Effect of airbrake blade height on glide slope

[Mike]

I've seen some airbrake blades that extend considerably over the top
of the wing and others that stop with their bottoms just flush with
the wing surface. I was wondering if any one out there has an idea of
at what point of airbrake blade height extention do they cease to have
effect on degrading glide slope.

__mike

[Bill Daniels]

"Mike" > wrote in message
om...
> I've seen some airbrake blades that extend considerably over the top
> of the wing and others that stop with their bottoms just flush with
> the wing surface. I was wondering if any one out there has an idea of
> at what point of airbrake blade height extention do they cease to have
> effect on degrading glide slope.
>
> __mike

I seems an airbrake blade gets progressively more effective as it rises
above the wing. The last few centimeters are much more effective than the
first part of the blade's rise.

I know this from many attempts to adjust the Tost wheel brake cable to gain
more braking on my Lark. The Larks' spoilers are on the same control as the
wheel brake, so a brake cable adjusted too short will cause the spoiler
handle reach its travel limit (Wheel brake fully applied.) before the
spoiler is fully deployed. This will result in significantly less spoiler
effectiveness than would be the case with the cable correctly adjusted.

(Eventually, I gave up on the wheel brake and adjusted the cable for full
spoiler travel and just didn't aim it at anything on the ground I wanted to
keep.)

Bill Daniels