Glider Weight/Wing Loading and determing speed for best L/D for a given weight

As a fairly new transitioned glider pilot I am interested in
information concerning wing loading and determining the speed to
achieve best L/D and effects on Minimum Sink

I think I have a basic understanding of the effects wing loading has on
the flight of the glider. The heavier the wing loading the move lift
needed to climb and the climb will be slower than a glider with light
wing loading. Once the altitude is gained the heavier glider will have
the higher speed between thermals as long as the correct speed for the
weight of the glider is flown.

I am also researching the used glider market for one day purchasing a
glider.

Which leads to what I am asking here. Is there an optimum wing loading
that is the best middle of the road for performance? And, which
gliders would exhibit them; LS3, LS4, ASW 19, DG300, Mosquito for
example?

What weight is used by the manufacturer to determine the wing loading
when it is published? All up max weight or some other arbitray value?
What weight is the glider flown at when the manfacturer is determining
the polar?

Once you have determined the weight of the glider How do you determined
the airspeed for best L/D and min sink?

Or, is this all non-issue?

Thanks
65E

Here start playing with the spreadsheet contained in this thread

http://www.gliderforum.com/thread-view.asp?threadid=32

Al

It's definitely not a non-issue, but requires a different perspective.

Assuming you are an experienced power pilot, you are used to going into
the airplane's performance charts and determining hard numbers to set
such things as cruise power, takeoff and landing distances, etc - all
based on actual loading of the plane. The bigger the plane, the more
critical (and precise) this becomes.

Gliders are different, for one big reason - you are trying to optimize
your performance (be it climb or cruise) in a constantly changing
environment. Every thermal will be of different strength, size,
turbulence. Every glide will be through a different airmass, with
different quantities (and gualities!) of lift and sink.

So it becomes less a matter of determining a hard number to set on the
airspeed indicator, and more a matter of always analyzing what point on
the polar (or performance range, if you will) you want to be at for the
immediate conditions, and for the goal of the flight (just floating
around the field or going for that 500k).

More specifically, wing loading is about going faster XC. As a rough
rule of thumb, a full load will bump all your reference speeds up about
10 knots.

You will find that you rarely fly at L/D max. If there is any lift at
all you will be cruising at least 10 - 20 knots faster.

And min sink when thermalling is the lowest speed you can comfortably
fly and climb at the wingloading and bank angle you decide on. And
this has to be pretty much determined by trial and error, although most
glider manuals have charts that are starting points.

Suggestion: Get a hold of Reichmann's "Cross Country Gliding" - the
first half is invaluable.

Good luck!

Kirk
66

65E wrote:

Which leads to what I am asking here. Is there an optimum wing loading
that is the best middle of the road for performance? And, which
gliders would exhibit them; LS3, LS4, ASW 19, DG300, Mosquito for
example?

Don't think about those other ships. You want a Mosquito. ;-)

Shawn