Rudder skin riveting

The hole in rib5 for the strobe cable was placed off-centre in accordance with current TAF plans. The 9.5mm hole in the skin was placed at the 2nd-from top rivet hole position, but was supplemented with additional rivets each side.

Two of the front mounting holes in rib 5 as supplied were substantially elongated. All three holes were upsized to take 4.8mm rivets.

The shims previously manufactured for rib 1 and the lower gusset were employed to maximise skin flatness.

A rivet cut back to 5mm was used to avoid conflict with the notch previously made in the lower gusset.

The weight was reattached to rib 5 with 4.8x10mm rivets smeared with Duralac yellow.

There was some rudder skin fold error at the bottom end of about 0.5mm, while the fold at the top was precise. To prevent this from causing a twist of the skin, much effort was made to find an optimal cleco sequence. Some hole misalignment was accepted and spread around the skin, keeping this in the 0.1-0.2mm range at most. This was thought sufficiently small as to not require rivet upsizing. The elonagtion with a chucking reamer was done carefully so as to not elongate the skin hole, but rather the underlying rib or spar channel. This would ensure proper exploitation of the much greater capacity of the rivet tail to expand.

Cleaning out of holes tended to concentrate near the top and bottom of the rudder with no reaming needed at the centre region, as expected.

Despite much effort to prevent the rudder from acquiring a twist, laser levelling revealed about a 5mm residual twist top to bottom. This is thought to be acceptable.

All overlapping skins were fay sealed with Sikeflex Pro+ white (white for greater pot life, according to a VANS forum entry).

Oil canning was eliminated/prevented on all panels except for the top. A simple oil canning mode is present both sides at the top. This may be modified/eliminated when the fibreglass tip is finally mounted.

Some skin - spar rivets near the top hinge have been left out. This is to allow fitment of a aluminium channel which will ensure the strobe cable is confined in position as it passes by the top hinge, thus avoiding possible conflict in flight.