I just did this fibreglass tube work last week and I'm happy with the result.
I had one (unintentional) "trial run" as my first attempt decided that it really
like being wrapped around the torque tube and would not let go. It had to be
hacksawed into segments before I was able to get it off - at least I had some
pieces of the tube to test to destruction (strong!). The centre part of this
first attempt had also been a bit uneven which meant some parts were wider than
TP5/6. The 2nd & 3rd times around I made sure the tube was flat between, and
no wider than TP5 & 6. After roughing up & cleaning TP5&6 I then (lightly) put
masking tape along the outer edges over the to-be-bonded surface to protect
them from the grease that (as I found out from the "trial run") has to be
everywhere
- this allows one to be less timid with the greasing process. This tape
is then removed as the last stage before epoxying starts. Also as the whole tube
is now about 2mm in diameter wider than the original TP5&6 I improvised a
"drill" made out of a long part of the round foam core!
from the torque tube "lightning hole" with 40 grit sand paper wrapped (taped)
around it. This was then successively & SLOWLY bored through the hole each time
testing for a "firm, snug, but not forced" fit of the retention tube. If the
hole was still too narrow then I would increase my "drill bit" diameter a
fraction
each time with a bit of cardboard pushed under the sandpaper. The real trick
here is to keep the new widened hole centred on the original hole, i.e. make
sure you increase the radius equally (by about 1 mm) in ALL directions. I
used a series of marks and measurements to make sure I'd done just this. When
one comes to the outboard rib layouts (which I did Tuesday & Wednesday nights)
the torque is quietly standing in a corner out of harms way.
It was good to be able to look through the tube and see the surfaces of TP5 &
TP6
completely encased in epoxy, with no bubbles, my hacksawed grooves completely
filled in, and knowing (from my destruction test) that if they were aligned
today they would be aligned tomorrow.
Philip (Tri-gear #426)
PS:
While trying to get the first (errr, "trial") attempt off the torque tube I
suspended
the entire assembly from the roof, gripped the stubbon retention tube and
then tried to use my entire body weight (68 kg) to pull it off. The result?
The tube did not budge, the rope (I'd fed through the torque tube holes) broke
after about 3 attempts, causing me to fall about 10cm to the floor and punch
myself in the jaw (causing a nice bruise and cut) as my tensed up arm muscles
suddenly had nothing pulling them the other way! I can only assume that it's
par for the course and that most people end up punching themselves in the face
a couple of times while building their Europas!
-----Original Message-----
Subject: TP5&6 Retention Tube?
I remember some comments a while ago ( Nigel, Jim Graham, Steve Hagar, Chris
Beck
? ) about making a fiberglass tube to contain TP5&6 in the tailplanes. Since
I am now in the midst of tailplane construction, could someone please comment
on the success/failure/necessity of this approach?
Also, my perma-grit tools are starting to clog up. Is there a recommended
cleaning
method?
Thanks in advance.
John "blue foam everywhere" Kilian A046
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