Static and Dynamic Response of a Design of Differential ... - aerade

Effect of inaccurate pressure hole location
In the manufacture of these instruments, evenwhen the pressure
holes are Jig-bored, there will inevitably be small location errors,
which, if allowance is not made for them, can introduce errors into the
incidence and roll angle measurements. Providing the manufacturing
errors are knovm it is possible to correct the indicated quantities
accordingly.
There are two results of inaccurate location. The joins of each
pair of holes may not be mutually perpendicular, end their intersection,
hereafter referred to as the virtual centre, may not be on the yawmeter
axis. The angular errors are assumed to be less than half a degree, so
that the errors from the first source, being of second order, may be
neglected. The second introduces a small misalignment error, as a
$3
a roll angle, 6
E'
(not necessarily small) relative to a datum fixed in
instrument (fig.21). Denoting the angles between the yawmeter axis arCI
the radii through the separate holes by 8D,, Cl02 etc, then, to first
order, we have that the virtual centre is removed from the axis a distance
eoj12 + (e, - eo212 1 Rsr(oo,
-
- 2.
+ 2