DG Differences...

On Apr 16, 5:50*pm, "noel.wade" wrote:
Thanks All,

On the flaps vs. no-flaps argument, I guess it would be best to use a
hypothetical situation:

Imagine you have cloudbases that are 3000' to 4000' AGL.
Terrain is somewhat mountainous, but the cloudbases rise with the
terrain (20 miles east of the airport you might have 7000' - 8000' MSL
bases over a 5000' MSL mountain).
The lift is maxing out between 4 knots and 6 knots, with a lot of 2 to
3 knotters mixed in.
The Cu are 4 - 6 miles apart.
Winds are 5 - 10 knots, with the best soaring areas downwind from your
home field (so you face a mild upwind glide home).
Your total "window" for soaring is a 5 hour period during the day when
conditions are going to be generating lift.
The lift is workable from 1000' AGL to cloudbase, but staying within
1500' of cloubase seems much more comfortable.

This is a pretty typical "decent" soaring day in Western Washington.

So the question for you flapped pilots is: *Would you be pushing your
speed up enough in this situation to actually be using your flaps?

...Assume you're trying to do good cross-country flying - not super-
agressive contest-like flying, but also not just puttering around
within 15 miles of the airport either.

Thanks!

--Noel

This is the typical soaring conditions at my home area. We always use
the flaps, no matter how strong or weak the soaring conditions are,
since you need to change from thermaling to cruising flap. In a flap
ship you must change flaps, otherwise your performance will probably
be worse then a standard ship. If you want to know how the glider
performance will impact your results, just look at the handicap
difference between the gliders you consider and can assume that your
speed and/or distance will roughly differ by this handicap, typically
in the 5% range.

Ramy