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Wire swivel

PostPosted: Mon Feb 04, 2013 3:37 pm
by preacoupe
Hi guys,

Well, this is embarrassing. After what seems like 20 years building this thing, I'm still asking very basic questions. But, since this could be a life altering experience, I'm going to ask it anyway. Back at the trim tab, you connect the trim cable to the tab on the trim tab with a "swivel". I know where the wire goes through (and the set-screw), but on which side do you count the swivel? If you slide the swivel through the tab, the "nut" end will hold it on one side and the cable itself will hold it on the other. But if you mount it with the nut end on the same side as the cable, then on the opposite side of the tab will require a screw (explains the threads) but then to tighten the screw, the swivel then wouldn't swivel. If you somehow loosened the screw, then it could easily come out. Can you say flutter?

Haven't seen any pics on the forum about this, and any of the manuals haven't shown a closeup.

Dennis

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 12:36 am
by HS-JAT
Does this help any?

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 1:43 am
by preacoupe
Yes, it does. It makes sense that when the nut side is on one side with the cable on the other, it is free to swivel and not move in or out. The only thing that was confusing me with this arrangement was the threads going into the nut side. Probably just for easier manufacturing...drilled and tapped all the way through. Thank you.

Dennis

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 11:49 am
by danerazz
Or electric trim. I'm building my own system with a linear actuator instead of the ray Allen servo. It should be a little more positive than the factory wire. I have seen too many broken/bent trim cables.

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 12:31 pm
by kenryan
Is electric trim a factory option? If not, is it a common modification? Has the mechanical trim proven to be trouble free?

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 5:35 pm
by levyland
On the early Glasairs for pitch trim we installed a used Cessna 150 flap motor, and they worked like a champ, The MAC (or Ray Allen) servo's work well for roll trim attached to a an aileron, plus they have all of the bling bling as well.

Just a thought

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 5:59 pm
by stede52
I've used Allen servos for elevator trim in both of my Highlanders and they work flawlessly. You'll also never have flutter issues.

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 7:56 pm
by kenryan
Steve, is the electric trim a factory option or do we need to engineer it ourselves? What's the flutter you allude to?

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 8:11 pm
by stede52
Ken,
In the my manuals of a few years ago they talk about the option of installing an electric trim. I bought my own servo motor to make sure I had the slowest servo possible because the trim on the highlander is very sensitive and small movements go along way. I'm not sure if Just AC will provide the hardware (switches, indicators, wiring, etc.)needed because there are a number ways you can set them up. The manual trim provided with the kit will work just fine assuming you set it up correctly. Using the spring and keeping the distance from the end of the boden cable housing to the control horn as short as you can, however, long enough to get the needed throw is essential to eliminate any chance of flutter.

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 8:30 pm
by kenryan
Thanks Steve.

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 8:32 pm
by danerazz
The flutter can happen if there is any slop in the system. There are a few that have had a trim cable failure and the trim tab then flaps out of control until it lets go. If you install an electric trim actuator, you can eliminate nearly all of the slop, though if you go with ray Allen, it can be a couple hundred bucks to get an actuator, switches, indicator and relays if you want a switch in each stick.

I am using a different actuator and making my own indicator circuit and relay deck, so should only have about $120 total in it.

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 9:11 pm
by Gil T
Ken

An electric trim system is very easy to install and I believe a D2-10A system from Ray Allen is $279. There is absolutely no slop in the installation and it will eliminate the chance of screwing up the cable as I did. I put a kink in it when I installed it and it broke on take off and made my heart rate go through the roof. The plane was shaking something terrible until I slowed it down to about 50. I had about 200 hours on it when it let go and it will catch your attention.

As I said it is an easy install and my recommendation is to put the trim switch on the panel. In turbulence it's too easy to hit the wrong button on the stick and the way I have mine set up it's right next to the throttle and all I have to do is put my finger on it with my hand still on the throttle.

Gil T

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 9:18 pm
by kenryan
Thanks Gil. Seems like the way to go. How do you attach the servo to the fabric? Do you glue in an aluminum "picture frame and bolt to that? How did you make that little fairing?

Re: Wire swivel

PostPosted: Tue Feb 05, 2013 10:52 pm
by SheepdogRD
Here's a whole thread on the topic: http://www.wingsforum.com/viewtopic.php?f=218&t=21926.

Re: Wire swivel

PostPosted: Wed Feb 06, 2013 11:14 am
by kenryan
Thanks for the link to the previous thread--good info! Still more questions though:

1. It looks like there are tabs already welded to the stabilizer where the standard bell crank is mounted, and that the Ray Allen servo can be attached directly to those same tabs without alteration. Have I got that right?

2. Did you guys set the throw so that you had an equal distance of travel up and down?

3. What's the speculation on T3-12A's 1.2 inch throw being sufficent to trim the SuperStol wing?