[rebel-builders] elevator tips

[Ken]

Hi Garry

Could someone have previously torn the rivets out to remove the tip?

My aftermarket tips from Dave do not have the ST-40 riveted to the end
rib and they are quite firm.

Only mod that I'm aware of is Wayne's method of triangular skin doublers
from the spar to end rib and also the angle bracket on the inboard side
of the end rib to spar joint to prevent the end rib from rotating as the
tip weight flexes up and down. That flexing would certainly help pull
the 3 rivets out if you don't have that mod.

Ken

Garry wrote:

When I took my tips off this week I noted that the rivets fastening the
ST40 to the outer elevator rib have pulled out both sides of the plane.
This makes the tip attachment flimsy and entirely dependent on the
integrity of the fibreglass. To build this assembly would have required
fastening these three rivets prior to joining the two halves of the tip
and finishing it. Subsequent removal would be impossible without tearing
these rivets out of the end rib which is exactly what has happened at
some point.

I looked at the instructions for assembly and my tips are as prescribed
except for the torn out rivets. Is everyone flying with this
arrangement? Surely not. Is there a mod that has been widely accepted
that I am not aware of?

Garry
068R

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[Garry]

Thanks Ken.

Someone almost certainly ripped them out some time back though there is
no sign of a blade or anything marring the parts. The bracket the rivets
are set in simply is not strong enough to sustain the force needed to
peel these back. If one wanted to get the tip off to check/service the
bearing points, then these would have to be removed by force. On the
other hand, sufficient worrying via the ST40 might over time tear them
out but I would expect it to cause the angle bracket attached to the
ST40 to fail first.

Since the bracket attached to the ST40 is rather flimsy, I see it adding
next to nothing in terms of stiffness to the assembly.

I will add the stiffening bracket to the end rib assemblies prior to
re-installing. I will also add some additional rivets to the
fibreglass/aluminum in the tips. I have very little cracking so far in
the fibreglass near the hinge point so that is good. I will make sure it
stays that way even without the ST40 angle bracket feature.

I'm not sure what you are referring to when you talk about Wayne's
'triangular skin doublers'. Can you point me to a picture of this?

Garry

Ken wrote:

Hi Garry

Could someone have previously torn the rivets out to remove the tip?

My aftermarket tips from Dave do not have the ST-40 riveted to the end
rib and they are quite firm.

Only mod that I'm aware of is Wayne's method of triangular skin doublers
from the spar to end rib and also the angle bracket on the inboard side
of the end rib to spar joint to prevent the end rib from rotating as the
tip weight flexes up and down. That flexing would certainly help pull
the 3 rivets out if you don't have that mod.

Ken

Garry wrote:

When I took my tips off this week I noted that the rivets fastening the
ST40 to the outer elevator rib have pulled out both sides of the plane.
This makes the tip attachment flimsy and entirely dependent on the
integrity of the fibreglass. To build this assembly would have required
fastening these three rivets prior to joining the two halves of the tip
and finishing it. Subsequent removal would be impossible without tearing
these rivets out of the end rib which is exactly what has happened at
some point.

I looked at the instructions for assembly and my tips are as prescribed
except for the torn out rivets. Is everyone flying with this
arrangement? Surely not. Is there a mod that has been widely accepted
that I am not aware of?

Garry
068R

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[Ken]

I'm not sure what you are referring to when you talk about Wayne's
'triangular skin doublers'. Can you point me to a picture of this?

Garry

Can't find any pics.

Something like a 4" by 4" triangle doubler under the top and bottom
elevator skin at the outboard forward corners of the elevators.

Also an angle bracket on the forward edge of the outboard rib to the
elevator spar. That resists the tendency for the rib to rotate on the
original one rivet that fastened it to the spar.

Ken



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[Ron Shannon]

On Sat, Aug 9, 2008 at 6:35 AM, Ken <klehman@albedo.net> wrote:

I'm not sure what you are referring to when you talk about Wayne's
'triangular skin doublers'. Can you point me to a picture of this?

Garry

I found a photo (from somebody) of the rib-to-spar reinforcement where the
rivet pattern for the triangle gusset is also visible at the corner of the
bottom skin. Put it up at http://n254mr.com/node/384

Ron




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[Ron Shannon]

On Sat, Aug 9, 2008 at 10:16 AM, Ron Shannon <rshannon@cruzcom.com> wrote:

On Sat, Aug 9, 2008 at 6:35 AM, Ken <klehman@albedo.net> wrote:

I'm not sure what you are referring to when you talk about Wayne's
'triangular skin doublers'. Can you point me to a picture of this?

Garry

I found a photo (from somebody) of the rib-to-spar reinforcement where the
rivet pattern for the triangle gusset is also visible at the corner of the
bottom skin. Put it up at http://n254mr.com/node/384

Ron

Aha. Found where this came from. It's one of two pics on the Builders site,
Files, Rebel, 202-Elevator section. The other pic there actually shows the
(rounded) triangle better.

Ron




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[Garry]

Yep! I have that one and am installing it now. Thanks.

G

Ron Shannon wrote:

On Sat, Aug 9, 2008 at 10:16 AM, Ron Shannon <rshannon@cruzcom.com> wrote:

On Sat, Aug 9, 2008 at 6:35 AM, Ken <klehman@albedo.net> wrote:

I found a photo (from somebody) of the rib-to-spar reinforcement where the
rivet pattern for the triangle gusset is also visible at the corner of the
bottom skin. Put it up at http://n254mr.com/node/384

Ron

Aha. Found where this came from. It's one of two pics on the Builders site,
Files, Rebel, 202-Elevator section. The other pic there actually shows the
(rounded) triangle better.

Ron




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[Garry]

Thanks Mike. I'm doing much the same in rebuilding this stuff. It was
getting pretty shaky and I'm not sure it wasn't the cause of the
vibration. We shall see soon.

Garry

indabush@hay.net wrote:

When I built the elevator tips, I extended the tip "spar" to the edge of
the fibreglass, so that the machine screw goes through the fibreglass, the
end rib of the elevator, the elevator tip "spar" and into a blind nut.
Seems to be quite solid - aluminum to aluminum connection.

Mike, C-FNBO




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[Ron Shannon]

I haven't installed my tips yet, but they're not too far off. If either of
you folks have pictures, I hope you'll post them. Thanks.

Ron


On Sun, Aug 10, 2008 at 3:34 PM, Garry <wright.garry30@gmail.com> wrote:

Thanks Mike. I'm doing much the same in rebuilding this stuff. It was
getting pretty shaky and I'm not sure it wasn't the cause of the
vibration. We shall see soon.

Garry

indabush@hay.net wrote:

When I built the elevator tips, I extended the tip "spar" to the edge of
the fibreglass, so that the machine screw goes through the fibreglass,

the

end rib of the elevator, the elevator tip "spar" and into a blind nut.
Seems to be quite solid - aluminum to aluminum connection.

Mike, C-FNBO

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