf of the 1977 C manual that I bought from someone else.  I keep the manual in the co-pilot's seat pocket .  PM me if you want the pdf. 

[Urs_Wildermuth]

Thanks a lot @Jpravi8tor

At first glance, there are a few improvements to the 65 edition, some of which really interesting indeed.

 

Currently I am trying to get to grips with a massive mistake: we installed a Hartzell 3 blade prop following a prop strike and non-availability of the 2 blade by Hartzell. There is no data anywhere, so actually we will have to test fly all the performance section.... big work which I hope I can do at some stage next year.

It's really funny how thin these old manuals are and how people have still operated those planes safely on grass and other surfaces, obviously just adding the popular factors and did just fine mostly.

I guess I will end up writing my own POH for my airplane in the end to get something which satisfies my planning requirements...

 

[carusoam]

Hey Urs!

See the response from OTree above… he has a pdf from the 1977 version….  

If you need to repeat the data collection… start with the most recent data available…

If you need… I can always copy a page or two from my copy of the 77 POH…

Best regards,

-a-

[Hank]

2 hours ago, Urs_Wildermuth said:

Currently I am trying to get to grips with a massive mistake: we installed a Hartzell 3 blade prop following a prop strike and non-availability of the 2 blade by Hartzell. There is no data anywhere, so actually we will have to test fly all the performance section....

I guess I will end up writing my own POH for my airplane in the end to get something which satisfies my planning requirements...

I bought my 1970 M20-C with a 3-blade Hartzell prop back in 2007. I have the guppy mouth closure and 201 windshield. I plan 145 knots. 

For operating and setting power, I use the charts in my Owners Manual. It's in the Download section here. I've read (and have an e-copy) of the 1977 Owners Manual, but haven't made a detailed comparison of the Performance Tables. There's also the Key Number, MP + RPM = 46. Both have worked well for me for the last decade and a half. 

Or you can spend weeks flight testing your own. I'd love to hear if there's much of a difference. Oh, the 3-blade will climb faster, but I've not noticed that it cruises any slower but it's been on the plane longer than I've owned it so I have nothing to compare against except my Manual.

Good luck, and let us know what you find. 

[Urs_Wildermuth]

16 hours ago, Hank said:

Or you can spend weeks flight testing your own. I'd love to hear if there's much of a difference. Oh, the 3-blade will climb faster, but I've not noticed that it cruises any slower but it's been on the plane longer than I've owned it so I have nothing to compare against except my Manual.

I am really hopefull that this will be the case with mine too. Thanks a bunch anyway for your experiences.

We will do some flight testing but I doubt we will need that much time, having some pretty neat equipment to do it with (TAS via Aspen, FF via Shadin, e.t.c.) . I am thinking of doing a series of runs with different power settings to cover 75/65/55% based on fuel flow and record TAS at various density altitudes and then compare that to the POH figures, which then should give a pretty good overview. Some of this can also be done enroute on normal flights.

 

[Urs_Wildermuth]

On 10/11/2022 at 8:18 PM, Jpravi8tor said:

I uploaded the 1974 M20C POH its in the download section

Thanks a lot again. I've had a bit of a browse and the results are interesting to say the least.

First of, the 74' edition has a performance table for sea level while the 65 edition only starts at 2500 ft.

However, what is really stunning is the fact that the very same engine yields rather different fuel flow for similar power settings and similar MP vs RPM!

The 1974 edition quotes 9.5 GPH for 75% power, 8.2 GPH for 65% and 7 GPH for 55% power.

The 1965 edition starts at 11 GPH for 75% power,  9.3 GPH for 65% and 8 GPH for 55% power.

That is a whopping 1 to 1.5 GPH difference. I wonder what the reason for this is? The engine is identical, the prop is identical so what happened there?

 

[carusoam]

Some changes were better methods of measuring things…

One significant change to be looking for…

The fuel jet in the carburetor may have been changed to a different size…

At the time… nobody had engine monitors or FF instrumentation… so there wasn’t a good way to know what the CHTs were actually doing.

 

Check your logs to see if you can find which fuel nozzle your carb has…

The larger sized fuel jet is better for keeping things cool… and FF is still controlled via the red knob…

 

Fuzzy old memories only, not a mechanic…

Best regards,

-a-

[jamesm]

hum  I feel cheated My '67C POH (1967 Mark 21 Owner's Manual) only has 46 pages

[Urs_Wildermuth]

15 hours ago, carusoam said:

At the time… nobody had engine monitors or FF instrumentation… so there wasn’t a good way to know what the CHTs were actually doing.

Well, in any case it is a really interesting discovery that the same engine at the same power can have such different fuel flows.

The carb model / nozzle type may be a good hint, will check it. But if you can reduce fuel flow by 1 GPH while getting the same power out of it, then I guess we all need new nozzles.

So the one bit I thought was kind of a fixed value to determine the % power set has just become a variable again...

[Shadrach]

20 hours ago, carusoam said:

Some changes were better methods of measuring things…

One significant change to be looking for…

The fuel jet in the carburetor may have been changed to a different size…

At the time… nobody had engine monitors or FF instrumentation… so there wasn’t a good way to know what the CHTs were actually doing.

 

Check your logs to see if you can find which fuel nozzle your carb has…

The larger sized fuel jet is better for keeping things cool… and FF is still controlled via the red knob…

 

Fuzzy old memories only, not a mechanic…

Best regards,

-a-

Joe pilot didn’t have access to engine monitors, but the factory test beds were well instrumented. Fuel nozzle size has an effect on full rich operations. However, it has no effect on leaned fuel consumption. Same model O360s at 23” of MP, turning 2500 rpm, should make the identical power at identical fuel flows. The error is in Mooney’s POH, not the laws of physics.

[Urs_Wildermuth]

1 hour ago, Shadrach said:

However, it has no effect on leaned fuel consumption. Same model O360s at 23” of MP, turning 2500 rpm, should make the identical power at identical fuel flows. The error is in Mooney’s POH, not the laws of physics.

Exactly. So the very interesting question will be, which one is right.

[carusoam]

Engine data in the old POHs started horribly and improved to just crummy over the years… 

And that is within in one POH…

Where data at different attitudes wasn’t consistent….

 

As the years went on… the inflight instrumentation got much better… the errors get found and fixed much quicker…

With the internet… we get to discuss this stuff directly with the factory….  

Best regards,

-a-

[Urs_Wildermuth]

Well, from my previous experience with the old prop I'd have said the '65 values were pretty good (fuel flow wise) but we will see what comes out when we testfly.

I am kind of wondering how to determine what % power I have standing with now 2 different fuel flow definitions between the 2 POH's. I guess MP will become the governing figure now.