Aileron centre of mass

In assessing the impact of adding 11g doublers to aileron ribs 2, an effort was made to determine the centre of mass of the aileron to get a feel for how sensitive the design would be to very slight mass distribution changes. The conclusion (stated elsewhere) is that the impact can be entirely disregarded given the many other variables that are uncontrolled. Here are the CofM observations.

Note that clecos were avoided. All ribs, etc not yet rivetted in place were held in location with tape and a few unpulled rivets.

The aileron balance tube is 382 grams, subject to a likely tolerance of +/-47 grams. Without the balance tube the CofM is 60mm aft of the hinge line, adding the tube moves it forward 45mm to be 15mm aft of the hinge line. TAF have confirmed that an exact balance is not required - owing to the limited never-exceed speed of the aircraft. This CofM is likely to mover several mm either way around this point, due to its own mass variation and other uncontrolled variables such as paint and primer mass. In particular a 11g doubler added to aileron rib 2 will have negligible effect on the CofM and actually in the "right" direction (forwards), as the CofM of the doubler itself is a few cm forward of the hinge line.

Calculation below:

Mass of aileron balance tube 382g

Wall thickness 1.5mm (0.059")

Outer diameter 25.5mm (~1.00")

Quoted wall thickness tolerance +/-0.007" deviation from mean

Expected mass deviation from mean +/- 0.007"/0.059" x 382g = +/- 45g