Ruddervator Trim Tab...idea

[GordonTurner]

So, I have seen a picture of the trim tab as used on the Sonex, and have the idea of installing one on EACH ruddervator. For pitch, they are moved together, and perhaps for yaw trim they are moved opposite.

What do the smart people on here think? And perhaps someone could email me a scan or photo of the trim tab part of the Sonex plans since that part is not included on the Waiex plans.

[phenry]

I considered this on my Waiex project but rejected it. My thought was that I would have to design some sort of 'mixer' to provide proportional tab input. This soon became very complicated when compared with alternate proven methods.

[GordonTurner]

I was thinking of using servos. Two DPDT (?) toggles, (ON)OFF(ON), wired in parallel so that one moved both servos the same way (mounted vertically) and the other moved the servos in opposite directions (mounted horizontally). Just don't use them both at the same time...

[MichaelFarley56]

Hey Gordon,

What you suggest is certainly possible. If you look at V tail Bonanzas, they all have a small tab on each ruddervator.

I'd hate to do this to you, but I have to ask...why bother with it? The Dial-A-Trim system that Sonex sells does a good job for "elevator" trim on the Waiex, is pretty fool proof, is ultra reliable, is cheap, and is light in weight. I've always been very happy with it.

I certainly have nothing wrong with adjustable trim tabs, but as a former Cirrus instructor, I do like that setup. The trims for aileron and elevator on a Cirrus move the entire control surface a little (it basically re-centers the neutral position) which eliminates extra moveable tabs. Simple and works; the Waiex trim follows the same idea.

If you really like electric trim, perhaps you can add a trim servo for spring trim adjustment, and still use the Dial-A-Trim (spring tension) idea? That may solve any issue and still keep things simple.

Of course, this is just my opinion...good luck!!

[GordonTurner]

Simple? Did simple get us to the moon?

I like the idea of having some backup to the control in the event of a disconnect or freeze. Plus maybe a little bit of rudder trim would be nice.

Would it be nice?

I have one of those little ray something or other trim servos, pretty light. Probably about a wash on weight, especially if you wanted to dial-a-trim in two axis.

Gordon

[N111YX]

LOL. I think that Sonex's and NASA's philosophy on "simplicity" well, differ. The design philosophy of these aircraft IS simplicity. In my opinion, you are merely adding weight and things that could fail. If the Waiex rods get jammed, how will a servo overcome what arm strength cannot? Landing with toggle switches after a disconnect would be one for the books, too.

It would be a great conversation starter at OSH and Crossville but I'll side with Mike and continue to add a bit of right rudder for climb, neutral rudder for cruise, and a little left rudder for descent. My leg works every time (and is light). Then again, I fly long distances with no autopilot so I'm an odd type I suppose... :D

Best of luck with whatever you decide and it is indeed great to hear of new ideas... :)

Simple? Did simple get us to the moon?

I like the idea of having some backup to the control in the event of a disconnect or freeze. Plus maybe a little bit of rudder trim would be nice.

Would it be nice?

I have one of those little ray something or other trim servos, pretty light. Probably about a wash on weight, especially if you wanted to dial-a-trim in two axis.

Gordon

[MichaelFarley56]

Actually Gordon, if you'd like to be considered a hero among the Sonex community, please feel free to design a simple aileron trim system! Perhaps something similar to the Dial-a-trim setup but for the ailerons.

Most of us have found that there's a small need for trim when flying solo versus flying with a passenger. I'd love for someone to make up a simple, spring system for under the seat that could work as a trim system.

Good luck in whatever you decide sir!

[Bryan Cotton]

You could use model airplane servos - and mix them in the same ratio as the ruddervators. It would be sort of cool. I like the idea as a former FBW guy but on the other hand I like simplicity on the things I own. None of my cars have electric locks or windows.

[Bryan Cotton]

You could also use cables like the original RV4 design for elevator trim and build a mini trim mixer. That would be cool.

[GordonTurner]

Anybody have the part of the Sonex plans with the elevator trim tab construction and installation?