Elevator bushings

[Nefj40]

Not the hinge bushings. What goes in-between the elevator horns that the control cable eyelet wears on?

[3Dreaming]

Re: Elevator bushings

The cable doesn't go all the way to the elevator. There is a link that attaches to the elevator horns, a turnbuckle, then the cable. The link is .090 thick material. It is a 1/2 inch wide. Length as required, but normally around 2" long. There are 2 washers welded on each side.

[Nefj40]

Re: Elevator bushings

Thanks. Has that been reamed to size with a bushing in it then like the hinges?

The cable doesn't go all the way to the elevator. There is a link that attaches to the elevator horns, a turnbuckle, then the cable. The link is .090 thick material. It is a 1/2 inch wide. Length as required, but normally around 2" long. There are 2 washers welded on each side.

[3Dreaming]

Re: Elevator bushings

Nope, just a 1/4" hole with a 1/4" clevis bolt. Tighten it up as tight as you can, but still have it move freely. You need to make sure that the hinge line of the two elevators and stabilizers are straight, so there is no binding through the range of motion.

[Ragwing nut]

Re: Elevator bushings

I finger tighten them only with a castle nut and cotter pin

[3Dreaming]

Re: Elevator bushings

I finger tighten them only with a castle nut and cotter pin

I have seen hand tight be to tight. That is why I said as tight as you can, but still move freely.

[Nefj40]

Re: Elevator bushings

Even though I'm currently working on my brakes, I'm starting to think ahead to my tail feathers. Most of the trim system never got welded on to my fuselage, and I'm thinking really hard on going with a simple push-pull lever mounted to the front spar carry-through. There'll be a single cable running all the way back to a trim arm that's between the elevator horns, and I don't know what I can get away with back at that attachment. My fuse. and tail feathers have never been drilled. I want to get away from the slop inducing factory trim system.

[Guest]

Re: Elevator bushings

Dave,

I assume you are making an experimental a/c so in light of that I suggest that you look at an Aeronca-Champ-like system.

They are somewhat like what you describe and pretty simple but use 2 small cables and 4 small pulleys near the elevator hinge.

It stays at the same trim as you move the elevator, I suspect that what you described will not.

Anyhow give it a look you may get some ideas from it.

Dave R

[Hank Jarrett]

Re: Elevator bushings

The original post war trim works fine IF you rig it properly and keep the screw jack properly lubricated. Proper rigging means NO sloppy holes on linkages, NO worn out screw jack threads, NO slipping cables, NO loose hinge attaches on the tab and probably the one thing I have seen most is NO PLAY IN AND OUT ON THE SCREW JACK IN THE ELEVATOR!!!! If you leave the shim washers out on the screw jack you WILL have a HUGE play in the tab that makes everything else in the system insignificant.
If you have the pre war flipper tabs they work just fine as long as you only have 50 HP like they were designed for. Does ANYONE still fly with flippers and 50HP?
Changing the design of the trim system is a MAJOR design change and to be legal you would need to do a full flight test. I know people have made changes and skipped the testing, but it is NOT a good idea.

Hank

[Nefj40]

Re: Elevator bushings

Dave,

I assume you are making an experimentak a/c so in light of that I suggest that you look at an Aeronca-Champ-like system.

They are somewhat like what you describe and pretty simple but use 2 small cables and small pulleys.

It stays at the same trim as you move the elevator, I suspect that what you described will not.

Anyhow give it a look you may get some ideas from it.

Dave R

Actually, I've looked at that system already and that's kind of where I got my ideas from. If it works out my trim will stay the same regardless of elevator position.

Edit> The Bearhawk LSA also has a trim system some what like the Aeronca. I've got a guy locally that's building one. His trim does change, and drastically with elevator position and I definitely don't want that.

[3Dreaming]

Re: Elevator bushings

Actually, I've looked at that system already and that's kind of where I got my ideas from. If it works out my trim will stay the same regardless of elevator position.

Edit> The Bearhawk LSA also has a trim system some what like the Aeronca. I've got a guy locally that's building one. His trim does change, and drastically with elevator position and I definitely don't want that.

Does it change like a servo tab? It may be designed that way to lessen control forces.

[Guest]

Re: Elevator bushings

Aeronca used 4 pulleys (2 sets of 2) located near the elevator hinge line.

One set is on the elevator and one set is in the tail near the elevator belcrank.

They have cables running between them and those cables run parallel to the elevator hinge line.

I think that the closer the pulleys and cables are to the elevator hinge line then the smaller the amount of trim change (and trim cable tension) that results from elevator movement.

[Guest]

Re: Elevator bushings

Does it change like a servo tab? It may be designed that way to lessen control forces.

That would be very nice, fighting trim is a bummer.

[Nefj40]

Re: Elevator bushings

Does it change like a servo tab? It may be designed that way to lessen control forces.

I hadn't considered that, and it's most probably the case. I was thinking that a simple sleaved push-pull that's anchored to the elevator horn. I don't know how much I'll be using or needing a lot of trim on this airplane. On my 46 I only touch the trim in cruise for some fine tuning to stay level.

[Ragwing nut]

Re: Elevator bushings

Even though I'm currently working on my brakes, I'm starting to think ahead to my tail feathers. Most of the trim system never got welded on to my fuselage, and I'm thinking really hard on going with a simple push-pull lever mounted to the front spar carry-through. There'll be a single cable running all the way back to a trim arm that's between the elevator horns, and I don't know what I can get away with back at that attachment. My fuse. and tail feathers have never been drilled. I want to get away from the slop inducing factory trim system.

That is how the L-2 trim system is except the slide is on the left wall. I had planned a similar type system for my clip wing.