Trim for Take Off

[ZuluZulu]

3 hours ago, KB4 said:

If he gave you that flat advice “always on bottom” yes tell him he is wrong. Or you can tell the manufacturer they are wrong your choice.    @ZuluZulu Since this Trim setting doesn’t apply to your J.  yours must have different guidance on Trim Settings, show me!  I’m very interested to see that, would you please take a pic.  What’s different?  My bet no pic the trim setting guidance IS exactly the same as yours.  

That might have been something to ask before rushing to declare us wrong, but I'll get you a photo of my POH next time I'm in the plane.

[KB4]

1 hour ago, ZuluZulu said:

That might have been something to ask before rushing to declare us wrong, but I'll get you a photo of my POH next time I'm in the plane.

I think your beef is with manufacturer and the sources’ familiarity with CG.  Manufacturer sets Trim limits for TO for a reason.  They give a range for a reason. If it was same setting for every TO, regardless of CG there would have been a notch not a range.  Don’t waste your time sending photo, that was rhetorical. Trim Settings in a J even MSE should be adjusted according to CG.  
 

Not to say M drivers don’t find a sweet spot and use it, but how about MTOW, with big guys up front maybe something Manufacturer wants pilots to consider,

or after TO you go thru some wind shear that makes the nose pitch up violently without warning or pilot input as AS bleeds off from Vy 90 to 70 in half a second, trust me, you don’t want to be fighting against CG or controls then. There isn’t time. I consider myself pretty good shape, had trim set for proper CG, and still had to push really hard to get nose down. We follow manufacturer guidance and when unexpected or expected happens are in best position to have success and safe fleet. 

[Guest]

5 hours ago, Don.Tulsa said:

I have a short video that shows what we think is slack, would you mind viewing it and letting me know what you think?

You can post it here or pm it to me.

Clarence

[haymak3r]

I'd like to see that video if possible  Thanks.

[philip_g]

On 10/12/2021 at 1:53 PM, A64Pilot said:

it’s going to vary with CG, but with just people in front my trim is above the mark.

I disagree with holding the nose down after landing though, I hold mine off as long as possible for aerodynamic braking, and having more tail wheel than tricycle time not holding the yoke aft all of the time just feels wrong.

I’ll relax pressure I was holding up after landing, but never push.

In my opinion take off trim is correct when if left alone the aircraft will takeoff and climb at the correct angle all by itself 

It's really difficult to hold our nose off. Soon as the mains touch the nose catapults down. Our k didn't do this and our rocket k did. Seems odd for a j. I've not found that it improves or gets worse at differing soeeds. Maybe I'm just cursed 

 

I feel like the rocket was better at half flaps in that regard. The j doesn't seem to matter half or full. I haven't landed zero in a long time so I don't recall

Edited February 1, 2022 by philip_g

[PT20J]

2 hours ago, philip_g said:

It's really difficult to hold our nose off. Soon as the mains touch the nose catapults down. Our k didn't do this and our rocket k did. Seems odd for a j. I've not found that it improves or gets worse at differing soeeds. Maybe I'm just cursed 

 

I feel like the rocket was better at half flaps in that regard. The j doesn't seem to matter half or full. I haven't landed zero in a long time so I don't recall

That’s pretty standard. The landing gear geometry contributes to this. If you compare it to a lot of other single engine retracts, you’ll notice that the gear is farther aft than most others and the trailing link design moves the axels even farther aft of the CG. Just before the airplane touches down, the nose up moment is equal to the tail down force times the arm from the CG to the tail. At touchdown, the pivot point changes to the main gear axels which have a shorter arm to the tail, but the tail down force is the same, so unless you add up elevator to compensate the nose will pitch down. It’s difficult to add just the right amount of back pressure because the bungees pull against you. If you pull too hard it will balloon back into the air. If you don’t pull enough, it will bang the nose wheel. One thing that helps is to land with an attitude that is just high enough to clear the nose wheel by a few inches so it has less distance to descend.

Skip

[Hank]

7 hours ago, philip_g said:

The other thing I've seen people do is trim slightly too nose high so they have to push the nose down a little to maintain speed on final. I don't love it but it works for them.

 

Nope, nope, nope. No thank you.

[N201MKTurbo]

I’ve been landing Mooneys with full nose up trim for 38 years. It sure makes landing easier. I’ve never had a problem with it. But then I do T&Gs and take off with no flaps, so I don’t do anything right.

[ArtVandelay]

I’ve been landing Mooneys with full nose up trim for 38 years. It sure makes landing easier. I’ve never had a problem with it. But then I do T&Gs and take off with no flaps, so I don’t do anything right.

Do you have the fix for trim jamming problem?

[N201MKTurbo]

1 hour ago, ArtVandelay said:

Do you have the fix for trim jamming problem?

My J has never jammed. My old F would jam sometimes so I put a 0.010 SS shim washer at the end of the indicator screw and it stopped the jamming.

[N201MKTurbo]

1 hour ago, ArtVandelay said:

Do you have the fix for trim jamming problem?

It also helps if you don't push hard when you get to the end of travel.....

[ArtVandelay]

It also helps if you don't push hard when you get to the end of travel.....

Push hard? I have electric trim, I had it jam when I did full up so I can try landing hands off…won’t do that again.

[PT20J]

The BK pitch trim servo has a lot of torque and can jam the pitch trim at the stops on unmodified airplanes. Other trim servos may be as powerful -- I'm not sure. I am pretty sure that a GFC 500 servo doesn't have enough torque to jam. But really, this is a good safety mod to do to any affected airplane.

https://www.mooney.com/wp-content/uploads/2020/12/SIM20-88A.pdf

Skip

[N201MKTurbo]

2 hours ago, ArtVandelay said:

Push hard? I have electric trim, I had it jam when I did full up so I can try landing hands off…won’t do that again.

Don't use the electric trim.

[A64Pilot]

A problem with trimming full up to land is what happens on a go-around, many airplanes will pitch up exceedingly hard requiring excessive force to hold the nose down.

I assume a Mooney is no different.

[jaylw314]

2 minutes ago, A64Pilot said:

A problem with trimming full up to land is what happens on a go-around, many airplanes will pitch up exceedingly hard requiring excessive force to hold the nose down.

I assume a Mooney is no different.

It's not excessive if you're prepared.  It may be more than other planes, but it's manageable with one hand, still.  In a seat, pushing is easier than pulling.

[Bartman]

I’m with Rich and trim with both the manual wheel and at or near the end of travel on nearly every landing. The manual trim part is because the switch died again and I got use to using the trim wheel. The use of full up trim is my choice and I did it with the electric trim too. 

[Hank]

10 hours ago, N201MKTurbo said:

I’ve been landing Mooneys with full nose up trim for 38 years. It sure makes landing easier. I’ve never had a problem with it. But then I do T&Gs and take off with no flaps, so I don’t do anything right.

I do TnGs, routinely take off with no flaps, visit short grass fields, etc. But I seem to land with trim pretty close to the Takeoff mark.

[ArtVandelay]

The BK pitch trim servo has a lot of torque and can jam the pitch trim at then stops on unmodified airplanes. Other trim servos may be as powerful -- I'm not sure. I am pretty sure that a GFC 500 servo doesn't have enough torque to jam. But really, this is a good safety mod to do to any affected airplane.
https://www.mooney.com/wp-content/uploads/2020/12/SIM20-88A.pdf
Skip

It’s very expensive mod for my J, new trim screw required, something like $2500 for the parts.

[ArtVandelay]

I’m with Rich and trim with both the manual wheel and at or near the end of travel on nearly every landing. The manual trim part is because the switch died again and I got use to using the trim wheel. The use of full up trim is my choice and I did it with the electric trim too. 

My trim wheel is small and there’s significant friction probably because of the trim motor (unlike the 172), so adjustments are slow. It’s just easier to not trim to “hands off”.

[N201MKTurbo]

11 minutes ago, ArtVandelay said:

It’s very expensive mod for my J, new trim screw required, something like $2500 for the parts.

Is it really that much? it is mostly standard parts. The screw and nuts are the only machined parts.

[ArtVandelay]

Is it really that much? it is mostly standard parts. The screw and nuts are the only machined parts.

Yeah, it’s expensive, don’t remember exact price, call LASAR if you’re interested.
Seems odd the K and J trim screws are different and Ks don’t need it?

[carusoam]

+1 For monitoring the trim wheel while using the trim switch… one hand lets you know it is turning….

+1 fine adjustments using the trim wheel, because the switch gives an unknown amount when you really want just a touch…

+1 for NOT running the electric trim to the end of the travel…. It has no method of stopping without jamming the threads together….

 

Jammed full nose up trim can be pretty hazardous during a go around…. If you bump into the end, turn it back a small amount…

 

PP thoughts only,

-a-

[PT20J]

11 hours ago, carusoam said:

Jammed full nose up trim can be pretty hazardous during a go around…. If you bump into the end, turn it back a small amount…

That’s only a problem on the older models. Sometime in the early 1990’s, the factory changed to the stepped stop nuts which won’t jam. My 1994 J has them.

Skip

[LANCECASPER]

On 2/1/2022 at 4:10 PM, jaylw314 said:

It's not excessive if you're prepared.  It may be more than other planes, but it's manageable with one hand, still.  In a seat, pushing is easier than pulling.

I had a couple mid body Mooneys and it wasn’t excessive. On the long bodies that I’ve had (M, R, TN) it’s more of a handful on a go-around. That being said I still am quite a ways nose-up (but not all they way - about 50% between take-off and full up) and it seems to work best for consistent landings on long bodies.