Jabiru J450 Constructors Manual
Pre-Paint>Wings>Mount flaps
Tuesday, April 6, 2010
177 of 343
Check the slot size
At this point you have mounted the flap to the wing with the flap upper surface correctly
aligned in relation to the trailing edge of the wing. Now the slot size – the gap between the
trailing edge of the wing and the leading edge of the flap – must be checked.
The slot size is very important – when the flap is extended the airflow through the slot
provides control of the airflow velocity over the flap, and thus the slot or gap size must be
identical along the width of the flap or there could be a rolling moment when the flaps are
extended.
To check this, turn the wing
right side up and fit the flap,
taking care to fit the bush
before each bolt.
Deflect each flap to as close to
39.5° as you can and hold the
flap in that position at each end
with cloth tape.
Now measure the slot size at
each flap post as shown in the
drawing at right: the slot size
should be as shown, but the
critical measurement is that the
slot size should be the
same
across the full width of the flap
and the slot size should be the same for both wings at the same flap deflection.
If you have been careful in the initial flap alignment the slot size should fall within the
acceptable tolerance range, but if you need to make adjustments then they should only be
minor and these adjustments should be made with a long straight sanding block, starting by
slightly
altering the angled under-face of the trailing edge of the wing and
only if necessary
then altering the trailing edge of the wing itself.
Final adjustments will be made in the
Testing>Flight testing
task.
This completes the
Pre-Paint>Wings>Mount flaps
task.