>On positioning my S1,2 & 3 foam blocks on the spar for an initial look-see.
The
>inboard solid block, although slightly warped on the spar face, appears about
>one quarter of an inch too high in comparison with the S2 block. The S1 and S2
>blocks seem to match with a reasonably straight leading edge. Has anyone else
>had the same sort of thing?
>Is it acceptable to sand the spar face a little to bring the leading edge into
>line with the S1 and S2 blocks.
>Also, where does one put the level on the leading edge blocks to check for the
>correct wash out; although not yet micro'd onto the spar my blocks seem to be
>about the same angle, give or take .2 of a degree - indeed, can one check for
>wash out this early in the wing build. I am measuring on the undersurface of
>the leading edge blocks using the spar as the lower datum.
The foam blocks are something of a variable quantity: 1/4 inch seems to be
somewhat excessive -you might want to ask for another one. On my wing, some
the blocks had to be packed in places and one or two of the ends sanded to
produce a straight wing (check the spar face/rib angle is 90 degrees...) I
glued foam strips 10mm wide where needed to the spar, and then sanded them
back so that the LE was absolutely straight. These then act as packing when
micro-ing them in position.
The spars are slightly wavy, however hard you try to set them up to true
up a mandrel exactly the same size as the spar pin, around 8" long, (I used
a piece of 4130 tube) and use that as the primary reference. This is matched
to lines marked on the ends of the inner 1" wide (flange forming) and outer
cores.
Carefully glue 3/4 channel or similar on the lines marked by the factory:
this provides a handy (and repeatable) place to put the level: with both
absolutely vertical -matching the mandrel- it will build in the correct
washout -it is visible when you look down the wing. The same applies to the
aft cores. When doing the flaps and ailerons, check the washout very
carefully (0.9 degrees for the flaps, 0.6 degrees for the ailerons) -all 4
of mine needed packing, and indeed, the factory are changing the proceedure
on these pieces to make sure that they built according to the plans: if you
just glue the jig blocks to a flat surface, they may be wrong.... This will
be announced (for those not on the 'net) in the next newsletter.
If haven't already got one, I suggest that you invest in a digital level:
for the sake of =A3150 or =A3200 -a very small part of the total cost- it will
repay you handsomely with a better flying aeroplane.
All the best,
Miles
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