The prime consideration is to make sure the torque tube has no (extra)
friction when you pull things straight - a canted over fin (or stab, for
that matter) won't be noticeable when flying.... only on the ground, if
you're unlucky.
For those not that far, I've always recommended making a proper jig that
holds the front and back of the tub properly. I keep reading about all sorts
of problems here, and know I didn't get them because I did...
(smugly)
Miles
> ----- Original Message -----
> From: Hans Jrgen Danielsen
> Hi all.
>
> As many of you have experienced aligning things can be timeconsuming and
frustrating! I have problems in adjusting the fin to a perfect vertical
position, after fitting top module. The mould is clecoed in placed (with
screws actually), but when fastening a plumb-bob string to the inside top
center of the fin leading edge, the weight indicates quite a few mm to the
right of center line in the lower mould.
>
> I think I know why. There is a built-in twist in the lower moulding which
went unnoticed when installing the Stabilizer torque tube and aft bulkhead.
The manual didn't warn about this possibility. So to recapitulate: The
torque tube was installed as per manual with horizontal alignment with the
forward part of the mould (straight edge between bolts in wing pin holes).
In other words the hole for the left bronze bushing had to be widened
slightly to obtain correct alignment before fastening the bushings - thus
building in the twist.
>
> The question is: What do I do? By grabbing the top of the fin and forceing
it to the left and cleco it in this position I'm still left with the weight
pointing 5-6 mm to the right of the centerline. I'm able to force it a bit
further to the side, but am reluctant to do so as not to introduce
unacceptable stress to the top moulding. Are there any others out there who
have experienced such annoying misalignment (who did not check twist and
corrected it before going ahead with torque tube installation)? Would a
slightly tilted fin be noticed at all - or affect flying to any degree??
>
> Hans.
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