Take off trim positions

[Releew]

I've had the 92 model M20 J MSE for just about a year now and have flown it for ~120 hours.  After various loading configurations I still come back to the same place on the trim indicator for the best take off's transitions.  I have time in M20 C's and a few different J models (years) and have noticed the J models with three blade props feel exceptionally nose heavy as compared to the 2 blade C model.  I realize there's more to it than 2 vrs. 3 blade prop configurations.  I was trained to allow the plane to fly off the ground with minimal back-pressure, no more than about 5 pounds.  There should never be  a point in rotation in which you have to jerk or pull back hard on the yoke to initiate a positive rate of climb.  My trim indication depicts ~2/3's back to get the ideal (smooth) transition to climb.  The M20 C with the 2 blade prop has always been right on the neutral position for take off.

 

So, my question is.......  Are 3 blade M20 J's naturally nose heavy creating a condition requiring trim settings outside of the indicated neutral take off position? 

 

Thanks again for sharing knowledge!

 

Rick

[carusoam]

Are you using T/O flaps?

There is a noticeable difference if you don't.

Best regards,

-a-

[Releew]

Yes......

[dougmilam]

I have an 89J with a 3 blade McCauley prop.  My usual TO trim setting has the black marker splitting the upper TO setting line.

[Hank]

On my 3-blade C, most take offs have the bottom edge of the indicator at the top edge of the stripe (slightly nose up, no flaps).

When I'm heavy, flaps to Takeoff, line up trim indicator evenly with mark.

Both timed, just like my Owners Manual says, lift it off the runway then relax some of the back pressure. It's worked well for me the last seven years.

[N601RX]

It's also possible the trim indicators are not all adjusted the same. It's just a lawn mower throttle cable held in place by clamps.

[Seth]

When I have one or two people aboard in the front seats I set the trim a bit above the takeoff trim position - otherwise I'm set to wheel barrel (front nose wheel on the ground with the mains off the pavement).

If I have the second person in back, 3 or 4 aboard, or myself up front with a lot of cargo I set takeoff trim similar to what others noted: touching the top portion of the takeoff range.

-Seth

[ArtVandelay]

When I have one or two people aboard in the front seats I set the trim a bit above the takeoff trim position - otherwise I'm set to wheel barrel (front nose wheel on the ground with the mains off the pavement).

h

Umm, when don't you have at least 1 person aboard in the front seats?

[Jeff H.]

Umm, when don't you have at least 1 person aboard in the front seats?

 

Trim position doesn't matter - it flies off by itself.

[KSMooniac]

The TO Trim mark had to be selected for some setting, but I'm not sure which.  Likely gross weight with CG in the middle of the range if I had to guess.  The further forward the CG actually is, the more trim you'll need.  This is affected by loading in the seats/cargo, and aftermarket installed equipment that move the CG forward like a 3 blade metal prop.  My 3 blade MT composite prop installation moved the CG aft since it was 12 lbs lighter than the 2 blade McCauley.  If you fly only with the front seats filled and no baggage, you'll need to dial in extra nose-up trim.  Just figure out what works best for you and use it!

 

If you really want to double-check, then you need a shop with the rigging boards to check elevator travel and trim position.  The trim indicator is easily adjustable, but shouldn't move itself under normal circumstances.

 

I'll add that the aftermarket Rocket and Missile mods add a LOT of weight to the nose compared to the stock J and K, and require a deliberate pull to get them to rotate, followed by a slight relaxation to get the proper climb attitude.