Air brake - speed brake is generally what we called it - has an effect
depending on how far it is above or below plus distance aft of the
center of gravity and the angle at which it meets the airstream. The
only aircraft I ever flew which had a pronounced reaction was the F86
Sabre - its speed brakes were mounted above the center of gravity and
had an axis of rotation canted forward. The plane would pitch up
noticeably on s/b extension, increasing with airspeed, and you learned
to deal with it. On occasion you might be flying the wing of a leader
(usually a desk pilot)who was shall we say out of practice and he'd
forget to signal (open and closing of hand much like a duck's bill
imitation followed shortly by nod of head for execution). he would
open his brakes and promptly have his wingmen struggling to get back
in formation - idle power, speed brakes, severe crossed controls to
generate drag.) Rather exciting in the weather, especially if he had
just dropped the nose to enter a jet penetration instrument letdown.
F102 had slight reaction (up), 104 even less, F4 about the same as
104. Air liners normaly have s/b (spoilers) on top of wing about on
the CG so any reaction is minimal. However, some, like the 727, say
'no speed brake use with flaps extended' since loss of lift because of
turbulence behind the s/b results in aero center shifting aft
resulting in a marked nose-down reaction and loss of altitude. Not
good on approach.
Walt BJ