M20C Weight and Balance

[bcconsult21]

When I figure W&B for more than 1 occupant in the back seat  I am Aft of the CG limit..... Has the log been miss handled or is this a common problem?   Please give any comments, as I am a new Mooney owner....  [1965 M20C]

 

Thanks - Brian

[Mooneymite]

Without knowing your specific aircraft and it's BOW/CG, it's impossible to comment.  I have a C model and have no such issues.  Would you care to post your '"vital statistics"?

Has the aircraft been modified, or is it more-or-less standard?

[bcconsult21]

I'll get those posted by Monday.  Thanks for replying... I don't think it has had any major upgrades...seems pretty standard as far as I've seen.

[Jerry 5TJ]

Quote: bcconsult21

I'll get those posted by Monday.  Thanks for replying... I don't think it has had any major upgrades...seems pretty standard as far as I've seen.

[takair]

It will depend how you distribute your weight (+ the basic numbers suggested above).  What are the weights of your 4 passengers and how much baggage.  My E-model, which has the battery in back, will typically run out of useful load before it goes out of CG.  With kids in back it is fine, but that is like having one adult.

[bcconsult21]

I have 2 adults up front - then 1x 170 back seat passenger is OK.  Add one more 170 pounder and the CG is AFT. Gross weight is not a factor.   I am not talking about 2 in back and one in front.   On other blogs it seemed people put 4 adults in and went no problems [with W&B]

[takair]

--

[takair]

I ran the following numbers for my E. 195, 190, 170, 170, 0 luggage and 30 gallons. It is just at gross, but well within CG. Somebody may have made an error in math along the way. Would be worth checking...it happens. It's hard to imagine that much equipment in the back.

[bcconsult21]

Item:                                                  Wt                                Arm                      Moment

Aircraft                                             1559.4                           44.41                   69239.4

Removed:      Narco Transponder             2.4                             19.0                       45.60

Added: II Morrow 618C                          4.96                             19.0                      94.24

            King 64 DME                              2.6                               19.0                      49.40

            Terra TDF 100 ADF...                  4.2                               21.0                      88.20

            Terra Transponder                    1.7                                19.0                       32.30

 

Totals:        Gross wt=2575                11.06?                            xxxxxx                      218.54?  [?= not sure where these values came from]

Empty Wt= 1570.46           New useful load= 1004.54

New acrft CG= 44.23          Moment= 69457.94

Note: 49"  is the aft limit [(all weights)    ..... and 42" is the fore limit up to 2100 lbs.]     Any thoughts? looks like done in 1990

[bcconsult21]

Here are my Garmin figures:

pilot & co-pilot 170 and 185  and 40.00 Arm

BUT Passengers arm = 118.9.....Does this sound like the right distance / value?

 

Bagage arm = 133.3

It figured this:   Moment = 135445                 Wt = 2465    and CG = 54.95          [too far aft]

[carusoam]

Brian,

Are you pulling these numbers from your POH?

Weights and station data usually don't change very much over time on one airplane.  The log books and POH are the places that the records are legally kept.

Make sure your Garmin has been updated with the proper data.

My C was difficult to load improperly without exceeding max gross wt.

200 X  2 in front

200 X 1 in back

60 in luggage

Max fuel based on allowable MTOW for the plane.

This is an example of three people headed to SNF a couple of years ago.  It's from my aged memory, make sure that you are using proper numbers.

Are you really getting over 1,000 # useful load?

That seems pretty high for an old plane with 180hp

Best regards,

-a-

[lamont337]

My POH lists the rear seat passenger arm as 70.7, baggage as 93, and hatrack at 114 so yeah, I can see how your numbers are coming up very far aft.  I have it in PDF form if you'd like me to email it to you.

[takair]

Lamont337 is correct.  Your rear passenger arm and luggage arms for the Garmin install are way off.  Also, keep in mind that the front seat arm changes with seat position.  I know you have had offers, but I too can send a spreadsheet tool including the CG graph if you send me a PM.

[m20b1961]

Following is a W&B calculator I made for my M20B.  It also displays the M20C limits.  Somthing to play with.

http://www.gnjpc.com/mark/flying/m20/wab/wandb.php

 

[bcconsult21]

To all you folk that sent info....Thank you all for your help.  I think the problem is an incorrect distance for the arm of the back seats....It is a good start to solving the mystery.    I will follow up with my mechanic,,,  Thanks again,  Brian

[captainglen]

  Use extreme caution in loading because the effects of opperation aft of Max aft C.G. limit are incidious and catastrophic. The bottom line is that the elevator will not be effective in the pitch down direction if a stall were to occur at low speed. This means that the only means left to break the stall would be a sharp increase in engine power which may be insufficient or take too long.

  I tend to keep as a rule no more than one adult and one child in the back but anytime there is more than just one adult in the back do a proper weight and balance. If you have to quibble over a few inches of arm as to where the exact center of the back seat or bagage compartment is to stay in envelope, don't! Your training and instincts in stall recovery are based on predictable stall performance and you could get away with being out of envelope for years. Get cut off in the pattern after having turned base leg and have to maneuver with low altitude, low speed or both and see what happens next.

[Hector]

I can put 400 pounds in the front, 340 in the rear seats, and 38 gallons and be at max weight, but CG not an issue (no baggage). You definitely have an issue with the arm lengths

[N201MKTurbo]

A Mooney friend of mine once made a long night cross country with the CG beyond aft limits. He says the plane was longitudinally unstable, it would not hold a trimmed airspeed. The pitch required constant attention but was not unmanageable. He said there were no problems with pitch authority, take off or landing. I told him not to do that again. He agreed.

[Bob_Belville]

Your front seats have 6 positions with arms from 36.5" to 44.0". (Each notch is 1.5") Be sure to use the forward positions in your calculations when you have rear seat passengers. 

[Bob_Belville]

Your front seats have 6 positions with arms from 36.5" to 44.0". (Each notch is 1.5") Be sure to use the forward positions in your calculations when you have rear seat passengers. 

I see some odd arm lengths in some of the replies above. The rear seats should be @ 70.7, baggage @ 93.0, hat rack @ 114.0 fuel @ 48.4. (I'm assuming C is the same as E which might not be so.)

[1964-M20E]

Sounds like you may have a question on the base empty weight and moment of your plane.  Find a mechanic who has a set of scales and have the plane weighed you will then know the exact empty weight and moment for your airplane. Then utilizing the information in the POH you can now figure out what your loading will do.

 

I've attached an Excell sheet that I use for W&B for an E model double check all numbers and calculations then use it as you desire.  I found this on line several years ago.

 

 

[1964-M20E]

Well i tried to attach it. no luck.

 

 

[1964-M20E]

OK how about this.

 

 

M20E wtbal rev 3.zip

[Bob_Belville]

Look in the files section of the home page for an excel spreadsheet for W&B for my '66E that I just uploaded. I think the administrator screens additions to this area so it might take a little while.

 

It is a very careful and detailed worksheet which anyone should be able to modify and adapt for their use.