The Murphy Builders Site

Hi Ron

I tapped the leading edge of two or three "crinkles" in but they were
only just barely touching. Didn't even notice them prior to flying. In
your case I wonder if new rudder brackets to move the rudder aft a bit
might be the answer. I did put a brass bushing in the bottom bracket.
If you didn't and a sixteenth of an inch is enough, perhaps you could
draw the holes aft that much and fit bushings into your existing brackets.

Ken

P.S. I just noticed a one page article in the Canadian RAA magazine
about the Ramble attributed to me. Someone had asked where we went and
I replied in point form. Darned if Gary didn't publish the e-mail.
Wish I'd known so I could of put it in context and made it more
readable and interesting. He must of got the accompanying photo from BobP.


Ron Shannon wrote:

After mounting the rudder, I found several of the stiffening "crinkles"
on both sides of the forward edge of the rudder skin hit the fin post,
significantly limiting rudder travel. At several crinkles, the
interference is substantial, including most of the crinkle's height off
the rudder tube. Has anyone else experienced this and/or how should it
be fixed?

Ron
254R

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Huh? What email?

Garry

Ken wrote:

Hi Ron

I tapped the leading edge of two or three "crinkles" in but they were
only just barely touching. Didn't even notice them prior to flying. In
your case I wonder if new rudder brackets to move the rudder aft a bit
might be the answer. I did put a brass bushing in the bottom bracket.
If you didn't and a sixteenth of an inch is enough, perhaps you could
draw the holes aft that much and fit bushings into your existing brackets.

Ken

P.S. I just noticed a one page article in the Canadian RAA magazine
about the Ramble attributed to me. Someone had asked where we went and
I replied in point form. Darned if Gary didn't publish the e-mail.
Wish I'd known so I could of put it in context and made it more
readable and interesting. He must of got the accompanying photo from BobP.


Ron Shannon wrote:

After mounting the rudder, I found several of the stiffening "crinkles"
on both sides of the forward edge of the rudder skin hit the fin post,
significantly limiting rudder travel. At several crinkles, the
interference is substantial, including most of the crinkle's height off
the rudder tube. Has anyone else experienced this and/or how should it
be fixed?

Ron
254R

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Maybe not yours. Ken spelled sender's name with just one "r". :-)

More on the crinkle crease resolution shortly.


Garry Wright wrote:

Huh? What email?

Garry

Ken wrote:

....

P.S. I just noticed a one page article in the Canadian RAA magazine
about the Ramble attributed to me. Someone had asked where we went and
I replied in point form. Darned if Gary didn't publish the e-mail.
Wish I'd known so I could of put it in context and made it more
readable and interesting. He must of got the accompanying photo from BobP.

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Thanks for your thoughts, Ken. Unfortunately, 1/16" gained from a new
bushing placement or tapping wouldn't do it. The crinkles (creases) hit
the post more than that.

I didn't build the rudder or fin post, though I did add the FUS-30
doubler, then used the original TS-3 with slight application of the
Irish C-clamp assembly method which didn't require much persuasion. It's
possible the fin post sides came together a tad during that assembly,
however, the current problem affects crease clearance along the whole
vertical dimension, both sides, though more on the right. As is, the
rudder hinge dimensions pull any rudder in pretty tight to the post.

I've resolved this where necessary by flat filing the forward "point" of
the crease, from the edge back about 1/4", but still within the vertical
flange portion of the skin. This created a "V" of thinner material in
the flange area which, without further attention, would be subject to
stress cracking. However, I then drilled a small stress relief hole at
the top (aft) end of the filed "V" and removed the thinned material
forward of the hole with small files. This leaves small notches at the
forward end of the creases which clear the fin post.

It's hardly noticeable. Besides, in a _hot_ Rebel there should be some
kind of gap seal there anyway. I'm thinking a specially formed smooth
flap of red RTV. :-)



Ken wrote:

Hi Ron

I tapped the leading edge of two or three "crinkles" in but they were
only just barely touching. Didn't even notice them prior to flying. In
your case I wonder if new rudder brackets to move the rudder aft a bit
might be the answer. I did put a brass bushing in the bottom bracket.
If you didn't and a sixteenth of an inch is enough, perhaps you could
draw the holes aft that much and fit bushings into your existing brackets.

Ken

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Retraction: I wouldn't recommend this technique after all. While
finishing up this morning, I managed to mess up one of these. A better
technique is to use a small diameter Dremel sander to remove (indent)
about 1/8" of the crease point, after which the crease point will tap
down nicely.


Ron Shannon wrote:
...

I've resolved this where necessary by flat filing the forward "point" of
the crease, from the edge back about 1/4", but still within the vertical
flange portion of the skin. This created a "V" of thinner material in
the flange area which, without further attention, would be subject to
stress cracking. However, I then drilled a small stress relief hole at
the top (aft) end of the filed "V" and removed the thinned material
forward of the hole with small files. This leaves small notches at the
forward end of the creases which clear the fin post.

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