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-   -   Can someone explain wing loading? (http://www.aviationbanter.com/showthread.php?t=727)

Frederick Wilson September 7th 03 02:45 PM

Can someone explain wing loading?
 
Thanks Kevin.

Other than the stall info, wing loading is pretty much the same as blade
loading in helicopters. I guess that is why the Blackhawk is so stable in
the rear. The tailrotor produces something like 10% of the total lifting
force for a given gross weight. That is a lot of lift for those little
paddles back there. But they are spinning quiet fast.

Fred

"Kevin Horton" wrote in message
...
On Sun, 07 Sep 2003 02:59:51 +0000, Frederick Wilson wrote:

I was reading my EAA book and one of the articles spoke about wing
loading of the Glassair III. What is the significant of this? Does it
lessin the amount of turbulence you feel compared to an airplane of
equal size/weight with low wing loading?

Thanks,
Fred


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.

So, if everything else is the same, the aircraft with the higher wing
loading will have a smoother ride in turbulence. Now, if everything else
is the same, it will also have a higher stall speed, use up more runway
during take-off and landing, and be more likely to kill you if you have to
do a forced landing. Nothing in life is free.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/




Corrie September 8th 03 04:21 AM

Wing loading is the weight supported by each square foot of wing. Two
aircraft with the same weight and the same wing area must have the
same wing loading. A light airplane with a small wing can have the
same wing loading as a heavy airplane with a large wing.

Aircraft with low wing loading bounce around more in bumpy air. They
also have lower stall speeds, take-off speeds, and landing speeds.
Disregarding structure, an aircraft with lower wing loading can pull
more g's without stalling than an a/c with high wing loading. The
massive six-prop B-36 bomber of the 1950's had lower wing loading than
contemporary jet fighters, depending on how it was loaded. It could
could often out-turn them, especially at altitude. Very embarrassing
for the jet jockeys.


Corrie

"Frederick Wilson" wrote in message news:[email protected]
I was reading my EAA book and one of the articles spoke about wing loading
of the Glassair III. What is the significant of this? Does it lessin the
amount of turbulence you feel compared to an airplane of equal size/weight
with low wing loading?

Thanks,
Fred


Big John September 8th 03 04:52 PM

Corrie

----clip----

The massive six-prop B-36 bomber of the 1950's had lower wing loading
than contemporary jet fighters, depending on how it was loaded. It
could could often out-turn them, especially at altitude. Very
embarrassing for the jet jockeys.


How true. At altitude, I many times went into a high speed stall and
'fell out of the sky' while trying to turn with some ex 'fighter jock'
flying a B-36 :o(


Big John

Corrie September 8th 03 10:09 PM

Big John wrote in message . ..
Corrie

----clip----

The massive six-prop B-36 bomber of the 1950's had lower wing loading
than contemporary jet fighters, depending on how it was loaded. It
could could often out-turn them, especially at altitude. Very
embarrassing for the jet jockeys.


How true. At altitude, I many times went into a high speed stall and
'fell out of the sky' while trying to turn with some ex 'fighter jock'
flying a B-36 :o(


Big John


And adding insult to injury, not only were they tracking you with
several pair of 20mm cannon during your gyrations, when you finally
departed the area, the aircraft commander probably unstrapped and went
downstairs for a cup of coffee!

Kevin Horton September 10th 03 02:33 AM

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,


Right.

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
(Remove DONTSPAMME from address to email reply.) ___ Make a commitment
to learn something from every flight. Share what you learn.


--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/



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