Adding rudder trim

[Marc_B]

Seems like short and mid bodies don’t typically have it. Long bodies added rudder trim along with the addition of more HP.  Some in the middle had STEC yaw damper that doubled as rudder trim.

Is there a path to add rudder trim if you don’t have it? Or to change to typical rocker switch with standard Globe rudder trim motor if you had to replace the STEC YD with a GFC500 install?

[toto]

12 minutes ago, bluehighwayflyer said:

Not pretty, but it works …

Jim

http://aerotriminc.com/id2.html

Anyone have one of these?

[Marc_B]

3 minutes ago, bluehighwayflyer said:

Not pretty, but it works …

I've got the cult movie Harley Davidson and the Marlboro Man in my head now..."It's better to be dead and cool, than alive and uncool."  ha.  Not quite the svelte solution I was thinking in my head.  In my particular situation I already have a rudder trim indicator, just wondering what would be involved (if at all possible) in adding a switch and the Globe motor?  Does a STC exist? could you get field approval? certainly one could show that other more modern evolutions of the M20 have this function. 

Aftermarket options: Aero Trim and S-Tec YD...any others?

[Utah20Gflyer]

3 hours ago, toto said:

Anyone have one of these?

I have one of those systems installed as aileron trim but it's INOP at the moment so I can't comment on it's efficacy or utility. Personally I don't see a great need for it which is why I haven't dived into figuring out what's going on with it.  It's on the list but very low priority.

[carusoam]

11 hours ago, Marc_B said:

Seems like short and mid bodies don’t typically have it. Long bodies added rudder trim along with the addition of more HP.  Some in the middle had STEC yaw damper that doubled as rudder trim.

Is there a path to add rudder trim if you don’t have it? Or to change to typical rocker switch with standard Globe rudder trim motor if you had to replace the STEC YD with a GFC500 install?

Kind of looks like a Mooney rudder trim installation, but using a split switch….

I bet there may be a collection of parts Mooney used for all of the LBs….

That may apply…

Best regards,

-a-

[Pinecone]

Hmm, wondering if a rudder trim using something like springs or bungees internally would work.

[N201MKTurbo]

26 minutes ago, Pinecone said:

Hmm, wondering if a rudder trim using something like springs or bungees internally would work.

It probably would. Just have a mechanical engineer draw it up, Submit it to a DER and the FAA for their opinion. If the FAA inspector agrees that he will sign off on it, Have the DER do a full engineering evaluation and submit the drawing package along with the DER analysis to the FAA inspector for approval. After you get approval, then you can install it. This gives you a field approval AKA one time STC. If you wanted to get a real STC, you would need to get a PMA for all the parts and voilà! In the airplane business.

If Norm can do it in his garage, anybody can.

[Marc_B]

11 hours ago, carusoam said:

a collection of parts Mooney used for all of the LBs

Anyone have the IPC pages showing rudder trim parts and PN's for a long body?

[Marc_B]

This looks surprisingly similar to schematic for long bodies.

And it looks like the rudder trim assembly just connects by a bracket to the bellcranks.  I think this seems to be a pretty simple addition.  Any difference in control tube length would be accounted for by the cable assembly.  I'd have to do a little investigation regarding how the trim indicator works with this.  BUT, the fact that this hasn't been offered as an aftermarket upgrade seems to suggest that most short and mid body Mooney pilots don't feel a huge need for rudder trim??

[LANCECASPER]

I really don't think you'll notice a huge difference even when you jump through all of the hoops to get this approved. I had a 231 (210hp) and never felt the need for rudder trim. After that I owned a Bravo (long body with 270hp, 3 blade prop) and I only forgot to have rudder trim set once and never forgot again - a lot of p-factor on that set-up. Later I owned an Encore (220hp, 2 blade) with the S-Tec yaw damper and never felt the need for rudder trim. To do everything that's gong to be required you'll have thousands into it and I don't think it will be world-changing. It looks like a solution in search of a problem.

One more thing: When Mooney did the M20S (Eagle), it had 244hp and they did not include rudder trim. On the 280hp and 310hp STC's for the Eagle, in my opinion, the FAA should have required that rudder trim be added. If a pilot transitioning to a 310hp Eagle w/o rudder trim had a distraction on take-off (maybe seat slides back) that could be a handful. A few years ago there was an accident of this type in Kansas in a newly-purchased 310hp Eagle on take-off, which turned into a sad disaster. 

[Marc_B]

39 minutes ago, LANCECASPER said:

To do everything that's gong to be required you'll have thousands into it and I don't think it will be world-changing.

That's kinda what I'm figuring...hopefully flight test sometime next week to confirm!

[Cruiser]

The 310 hp STC and three blade prop for the Ovations increases the need for right rudder under full power take-off and extended climb conditions. While the airplane is fully controllable and quite capable WITHOUT rudder trim, the use of trim to take out the right rudder pressure needed on long climbs can reduce leg fatigue. 
I have no experience on a M20K but unless your leg tires now in T/O or climb conditions, the trim is not going to do anything. 

[jlunseth]

When I first got my 231 I thought I might need it, but not anymore. The plane does not need rudder trim at cruise at all, which is most of the time. The rudder is needed if at all on takeoff, the initial climb, and then turnout to your cruise course. There are constant changes during that period and they need to be made manually, or should I say pedally. During a long climb to altitude the plane can be a little out of trim but so little it would not be worth the cost of a rudder trim.

[toto]

My Piper has rudder trim, and I definitely look like a more coordinated pilot in that a/c. I trim for each phase of flight, it takes two seconds, and the plane basically stays coordinated. In the Mooney, I have times during every flight where my attention is on something else and the ball gets out of center (especially on a long initial climb to cruise altitude).

Neither plane needs rudder trim, and it’s worth zero dollars for me to add it. But since the factory put it on the Piper, I do use it, and I look less sloppy flying it

[tls pilot]

On 9/28/2022 at 6:02 PM, toto said:

Anyone have one of these?

The AeroTrim works extremely well

Had one on my J 201 back in 1980s for years. It was trouble free

Norm Smith was a wonderful person and loved Mooneys 

I was surprised to see that aerotrim was still in production as Norm passed away in 2008.

If you desire a rudder trim, get the aerotrim