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OK, bolting elevator horns together?

PostPosted: Sun Aug 21, 2011 6:51 pm
by xpflyr
Scott at Just told me to clamp the elevator to the horizontal stabs, the horns will not line up but thats the way it should be. Clamp them together where they are and drill them.
This just doesn't make sense. I must be missing something.
NO MENTION OF IT IN THE MANUAL!
No pictures of it being offset. I searched the forum and couldn't find any mention of this.
To me, if the horns were bolted together lined up, maybe that's how it should be to compensate for prop torque?
But then what if you installed a car engine that turns a different way.
Pictures attached. This is what gets to me! I just want to get it done right.

Re: OK, bolting elevator horns together?

PostPosted: Mon Aug 22, 2011 7:53 am
by jak
Don the way the welding goes after the part is removed from the jig is why there is a discrepancy in the tabs not lining up, its not a big deal the leading edges should be as in your picture and drill both holes (Clamp the tabs tight while drilling so they don't creep on you.) When you look across the trailing edge they should not be straight. (One should be higher than ther other I don't remember which.) This un evenness stops the flutter that a lot of small planes have. Jak

Re: OK, bolting elevator horns together?

PostPosted: Mon Aug 22, 2011 8:37 am
by xpflyr
jak wrote:Don the way the welding goes after the part is removed from the jig is why there is a discrepancy in the tabs not lining up, its not a big deal the leading edges should be as in your picture and drill both holes (Clamp the tabs tight while drilling so they don't creep on you.) When you look across the trailing edge they should not be straight. (One should be higher than ther other I don't remember which.) This un evenness stops the flutter that a lot of small planes have. Jak


OK, thanks Jak! :)
Still, I would think that sense it is not mentioned in the manual, most just lined up the horns and drilled the holes. Then that one elevator is a little higher than the other on their planes must not make a difference or maybe that's why many builders tell of a left heavy wing. Either way, why can't it be in the manual that states for us idiots that you must,

"Clamp the elevators to the horizontal stabilizer at leading edge, then drill out the other horn. "
"the horns will not line up exactly."

Would have saved me hrs of searching for the answer. :x

Re: OK, bolting elevator horns together?

PostPosted: Mon Aug 22, 2011 11:05 am
by GDS
When I drilled mine the hole came out ovalized, I thought poor drilling technique had introduced a twist. I re-drilled in a jig and I don't think there will be any offset on the trailing edge of my elevators.


Image

Image

You guys with flying AC, do you have an offset between trailing edges of your elevators? Is this a factor?

thanks, GDS

Re: OK, bolting elevator horns together?

PostPosted: Mon Aug 22, 2011 12:31 pm
by Johnny C!
Just to be clear, the leading edges of
the balances should be even with the
leading edges of the horzontal stabs,
when finished. The offset is a twist
built into the elev halves.

GDS. I like your drill fixtue. I am in the
process of re-drilling my through hole.
I ovaled my first attempt & Troy had that
side re-welded. I don't see why your
set up won't work. I was thinking of the
same concept clamping my elev halves,
by their hinge line & the balance leading
edges on a table, just to be able to get
at it better, but I haven't ran that past
Troy. I would really hate to have to get
it re-welded again.

XP, You have a good shot at getting it correct,
since your airframe is not covered. My covering
is finished & I have to align the leading edges, and
then try to clamp the horns together & then index
it up enough to drill through the inspection hole.
Not to fun, so far...

John

Re: OK, bolting elevator horns together?

PostPosted: Sun Sep 18, 2011 4:42 pm
by Dave Krall CFII SEL SES
How much should the left and right elevator planes vary from each other at their trailing edges to get the anti-flutter effect?

Re: OK, bolting elevator horns together?

PostPosted: Sun Sep 18, 2011 5:01 pm
by jak
Dont know that its ever been measured, and I have seen it vary from plane to plane. I'm sure sombody has a picture of it somewhere. Jak

Re: OK, bolting elevator horns together?

PostPosted: Mon Sep 19, 2011 12:55 pm
by Johnny C!
Ok. Here is what I did this
past Saturday to get this
finished up.

I added a liberal coating of Hysol
between the control arms on the
elev halves, and then clamped them
at the leading edges. I did not get to
drill the 3/8" through hole, as I was
still waiting for the epoxy to harden
up. I will drill it on the next trip
down. I feel confident that it will
not slip, on this second attempt.

Not the cleanest or slickest method,
but I feel I will get an acceptable
result.

Later!

John