At 09:41 15 February 2011, Ronald Locke wrote:

'Andy[_10_ Wrote:
;762804']On Feb 14, 1:15*pm, Ronald Locke Ronald.Locke.
wrote:
-
Given a Blanik at, say 28 to 1 no brake deployed, would around 8 to 1
full brake and say around 15 to one half brake sound about right?

Thanks in advance.

Ronald Locke-

If they're terminal velocity brakes then 0:1 (straight down) is
possible without exceeding Vne. Form drag is highly speed-dependent so
speed affects the answer a lot. The size of the brakes also matters so
it is unlikely you will get a consistent number across multiple types.
You'd also need to define "half brake" - halfway out, half the
additional drag, half the difference in glide angle, one brake in and
one out?

Given all the variables I suspect it's possible to fly a Blanik to
achieve the glide angles you describe. The tricky calculation would be
to estimate the best L with dive brakes deployed. I'm trying to
figure out the circumstances under which someone would try to achieve
best L with the brakes out rather than just retracting the brakes.

9B

My query is simply related to the different approach angles on final
glide to the aiming point during final approach for landing. Obviously
different gliders will have different glide ratios for full brake and
half brake approaches. Hope this explanation clears up any
misunderstanding.




--
Ronald Locke


So do you want to teach gliding by numbers?? Using airbrakes on finals
involves a feedback loop - Aiming point going up the view? Close the
brakes a bit. Aiming point disappearing under the nose? open the brakes
some more. It isn't rocket science, nor can you define how open or
closed the brakes need to be at a specific point.