M20J Trim for take off

[Mckipper]

I had a moment in the  Mooney M20J, 2 up, 50Gl fuel evenly split between the 2 tanks, out of FALA with a 7000f DA.

I had TO flaps set, and the trim set to the TO marker. Just before rotation she seemed to get up on the nose wheel, despite me holding back pressure on the yoke, and after rotation the stick forces were very heavy. needless to say, I trimmed vigorously nose up.

I then did a number of landings and take offs (not touch and go's) and found the best feeling trim was about half way between the TO marker and full nose up.  I ran the trim back and forward and it seems to indicate correctly for full nose down and full nose up, and moves proportional in between.

The plane has just returned from the AMO after an undercarriage collapse and resulting prop strike, and I'm wondering if there is anything that could have happened during the maintenance work that would have either changed the CoG, or flap rigging as she always used to be fine in the indicated TO trim band.

The flaps look normal when retracted and fully extended, and seem to be extending evenly on both sides.

My question, do you normally use flap on TO (I notice a big nose down pitch change when deploying flaps) and do you use the TO mark on the trim tab, or do you have your own mark. I have noticed that that all moving tail needs constant trimming, and that she seems to be very sensitive to loading (ie, front only or front and back seats occupied makes a huge difference to the trim setting)

[Magnum]

I usually have the trim at the upper T/O range and still need a little back pressure. As soon as the flaps are retracted the back pressure goes away for the climb. Where do you have the trim on approach for landing with full flaps? During the flare my trim setting is almost completely nose up. If your setting (indication) is not correct you'd run out of trim during the flare and still have some back pressure on the yoke. Usually I fly alone or with 1 pax.

I attached the rigging procedure of the maintenance manual.

[Cruiser]

Good questions. Was the engine removed from the mount? Check around the nose of the cowl for alignment of the propeller to the cowling. Some engines droop on the mounts. How much and to what extent that changes trim I am not sure.

[rogerl]

Quote: Mckipper

...

My question, do you normally use flap on TO (I notice a big nose down pitch change when deploying flaps) and do you use the TO mark on the trim tab, or do you have your own mark. I have noticed that that all moving tail needs constant trimming, and that she seems to be very sensitive to loading (ie, front only or front and back seats occupied makes a huge difference to the trim setting)

[231Pilot]

I use the same TO setting as Magnus and Jim R.  Always works well for me.  I have gone 0

[Jeff_S]

I've been using the POH specs for T/O and that seems comfortable. To rogerl's point about the use of flaps keeping the nose down, though, it seems he's thinking of only one part of the equation. Yes, with trim set to the T/O mark, having flaps in will cause the nose-down pitch to keep things in equilibrium. But there's no law that says trim has to be set at T/O level. One of the J's I test flew with an instructor was done entirely without use of flaps for T/O or landing.  He just modified the way he used trim, and it seemed just fine to me.

In fact, this is one thing I've noticed in the J compared to my old Warrior.  Flaps have a much more noticeable nose-down pitching effect which causes much more need for trim.  I'm feeling the need to practice no-flap landings much more in case I ever have an electrical outage that would require such a thing.

[Mckipper]

Recently I tried a takeoff with 0 flaps and found that the angle of attack became too great after departing ground effect (so _that's_ why there's a stall horn ...). 

 

My problem was the opposite - with 15" flaps and Trimmed to the T/O mark I found myself in a nose down attitude at 3 foot AGL, and it took a serious effort not to leave a groove in the runway.

[Piloto]

Try take off with no flaps. On my M20J take off with no flaps is very smooth and solid. After rotation the plane assumes a climb pitch angle without the need of trimmng. With no flaps the nose wheel will raise before the mains with no pull on the yoke. This is desirable for uneven runways to avoid purpoising or prop strike.

José

[N201MKTurbo]

I haven’t used flaps for take off sense '84 ~5000 hours of Mooney flying. Except for very short or soft fields. My plane will take off virtually hands free with the trim set to the TO position.

[Jeev]

Quote: JimR

For what it is worth, my t/o and landing trim/flap procedure and observations are the same as Magnus'.   

Jim