Back to Tim's original question ---- it appears that the effectiveness of
the high parasite drag (HPD) approach varies depending on the glider. Even
if we don't have the absolute speed polar of a given glider with the
spoilers out, we should be able to figure out a relative measurement that
gives us some idea of a "good" HPD glider vs a "not so good" HPD glider.
It's been about 26 years since my last aero course, but I think I remember
that the term we care about here is wetted area; however you smarter people
please correct me as needed. The measure I propose would be:

Wetted area clean / wetted area with full spoilers, then multiply by the
wing loading. The bigger the number - the less effective the HPD maneuver
in that glider. Maybe we don't even need the wing loading - I'm not
certain, but it would seem reasonable to me that the HPD maneuver would be
progressively less effective with higher wing loadings.

Alright --- ready to be shot full of holes.

Lou McDonald
"LM"





"Tim Taylor" wrote in message
ps.com...
I am working though some calculations and need the sink rate as a
function of speed with the spoilers fully extended. Does anyone know
of such data for a glider? How do spoilers extended affect sink rate
as a function of speed?

Thanks,

Tim