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John Womer

Considering adding electric trim

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I am thinking about adding electric elevator trim to my 2010 J230. I have comparatively short arms and, even with longer trim levers installed, I still find myself wishing I could make adjustments with a switch on my control stick or panel.

 

The two possible approaches I have identified at this point are 1) a servo based trim system kit from Ray Allen Company and 2) using a electric linear actuator.

 

I would appreciate hearing from those who have made this modification.

 

Thanks!

 

 

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You will need to check that if you hold trim lever fixed in both extreme up and down that there is still full control movement and that you can overpower the springs. Now if you move control full deflection the trim lever will be overpowered and will move on the friction washers. Tom

 

 

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Actually I don't think fitting an electric trim this way is a good idea, it will change the control feel and may also limit control deflection.

 

Is it 19 registered?

 

 

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Actually I don't think fitting an electric trim this way is a good idea, it will change the control feel and may also limit control deflection.Is it 19 registered?

John is based in the USA by the looks of his Avatar.

 

 

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I have flown both the Jabiru LSA and SP500 with manual trim and the foxbat with electric. Hands down, electric trim is the worst, most finicky thing you have to deal with...

 

 

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Hello John,

 

I have been seriously considering adding electric trim to the J230 I am building.

 

I investigated adding the electric servo to the existing trim mechanism but it does not seem possible as others have mentioned due the trim being required to slip at elevator movement extremes.

 

I am considering (not ready to say planning) to cut a control surface out of the trailing edge of my elevator and connect the Ray Allen servo to it. I will probably omit the mechanical trim mechanism to save weight.

 

I assume the problem others have had with an electrical is the trim movement was too course. The Ray Allen system has a couple ways of dealing with that. The geometry of the throw can be changed, the smaller servo can be used, or a speed reduction unit can be added the the electrical system.

 

I purchased the Ray Allen servo several years ago for another airplane but never installed it. The elevator of that plane (Rans S-14) has a fabric covering and I could not come up with a mounting scheme the wouldn't require me to replace the fabric.

 

 

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I have flown both the Jabiru LSA and SP500 with manual trim and the foxbat with electric. Hands down, electric trim is the worst, most finicky thing you have to deal with...

Part of the Foxbat issue is the lousy grip and buttons, plus its a bit slow. The Sportstar I fly has the same grip and buttons, but trim is a bit too fast. Finicky just about sums it up. I've always reckoned that the overhead coffee grinder trim on early Cherokees worked well, but many disliked it.

 

 

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Thanks everybody for the feedback. I appreciate it.

 

My thought was to add an actuator to control the existing trim mechanism -- something that would move the existing lever. I forgot about the need for the system to slip on its friction washers at elevator movement extremes. A linear actuator like Dave Jacka ("On a Wing and a Chair") used in his plane would not allow the system to slip like that. And I would think that any servo motor based system that was set "loose" enough to slip like that, wouldn't be able to move the lever.

 

Not interested in adding anything like movable trim tabs... I seem to remember reading somewhere that some of Rod Stiff's early experimentation with control surfaces resulted in a decapitated horse!

 

 

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Guest Andys@coffs

Maybe my J230 is different to others (possible because its 19 registered....but was a factory assist build...so shouldn't really be different) I cant see any advantage in an electric trim by virtue that when in the cruise my trim is full forward and has no more to give... but I don't ever find myself wishing there was more movement...

 

I may well be agricultural in my application of trim but if I know Im going long distance its mid trim for takeoff and as soon as I get to circuit plus height I tend to adjust to full forward, drop the nose and let the speed build up and then use minor RPM adjustment (while always watching CHT's) to fine tune the altitude station keeping....

 

I cant help but think Electric trim is a solution in search of a problem, at least for the 2 seater, having the extra load in the back for the 4 seater may very well change things....but to my mind I would think that would result in even greater need for more forward movement of the trim lever, movement that in my aircraft isn't available....... Might just be a rigging issue in mine

 

Andy

 

 

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With manual trim you move the lever and the trim moves (unless something is horribly wrong) With electric trim you press a button and have to look at an indicator to check it's moving. Trim can be quite sensitive which favours manual. You feel the control force change as you move it, without having to look.

 

You have more connection with the feel of the plane with manual trim (and Flaps).

 

Larger aircraft need powered trim to alleviate the effort (which is considerable as you are often moving the entire horizontal stabiliser) and Speed of movement when you rate of change of airspeed is fast or a big power change with underslung engines or a flying boat with high thrustline.

 

Powered trim systems need over ride capacity too. Just more complication. Keep it simple.. Nev

 

 

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Andy

 

The <2008 J230s use full forward trim (& run out of forward trim with one up) above 120kts requiring slight forward pressure OR slow to <120. The later ones have the incidence of the stabilator changed and cruise mid range trim. At least in the ones I have had anything to do with. Mine (2008) does not require full forward or aft trim in any phase of flight.

 

A big job to change the incidence of the stabilator though.

 

I think the cruise speed is slightly higher then initially planned.

 

 

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Take a look at the post below. It appears someone has added a Ray Allen powered trim tab to their Jabiru.

 

Another benefit of electric trim is the opportunity to remove mechanical slop. My current airplane, a Rans S-14, has a mechanical trim with a push pull wire. Unfortunately, there is a fair amount of slop in the system which makes the trim very frustrating to use. Because of this, I want to make sure the J230 I am building has a smooth working trim system.

 

Hopefully Checkride's experiment works well.

 

http://www.avcom.co.za/phpBB3/viewtopic.php?f=59&t=137074&sid=a9f2a9c52bc455b12f95eaeb1fad94cf&start=465#p1610866

 

 

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