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Effect of weight on the Polar



 
 
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  #1  
Old October 15th 09, 10:55 PM posted to rec.aviation.soaring
Pawnee Pilot[_2_]
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Default Effect of weight on the Polar

If I have 2 polars for the same glider, say at 28kg/m2 vs 43kg/m2,
the polar for the heavier glider is displaced to the right and down.
Applying the square root of the ratio of the wing loading, ie sqrt
(43/28), would give the higher speed for the increased loading, what
is displacing the polar down? Is it just the additional profile drag
at the higher speed?
  #2  
Old October 16th 09, 03:32 PM posted to rec.aviation.soaring
mattm[_2_]
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Posts: 167
Default Effect of weight on the Polar

On Oct 15, 5:55*pm, Pawnee Pilot wrote:
If I have 2 polars for *the same glider, say at 28kg/m2 vs 43kg/m2,
the polar for the heavier glider is displaced to the right and down.
Applying the square root of the ratio of the wing loading, ie sqrt
(43/28), would give the higher speed for the increased loading, what
is displacing the polar down? Is it just the additional profile drag
at the higher speed?


No, I believe it's the higher induced drag since you have to fly at a
higher angle of attack to generate more lift of offset the wing
loading.
To see exactly what it does to the polar multiply the x and y value
for each point by sqrt(w1/w0). At higher speeds the actual sink
rate should be less -- this is the advantage that ballast gives you.

-- Matt
 




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