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Old September 10th 03, 02:33 AM
Kevin Horton
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On Tue, 09 Sep 2003 12:22:27 -0400, Todd Pattist wrote:

Kevin Horton wrote:

Imagine that you have two aircraft that weigh the same, one with a high
wing loading, and one with a low wing loading, flying the same speed
through the same up-drafts and down-drafts. The angle of attack changes
instantly as the aircraft penetrates into the up-drafts and down-drafts.
Both aircraft are going the same speed, so the amount that the angle of
attack changes is the same.
But, the aircraft that has a lower wing loading will experience more g
in the bumps,


because the bigger wing will
have a larger change in the amount of lift developed due to that change
in angle of attack.

This assumes a larger wing on one plane (and presumably about the same
weight for both aircraft). That's possible, but it's also possible that
we're talking about two identical aircraft (same size wing on both) and
one is just carrying more weight. In that case, the "change in amount
of lift" would be roughly the same for both since the coefficient of
lift changes roughly linearly with AOA.

You'd still get less g-load in the higher wing loaded aircraft simply
because the heavier aircraft accelerates more slowly when the same
amount of lift is applied.

Agreed. My explanation only covered one case, but the logic and result
(higher wing loading = lower g excursions in turbulence) are valid over a
wide range of scenarios. The premise falls apart a bit if the aircraft
with lower wing loading also has a very low aspect ratio (e.g. 60 deg
delta wing), as the lift curve slope is lower on the lower aspect ratio
wing. Lower lift curve slope = lower increase in lift for the same change
in angle of attack. While the effect of very low aspect ratio on ride
quality in turbulence is technically interesting, it probably isn't
relevant to many homebuilt aircraft.

Todd Pattist
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Kevin Horton RV-8 (finishing kit)
Ottawa, Canada